Logistics for the implementation of lead-free solders on electronic assemblies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vianco, P.T.; Artaki, I.

1993-12-31

The prospects of legislative and regulatory action aimed at taxing, restricting or banning lead-bearing materials from manufactured products has prompted the electronics community to examine the implementation of lead-free solders to replace currently used lead-containing alloys in the manufacture of electronic devices and assemblies. The logistics for changing the well established ``tin-lead solder technology`` require not only the selection of new compositions but also the qualification of different surface finishes and manufacturing processes. The meniscometer/wetting balance technique was used to evaluate the wettability of several candidate lead-free solders as well as to establish windows on processing parameters so as tomore » facilitate prototype manufacturing. Electroplated and electroless 100Sn coatings, as well as organic preservatives, were also examined as potential alternative finishes for device leads and terminations as well as circuit board conductor surfaces to replace traditional tin-lead layers. Sandia National Laboratories and AT&T have implemented a program to qualify the manufacturing feasibility of surface mount prototype circuit boards using several commercial lead-free solders by infrared reflow technology.« less

Thermal cycling tests on surface-mount assemblies

NASA Astrophysics Data System (ADS)

Jennings, C. W.

1988-03-01

The capability of surface-mount (SM) solder joints to withstand various thermal cycle stresses was evaluated through electrical circuit resistance changes of a test pattern and by visual examination for cracks in the solder after exposure to thermal cycling. The joints connected different electrical components, primarily leadless-chip carriers (LCCs), and printed wiring-board (PWB) pads on different laminate substrates. Laminate compositions were epoxy-glass and polyimide-glass with and without copper/Invar/copper (CIC) inner layers, polyimide-quartz, epoxy-Kevlar, and polyimide-Kevlar. The most resistant joints were between small LCCs (24 and 48 pins) and polyimide-glass laminate with CIC inner layers. Processing in joint formation was found to be an important part of joint resistant. Thermal cycling was varied with respect to both time and temperature. A few resistors, capacitors, and inductors showed opens after 500 30-min cycles between -65 C and 125 C. Appreciable moisture contents were measured for laminate materials, especially those of polyimide-Kevlar after equilibration in 100 percent relative humidity at room temperature. If not removed or reduced, moisture can cause delamination in vapor-phase soldering.

Fatigue failure of pb-free electronic packages under random vibration loads

NASA Astrophysics Data System (ADS)

Saravanan, S.; Prabhu, S.; Muthukumar, R.; Gowtham Raj, S.; Arun Veerabagu, S.

2018-03-01

The electronic equipment are used in several fields like, automotive, aerospace, consumer goods where they are subjected to vibration loads leading to failure of solder joints used in these equipment. This paper presents a methodology to predict the fatigue life of Pb-free surface mounted BGA packages subjected to random vibrations. The dynamic characteristics of the PCB, such as the natural frequencies, mode shapes and damping ratios were determined. Spectrum analysis was used to determine the stress response of the critical solder joint and the cumulative fatigue damage accumulated by the solder joint for a specific duration was determined.

Intelligent laser soldering inspection and process control

NASA Technical Reports Server (NTRS)

Vanzetti, Riccardo

1987-01-01

Component assembly on printed circuitry keeps making giant strides toward denser packaging and smaller dimensions. From a single layer to multilayer, from through holes to surface mounted components and tape applied bonds, unrelenting progress results in new, difficult problems in assembling, soldering, inspecting and controlling the manufacturing process of the new electronics. Among the major problems are the variables introduced by human operators. The small dimensions and the tight assembly tolerances are now successfully met by machines which are faster and more precise than the human hand. The same is true for soldering. But visual inspection of the solder joints is now so severely limited by the ever shrinking area accessible to the human eye that the inspector's diagnosis cannot be trusted any longer. Solutions to correcting these problems are discussed.

Fixture facilitates soldering operations

NASA Technical Reports Server (NTRS)

White, C. M.

1968-01-01

Soldering fixture, designed for printed circuit cards, is a basic bench-mounted, self-contained integral unit combining all soldering needs into a compact, readily available work station. All tools, materials, and accessories are available to provide an ideal station to perform critical soldering.

Soldering Tested in Reduced Gravity

NASA Technical Reports Server (NTRS)

Struk, Peter M.; Pettegrew, Richard D.; Watson, J. Kevin; Down, Robert S.; Haylett, Daniel R.

2005-01-01

Whether used occasionally for contingency repair or routinely in nominal repair operations, soldering will become increasingly important to the success of future long-duration human space missions. As a result, it will be critical to have a thorough understanding of the service characteristics of solder joints produced in reduced-gravity environments. The National Center for Space Exploration Research (via the Research for Design program), the NASA Glenn Research Center, and the NASA Johnson Space Center are conducting an experimental program to explore the influence of reduced gravity environments on the soldering process. Solder joint characteristics that are being considered include solder fillet geometry, porosity, and microstructural features. Both through-hole (see the drawing and image on the preceding figure) and surface-mounted devices are being investigated. This effort (the low-gravity portion being conducted on NASA s KC-135 research aircraft) uses the soldering hardware currently available on the International Space Station. The experiment involves manual soldering by a contingent of test operators, including both highly skilled technicians and less skilled individuals to provide a skill mix that might be encountered in space mission crews. The experiment uses both flux-cored solder and solid-core solder with an externally applied flux. Other experimental parameters include the type of flux, gravitational level (nominally zero,

Utilization of Pb-free solders in MEMS packaging

NASA Astrophysics Data System (ADS)

Selvaduray, Guna S.

2003-01-01

Soldering of components within a package plays an important role in providing electrical interconnection, mechanical integrity and thermal dissipation. MEMS packages present challenges that are more complex than microelectronic packages because they are far more sensitive to shock and vibration and also require precision alignment. Soldering is used at two major levels within a MEMS package: at the die attach level and at the component attach level. Emerging environmental regulations worldwide, notably in Europe and Japan, have targeted the elimination of Pb usage in electronic assemblies, due to the inherent toxicity of Pb. This has provided the driving force for development and deployment of Pb-free solder alloys. A relatively large number of Pb-free solder alloys have been proposed by various researchers and companies. Some of these alloys have also been patented. After several years of research, the solder alloy system that has emerged is based on Sn as a major component. The electronics industry has identified different compositions for different specific uses, such as wave soldering, surface mount reflow, etc. The factors that affect choice of an appropriate Pb-free solder can be divided into two major categories, those related to manufacturing, and those related to long term reliability and performance.

Effect of Strain Rate on Joint Strength and Failure Mode of Lead-Free Solder Joints

NASA Astrophysics Data System (ADS)

Lin, Jian; Lei, Yongping; Fu, Hanguang; Guo, Fu

2018-03-01

In surface mount technology, the Sn-3.0Ag-0.5Cu solder joint has a shorter impact lifetime than a traditional lead-tin solder joint. In order to improve the impact property of SnAgCu lead-free solder joints and identify the effect of silver content on tensile strength and impact property, impact experiments were conducted at various strain rates on three selected SnAgCu based solder joints. It was found that joint failure mainly occurred in the solder material with large plastic deformation under low strain rate, while joint failure occurred at the brittle intermetallic compound layer without any plastic deformation at a high strain rate. Joint strength increased with the silver content in SnAgCu alloys in static tensile tests, while the impact property of the solder joint decreased with increasing silver content. When the strain rate was low, plastic deformation occurred with failure and the tensile strength of the Sn-3.0Ag-0.5Cu solder joint was higher than that of Sn-0.3Ag-0.7Cu; when the strain rate was high, joint failure mainly occurred at the brittle interface layer and the Sn-0.3Ag-0.7Cu solder joint had a better impact resistance with a thinner intermetallic compound layer.

Experimental Methods in Reduced-gravity Soldering Research

NASA Technical Reports Server (NTRS)

Pettegrew, Richard D.; Struk, Peter M.; Watson, John K.; Haylett, Daniel R.

2002-01-01

The National Center for Microgravity Research, NASA Glenn Research Center, and NASA Johnson Space Center are conducting an experimental program to explore the influence of reduced gravity environments on the soldering process. An improved understanding of the effects of the acceleration environment is important to application of soldering during current and future human space missions. Solder joint characteristics that are being considered include solder fillet geometry, porosity, and microstructural features. Both through-hole and surface mounted devices are being investigated. This paper focuses on the experimental methodology employed in this project and the results of macroscopic sample examination. The specific soldering process, sample configurations, materials, and equipment were selected to be consistent with those currently on-orbit. Other apparatus was incorporated to meet requirements imposed by operation onboard NASA's KC-135 research aircraft and instrumentation was provided to monitor both the atmospheric and acceleration environments. The contingent of test operators was selected to include both highly skilled technicians and less skilled individuals to provide a population cross-section that would be representative of the skill mix that might be encountered in space mission crews.

Effects of High-Temperature Treatment on the Reaction Between Sn-3%Ag-0.5%Cu Solder and Sputtered Ni-V Film on Ferrite Substrate

NASA Astrophysics Data System (ADS)

Shen, Xiaohu; Jin, Hao; Dong, Shurong; Wong, Hei; Zhou, Jian; Guo, Zhaodi; Wang, Demiao

2012-11-01

We have demonstrated a novel sputtering method for lead-free thin metal films on ferrite substrates for surface-mount inductor applications. In a surface-mounting process, the cladding of enameled wire needs to be burnt off at high temperature, which requires the devices to withstand a high-temperature reliability test at 420°C for 10 s. There are no reports that a sputtered film of thickness less than 6 μm can withstand this test. In this work, we used Ag/Ni-7 wt.%V double metal layers for the metallization. The dissolution of Ni-7 wt.%V in Sn-3%Ag-0.5%Cu lead-free solder at various temperatures was studied in detail. Scanning electron microscopy with energy-dispersive x-ray spectroscopy was used to investigate the interfacial reaction between the sputtered films and the solder. The intermetallic compounds are mainly (Cu,Ni)6Sn5 at 250°C; however, (Ni,Cu)3Sn4 becomes the predominant composition at 420°C. In addition, although outdiffusion of V atoms from the Ni-V layer was observed, its effect on the intermetallic compound (IMC) was insignificant. We further confirmed that the proposed metallization is able to pass the aforementioned high-temperature reliability test.

Three-Dimensional Waveguide Arrays for Coupling Between Fiber-Optic Connectors and Surface-Mounted Optoelectronic Devices

NASA Astrophysics Data System (ADS)

Hiramatsu, Seiki; Kinoshita, Masao

2005-09-01

This paper describes the fabrication of novel surface-mountable waveguide connectors and presents test results for them. To ensure more highly integrated and low-cost fabrication, we propose new three-dimensional (3-D) waveguide arrays that feature two-dimensionally integrated optical inputs/outputs and optical path redirection. A wafer-level stack and lamination process was used to fabricate the waveguide arrays. Vertical-cavity surface-emitting lasers (VCSELs) and photodiodes were directly mounted on the arrays and combined with mechanical transferable ferrule using active alignment. With the help of a flip-chip bonder, the waveguide connectors were mounted on a printed circuit board by solder bumps. Using mechanical transferable connectors, which can easily plug into the waveguide connectors, we obtained multi-gigabits-per-second transmission performance.

Cleaning of printed circuit assemblies with surface-mounted components

NASA Astrophysics Data System (ADS)

Arzigian, J. S.

The need for ever-increasing miniaturization of airborne instrumentation through the use of surface mounted components closely placed on printed circuit boards highlights problems with traditional board cleaning methods. The reliability of assemblies which have been cleaned with vapor degreasing and spray cleaning can be seriously compromised by residual contaminants leading to solder joint failure, board corrosion, and even electrical failure of the mounted parts. In addition, recent government actions to eliminate fully halogenated chlorofluorocarbons (CFC) and chlorinated hydrocarbons from the industrial environment require the development of new cleaning materials and techniques. This paper discusses alternative cleaning materials and techniques and results that can be expected with them. Particular emphasis is placed on problems related to surface-mounted parts. These new techniques may lead to improved circuit reliability and, at the same time, be less expensive and less environmentally hazardous than the traditional systems.

Tinning/Trimming Robot System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fureigh, M.L.

In a new surface mount assembly area at AlliedSignal Inc., Kansas City Division (KCD), a tinning/trimming robot system tins and trims the gold-plated leads of surface mount technology (SMT) transistors. The KCD-designed system uses a Unimation PUMA 260 robot, a General Production Devices SP-2000 solder pot; water-soluble Blackstone No. 2508 flux; and a Virtual Industries high-temperature, ESD-conductive, miniature suction cup. After the manual cleaning operation, the processed SMT transistors go to the QUADSTAR Automated Component Placement System for a Radar Logic Assembly. The benefits are reductions in the cost of nonconformance, worker fatigue, and standard hours.

Hot-air soldering technique prevents overheating of electrical components

NASA Technical Reports Server (NTRS)

1964-01-01

By using a hot-air gun with a small orifice, heat may be localized to the soldering area of the chassis. The solder is placed around the capacitor which is inserted in the mounting hole so the ring is in contact with the chassis.

Flexible hybrid circuit fully inkjet-printed: Surface mount devices assembled by silver nanoparticles-based inkjet ink

NASA Astrophysics Data System (ADS)

Arrese, J.; Vescio, G.; Xuriguera, E.; Medina-Rodriguez, B.; Cornet, A.; Cirera, A.

2017-03-01

Nowadays, inkjet-printed devices such as transistors are still unstable in air and have poor performances. Moreover, the present electronics applications require a high degree of reliability and quality of their properties. In order to accomplish these application requirements, hybrid electronics is fulfilled by combining the advantages of the printing technologies with the surface-mount technology. In this work, silver nanoparticle-based inkjet ink (AgNP ink) is used as a novel approach to connect surface-mount devices (SMDs) onto inkjet-printed pads, conducted by inkjet printing technology. Excellent quality AgNP ink-junctions are ensured with high resolution picoliter drop jetting at low temperature (˜150 °C). Electrical, mechanical, and morphological characterizations are carried out to assess the performance of the AgNP ink junction. Moreover, AgNP ink is compared with common benchmark materials (i.e., silver epoxy and solder). Electrical contact resistance characterization shows a similar performance between the AgNP ink and the usual ones. Mechanical characterization shows comparable shear strength for AgNP ink and silver epoxy, and both present higher adhesion than solder. Morphological inspections by field-emission scanning electron microscopy confirm a high quality interface of the silver nanoparticle interconnection. Finally, a flexible hybrid circuit on paper controlled by an Arduino board is manufactured, demonstrating the viability and scalability of the AgNP ink assembling technique.

Determination of Anand parameters for SnAgCuCe solder

NASA Astrophysics Data System (ADS)

Zhang, Liang; Xue, Songbai; Gao, Lili; Zeng, Guang; Sheng, Zhong; Chen, Yan; Yu, Shenglin

2009-10-01

A unified viscoplastic constitutive model, Anand equations, was used to represent the inelastic deformation behavior for Sn3.8Ag0.7Cu/Sn3.8Ag0.7 Cu0.03Ce solders in surface mount technology. The Anand parameters of the constitutive equations for the SnAgCu and SnAgCuCe solders were determined from separated constitutive relations and experimental results. Non-linear least-squares fitting was selected to determine the model constants. Comparisons were then made with experimental measurements of the stress-inelastic strain curves: excellent agreement was found. The model accurately predicted the overall trend of steady-state stress-strain behavior of SnAgCu and SnAgCuCe solders for the temperature ranges from -55 to 125 °C and for the strain rate range from 1% s-1 to 0.01% s-1. It is concluded that the Anand model can be applied to represent the inelastic deformation behavior of solders at high homologous temperatures and can be recommended for finite element simulation of the stress-strain response of lead-free soldered joints. Based on the Anand model, the investigations of thermo-mechanical behavior of SnAgCu and SnAgCuCe soldered joints in fine pitch quad flat package by the finite element code have been done under thermal cyclic loading, and it is found that the reliability of the SnAgCuCe soldered joints is better than that of the SnAgCu soldered joints.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paulus, Wilfred; Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor; Rahman, Irman Abdul

Lead-free solders are important material in nano and microelectronic surface mounting technology for various applications in bio medicine, environmental monitoring, spacecraft and satellite instrumentation. Nevertheless solder joint in radiation environment needs higher reliability and resistance to any damage caused by ionizing radiations. In this study a lead-free 99.0Sn0.3Ag0.7Cu wt.% (SAC) solder joint was developed and subjected to various doses of gamma radiation to investigate the effects of the ionizing radiation to micromechanical hardness of the solder. Averaged hardness of the SAC joint was obtained from nanoindentation test. The results show a relationship between hardness values of indentations and the incrementmore » of radiation dose. Highest mean hardness, 0.2290 ± 0.0270 GPa was calculated on solder joint which was exposed to 5 Gray dose of gamma radiation. This value indicates possible radiation hardening effect on irradiated solder. The hardness gradually decreased to 0.1933 ± 0.0210 GPa and 0.1631 ± 0.0173 GPa when exposed to doses 50 and 500 gray respectively. These values are also lower than the hardness of non irradiated sample which was calculated as 0.2084 ± 0.0.3633 GPa indicating possible radiation damage and needs further related atomic dislocation study.« less

Solder Creep-Fatigue Interactions with Flexible Leaded Part

NASA Technical Reports Server (NTRS)

Ross, R. G., Jr.; Wen, L. C.

1994-01-01

In most electronic packaging applications it is not a single high stress event that breaks a component solder joint; rather it is repeated or prolonged load applications that result in fatigue or creep failure of the solder. The principal strain in solder joints is caused by differential expansion between the part and its mounting environment due to hanges in temperature (thermal cycles) and/or due to temperature gradients between the part and the board.

Modified soldering iron speeds cutting of synthetic materials

NASA Technical Reports Server (NTRS)

Schafer, W. G., Jr.

1966-01-01

Modified soldering iron cuts large lots of synthetic materials economically without leaving frayed or jagged edges. The soldering iron is modified by machining an axial slot in its heating element tip and mounting a cutting disk in it. An alternate design has an axially threaded bore in the tip to permit the use of various shapes of cutting blades.

Investigation of discrete component chip mounting technology for hybrid microelectronic circuits

NASA Technical Reports Server (NTRS)

Caruso, S. V.; Honeycutt, J. O.

1975-01-01

The use of polymer adhesives for high reliability microcircuit applications is a radical deviation from past practices in electronic packaging. Bonding studies were performed using two gold-filled conductive adhesives, 10/90 tin/lead solder and Indalloy no. 7 solder. Various types of discrete components were mounted on ceramic substrates using both thick-film and thin-film metallization. Electrical and mechanical testing were performed on the samples before and after environmental exposure to MIL-STD-883 screening tests.

How Many Peripheral Solder Joints in a Surface Mounted Design Experience Inelastic Strains?

NASA Astrophysics Data System (ADS)

Suhir, E.; Yi, S.; Ghaffarian, R.

2017-03-01

It has been established that it is the peripheral solder joints that are the most vulnerable in the ball-grid-array (BGA) and column-grid-array (CGA) designs and most often fail. As far as the long-term reliability of a soldered microelectronics assembly as a whole is concerned, it makes a difference, if just one or more peripheral joints experience inelastic strains. It is clear that the low cycle fatigue lifetime of the solder system is inversely proportional to the number of joints that simultaneously experience inelastic strains. A simple and physically meaningful analytical expression (formula) is obtained for the prediction, at the design stage, of the number of such joints, if any, for the given effective thermal expansion (contraction) mismatch of the package and PCB; materials and geometrical characteristics of the package/PCB assembly; package size; and, of course, the level of the yield stress in the solder material. The suggested formula can be used to determine if the inelastic strains in the solder material could be avoided by the proper selection of the above characteristics and, if not, how many peripheral joints are expected to simultaneously experience inelastic strains. The general concept is illustrated by a numerical example carried out for a typical BGA package. The suggested analytical model (formula) is applicable to any soldered microelectronics assembly. The roles of other important factors, such as, e.g., solder material anisotropy, grain size, and their random orientation within a joint, are viewed in this analysis as less important factors than the level of the interfacial stress. The roles of these factors will be accounted for in future work and considered, in addition to the location of the joint, in a more complicated, more sophisticated, and more comprehensive reliability/fatigue model.

Simulation of thermomechanical fatigue in solder joints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, H.E.; Porter, V.L.; Fye, R.M.

1997-12-31

Thermomechanical fatigue (TMF) is a very complex phenomenon in electronic component systems and has been identified as one prominent degradation mechanism for surface mount solder joints in the stockpile. In order to precisely predict the TMF-related effects on the reliability of electronic components in weapons, a multi-level simulation methodology is being developed at Sandia National Laboratories. This methodology links simulation codes of continuum mechanics (JAS3D), microstructural mechanics (GLAD), and microstructural evolution (PARGRAIN) to treat the disparate length scales that exist between the macroscopic response of the component and the microstructural changes occurring in its constituent materials. JAS3D is used tomore » predict strain/temperature distributions in the component due to environmental variable fluctuations. GLAD identifies damage initiation and accumulation in detail based on the spatial information provided by JAS3D. PARGRAIN simulates the changes of material microstructure, such as the heterogeneous coarsening in Sn-Pb solder, when the component`s service environment varies.« less

Effect of Ni-P Plating Temperature on Growth of Interfacial Intermetallic Compound in Electroless Nickel Immersion Gold/Sn-Ag-Cu Solder Joints

NASA Astrophysics Data System (ADS)

Seo, Wonil; Kim, Kyoung-Ho; Kim, Young-Ho; Yoo, Sehoon

2018-01-01

The growth of interfacial intermetallic compound and the brittle fracture behavior of Sn-3.0Ag-0.5-Cu solder (SAC305) joints on electroless nickel immersion gold (ENIG) surface finish have been investigated using Ni-P plating solution at temperatures from 75°C to 85°C and fixed pH of 4.5. SAC305 solder balls with diameter of 450 μm were mounted on the prepared ENIG-finished Cu pads and reflowed with peak temperature of 250°C. The interfacial intermetallic compound (IMC) thickness after reflow decreased with increasing Ni-P plating temperature. After 800 h of thermal aging, the IMC thickness of the sample prepared at 85°C was higher than for that prepared at 75°C. Scanning electron microscopy of the Ni-P surface after removal of the Au layer revealed a nodular structure on the Ni-P surface. The nodule size of the Ni-P decreased with increasing Ni-P plating temperature. The Cu content near the IMC layer increased to 0.6 wt.%, higher than the original Cu content of 0.5 wt.%, indicating that Cu diffused from the Cu pad to the solder ball through the Ni-P layer at a rate depending on the nodule size. The sample prepared at 75°C with thicker interfacial IMC showed greater high-speed shear strength than the sample prepared at 85°C. Brittle fracture increased with decreasing Ni-P plating temperature.

Thermal Cycling Fatigue in DIPs Mounted with Eutectic Tin-Lead Solder Joints in Stub and Gullwing Geometries

NASA Technical Reports Server (NTRS)

Winslow, J. W.; Silveira, C. de

1993-01-01

It has long been known that solder joints under mechanical stress are subject to failure. In early electronic systems, such failures were avoided primarily by avoiding the use of solder as a mechanical structural component. The rule was first to make sound wire connections that did not depend mechanically on solder, and only then to solder them. Careful design and miniaturization in modern electronic systems limits the mechanical stresses exerted on solder joints to values less than their yield points, and these joints have become integral parts of the mechanical structures. Unfortunately, while these joints are strong enough when new, they have proven vulnerable to fatigue failures as they age. Details of the fatigue process are poorly understood, making predictions of expected lifetimes difficult.

1060-nm VCSEL-based parallel-optical modules for optical interconnects

NASA Astrophysics Data System (ADS)

Nishimura, N.; Nagashima, K.; Kise, T.; Rizky, A. F.; Uemura, T.; Nekado, Y.; Ishikawa, Y.; Nasu, H.

2015-03-01

The capability of mounting a parallel-optical module onto a PCB through solder-reflow process contributes to reduce the number of piece parts, simplify its assembly process, and minimize a foot print for both AOC and on-board applications. We introduce solder-reflow-capable parallel-optical modules employing 1060-nm InGaAs/GaAs VCSEL which leads to the advantages of realizing wider modulation bandwidth, longer transmission distance, and higher reliability. We demonstrate 4-channel parallel optical link performance operated at a bit stream of 28 Gb/s 231-1 PRBS for each channel and transmitted through a 50-μm-core MMF beyond 500 m. We also introduce a new mounting technology of paralleloptical module to realize maintaining good coupling and robust electrical connection during solder-reflow process between an optical module and a polymer-waveguide-embedded PCB.

Investigation of Dynamic Oxygen Adsorption in Molten Solder Jetting Technology

NASA Technical Reports Server (NTRS)

Megaridis, Constantine M.; Bellizia, Giulio; McNallan, Michael; Wallace, David B.

2003-01-01

Surface tension forces play a critical role in fluid dynamic phenomena that are important in materials processing. The surface tension of liquid metals has been shown to be very susceptible to small amounts of adsorbed oxygen. Consequently, the kinetics of oxygen adsorption can influence the capillary breakup of liquid-metal jets targeted for use in electronics assembly applications, where low-melting-point metals (such as tin-containing solders) are utilized as an attachment material for mounting of electronic components to substrates. By interpreting values of surface tension measured at various surface ages, adsorption and diffusion rates of oxygen on the surface of the melt can be estimated. This research program investigates the adsorption kinetics of oxygen on the surface of an atomizing molten-metal jet. A novel oscillating capillary jet method has been developed for the measurement of dynamic surface tension of liquids, and in particular, metal melts which are susceptible to rapid surface degradation caused by oxygen adsorption. The experimental technique captures the evolution of jet swells and necks continuously along the jet propagation axis and is used in conjunction with an existing linear, axisymmetric, constant-property model to determine the variation of the instability growth rate, and, in turn, surface tension of the liquid as a function of surface age measured from the exit orifice. The conditions investigated so far focus on a time window of 2-4ms from the jet orifice. The surface properties of the eutectic 63%Sn-37%Pb solder alloy have been investigated in terms of their variation due to O2 adsorption from a N2 atmosphere containing controlled amounts of oxygen (from 8 ppm to 1000 ppm). The method performed well for situations where the oxygen adsorption was low in that time window. The value of surface tension for the 63Sn-37Pb solder in pure nitrogen was found to be 0.49 N/m, in good agreement with previously published work. A characteristic time of O(1ms) or less was determined for the molten-metal surface to be saturated by oxygen at 1000 ppm concentration in N2.

Thermal Fatigue Evaluation of Pb-Free Solder Joints: Results, Lessons Learned, and Future Trends

NASA Astrophysics Data System (ADS)

Coyle, Richard J.; Sweatman, Keith; Arfaei, Babak

2015-09-01

Thermal fatigue is a major source of failure of solder joints in surface mount electronic components and it is critically important in high reliability applications such as telecommunication, military, and aeronautics. The electronic packaging industry has seen an increase in the number of Pb-free solder alloy choices beyond the common near-eutectic Sn-Ag-Cu alloys first established as replacements for eutectic SnPb. This paper discusses the results from Pb-free solder joint reliability programs sponsored by two industry consortia. The characteristic life in accelerated thermal cycling is reported for 12 different Pb-free solder alloys and a SnPb control in 9 different accelerated thermal cycling test profiles in terms of the effects of component type, accelerated thermal cycling profile and dwell time. Microstructural analysis on assembled and failed samples was performed to investigate the effect of initial microstructure and its evolution during accelerated thermal cycling test. A significant finding from the study is that the beneficial effect of Ag on accelerated thermal cycling reliability (measured by characteristic lifetime) diminishes as the severity of the accelerated thermal cycling, defined by greater ΔT, higher peak temperature, and longer dwell time increases. The results also indicate that all the Pb-free solders are more reliable in accelerated thermal cycling than the SnPb alloy they have replaced. Suggestions are made for future work, particularly with respect to the continued evolution of alloy development for emerging application requirements and the value of using advanced analytical methods to provide a better understanding of the effect of microstructure and its evolution on accelerated thermal cycling performance.

Analysis of lead free tin-silver-copper and tin-lead solder wetting reactions

NASA Astrophysics Data System (ADS)

Anson, Scott J.

Lead free electronics soldering is driven by a combination of health and environmental concerns, international legislation and marketing pressure by lead free electronics manufacturing competitors. Since July 1, 2006, companies that do not comply with the European Union legislation are not able to sell circuit assemblies with lead solder in the European Union. China has developed its own regulations, based on the European Union documents with a compliance date of March 1, 2007. Extensive testing by the electronics community has determined that the Sn - Ag - Cu (SAC) family of alloys is the preferred choice for lead free Surface Mount Technology (SMT) soldering. The 96.5Sn/3.0Ag/0.5Cu alloy was used in this study. Lead free soldering requires an increase in reflow peak temperatures which further aggravates component moisture sensitivity risks and thereby decreases assembly yield. Prior research has revealed an enhanced solder spreading phenomena at lower peak temperature and shorter time above liquidus with 63Sn/37Pb solder. This current research investigated solder wetting reactions in 63Sn/37Pb and 96.5Sn/3.0Ag/0.5Cu (SAC305) using materials and manufacturing systems that are industry relevant. The objective was to advance the knowledge base of metal wetting while developing a reflow assembly process that minimized the component defect rates. The components are damaged during reflow by popcorn delamination, which is the result of moisture absorption and subsequent rapid evaporation. A classical Design Of Experiments (DOE) approach was used, with wetted area as the response variable. Outside of the DOE, substrate dissolution depth, and substrate surface new phase formation (reaction product) distance from the triple line (solder wetting front) and reaction product thickness in the solder joint (under the solder) were also analyzed. The samples were analyzed for correlation of reflow peak temperature, reflow Time Above Liquidus (TAL), wetted area, reaction product distance from the triple line, substrate dissolution depth, triple line ridge (substrate protrusion into the molten solder) formation and reaction product thickness in the solder joint. The general results are (1) an improved understanding of 63Sn/37Pb and 96.5Sn/3.0Ag/0.5Cu WT% solder wetting reactions, (2) reduced 63Sn/37Pb and SAC reflow peak temperatures, and thereby reduced risk of moisture sensitivity damage to components. The significance of these results are (1) enhanced applied understanding of the complexity of molten metal wetting a substrate and (2) enhanced assembly yield due to minimal aggravation of component moisture sensitivity. The uniqueness of this research is that it utilized a holistic Systems Science approach which provided a combined microscopic (substrate and molten metal reactions) and macroscopic (wetted area) analysis of metal wetting using materials and processes that were directly relevant to electronics manufacturing.

The Investigation of 6mu Biaxially Oriented Polyethylene 2, 6, -Naphthalate As a Possible Dielectric For Pulse Power Capacitors

NASA Technical Reports Server (NTRS)

Yen, S. P. S.; Lowry, L.; Cygan, P. J.; Jow, T. R.

1993-01-01

The introduction of polythylene -2, 6-Naphthalate (PEN) semicrystalline film with thicknesses of 0.9mu, 1.5mu, 4.0Mu and community. Its unique chemical and high temparterure stability, as well as superior thermo-mechanical properties allow ultra thin ( 2mu) PEN film to be processed into miniature multilayer chip capacitors for surface mount technology (SMT) application that can be used with standard soldering techniques.

Workmanship Standards Personnel Training and Certification Explained

NASA Technical Reports Server (NTRS)

Plante, Jeannette F.

2010-01-01

This slide presentation reviews the standards that NASA requires for workmanship and discusses the rationale and the NASA-STD-8739.x standard series. The training and certification of inspectors and operators is to guarantee that workmanship is qualified for NASA applications. The NASA workmanship standard documents review the standards for: Polymeric Applications, Surface Mount Technology, Soldered Electrical Connections, Crimp, Cable and Harnesses, Fiber Optic Terminations, including ANSI and IPC standards for Electrostatic Discharge Safety, Space Applications Electronic Hardware and Requirements for Soldered Electrical and Electronic Assemblies. It also reviews the certification requirements for appropriate personnel. It also reviews the various levels of trainers for the various requirements. There is also a review of calibration requirements for training equipment. Some variations on the curriculum are allowed. NASA requires operators and inspectors to be certified by their employer to ensure that oversight is being performed.

Effect of Epoxy on Mechanical Property of SAC305 Solder Joint with Various Surface Finishes Under 3-Point Bend Test.

PubMed

Jeong, Haksan; Myung, Woo-Ram; Sung, Yong-Gue; Kim, Kyung-Yeol; Jung, Seung-Boo

2018-09-01

Microstructures and mechanical property of Sn-3.0Ag-0.5Cu (SAC305) and epoxy Sn-3.0Ag-0.5Cu (epoxy SAC) solder joints were investigated with various surface finishes; organic solderability preservative (OSP), electroless nickel immersion gold (ENIG) and electroless nickel electroless palladium immersion gold (ENEPIG). Bending property of solder joints was evaluated by 3-point bend test method. Microstructure and chemical composition of solder joints was characterized by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX), respectively. Epoxy did not effect on intermetallic compound (IMC) morphology. Scalloped shaped Cu6Sn5 IMC was observed at OSP surface finish. Chunky-like shaped and needle-like shaped (Ni,Cu)6Sn5 IMC were observed at the solder/ENIG joint and solder/ENEPIG joint, respectively. The bending cycles of SAC305/OSP joint, SAC305/ENIG joints and SAC305/ENEPIG joints were 720, 440 and 481 cycle numbers. The bending cycles of epoxy SAC and three types surface finished solder joints were over 1000 bending cycles. Under OSP surface finish, bending cycles of epoxy SAC solder was approximately 1.5 times higher than those of SAC305 solder joint. Bending cycles of epoxy SAC solder was over twice times higher than those of SAC305 solder with ENIG and ENEPIG surface finishes. The bending property of epoxy solder joint was enhanced due to epoxy fillet held the solder joint.

Solder flow over fine line PWB surface finishes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hosking, F.M.; Hernandez, C.L.

1998-08-01

The rapid advancement of interconnect technology has stimulated the development of alternative printed wiring board (PWB) surface finishes to enhance the solderability of standard copper and solder-coated surfaces. These new finishes are based on either metallic or organic chemistries. As part of an ongoing solderability study, Sandia National Laboratories has investigated the solder flow behavior of two azole-based organic solderability preservations, immersion Au, immersion Ag, electroless Pd, and electroless Pd/Ni on fine line copper features. The coated substrates were solder tested in the as-fabricated and environmentally-stressed conditions. Samples were processed through an inerted reflow machine. The azole-based coatings generally providedmore » the most effective protection after aging. Thin Pd over Cu yielded the best wetting results of the metallic coatings, with complete dissolution of the Pd overcoat and wetting of the underlying Cu by the flowing solder. Limited wetting was measured on the thicker Pd and Pd over Ni finishes, which were not completely dissolved by the molten solder. The immersion Au and Ag finishes yielded the lowest wetted lengths, respectively. These general differences in solderability were directly attributed to the type of surface finish which the solder came in contact with. The effects of circuit geometry, surface finish, stressing, and solder processing conditions are discussed.« less

SOLDERING OF ALUMINUM BASE METALS

DOEpatents

Erickson, G.F.

1958-02-25

This patent deals with the soldering of aluminum to metals of different types, such as copper, brass, and iron. This is accomplished by heating the aluminum metal to be soldered to slightly above 30 deg C, rubbing a small amount of metallic gallium into the part of the surface to be soldered, whereby an aluminum--gallium alloy forms on the surface, and then heating the aluminum piece to the melting point of lead--tin soft solder, applying lead--tin soft solder to this alloyed surface, and combining the aluminum with the other metal to which it is to be soldered.

Scalable Manufacturing of Solderable and Stretchable Physiologic Sensing Systems.

PubMed

Kim, Yun-Soung; Lu, Jesse; Shih, Benjamin; Gharibans, Armen; Zou, Zhanan; Matsuno, Kristen; Aguilera, Roman; Han, Yoonjae; Meek, Ann; Xiao, Jianliang; Tolley, Michael T; Coleman, Todd P

2017-10-01

Methods for microfabrication of solderable and stretchable sensing systems (S4s) and a scaled production of adhesive-integrated active S4s for health monitoring are presented. S4s' excellent solderability is achieved by the sputter-deposited nickel-vanadium and gold pad metal layers and copper interconnection. The donor substrate, which is modified with "PI islands" to become selectively adhesive for the S4s, allows the heterogeneous devices to be integrated with large-area adhesives for packaging. The feasibility for S4-based health monitoring is demonstrated by developing an S4 integrated with a strain gauge and an onboard optical indication circuit. Owing to S4s' compatibility with the standard printed circuit board assembly processes, a variety of commercially available surface mount chip components, such as the wafer level chip scale packages, chip resistors, and light-emitting diodes, can be reflow-soldered onto S4s without modifications, demonstrating the versatile and modular nature of S4s. Tegaderm-integrated S4 respiration sensors are tested for robustness for cyclic deformation, maximum stretchability, durability, and biocompatibility for multiday wear time. The results of the tests and demonstration of the respiration sensing indicate that the adhesive-integrated S4s can provide end users a way for unobtrusive health monitoring. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Substrate solder barriers for semiconductor epilayer growth

DOEpatents

Drummond, Timothy J.; Ginley, David S.; Zipperian, Thomas E.

1989-01-01

During the growth of compound semiconductors by epitaxial processes, substrates are typically mounted to a support. In modular beam epitaxy, mounting is done using indium as a solder. This method has two drawbacks: the indium reacts with the substrate, and it is difficult to uniformly wet the back of a large diameter substrate. Both of these problems have been successfully overcome by sputter coating the back of the substrate with a thin layer of tungsten carbide or tungsten carbide and gold. In addition to being compatible with the growth of high quality semiconductor epilayers this coating is also inert in all standard substrate cleaning etchants used for compound semiconductors, and provides uniform distribution of energy in radiant heating.

Substrate solder barriers for semiconductor epilayer growth

DOEpatents

Drummond, T.J.; Ginley, D.S.; Zipperian, T.E.

1989-05-09

During the growth of compound semiconductors by epitaxial processes, substrates are typically mounted to a support. In modular beam epitaxy, mounting is done using indium as a solder. This method has two drawbacks: the indium reacts with the substrate, and it is difficult to uniformly wet the back of a large diameter substrate. Both of these problems have been successfully overcome by sputter coating the back of the substrate with a thin layer of tungsten carbide or tungsten carbide and gold. In addition to being compatible with the growth of high quality semiconductor epilayers this coating is also inert in all standard substrate cleaning etchants used for compound semiconductors, and provides uniform distribution of energy in radiant heating.

Substrate solder barriers for semiconductor epilayer growth

DOEpatents

Drummond, T.J.; Ginley, D.S.; Zipperian, T.E.

1987-10-23

During the growth of compound semiconductors by epitaxial processes, substrates are typically mounted to a support. In molecular beam epitaxy, mounting is done using indium as a solder. This method has two drawbacks: the indium reacts with the substrate, and it is difficult to uniformly wet the back of a large diameter substrate. Both of these problems have been successfully overcome by sputter coating the back of the substrate with a thin layer of tungsten carbide or tungsten carbide and gold. In addition to being compatible with the growth of high quality semiconductor epilayers this coating is also inert in all standard substate cleaning etchants used for compound semiconductors, and provides uniform distribution of energy in radiant heating. 1 tab.

Assembling surface mounted components on ink-jet printed double sided paper circuit board.

PubMed

Andersson, Henrik A; Manuilskiy, Anatoliy; Haller, Stefan; Hummelgård, Magnus; Sidén, Johan; Hummelgård, Christine; Olin, Håkan; Nilsson, Hans-Erik

2014-03-07

Printed electronics is a rapidly developing field where many components can already be manufactured on flexible substrates by printing or by other high speed manufacturing methods. However, the functionality of even the most inexpensive microcontroller or other integrated circuit is, at the present time and for the foreseeable future, out of reach by means of fully printed components. Therefore, it is of interest to investigate hybrid printed electronics, where regular electrical components are mounted on flexible substrates to achieve high functionality at a low cost. Moreover, the use of paper as a substrate for printed electronics is of growing interest because it is an environmentally friendly and renewable material and is, additionally, the main material used for many packages in which electronics functionalities could be integrated. One of the challenges for such hybrid printed electronics is the mounting of the components and the interconnection between layers on flexible substrates with printed conductive tracks that should provide as low a resistance as possible while still being able to be used in a high speed manufacturing process. In this article, several conductive adhesives are evaluated as well as soldering for mounting surface mounted components on a paper circuit board with ink-jet printed tracks and, in addition, a double sided Arduino compatible circuit board is manufactured and programmed.

Mechanical Reliability of the Epoxy Sn-58wt.%Bi Solder Joints with Different Surface Finishes Under Thermal Shock

NASA Astrophysics Data System (ADS)

Sung, Yong-Gue; Myung, Woo-Ram; Jeong, Haksan; Ko, Min-Kwan; Moon, Jeonghoon; Jung, Seung-Boo

2018-04-01

The effect of thermal shock on the mechanical reliability of epoxy Sn-58wt.%Bi composite (epoxy Sn-58wt.%Bi) solder joints was investigated with different surface-finished substrates. Sn-58wt.%Bi-based solder has been considered as a promising candidate for low-temperature solder among various lead-free solders. However, Sn-58wt.%Bi solder joints can be easily broken under impact conditions such as mechanical shock, drop tests, and bending tests because of their poor ductility. Therefore, previous researchers have tried to improve the mechanical property of Sn-58wt.%Bi solder by additional elements and mixtures of metal powder and epoxy resin. Epoxy Sn-58wt.%Bi solder paste was fabricated by mixing epoxy resin and Sn-58wt.%Bi solder powder to enhance the mechanical reliability of Sn-58wt.%Bi solder joints. The epoxy Sn-58wt.%Bi solder paste was screen-printed onto various printed circuit board surfaces finished with organic solder preservatives (OSP), electroless nickel immersion gold (ENIG), and electroless nickel electroless palladium immersion gold (ENEPIG). The test components were prepared by a reflow process at a peak temperature of 190°C. The thermal shock test was carried out under the temperature range of - 40 to 125°C to evaluate the reliability of Sn-58wt.%Bi and epoxy Sn-58wt.%Bi solder joints. The OSP-finished sample showed a relatively higher mechanical property than those of ENIG and ENEPIG after thermal shock. The average number of cycles for epoxy Sn-58wt.%Bi solder with the OSP surface finish were 6 times higher than that for Sn-58wt.%Bi solder with the same finish. The microstructures of the solder joints were investigated by scanning electron microscopy, and the composition of the intermetallic compound (IMC) layer was analyzed by using energy dispersive spectrometry. Cu6Sn5 IMC was formed by the reaction between Sn-58wt.%Bi solder and a OSP surface-finished Cu after the reflow process. Ni3Sn4 IMC and (Ni, Pd)3Sn4 IMC were formed at the solder joints between the ENIG and solder, and between ENEPIG surface finish and solders, respectively.

Mechanical Reliability of the Epoxy Sn-58wt.%Bi Solder Joints with Different Surface Finishes Under Thermal Shock

NASA Astrophysics Data System (ADS)

Sung, Yong-Gue; Myung, Woo-Ram; Jeong, Haksan; Ko, Min-Kwan; Moon, Jeonghoon; Jung, Seung-Boo

2018-07-01

The effect of thermal shock on the mechanical reliability of epoxy Sn-58wt.%Bi composite (epoxy Sn-58wt.%Bi) solder joints was investigated with different surface-finished substrates. Sn-58wt.%Bi-based solder has been considered as a promising candidate for low-temperature solder among various lead-free solders. However, Sn-58wt.%Bi solder joints can be easily broken under impact conditions such as mechanical shock, drop tests, and bending tests because of their poor ductility. Therefore, previous researchers have tried to improve the mechanical property of Sn-58wt.%Bi solder by additional elements and mixtures of metal powder and epoxy resin. Epoxy Sn-58wt.%Bi solder paste was fabricated by mixing epoxy resin and Sn-58wt.%Bi solder powder to enhance the mechanical reliability of Sn-58wt.%Bi solder joints. The epoxy Sn-58wt.%Bi solder paste was screen-printed onto various printed circuit board surfaces finished with organic solder preservatives (OSP), electroless nickel immersion gold (ENIG), and electroless nickel electroless palladium immersion gold (ENEPIG). The test components were prepared by a reflow process at a peak temperature of 190°C. The thermal shock test was carried out under the temperature range of - 40 to 125°C to evaluate the reliability of Sn-58wt.%Bi and epoxy Sn-58wt.%Bi solder joints. The OSP-finished sample showed a relatively higher mechanical property than those of ENIG and ENEPIG after thermal shock. The average number of cycles for epoxy Sn-58wt.%Bi solder with the OSP surface finish were 6 times higher than that for Sn-58wt.%Bi solder with the same finish. The microstructures of the solder joints were investigated by scanning electron microscopy, and the composition of the intermetallic compound (IMC) layer was analyzed by using energy dispersive spectrometry. Cu6Sn5 IMC was formed by the reaction between Sn-58wt.%Bi solder and a OSP surface-finished Cu after the reflow process. Ni3Sn4 IMC and (Ni, Pd)3Sn4 IMC were formed at the solder joints between the ENIG and solder, and between ENEPIG surface finish and solders, respectively.

Solder for oxide layer-building metals and alloys

DOEpatents

Kronberg, James W.

1992-01-01

A low temperature solder and method for soldering an oxide layer-building metal such as aluminum, titanium, tantalum or stainless steel. The comosition comprises tin and zinc; germanium as a wetting agent; preferably small amounts of copper and antimony; and a grit, such as silicon carbide. The grit abrades any oxide layer formed on the surface of the metal as the germanium penetrates beneath and loosens the oxide layer to provide good metal-to-metal contact. The germanium comprises less than aproximatley 10% by weight of the solder composition so that it provides sufficient wetting action but does not result in a melting temperature above approximately 300.degree. C. The method comprises the steps rubbing the solder against the metal surface so the grit in the solder abrades the surface while heating the surface until the solder begins to melt and the germanium penetrates the oxide layer, then brushing aside any oxide layer loosened by the solder.

Solder for oxide layer-building metals and alloys

DOEpatents

Kronberg, J.W.

1992-09-15

A low temperature solder and method for soldering an oxide layer-building metal such as aluminum, titanium, tantalum or stainless steel is disclosed. The composition comprises tin and zinc; germanium as a wetting agent; preferably small amounts of copper and antimony; and a grit, such as silicon carbide. The grit abrades any oxide layer formed on the surface of the metal as the germanium penetrates beneath and loosens the oxide layer to provide good metal-to-metal contact. The germanium comprises less than approximately 10% by weight of the solder composition so that it provides sufficient wetting action but does not result in a melting temperature above approximately 300 C. The method comprises the steps rubbing the solder against the metal surface so the grit in the solder abrades the surface while heating the surface until the solder begins to melt and the germanium penetrates the oxide layer, then brushing aside any oxide layer loosened by the solder.

Optimal parameters for laser tissue soldering: II. Premixed versus separate dye-solder techniques.

PubMed

McNally, K M; Sorg, B S; Chan, E K; Welch, A J; Dawes, J M; Owen, E R

2000-01-01

Laser tissue soldering by using an indocyanine green (ICG)-doped protein solder applied topically to the tissue surface and denatured with a diode laser was investigated in Part I of this study. The depth of light absorption was predominantly determined by the concentration of the ICG dye added to the solder. This study builds on that work with an in vitro investigation of the effects of limiting the zone of heat generation to the solder-tissue interface to determine whether more stable solder-tissue fusion can be achieved. An alternative laser tissue soldering technique was investigated, which increased light absorption at the vital solder-tissue interface. A thin layer of ICG dye was smeared over the surface to be treated, the protein solder was then placed directly on top of the dye, and the solder was denatured with an 808-nm diode laser. Because laser light at approximately 800 nm is absorbed primarily by the ICG dye, this thin layer of ICG solution restricted the heat source to the space between the solder and the tissue surfaces. A tensile strength analysis was conducted to compare the separate dye-solder technique with conventional techniques of laser tissue soldering for which a premixed dye-solder is applied directly to the tissue surface. The effect of hydration on bond stability of repairs formed by using both techniques was also investigated using tensile strength and scanning electron microscopy analysis. Equivalent results in terms of tensile strength were obtained for the premixed dye-solder technique using protein solders containing 0.25 mg/ml ICG (liquid solder, 220 +/- 35 N/cm(2); solid solder, 602 +/- 32 N/cm(2)) and for the separate dye-solder technique (liquid solder, 228 +/- 41 N/cm(2); solid solder, 578 +/- 29 N/cm(2)). The tensile strength of native bovine thoracic aorta was 596 +/- 31 N/cm(2). Repairs created by using the separate dye-solder technique were more stable during hydration than their premixed dye-solder counterparts. The conventional premixed dye-solder was simpler and approximately twice as fast to apply. The separate dye-solder technique, however, increased the shelf-life of the solder, because the dye was mixed at the time of the experiment, thus conserving its spectral absorbency properties. Two laser-assisted tissue soldering techniques have been evaluated for repairing aorta incisions in vitro. The advantages and disadvantages of each of these techniques are discussed. Copyright 2000 Wiley-Liss, Inc.

Experimental investigation on sandwich structure ring-type ultrasonic motor.

PubMed

Peng, Taijiang; Shi, Hongyan; Liang, Xiong; Luo, Feng; Wu, Xiaoyu

2015-02-01

This paper presents a manufacture method for a sandwich structure Ultrasonic Motor (USM) and experiment. Two pieces of rotor clamped on a stator, and a stainless steel disk-spring is bonded on the hollow rotor disk to provide the press by a nut assembled on the shaft. The stator is made of a double-side Printed-Circuit Board (PCB) which is sawed out the ring in the center and connected on the board with three legs. On each side of the ring surface, there are electrodes connected at the same position via through hole. The three layer drive circuit for sine, cosine, and ground signal is connected on the board through each leg. There are many piezoelectric components (PZT) bonded between two electrodes and fill soldering tin on each electrode. Then PZT is welded on PCB by reflow soldering. Finally, rub the gibbous soldering tin down to the position of PZT surface makes sure the surface contacts with rotor evenly. The welding process can also be completed by Surface Mounted Technology (SMT). A prototype motor is manufactured by this method. Two B03 model shapes of the stator are obtained by the finite element analysis and the optimal frequency of the motor is 56.375 kHz measured by impedance instrument. The theoretical analysis is conducted for the relationship between the revolving speed of the USM and thickness of stator ring, number of the travelling waves, PZT amplitude, frequency and the other parameters. The experiment result shows that the maximum revolving speed is 116 RPM and the maximum torque is 25 N mm, when the actuate voltage is 200 VAC. Copyright © 2014 Elsevier B.V. All rights reserved.

Corrosive microenvironments at lead solder surfaces arising from galvanic corrosion with copper pipe.

PubMed

Nguyen, Caroline K; Stone, Kendall R; Dudi, Abhijeet; Edwards, Marc A

2010-09-15

As stagnant water contacts copper pipe and lead solder (simulated soldered joints), a corrosion cell is formed between the metals in solder (Pb, Sn) and the copper. If the resulting galvanic current exceeds about 2 μA/cm(2), a highly corrosive microenvironment can form at the solder surface, with pH < 2.5 and chloride concentrations at least 11 times higher than bulk water levels. Waters with relatively high chloride tend to sustain high galvanic currents, preventing passivation of the solder surface, and contributing to lead contamination of potable water supplies. The total mass of lead corroded was consistent with predictions based on the galvanic current, and lead leaching to water was correlated with galvanic current. If the concentration of sulfate in the water increased relative to chloride, galvanic currents and associated lead contamination could be greatly reduced, and solder surfaces were readily passivated.

Johnson Space Center: Workmanship Training

NASA Technical Reports Server (NTRS)

Patterson, Ashley; Sikes, Larry; Corbin, Cheryl; Rucka, Becky

2015-01-01

Special processes require special skills, knowledge and experienced application. For over 15 years, the NASA Johnson Space Center's Receiving, Inspection and Test Facility (RITF) has provided Agency-wide NASA Workmanship Standards compliance training, issuing more than 500 to 800 training completion certificates annually. It is critical that technicians and inspectors are trained and that they maintain their proficiency to implement the applicable standards and specifications. Training services include "hands-on" training to engineers, technicians, and inspectors in the areas of electrostatic discharge (ESD), soldering, surface mount technology (SMT), crimping, conformal coating, and fiber-optic terminations.

Multi-objective optimization on laser solder jet bonding process in head gimbal assembly using the response surface methodology

NASA Astrophysics Data System (ADS)

Deeying, J.; Asawarungsaengkul, K.; Chutima, P.

2018-01-01

This paper aims to investigate the effect of laser solder jet bonding parameters to the solder joints in Head Gimbal Assembly. Laser solder jet bonding utilizes the fiber laser to melt solder ball in capillary. The molten solder is transferred to two bonding pads by nitrogen gas. The response surface methodology have been used to investigate the effects of laser energy, wait time, nitrogen gas pressure, and focal position on the shear strength of solder joints and the change of pitch static attitude (PSA). The response surface methodology is employed to establish the reliable mathematical relationships between the laser soldering parameters and desired responses. Then, multi-objective optimization is conducted to determine the optimal process parameters that can enhance the joint shear strength and minimize the change of PSA. The validation test confirms that the predicted value has good agreement with the actual value.

Dry soldering with hot filament produced atomic hydrogen

DOEpatents

Panitz, Janda K. G.; Jellison, James L.; Staley, David J.

1995-01-01

A system for chemically transforming metal surface oxides to metal that is especially, but not exclusively, suitable for preparing metal surfaces for dry soldering and solder reflow processes. The system employs one or more hot, refractory metal filaments, grids or surfaces to thermally dissociate molecular species in a low pressure of working gas such as a hydrogen-containing gas to produce reactive species in a reactive plasma that can chemically reduce metal oxides and form volatile compounds that are removed in the working gas flow. Dry soldering and solder reflow processes are especially applicable to the manufacture of printed circuit boards, semiconductor chip lead attachment and packaging multichip modules. The system can be retrofitted onto existing metal treatment ovens, furnaces, welding systems and wave soldering system designs.

Influence of the volume-contact area ratio on the growth behavior of the Cu-Sn intermetallic phase

NASA Astrophysics Data System (ADS)

Giddaluri, Venkatakamakshi Supraja

Solder Joints play a very important role in electronic packaging industry by serving as mechanical support and provides integrity to the device. The increasing demand for high performance, environmental and economic feasibility and miniaturization led to the development of high density interconnects. With the reduction in the size/standoff height of the solder reliability issues in the surface mount assemblies and packaging structures under various rigorous environments are becoming significant. One of the most important impact factors that affect the solder joint reliability is the growth rate IMC formed between the solder and substrate with reduction in joint size. IMC formation is required to ensure good bonding and connectivity of the device in packaging. However excess IMC growth rate is detrimental to the device from mechanical aspects due to its brittle nature. Thus there is a need to study effect the IMC growth rate behavior with the solder joint size/standoff height. In this present study, two solder joints of different standoff heights and same composition (pure Sn solder) are used subjected to reflow process at 270°C for 1--7 min to study solid liquid interfacial reaction on joint size and the same experiment is repeated with SAC alloy of composition (96.5% Sn, 3.0% Ag, 0.5% Cu) to investigate the effect of joint size and initial copper concentration on IMC growth rate. The IMC thickness of the Sn 15microm solder joint at 1 min and 7 min is found to be 1.52microm and 2.86microm respectively while that of Sn 150microm solder joint is 1.31microm and 3.16 microm. The thickness is high in low standoff height sample at the early stage of reaction with decrease in IMC growth rate as the time of reflow increases. In case of 25microm SAC alloy solder joint the IMC thickness from 1 and 7 min is found to be 2.1microm and 3.5microm while that of 250microm SAC alloy solder joint its 1.43microm and3.235microm. Similar trend is observed but the IMC thickness is more in SAC alloy compared to Pure Sn due to initial Cu concentration effect. The CGC model is applied for growth kinetics of IMC formation and is in well agreement with the experimental results. It is found that the low standoff height solder joint follow t1/3 law and high standoff height solder joint deviates from the t1/3 due to unsaturation. The pure Sn solder of two different standoff heights is also subjected to isothermal aging tests at 120°C for 0--600 hours to investigate the effect of IMC growth rate on solder joint size in solid state diffusion. It has been found that low solder joint height is having high growth rate compared to high standoff height joint and it is found to obey parabolic law and follow reaction diffusion control mechanism.

NTF: Soldering Technology Development for Cryogenics

NASA Technical Reports Server (NTRS)

Hall, E. T., Jr.

1985-01-01

The advent of the National Transonic Facility (NTF) brought about a new application for an old joining method, soldering. Soldering for use at cryogenic temperatures requires that solders remain ductile and free from tin-pest (grey tin), have toughness to withstand aerodynamic loads associated with flight research, and maintain their surface finishes. Solders are used to attach 347 Stainless-Steel tubing in surface grooves of models. The solder must fill up the gap and metallurgically bound to the tubing and model. Cryogenic temperatures require that only specific materials for models can be used, including: Vasco Max 200 CVM, lescalloy A-286 Vac Arc, pH 13-8 Mo. Solders identified for testing at this time are: 50% Sn - 49.5% Pb - 0.5% Sb, 95% Sn - 5% Sb, 50% In 50% Pb, and 37.5% Sn - 37.5% Pb - 25% In. With these materials and solders, it is necessary to determine their solderability. After solderability is determined, tube/groove specimens are fabricated and stressed under cryogenic temperatures. Compatible solders are then used for acutual models.

Effects of Solder Temperature on Pin Through-Hole during Wave Soldering: Thermal-Fluid Structure Interaction Analysis

PubMed Central

Abdul Aziz, M. S.; Abdullah, M. Z.; Khor, C. Y.

2014-01-01

An efficient simulation technique was proposed to examine the thermal-fluid structure interaction in the effects of solder temperature on pin through-hole during wave soldering. This study investigated the capillary flow behavior as well as the displacement, temperature distribution, and von Mises stress of a pin passed through a solder material. A single pin through-hole connector mounted on a printed circuit board (PCB) was simulated using a 3D model solved by FLUENT. The ABAQUS solver was employed to analyze the pin structure at solder temperatures of 456.15 K (183°C) < T < 643.15 K (370°C). Both solvers were coupled by the real time coupling software and mesh-based parallel code coupling interface during analysis. In addition, an experiment was conducted to measure the temperature difference (ΔT) between the top and the bottom of the pin. Analysis results showed that an increase in temperature increased the structural displacement and the von Mises stress. Filling time exhibited a quadratic relationship to the increment of temperature. The deformation of pin showed a linear correlation to the temperature. The ΔT obtained from the simulation and the experimental method were validated. This study elucidates and clearly illustrates wave soldering for engineers in the PCB assembly industry. PMID:25225638

Effects of solder temperature on pin through-hole during wave soldering: thermal-fluid structure interaction analysis.

PubMed

Aziz, M S Abdul; Abdullah, M Z; Khor, C Y

2014-01-01

An efficient simulation technique was proposed to examine the thermal-fluid structure interaction in the effects of solder temperature on pin through-hole during wave soldering. This study investigated the capillary flow behavior as well as the displacement, temperature distribution, and von Mises stress of a pin passed through a solder material. A single pin through-hole connector mounted on a printed circuit board (PCB) was simulated using a 3D model solved by FLUENT. The ABAQUS solver was employed to analyze the pin structure at solder temperatures of 456.15 K (183(°)C) < T < 643.15 K (370(°)C). Both solvers were coupled by the real time coupling software and mesh-based parallel code coupling interface during analysis. In addition, an experiment was conducted to measure the temperature difference (ΔT) between the top and the bottom of the pin. Analysis results showed that an increase in temperature increased the structural displacement and the von Mises stress. Filling time exhibited a quadratic relationship to the increment of temperature. The deformation of pin showed a linear correlation to the temperature. The ΔT obtained from the simulation and the experimental method were validated. This study elucidates and clearly illustrates wave soldering for engineers in the PCB assembly industry.

Solder Reflow Failures in Electronic Components During Manual Soldering

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander; Greenwell, Chris; Felt, Frederick

2008-01-01

This viewgraph presentation reviews the solder reflow failures in electronic components that occur during manual soldering. It discusses the specifics of manual-soldering-induced failures in plastic devices with internal solder joints. The failure analysis turned up that molten solder had squeezed up to the die surface along the die molding compound interface, and the dice were not protected with glassivation allowing solder to short gate and source to the drain contact. The failure analysis concluded that the parts failed due to overheating during manual soldering.

Dry soldering with hot filament produced atomic hydrogen

DOEpatents

Panitz, J.K.G.; Jellison, J.L.; Staley, D.J.

1995-04-25

A system is disclosed for chemically transforming metal surface oxides to metal that is especially, but not exclusively, suitable for preparing metal surfaces for dry soldering and solder reflow processes. The system employs one or more hot, refractory metal filaments, grids or surfaces to thermally dissociate molecular species in a low pressure of working gas such as a hydrogen-containing gas to produce reactive species in a reactive plasma that can chemically reduce metal oxides and form volatile compounds that are removed in the working gas flow. Dry soldering and solder reflow processes are especially applicable to the manufacture of printed circuit boards, semiconductor chip lead attachment and packaging multichip modules. The system can be retrofitted onto existing metal treatment ovens, furnaces, welding systems and wave soldering system designs. 1 fig.

Micromechanical die attachment surcharge

DOEpatents

Filter, William F.; Hohimer, John P.

2002-01-01

An attachment structure is disclosed for attaching a die to a supporting substrate without the use of adhesives or solder. The attachment structure, which can be formed by micromachining, functions purely mechanically in utilizing a plurality of shaped pillars (e.g. round, square or polygonal and solid, hollow or slotted) that are formed on one of the die or supporting substrate and which can be urged into contact with various types of mating structures including other pillars, a deformable layer or a plurality of receptacles that are formed on the other of the die or supporting substrate, thereby forming a friction bond that holds the die to the supporting substrate. The attachment structure can further include an alignment structure for precise positioning of the die and supporting substrate to facilitate mounting the die to the supporting substrate. The attachment structure has applications for mounting semiconductor die containing a microelectromechanical (MEM) device, a microsensor or an integrated circuit (IC), and can be used to form a multichip module. The attachment structure is particularly useful for mounting die containing released MEM devices since these devices are fragile and can otherwise be damaged or degraded by adhesive or solder mounting.

Electromigration Failure Mechanism in Sn-Cu Solder Alloys with OSP Cu Surface Finish

NASA Astrophysics Data System (ADS)

Chu, Ming-Hui; Liang, S. W.; Chen, Chih; Huang, Annie T.

2012-09-01

Organic solderable preservative (OSP) has been adopted as the Cu substrate surface finish in flip-chip solder joints for many years. In this study, the electromigration behavior of lead-free Sn-Cu solder alloys with thin-film under bump metallization and OSP surface finish was investigated. The results showed that severe damage occurred on the substrate side (cathode side), whereas the damage on the chip side (cathode side) was not severe. The damage on the substrate side included void formation, copper dissolution, and formation of intermetallic compounds (IMCs). The OSP Cu interface on the substrate side became the weakest point in the solder joint even when thin-film metallization was used on the chip side. Three-dimensional simulations were employed to investigate the current density distribution in the area between the OSP Cu surface finish and the solder. The results indicated that the current density was higher along the periphery of the bonding area between the solder and the Cu pad, consistent with the area of IMC and void formation in our experimental results.

Vibration characteristics of aluminum surface subjected to ultrasonic waves and their effect on wetting behavior of solder droplets.

PubMed

Ma, Lin; Xu, Zhiwu; Zheng, Kun; Yan, Jiuchun; Yang, Shiqin

2014-03-01

The vibration characteristics of an aluminum surface subjected to ultrasonic waves were investigated with a combination of numerical simulation and experimental testing. The wetting behavior of solder droplets on the vibrating aluminum surface was also examined. The results show that the vibration pattern of the aluminum surface is inhomogeneous. The amplitude of the aluminum surface exceeds the excitation amplitude in some zones, while the amplitude decreases nearly to zero in other zones. The distribution of the zero-amplitude zones is much less dependent on the strength of the vibration than on the location of the vibration source. The surface of the liquid solder vibrates at an ultrasonic frequency that is higher than the vibration source, and the amplitude of the liquid solder is almost twice that of the aluminum surface. The vibration of the surface of the base metal (liquid solder) correlates with the oxide film removal effect. Significant removal of the oxide film can be achieved within 2s when the amplitude of the aluminum surface is higher than 5.4 μm or when the amplitude of the liquid solder surface is higher than 10.2 μm. Copyright © 2013 Elsevier B.V. All rights reserved.

Ultrasonic soldering of Cu alloy using Ni-foam/Sn composite interlayer.

PubMed

Xiao, Yong; Wang, Qiwei; Wang, Ling; Zeng, Xian; Li, Mingyu; Wang, Ziqi; Zhang, Xingyi; Zhu, Xiaomeng

2018-07-01

In this study, Cu alloy joints were fabricated with a Ni-foam reinforced Sn-based composite solder with the assistance of ultrasonic vibration. Effects of ultrasonic soldering time on the microstructure and mechanical properties of Cu/Ni-Sn/Cu joints were investigated. Results showed that exceptional metallurgic bonding could be acquired with the assistance of ultrasonic vibration using a self-developed Ni-foam/Sn composite solder. For joint soldered for 5 s, a (Cu,Ni) 6 Sn 5 intermetallic compound (IMC) layer was formed on the Cu substrate surface, Ni skeletons distributed randomly in the soldering seam and a serrated (Ni,Cu) 3 Sn 4 IMC layer was formed on the Ni skeleton surface. Increasing the soldering time to 20 s, the (Ni,Cu) 3 Sn 4 IMC layer grew significantly and exhibited a loose porous structure on the Ni skeleton surface. Further increase the soldering time to 30 s, Ni skeletons were largely dissolved in the Sn base solder, and micro-sized (Ni,Cu) 3 Sn 4 particles were formed and dispersed homogeneously in the soldering seam. The formation of (Ni,Cu) 3 Sn 4 particles was mainly ascribed to acoustic cavitations induced erosion and grain refining effects. The joint soldered for 30 s exhibited the highest shear strength of 64.9 ± 3.3 MPa, and the shearing failure mainly occurred at the soldering seam/Cu substrate interface. Copyright © 2018 Elsevier B.V. All rights reserved.

Gamma ray detector modules

NASA Technical Reports Server (NTRS)

Capote, M. Albert (Inventor); Lenos, Howard A. (Inventor)

2009-01-01

A radiation detector assembly has a semiconductor detector array substrate of CdZnTe or CdTe, having a plurality of detector cell pads on a first surface thereof, the pads having a contact metallization and a solder barrier metallization. An interposer card has planar dimensions no larger than planar dimensions of the semiconductor detector array substrate, a plurality of interconnect pads on a first surface thereof, at least one readout semiconductor chip and at least one connector on a second surface thereof, each having planar dimensions no larger than the planar dimensions of the interposer card. Solder columns extend from contacts on the interposer first surface to the plurality of pads on the semiconductor detector array substrate first surface, the solder columns having at least one solder having a melting point or liquidus less than 120 degrees C. An encapsulant is disposed between the interposer circuit card first surface and the semiconductor detector array substrate first surface, encapsulating the solder columns, the encapsulant curing at a temperature no greater than 120 degrees C.

NCMS PWB Surface Finishes Team project summary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kokas, J.; DeSantis, C.; Wenger, G.

1996-04-01

The NCMS PWB Surface Finishes Consortium is just about at the end of the five year program. Dozens of projects related to surface finishes and PWB solder-ability were performed by the team throughout the program, and many of them are listed in this paper. They are listed with a cross reference to where and when a technical paper was presented describing the results of the research. However, due to time and space constraints, this paper can summarize the details of only three of the major research projects accomplished by the team. The first project described is an ``Evaluation of PWBmore » Surface Finishes.`` It describes the solderability, reliability, and wire bondability of numerous surface finishes. The second project outlined is an ``Evaluation of PWB Solderability Test Methods.`` The third project outlined is the ``Development and Evaluation of Organic Solderability Preservatives.``« less

Solderability study of RABiTS-based YBCO coated conductors

NASA Astrophysics Data System (ADS)

Zhang, Yifei; Duckworth, Robert C.; Ha, Tam T.; Gouge, Michael J.

2011-08-01

The solderability of commercially available YBa2Cu3O7-x (YBCO) coated conductors that were made from Rolling Assisted Biaxially Textured Substrates (RABiTS)-based templates was studied. The coated conductors, also known as second-generation (2G) high temperature superconductor (HTS) wires (in the geometry of flat tapes about 4 mm wide), were laminated with copper, brass, or stainless steel strips as stabilizers. To understand the factors that influence their solderability, surface profilometry and scanning electron microscopy were used to characterize the wire surfaces. The solderability of three solders, 52In48Sn, 67Bi33In, and 100In (wt.%), was evaluated using a standard test (IPC/ECA J-STD-002) and with two different commercial fluxes. It was found that the solderability varied with the solder and flux but the three different wires showed similar solderability for a fixed combination of solder and flux. Solder joints of the 2G wires were fabricated using the tools and the procedures recommended by the HTS wire manufacturer. The solder joints were made in a lap-joint geometry and with the superconducting sides of the two wires face-to-face. The electrical resistances of the solder joints were measured at 77 K, and the results were analyzed to qualify the soldering materials and evaluate the soldering process. It was concluded that although the selection of soldering materials affected the resistance of a solder joint, the resistivity of the stabilizer was the dominant factor.

Solderability Study of RABiTS-Based YBCO Coated Conductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yifei; Duckworth, Robert C; Ha, Tam T

2011-01-01

The solderability of commercially available YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) coated conductors that were made from Rolling Assisted Biaxially Textured Substrates (RABiTS)-based templates was studied. The coated conductors, also known as second-generation (2G) high temperature superconductor (HTS) wires (in the geometry of flat tapes about 4 mm wide), were laminated with copper, brass, or stainless steel strips as stabilizers. To understand the factors that influence their solderability, surface profilometry and scanning electron microscopy were used to characterize the wire surfaces. The solderability of three solders, 52In48Sn, 67Bi33In, and 100In (wt.%), was evaluated using a standard test (IPC/ECA J-STD-002) and withmore » two different commercial fluxes. It was found that the solderability varied with the solder and flux but the three different wires showed similar solderability for a fixed combination of solder and flux. Solder joints of the 2G wires were fabricated using the tools and the procedures recommended by the HTS wire manufacturer. The solder joints were made in a lap-joint geometry and with the superconducting sides of the two wires face-to-face. The electrical resistances of the solder joints were measured at 77 K, and the results were analyzed to qualify the soldering materials and evaluate the soldering process. It was concluded that although the selection of soldering materials affected the resistance of a solder joint, the resistivity of the stabilizer was the dominant factor.« less

Tin soldering of aluminum and its alloys

NASA Technical Reports Server (NTRS)

Gallo, Gino

1921-01-01

A method is presented for soldering aluminum to other metals. The method adopted consists of a galvanic application to the surface of the light-metal parts to be soldered, of a layer of another metal, which, without reacting electrolytically on the aluminum, adheres strongly to the surface to which it is applied, and is, on the other hand, adapted to receive the soft solder. The metal found to meet the criteria best was iron.

Decapsulation Method for Flip Chips with Ceramics in Microelectronic Packaging

NASA Astrophysics Data System (ADS)

Shih, T. I.; Duh, J. G.

2008-06-01

The decapsulation of flip chips bonded to ceramic substrates is a challenging task in the packaging industry owing to the vulnerability of the chip surface during the process. In conventional methods, such as manual grinding and polishing, the solder bumps are easily damaged during the removal of underfill, and the thin chip may even be crushed due to mechanical stress. An efficient and reliable decapsulation method consisting of thermal and chemical processes was developed in this study. The surface quality of chips after solder removal is satisfactory for the existing solder rework procedure as well as for die-level failure analysis. The innovative processes included heat-sink and ceramic substrate removal, solder bump separation, and solder residue cleaning from the chip surface. In the last stage, particular temperatures were selected for the removal of eutectic Pb-Sn, high-lead, and lead-free solders considering their respective melting points.

METHOD FOR SOLDERING NORMALLY NON-SOLDERABLE ARTICLES

DOEpatents

McGuire, J.C.

1959-11-24

Methods are presented for coating and joining materials which are considered difficult to solder by utilizing an abrasive wheel and applying a bar of a suitable coating material, such as Wood's metal, to the rotating wheel to fill the cavities of the abrasive wheel and load the wheel with the coating material. The surface of the base material is then rubbed against the loaded rotating wheel, thereby coating the surface with the soft coating metal. The coating is a cohesive bonded layer and holds the base metal as tenaciously as a solder holds to easily solderable metals.

STUDY OF THE RHIC BPM SMA CONNECTOR FAILURE PROBLEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

LIAW,C.; SIKORA, R.; SCHROEDER, R.

2007-06-25

About 730 BPMs are mounted on the RHIC CQS and Triplet super-conducting magnets. Semi-rigid coaxial cables are used to bring the electrical signal from the BPM feedthroughs to the outside flanges. at the ambient temperature. Every year around 10 cables will lose their signals during the operation. The connection usually failed at the warm end of the cable. The problems were either the solder joint failed or the center conductor retracted out of the SMA connector. Finite element analyses were performed to understand the failure mechanism of the solder joint. The results showed that (1) The SMA center conductor canmore » separate from the mating connector due to the thermal retraction. (2) The maximum thermal stress at the warm end solder joint can exceed the material strength of the Pb37/Sn63 solder material and (3) The magnet ramping frequency (-10 Hz), during the machine startup, can possibly resonant the coaxial cable and damage the solder joints, especially when a fracture is initiated. Test results confirmed that by using the silver bearing solder material (a higher strength material) and by crimping the cable at the locations close to the SMA connector (to prevent the center conductor from retracting) can effectively resolve the connector failure problem.« less

Method for making a high current fiber brush collector

NASA Astrophysics Data System (ADS)

Scuro, S. J.

1986-05-01

An axial-type homopolar motor having high density, high current fiber brush collectors affording efficient, low contact resistance and low operating temperatures is discussed. The collectors include a ring of concentric row of brushes in equally spaced beveled holes soldered in place using a fixture for heating the ring to just below the solder melting point at a soldering iron for the local application of additional heat at each brush. Prior to soldering, an oxide film is formed on the surfaces of the brushes and ring, and the bevels are burnished to form a wetting surface. Flux applied with the solder at each bevel removes to an effective soldering depth the oxide film on the brushes and the holes.

Mounting for diodes provides efficient heat sink

NASA Technical Reports Server (NTRS)

1964-01-01

Efficient heat sink is provided by soldering diodes to metal support bars which are brazed to a ceramic base. Electrical connections between diodes on adjacent bars are made flexible by metal strips which aid in heat dissipation.

Dynamic measurements of the spreading of liquid metals in controlled atmospheres with in situ surface preparation and analysis

NASA Astrophysics Data System (ADS)

Peebles, D. E.; Peebles, H. C.; Ohlhausen, J. A.; Hurst, M. J.

1996-02-01

A specially designed ultrahigh vacuum in situ surface analysis and wetting system has been constructed to study the spreading of liquid metal solders on carefully prepared and well-characterized solid substrates. The system consists of a standard ultrahigh vacuum surface analysis chamber linked to a reaction chamber for wetting or other experiments at pressures up to atmospheric. A sophisticated video system allows real-time monitoring of the spreading of the liquid metal through both side and top views. An infrared imaging system allows accurate remote temperature measurements. Sample surfaces are prepared and spreading experiments performed without intermediate exposure of the surfaces to the contaminating atmospheres. Solder spreading is performed under 50 Torr of highly purified helium gas to allow for adequate thermal coupling between the solder and the substrate. Initial studies have been completed for the spreading of pure tin solder on copper substrates in the absence of any fluxing agent. Three types of copper substrate surfaces were investigated in these experiments: the sputter-cleaned, air-exposed, and the as-received surface. Surface chemical analysis by x-ray photoelectron spectroscopy showed the air-exposed surface to consist of about 3 nm of Cu2O, while the as-received surface consisted of about 8 nm of Cu2O. The sputter-cleaned surface contained less than one monolayer (0.3 nm) of Cu2O. Spreading experiments utilizing a linear temperature ramp show that pure tin solder spreads readily on oxidized copper surfaces at elevated temperatures. The initiation temperature for rapid tin spreading on the as-received copper surface was 325 °C. Decreasing the thickness of the oxide on the surface lowered the observed temperature for the initiation of spreading and increased the rate of spreading. On the sputter-cleaned copper surface, rapid solder spreading was observed immediately upon melting of the solder.

Derivation of mechanical characteristics for Ni/Au intermetallic surface with SAC305 solder

NASA Astrophysics Data System (ADS)

Kim, Jong-Min; Lee, Hyun-Boo; Chang, Yoon-Suk; Choi, Jae-Boong

2013-03-01

Many surface finish methods are used to connect a substrate with the electric components of IT products in the micro-packaging process, and various types of lead-free solder have been developed as alternative materials to lead-based solder to reduce environmental contamination. However, there has been little research on the mechanical properties of the inter-metallic surface which is generated in the bumping process between the lead-free solder and surface films such as Ni/Au. The present work is to derive the material properties of a Ni/Au inter-metallic surface with SAC305 solder. A series of indentation tests were carried out by changing four nano-scale indentation depths and two strain rates. Also, a reverse algorithm method was adopted to determine the elastic-plastic stress-strain curve based on the load-displacement curve from the indentation test data. As a result of the material characterization effort, the mean elastic modulus, yield strength and strain hardening exponent of IMC with Ni/Au finish were determined.

Solder dross removal apparatus

NASA Technical Reports Server (NTRS)

Webb, Winston S. (Inventor)

1990-01-01

An automatic dross removal apparatus is disclosed for removing dross from the surface of a solder bath in an automated electric component handling system. A rotatable wiper blade is positioned adjacent the solder bath which skims the dross off of the surface prior to the dipping of a robot conveyed component into the bath. An electronic control circuit causes a motor to rotate the wiper arm one full rotational cycle each time a pulse is received from a robot controller as a component approaches the solder bath.

Integrated LTCC pressure/flow/temperature multisensor for compressed air diagnostics.

PubMed

Fournier, Yannick; Maeder, Thomas; Boutinard-Rouelle, Grégoire; Barras, Aurélie; Craquelin, Nicolas; Ryser, Peter

2010-01-01

We present a multisensor designed for industrial compressed air diagnostics and combining the measurement of pressure, flow, and temperature, integrated with the corresponding signal conditioning electronics in a single low-temperature co-fired ceramic (LTCC) package. The developed sensor may be soldered onto an integrated electro-fluidic platform by using standard surface mount device (SMD) technology, e.g., as a standard electronic component would be on a printed circuit board, obviating the need for both wires and tubes and thus paving the road towards low-cost integrated electro-fluidic systems. Several performance aspects of this device are presented and discussed, together with electronics design issues.

Integrated LTCC Pressure/Flow/Temperature Multisensor for Compressed Air Diagnostics†

PubMed Central

Fournier, Yannick; Maeder, Thomas; Boutinard-Rouelle, Grégoire; Barras, Aurélie; Craquelin, Nicolas; Ryser, Peter

2010-01-01

We present a multisensor designed for industrial compressed air diagnostics and combining the measurement of pressure, flow, and temperature, integrated with the corresponding signal conditioning electronics in a single low-temperature co-fired ceramic (LTCC) package. The developed sensor may be soldered onto an integrated electro-fluidic platform by using standard surface mount device (SMD) technology, e.g., as a standard electronic component would be on a printed circuit board, obviating the need for both wires and tubes and thus paving the road towards low-cost integrated electro-fluidic systems. Several performance aspects of this device are presented and discussed, together with electronics design issues. PMID:22163518

Low thermal resistance power module assembly

DOEpatents

Hassani, Vahab; Vlahinos, Andreas; Bharathan, Desikan

2007-03-13

A power module assembly with low thermal resistance and enhanced heat dissipation to a cooling medium. The assembly includes a heat sink or spreader plate with passageways or openings for coolant that extend through the plate from a lower surface to an upper surface. A circuit substrate is provided and positioned on the spreader plate to cover the coolant passageways. The circuit substrate includes a bonding layer configured to extend about the periphery of each of the coolant passageways and is made up of a substantially nonporous material. The bonding layer may be solder material which bonds to the upper surface of the plate to provide a continuous seal around the upper edge of each opening in the plate. The assembly includes power modules mounted on the circuit substrate on a surface opposite the bonding layer. The power modules are positioned over or proximal to the coolant passageways.

Natural radioactive contaminants in solder

NASA Astrophysics Data System (ADS)

Bunzl, K.; Kracke, W.

1985-07-01

Comparatively high surface count rates for alpha- and beta-radiation were observed for several solders. They were identified as 210Pb and 210Po. The corresponding specific activities in solder were determined.

Pb-free surface-finishing on electronic components' terminals for Pb-free soldering assembly

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, Hitoshi; Tanimoto, Morimasa; Matsuda, Akira

1999-11-01

Pb-free solderable surface finishing is essential to implement Pb-free solder assembly in order to meet with the growing demand of environmental consciousness to eliminate Pb from electronic products. Two types of widely applicable Pb-free surface finishing technologies are developed. One is the multilayer-system including Pd with Ni undercoat. Heat-resistance of Pd enables whole-surface-plating on to leadframe before IC-assembling process. The other is the double-layer-system with low-melting-point-materials, for example, thicker Sn underlayer and thinner Sn-Bi alloy overlayer, dilutes Sn-Bi alloy's defects of harmful reactivity along with substrate metal and mechanical brittleness with keeping its advantages of solder-wettability and no whisker.

Solder dross removal apparatus

NASA Technical Reports Server (NTRS)

Webb, Winston S. (Inventor)

1992-01-01

An automatic dross removal apparatus (10) is disclosed for removing dross from the surface of a solder bath (22) in an automated electric component handling system. A rotatable wiper blade (14) is positioned adjacent the solder bath (22) which skims the dross off of the surface prior to the dipping of a robot conveyed component into the bath. An electronic control circuit (34) causes a motor (32) to rotate the wiper arm (14) one full rotational cycle each time a pulse is received from a robot controller (44) as a component approaches the solder bath (22).

Effect of Plasma Surface Finish on Wettability and Mechanical Properties of SAC305 Solder Joints

NASA Astrophysics Data System (ADS)

Kim, Kyoung-Ho; Koike, Junichi; Yoon, Jeong-Won; Yoo, Sehoon

2016-12-01

The wetting behavior, interfacial reactions, and mechanical reliability of Sn-Ag-Cu solder on a plasma-coated printed circuit board (PCB) substrate were evaluated under multiple heat-treatments. Conventional organic solderability preservative (OSP) finished PCBs were used as a reference. The plasma process created a dense and highly cross-linked polymer coating on the Cu substrates. The plasma finished samples had higher wetting forces and shorter zero-cross times than those with OSP surface finish. The OSP sample was degraded after sequential multiple heat treatments and reflow processes, whereas the solderability of the plasma finished sample was retained after multiple heat treatments. After the soldering process, similar microstructures were observed at the interfaces of the two solder joints, where the development of intermetallic compounds was observed. From ball shear tests, it was found that the shear force for the plasma substrate was consistently higher than that for the OSP substrate. Deterioration of the OSP surface finish was observed after multiple heat treatments. Overall, the plasma surface finish was superior to the conventional OSP finish with respect to wettability and joint reliability, indicating that it is a suitable material for the fabrication of complex electronic devices.

Insert sleeve prevents tube soldering contamination

NASA Technical Reports Server (NTRS)

Stein, J.

1966-01-01

Teflon sleeve insert prevents contamination of internal tube surfaces by solder compound during soldering operations that connect and seal the tube ends. The sleeve insert is pressed into the mating tube ends with a slight interference fit.

Effects of Solder Volume and Reflow Conditions on Self-Alignment Accuracy for Fan-Out Package Applications

NASA Astrophysics Data System (ADS)

Park, Hwan-Pil; Seo, Gwancheol; Kim, Sungchul; Kim, Young-Ho

2018-01-01

The effects of solder volume and reaction time between molten solder and a metal pad at the peak temperature of reflow on the self-alignment effect have been investigated in flip chip bonding. A glass die with two different pad designs and a flame retardant-4 (FR-4) organic substrate were used. Sn-3.0Ag-0.5Cu and Sn-3.5Ag solders were formed on Cu-organic solderability preservation (Cu-OSP) and electroless nickel electroless palladium immersion gold (ENEPIG) pads on FR-4 substrates using the stencil printing method. To assess the effect of solder volume, the thickness and opening size of the stencil mask were controlled. Reflow experiments were performed at 250°C with wetting times of 40 s, 55 s, 65 s, and 75 s. After flip chip reflow soldering, the bonding areas were cross-sectioned to inspect the shape of the interconnected solder using scanning electron microscopy. The results revealed that using an insufficient solder volume on the pad was responsible for die shifts larger than 1 μm, while a sufficient solder volume on the pad and a stable solder joint shape could ensure misalignment less than 1 μm. The Sn-3.0Ag-0.5Cu solder showed a lower die shift value than the Sn-3.5Ag solder because the Sn-3.0Ag-0.5Cu solder has stronger surface tension than the Sn-3.5Ag solder. Using a longer wetting time between the solder and the pad at the peak temperature also improved the die shift value because the increased reaction time changed the interconnected solder shape between the die and substrate from concave to convex, moving the die to a more accurate position. Furthermore, the restoring forces on die self-alignment influenced the die shift value. A stronger solder surface tension and a larger volume of solder on the pad produced stronger restoring forces for die self-alignment, thereby improving the die shift value.

Photothermal effects of laser tissue soldering.

PubMed

McNally, K M; Sorg, B S; Welch, A J; Dawes, J M; Owen, E R

1999-04-01

Low-strength anastomoses and thermal damage of tissue are major concerns in laser tissue welding techniques where laser energy is used to induce thermal changes in the molecular structure of the tissues being joined, hence allowing them to bond together. Laser tissue soldering, on the other hand, is a bonding technique in which a protein solder is applied to the tissue surfaces to be joined, and laser energy is used to bond the solder to the tissue surfaces. The addition of protein solders to augment tissue repair procedures significantly reduces the problems of low strength and thermal damage associated with laser tissue welding techniques. Investigations were conducted to determine optimal solder and laser parameters for tissue repair in terms of tensile strength, temperature rise and damage and the microscopic nature of the bonds formed. An in vitro study was performed using an 808 nm diode laser in conjunction with indocyanine green (ICG)-doped albumin protein solders to repair bovine aorta specimens. Liquid and solid protein solders prepared from 25% and 60% bovine serum albumin (BSA), respectively, were compared. The efficacy of temperature feedback control in enhancing the soldering process was also investigated. Increasing the BSA concentration from 25% to 60% greatly increased the tensile strength of the repairs. A reduction in dye concentration from 2.5 mg ml(-1) to 0.25 mg ml(-1) was also found to result in an increase in tensile strength. Increasing the laser irradiance and thus surface temperature resulted in an increased severity of histological injury. Thermal denaturation of tissue collagen and necrosis of the intimal layer smooth muscle cells increased laterally and in depth with higher temperatures. The strongest repairs were produced with an irradiance of 6.4 W cm(-2) using a solid protein solder composed of 60% BSA and 0.25 mg ml(-1) ICG. Using this combination of laser and solder parameters, surface temperatures were observed to reach 85+/-5 degrees C with a maximum temperature difference through the 150 microm thick solder strips of about 15 degrees C. Histological examination of the repairs formed using these parameters showed negligible evidence of collateral thermal damage to the underlying tissue. Scanning electron microscopy suggested albumin intertwining within the tissue collagen matrix and subsequent fusion with the collagen as the mechanism for laser tissue soldering. The laser tissue soldering technique is shown to be an effective method for producing repairs with improved tensile strength and minimal collateral thermal damage over conventional laser tissue welding techniques.

21 CFR 189.240 - Lead solders.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Lead solders. 189.240 Section 189.240 Food and...-Contact Surfaces § 189.240 Lead solders. (a) Lead solders are alloys of metals that include lead and are used in the construction of metal food cans. (b) Food packaged in any container that makes use of lead...

21 CFR 189.240 - Lead solders.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Lead solders. 189.240 Section 189.240 Food and... Addition to Human Food Through Food-Contact Surfaces § 189.240 Lead solders. (a) Lead solders are alloys of metals that include lead and are used in the construction of metal food cans. (b) Food packaged in any...

21 CFR 189.240 - Lead solders.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Lead solders. 189.240 Section 189.240 Food and... Addition to Human Food Through Food-Contact Surfaces § 189.240 Lead solders. (a) Lead solders are alloys of metals that include lead and are used in the construction of metal food cans. (b) Food packaged in any...

21 CFR 189.240 - Lead solders.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Lead solders. 189.240 Section 189.240 Food and... Addition to Human Food Through Food-Contact Surfaces § 189.240 Lead solders. (a) Lead solders are alloys of metals that include lead and are used in the construction of metal food cans. (b) Food packaged in any...

21 CFR 189.240 - Lead solders.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Lead solders. 189.240 Section 189.240 Food and... Addition to Human Food Through Food-Contact Surfaces § 189.240 Lead solders. (a) Lead solders are alloys of metals that include lead and are used in the construction of metal food cans. (b) Food packaged in any...

Evaluation of ENEPIG and Immersion Silver Surface Finishes Under Drop Loading

NASA Astrophysics Data System (ADS)

Pearl, Adam; Osterman, Michael; Pecht, Michael

2016-01-01

The effect of printed circuit board surface finish on the drop loading reliability of ball grid array (BGA) solder interconnects has been examined. The finishes examined include electroless nickel/electroless palladium/immersion gold (ENEPIG) and immersion silver (ImAg). For the ENEPIG finish, the effect of the Pd plating layer thickness was evaluated by testing two different thicknesses: 0.05 μm and 0.15 μm. BGA components were assembled onto the boards using either eutectic Sn-Pb or Sn-3.0Ag-0.5Cu (SAC305) solder. Prior to testing, the assembled boards were aged at 100°C for 24 h or 500 h. The boards were then subjected to multiple 1500-g drop tests. Failure analysis indicated the primary failure site for the BGAs to be the solder balls at the board-side solder interface. Cratering of the board laminate under the solder-attached pads was also observed. In all cases, isothermal aging reduced the number of drops to failure. The components soldered onto the boards with the 0.15- μm-Pd ENEPIG finish with the SAC305 solder had the highest characteristic life, at 234 drops to failure, compared with the other finish-solder combinations.

Programmable Multi-Chip Module

DOEpatents

Kautz, David; Morgenstern, Howard; Blazek, Roy J.

2005-05-24

A multi-chip module comprising a low-temperature co-fired ceramic substrate having a first side on which are mounted active components and a second side on which are mounted passive components, wherein this segregation of components allows for hermetically sealing the active components with a cover while leaving accessible the passive components, and wherein the passive components are secured using a reflow soldering technique and are removable and replaceable so as to make the multi-chip module substantially programmable with regard to the passive components.

Programmable Multi-Chip Module

DOEpatents

Kautz, David; Morgenstern, Howard; Blazek, Roy J.

2004-11-16

A multi-chip module comprising a low-temperature co-fired ceramic substrate having a first side on which are mounted active components and a second side on which are mounted passive components, wherein this segregation of components allows for hermetically sealing the active components with a cover while leaving accessible the passive components, and wherein the passive components are secured using a reflow soldering technique and are removable and replaceable so as to make the multi-chip module substantially programmable with regard to the passive components.

Programmable multi-chip module

DOEpatents

Kautz, David; Morgenstern, Howard; Blazek, Roy J.

2004-03-02

A multi-chip module comprising a low-temperature co-fired ceramic substrate having a first side on which are mounted active components and a second side on which are mounted passive components, wherein this segregation of components allows for hermetically sealing the active components with a cover while leaving accessible the passive components, and wherein the passive components are secured using a reflow soldering technique and are removable and replaceable so as to make the multi-chip module substantially programmable with regard to the passive components.

A family of neuromuscular stimulators with optical transcutaneous control.

PubMed

Jarvis, J C; Salmons, S

1991-01-01

A family of miniature implantable neuromuscular stimulators has been developed using surface-mounted Philips 4000-series integrated circuits. The electronic components are mounted by hand on printed circuits (platinum/gold on alumina) and the electrical connections are made by reflow soldering. The plastic integrated-circuit packages, ceramic resistors and metal interconnections are protected from the body fluids by a coating of biocompatible silicone rubber. This simple technology provides reliable function for at least 4 months under implanted conditions. The circuits have in common a single lithium cell power-supply (3.2 V) and an optical sensor which can be used to detect light flashes through the skin after the device has been implanted. This information channel may be used to switch the output of a device on or off, or to cycle through a series of pre-set programs. The devices are currently finding application in studies which provide an experimental basis for the clinical exploitation of electrically stimulated skeletal muscle in cardiac assistance, sphincter reconstruction or functional electrical stimulation of paralysed limbs.

Molten-Metal Droplet Deposition on a Moving Substrate in Microgravity: Aiding the Development of Novel Technologies for Microelectronic Assembly

NASA Technical Reports Server (NTRS)

Megaridis, C. M.; Bayer, I. S.; Poulikakos, D.; Nayagam, V.

2002-01-01

Driven by advancements in microelectronics manufacturing, this research investigates the oblique (non-axisymmetric) impact of liquid-metal droplets on flat substrates. The problem of interest is relevant to the development of the novel technology of on-demand dispension (printing) of microscopic solder deposits for the surface mounting of microelectronic devices. The technology, known as solder jetting, features on-demand deposition of miniature solder droplets (30 to 120 microns in diameter) in very fine, very accurate patterns using techniques analogous to those developed for the ink-jet printing industry. Despite its promise, severe limitations exist currently with regards to the throughput rates of the technology; some of these limitations are largely due to the lack of the capability for reliable prediction of solder bump positioning and shapes, especially under ballistic deposition conditions where the droplet impact phenomena are inherently three-dimensional. The study consists of a theoretical and an experimental component. The theoretical work uses a finite element formulation to simulate numerically the non-axisymmetric (3-D) fluid mechanics and heat transfer phenomena of a liquid solder droplet impacting at an angle alpha on a flat substrate. The work focuses on the pre-solidification regime. The modeling of the most challenging fluid mechanics part of the process has been completed successfully. It is based upon the full laminar Navier-Stokes equations employing a Lagrangian frame of reference. Due to the large droplet deformation, the surface (skin) as well as the volumetric mesh have to be regenerated during the calculations in order to maintain the high accuracy of the numerical scheme. The pressure and velocity fields are then interpolated on the newly created mesh. The numerical predictions are being tested against experiments, for cases where wetting phenomena are not important. For the impact parameters used in the example shown (We = 2.38, Fr = 16300, Re = 157), the droplet rolls along the substrate, but its shape remains practically axisymmetric for all impact angles within the range from 0 to 60 deg. Interestingly, the substrate/droplet contact area during the recoiling phase of the impact is not a monotonically decreasing function of time. The experimental component of the research tests the numerical predictions and provides necessary input data (contact angles) for the theoretical model. The experiments are performed in microgravity (2.2s drop tower of the NASA GRC) in order to allow for the use of mm-size solder droplets, which make feasible the performance of accurate measurements, while maintaining similitude of the relevant fluid dynamic groups (Re, Fr, We, Ste). Preliminary oblique impact experiments have been performed using water droplets in normal gravity.

Merging parallel optics packaging and surface mount technologies

NASA Astrophysics Data System (ADS)

Kopp, Christophe; Volpert, Marion; Routin, Julien; Bernabé, Stéphane; Rossat, Cyrille; Tournaire, Myriam; Hamelin, Régis

2008-02-01

Optical links are well known to present significant advantages over electrical links for very high-speed data rate at 10Gpbs and above per channel. However, the transition towards optical interconnects solutions for short and very short reach applications requires the development of innovative packaging solutions that would deal with very high volume production capability and very low cost per unit. Moreover, the optoelectronic transceiver components must be able to move from the edge to anywhere on the printed circuit board, for instance close to integrated circuits with high speed IO. In this paper, we present an original packaging design to manufacture parallel optic transceivers that are surface mount devices. The package combines highly integrated Multi-Chip-Module on glass and usual IC ceramics packaging. The use of ceramic and the development of sealing technologies achieve hermetic requirements. Moreover, thanks to a chip scale package approach the final device exhibits a much minimized footprint. One of the main advantages of the package is its flexibility to be soldered or plugged anywhere on the printed circuit board as any other electronic device. As a demonstrator we present a 2 by 4 10Gbps transceiver operating at 850nm.

Repair strength dependence on solder protein concentration: a study in laser tissue-welding.

PubMed

Lauto, A

1998-01-01

A novel laser-activated solid solder has been coupled with a diode laser to investigate the dependence of the solder protein concentration on the tensile strength of the soldered tissues. The uncertainty of laser welding, due to the fluid glue, was overcome using the solid solder. Sixty-two severed rat tibial nerves and vas deferens were repaired using rectangular protein bands with two different albumin concentrations (58% and 68% by weight). The laser power (90 mW and 140 mW), dose (12.9 +/- 0.7 J/mg, mean +/- s.d.), and solder dimensions (thickness = 0.15 +/- 0.01 mm, surface area = 7.8 +/- 0.4 mm2) were kept constant during the operations. The laser welds with high protein solder concentration were significantly (P < 0.05) stronger (28 +/- 3.5 g) than the welds with low protein solder concentration (23 +/- 5 g). The average tensile strength of the laser soldered tissues increased as the protein solder concentration increased.

Solderability test system

DOEpatents

Yost, Fred; Hosking, Floyd M.; Jellison, James L.; Short, Bruce; Giversen, Terri; Reed, Jimmy R.

1998-01-01

A new test method to quantify capillary flow solderability on a printed wiring board surface finish. The test is based on solder flow from a pad onto narrow strips or lines. A test procedure and video image analysis technique were developed for conducting the test and evaluating the data. Feasibility tests revealed that the wetted distance was sensitive to the ratio of pad radius to line width (l/r), solder volume, and flux predry time.

Decomposition of Ag-based soldering alloys used in space maintainers after intra-oral exposure. A retrieval analysis study.

PubMed

Soteriou, Despo; Ntasi, Argyro; Papagiannoulis, Lisa; Eliades, Theodore; Zinelis, Spiros

2014-02-01

The aim of this study was to evaluate the elemental alterations of Ag soldering alloys used in space maintainers after intra-oral exposure. Twenty devices were fabricated by using two different soldering alloys; US (Dentaurum Universal Silver Solder, n = 10) and OS (Leone Orthodontic Solder, n = 10). All devices were manufactured by the same technician. Surface morphology and elemental quantitative analysis of the soldering alloys before and after intra-oral placement in patients was determined by scanning electron microscopy and energy-dispersive X-ray microanalysis (SEM/EDX). Statistical analysis was performed by t-test, Mann Whitney tests and Pearson's correlation. For all tests a 95% confidence level was used (α = 0.05). Both soldering alloys demonstrated substantially increase in surface roughness after intra-oral aging. Statistical analysis illustrated a significant decrease in the Cu and Zn content after treatment. OS demonstrated higher Cu release than US (p < 0.05). The remaining relative concentrations of Cu and Zn after the treatment did not show any correlation (p > 0.05) with intra-oral exposure time, apart from Zn in OS (r = 0.840, p = 0.04). Both soldering alloys demonstrated a significant Cu and Zn reduction after intra-oral exposure that may raise biocompatibility concerns.

Low thermal resistance power module assembly

DOEpatents

Hassani, Vahab; Vlahinos, Andreas; Bharathan, Desikan

2010-12-28

A power module assembly (400) with low thermal resistance and enhanced heat dissipation to a cooling medium. The assembly includes a heat sink or spreader plate (410) with passageways or openings (414) for coolant that extend through the plate from a lower surface (411) to an upper surface (412). A circuit substrate (420) is provided and positioned on the spreader plate (410) to cover the coolant passageways. The circuit substrate (420) includes a bonding layer (422) configured to extend about the periphery of each of the coolant passageways and is made up of a substantially nonporous material. The bonding layer (422) may be solder material which bonds to the upper surface (412) of the plate to provide a continuous seal around the upper edge of each opening (414) in the plate. The assembly includes power modules (430) mounted on the circuit substrate (420) on a surface opposite the bonding layer (422). The power modules (430) are positioned over or proximal to the coolant passageways.

Characterization of Low-Melting-Point Sn-Bi-In Lead-Free Solders

NASA Astrophysics Data System (ADS)

Li, Qin; Ma, Ninshu; Lei, YongPing; Lin, Jian; Fu, HanGuang; Gu, Jian

2016-11-01

Development of lead-free solders with low melting temperature is important for substitution of Pb-based solders to reduce direct risks to human health and the environment. In the present work, Sn-Bi-In solders were studied for different ratios of Bi and Sn to obtain solders with low melting temperature. The microstructure, thermal properties, wettability, mechanical properties, and reliability of joints with Cu have been investigated. The results show that the microstructures of the Sn-Bi-In solders were composed of β-Sn, Bi, and InBi phases. The intermetallic compound (IMC) layer was mainly composed of Cu6Sn5, and its thickness increased slightly as the Bi content was increased. The melting temperature of the solders was around 100°C to 104°C. However, when the Sn content exceeded 50 wt.%, the melting range became larger and the wettability became worse. The tensile strength of the solder alloys and solder joints declined with increasing Bi content. Two fracture modes (IMC layer fracture and solder/IMC mixed fracture) were found in solder joints. The fracture mechanism of solder joints was brittle fracture. In addition, cleavage steps on the fracture surface and coarse grains in the fracture structure were comparatively apparent for higher Bi content, resulting in decreased elongation for both solder alloys and solder joints.

Effect of soldering techniques and gap distance on tensile strength of soldered Ni-Cr alloy joint.

PubMed

Lee, Sang-Yeob; Lee, Jong-Hyuk

2010-12-01

The present study was intended to evaluate the effect of soldering techniques with infrared ray and gas torch under different gap distances (0.3 mm and 0.5 mm) on the tensile strength and surface porosity formation in Ni-Cr base metal alloy. Thirty five dumbbell shaped Ni-Cr alloy specimens were prepared and assigned to 5 groups according to the soldering method and the gap distance. For the soldering methods, gas torch (G group) and infrared ray (IR group) were compared and each group was subdivided by corresponding gap distance (0.3 mm: G3 and IR3, 0.5 mm: G5, IR5). Specimens of the experimental groups were sectioned in the middle with a diamond disk and embedded in solder blocks according to the predetermined distance. As a control group, 7 specimens were prepared without sectioning or soldering. After the soldering procedure, a tensile strength test was performed using universal testing machine at a crosshead speed 1 mm/min. The proportions of porosity on the fractured surface were calculated on the images acquired through the scanning electronic microscope. Every specimen of G3, G5, IR3 and IR5 was fractured on the solder joint area. However, there was no significant difference between the test groups (P > .05). There was a negative correlation between porosity formation and tensile strength in all the specimens in the test groups (P < .05). There was no significant difference in ultimate tensile strength of joints and porosity formations between the gas-oxygen torch soldering and infrared ray soldering technique or between the gap distance of 0.3 mm and 0.5 mm.

Effect of soldering techniques and gap distance on tensile strength of soldered Ni-Cr alloy joint

PubMed Central

Lee, Sang-Yeob

2010-01-01

PURPOSE The present study was intended to evaluate the effect of soldering techniques with infrared ray and gas torch under different gap distances (0.3 mm and 0.5 mm) on the tensile strength and surface porosity formation in Ni-Cr base metal alloy. MATERIALS AND METHODS Thirty five dumbbell shaped Ni-Cr alloy specimens were prepared and assigned to 5 groups according to the soldering method and the gap distance. For the soldering methods, gas torch (G group) and infrared ray (IR group) were compared and each group was subdivided by corresponding gap distance (0.3 mm: G3 and IR3, 0.5 mm: G5, IR5). Specimens of the experimental groups were sectioned in the middle with a diamond disk and embedded in solder blocks according to the predetermined distance. As a control group, 7 specimens were prepared without sectioning or soldering. After the soldering procedure, a tensile strength test was performed using universal testing machine at a crosshead speed 1 mm/min. The proportions of porosity on the fractured surface were calculated on the images acquired through the scanning electronic microscope. RESULTS Every specimen of G3, G5, IR3 and IR5 was fractured on the solder joint area. However, there was no significant difference between the test groups (P > .05). There was a negative correlation between porosity formation and tensile strength in all the specimens in the test groups (P < .05). CONCLUSION There was no significant difference in ultimate tensile strength of joints and porosity formations between the gas-oxygen torch soldering and infrared ray soldering technique or between the gap distance of 0.3 mm and 0.5 mm. PMID:21264189

Estimation of the Viscosities of Liquid Sn-Based Binary Lead-Free Solder Alloys

NASA Astrophysics Data System (ADS)

Wu, Min; Li, Jinquan

2018-01-01

The viscosity of a binary Sn-based lead-free solder alloy was calculated by combining the predicted model with the Miedema model. The viscosity factor was proposed and the relationship between the viscosity and surface tension was analyzed as well. The investigation result shows that the viscosity of Sn-based lead-free solders predicted from the predicted model shows excellent agreement with the reported values. The viscosity factor is determined by three physical parameters: atomic volume, electronic density, and electro-negativity. In addition, the apparent correlation between the surface tension and viscosity of the binary Sn-based Pb-free solder was obtained based on the predicted model.

Solderability test system

DOEpatents

Yost, F.; Hosking, F.M.; Jellison, J.L.; Short, B.; Giversen, T.; Reed, J.R.

1998-10-27

A new test method to quantify capillary flow solderability on a printed wiring board surface finish. The test is based on solder flow from a pad onto narrow strips or lines. A test procedure and video image analysis technique were developed for conducting the test and evaluating the data. Feasibility tests revealed that the wetted distance was sensitive to the ratio of pad radius to line width (l/r), solder volume, and flux predry time. 11 figs.

Wafer-to-wafer bonding of nonplanarized MEMS surfaces using solder

NASA Astrophysics Data System (ADS)

Sparks, D.; Queen, G.; Weston, R.; Woodward, G.; Putty, M.; Jordan, L.; Zarabadi, S.; Jayakar, K.

2001-11-01

The fabrication and reliability of a solder wafer-to-wafer bonding process is discussed. Using a solder reflow process allows vacuum packaging to be accomplished with unplanarized complementary metal-oxide semiconductor (CMOS) surface topography. This capability enables standard CMOS processes, and integrated microelectromechanical systems devices to be packaged at the chip-level. Alloy variations give this process the ability to bond at lower temperatures than most alternatives. Factors affecting hermeticity, shorts, Q values, shifting cavity pressure, wafer saw cleanliness and corrosion resistance will be covered.

Evaluation on Dorsey Method in Surface Tension Measurement of Solder Liquids Containing Surfactants

NASA Astrophysics Data System (ADS)

Zhao, Xingke; Xie, Feiming; Fan, Jinsheng; Liu, Dayong; Huang, Jihua; Chen, Shuhai

2018-06-01

With the purpose of developing a feasible approach for measuring the surface tension of solders containing surfactants, the surface tension of Sn-3Ag-0.5Cu-xP solder alloys, with various drop sizes as well as different phosphorus (P) content, was evaluated using the Dorsey method based on the sessile drop test. The results show that the accuracy of the surface tension calculations depends on both of sessile drop size and the liquid metal composition. With a proper drop size, in the range of 4.5 mm to 5.3 mm in equivalent spherical diameters, the deviation of the surface tension calculation can be limited to 1.43 mN·m-1 and 6.30 mN·m-1 for SnAgCu and SnAgCu-P, respectively. The surface tension of SnAgCu-xP solder alloys decreases quickly to a minimum value when the P content reaches 0.5 wt% and subsequently increases slowly with the P content further increasing. The formation of a P-enriched surface layer and Sn4P3 intermetallic phases is regarded to be responsible for the decreasing and subsequent increasing of surface tension, respectively.

Comparison of torsional stability of 2 types of split crimpable surgical hooks with soldered brass surgical hooks.

PubMed

O'Bannon, Shawn P; Dunn, William J; Lenk, Jason S

2006-10-01

The purpose of this in-vitro study was to compare the torsional stability of split crimpable surgical hooks and soldered brass surgical hooks on a rectangular stabilizing archwire. Coated split crimpable hooks (Never-Slip Grip, TP Orthodontics, LaPorte, Ind), ribbed crimpable hooks (TP Orthodontics), and .032-in brass soldered hooks/notched electrodes (Ormco/Sybron Dental Specialties, Orange, Calif) were attached to a 0.019 x 0.025-in stainless steel archwire. The archwire/hook attachment assembly was secured into a dual contact jig and statically mounted to the base of a universal testing machine. The hooks were engaged by a wire loop attached to the upper load cell of the machine, which pulled the wire until the hook was torsionally displaced from the archwire. The mean forces, measured in newtons (N), required to dislodge the hooks were as follows: soldered brass surgical hooks (51.3 +/- 5.2 N), coated split crimpable hooks (49.9 +/- 6.6 N), and ribbed split crimpable hooks (31.3 +/- 5.4 N). Data were analyzed with 1-way ANOVA and Tukey HSD post-hoc tests at alpha = .05. Ribbed split crimpable hooks provided significantly less resistance to torsional displacement than the other types of hooks (P <001). There was no difference between coated split crimpable hooks and soldered brass surgical hooks (P >05). Under the conditions of this study, the results suggest that soldered brass surgical hooks and coated split crimpable hook attachments provide more stability to torsional dislodgement from a rectangular stabilizing archwire than ribbed split crimpable hooks.

Impact of Isothermal Aging on Long-Term Reliability of Fine-Pitch Ball Grid Array Packages with Sn-Ag-Cu Solder Interconnects: Surface Finish Effects

NASA Astrophysics Data System (ADS)

Lee, Tae-Kyu; Ma, Hongtao; Liu, Kuo-Chuan; Xue, Jie

2010-12-01

The interaction between isothermal aging and the long-term reliability of fine-pitch ball grid array (BGA) packages with Sn-3.0Ag-0.5Cu (wt.%) solder ball interconnects was investigated. In this study, 0.4-mm fine-pitch packages with 300- μm-diameter Sn-Ag-Cu solder balls were used. Two different package substrate surface finishes were selected to compare their effects on the final solder composition, especially the effect of Ni, during thermal cycling. To study the impact on thermal performance and long-term reliability, samples were isothermally aged and thermally cycled from 0°C to 100°C with 10 min dwell time. Based on Weibull plots for each aging condition, package lifetime was reduced by approximately 44% by aging at 150°C. Aging at 100°C showed a smaller impact but similar trend. The microstructure evolution was observed during thermal aging and thermal cycling with different phase microstructure transformations between electrolytic Ni/Au and organic solderability preservative (OSP) surface finishes, focusing on the microstructure evolution near the package-side interface. Different mechanisms after aging at various conditions were observed, and their impacts on the fatigue lifetime of solder joints are discussed.

Direct-soldering 6061 aluminum alloys with ultrasonic coating.

PubMed

Ding, Min; Zhang, Pei-lei; Zhang, Zhen-yu; Yao, Shun

2010-02-01

In this study, the authors applied furnace soldering with ultrasonic coating method to solder 6061 aluminum alloy and investigated the effects of both coating time and soldering temperature on its properties. The following results were obtained: firstly, the solder region mainly composed of four kinds of microstructure zones: rich Sn zone, rich-Pb zone, Sn-Pb eutectic phase and rich Al zone. Meanwhile, the microanalysis identified a continuous reaction product at the alumina-solder interface as a rich-Pb zone. Therefore, the joint strength changed with soldering time and soldering temperature. Secondly, the tensile data had significantly greater variability, with values ranging from 13.99MPa to 24.74MPa. The highest value was obtained for the samples coated with Sn-Pb-Zn alloy for 45s. Fractures occurred along the solder-alumina interface for the 6061 aluminum alloy with its surface including hybrid tough fracture of dimple and tear ridge. The interface could initially strip at the rich Bi zone with the effect of shear stress.

A scanning electron microscopy study of CO2 laser-albumin soldering in the rabbit model.

PubMed

Levanon, Daniel; Katzir, Abraham; Ravid, Avi

2004-12-01

We sought to assess the rabbit as an experimental animal in the investigation of laser skin soldering. We studied, using the scanning electron microscope (SEM), the surface appearances of experimental incisions made on the rabbit back skin and soldered by CO(2) laser. Laser soldering of incisions in various tissues is a modality of wound healing of a very promising clinical value. At present, more component studies on animals directed at paving the way towards clinical protocols are needed. Surgical incisions on rabbits back skin were bonded using either albumin-assisted CO(2) laser soldering (experimental) or thread suturing (reference). The incisions closed were excised 2, 3, 4, and 5 days postoperatively, and skin surfaces were studied in the SEM. Naked eye inspection and SEM analysis showed that full-length sealing of soldered and sutured incisions was discernible as early as day 2. In the SEM, all incisions were found confluently coated by epidermal cells along the former cut streak. Soldering subserved to bond incisions efficiently, with surface smooth and close to normal skin. On the other hand, the surface of sutured incisions appeared convoluted and its aesthetic quality inferior to that of the former. Some of the days two and three soldered incisions suffered dehiscence on excision, which suggests an incomplete regeneration of tensile strength at this early phase of healing. Sutured incisions tolerated excision, very probably due to the microthread still present in the skin tissue rather than because of breaking strength regained during wound healing. Also, hair stumps re-grown on the skin by day 5 postoperative might impair satisfactory microscopy of bonded incisions. CO(2) laser soldering of incisions on the rabbit back skin effected rapid wound sealing and resulted in smooth scars indistinguishable from normal skin. The rabbit is well suited for this kind of studies, provided that excision of experimental cuts takes place not later than 5 days post-incision so that hair stumps may not grow large enough to jeopardize the quality of scanning electron microscopy.

Reduced impedance and superconductivity of SnAgCu solder alloy at high frequency

NASA Astrophysics Data System (ADS)

Yao, Wei; Basaran, Cemal

2012-10-01

Skin effect of lead-free solder joints is investigated over a wide frequency band. Contrary to common believe that `effective impedance of solder alloys increases with frequency', resistance tends to saturate when frequency reaches a critical value, 10 MHz for SAC solder alloys. Negative surface impedance growth rate is observed when employs square waveform AC current loading at high current density. Further increased frequency causes a dramatic reduction of effective resistance. At 11 MHz with current density of 106 A/cm2, effective resistance of solder alloy drops to near zero value.

A CTE matched hard solder passively cooled laser diode package combined with nXLT facet passivation enables high power, high reliability operation

NASA Astrophysics Data System (ADS)

Hodges, Aaron; Wang, Jun; DeFranza, Mark; Liu, Xingsheng; Vivian, Bill; Johnson, Curt; Crump, Paul; Leisher, Paul; DeVito, Mark; Martinsen, Robert; Bell, Jacob

2007-04-01

A conductively cooled laser diode package design with hard AuSn solder and CTE matched sub mount is presented. We discuss how this platform eliminates the failure mechanisms associated with indium solder. We present the problem of catastrophic optical mirror damage (COMD) and show that nLight's nXLT TM facet passivation technology effectively eliminates facet defect initiated COMD as a failure mechanism for both single emitter and bar format laser diodes. By combining these technologies we have developed a product that has high reliability at high powers, even at increased operation temperatures. We present early results from on-going accelerated life testing of this configuration that suggests an 808nm, 30% fill factor device will have a MTTF of more than 21khrs at 60W CW, 25°C operating conditions and a MTTF of more than 6.4khrs when operated under hard pulsed (1 second on, 1 second off) conditions.

Effect of soldering on the metal-ceramic bond strength of an Ni-Cr base alloy.

PubMed

Nikellis, Ioannis; Levi, Anna; Zinelis, Spiros

2005-11-01

Although soldering is a common laboratory procedure, the use of soldering alloys may adversely affect metal-ceramic bond strength and potentially decrease the longevity of metal-ceramic restorations. The purpose of this study was to investigate the effect of soldering on metal-ceramic bond strength of a representative Ni-Cr base metal alloy. Twenty-eight rectangular (25 x 3 x 0.5 mm) Ni-based alloy (Wiron 99) specimens were equally divided into soldering (S) and reference (R) groups. Soldering group specimens were covered with a 0.1-mm layer of the appropriate solder (Wiron-Lot) and reduced by 0.1 mm on the opposite side. Five specimens of each group were used for the measurement of surface roughness parameter (R(z)) and hardness, and 3 were used for measurement of the modulus of elasticity. Six specimens of each group were covered with porcelain (Ceramco 3) and subjected to a 3-point bending test for evaluation of the metal-ceramic bond strength according to the ISO 9693 specification. The data from surface roughness, hardness, modulus of elasticity, and metal-ceramic bond strength were analyzed statistically, using independent t tests (alpha=.05). Statistical analysis of the R(z) surface roughness parameter (S: 3.4 +/- 0.3 mum; R: 3.7 +/- 0.7 microm; P=.07) and bond strength (S: 46 +/- 3 MPa; R: 40 +/- 5 MPa; P=.057) failed to reveal any significant difference between the 2 groups. The specimens of the soldering group demonstrated significantly lower values both in hardness (S: 128 +/- 11 VHN; R: 217 +/- 4 VHN; P<.001) and in modulus of elasticity (S: 135 +/- 4 GPa; R: 183 +/- 6 GPa; P=.035) than the reference group. Under the conditions of the present study, the addition of solder to the base metal alloy did not affect the metal-ceramic bond strength.

Design and fabrication of lanthanum-doped tin-silver-copper lead-free solder for the next generation of microelectronics applications in severe environment

NASA Astrophysics Data System (ADS)

Sadiq, Muhammad

Tin-Lead solder (Sn-Pb) has long been used in the Electronics industry. But, due to its toxic nature and environmental effects, certain restrictions are made on its use by the European Rehabilitation of Hazardous Substances (RoHS) directive, and therefore, many researchers are looking to replace it. The urgent need for removing lead from solder alloys led to the very fast introduction of lead-free solder alloys without a deep knowledge of their behavior. Therefore, an extensive knowledge and understanding of the mechanical behavior of the emerging generation of lead-free solders is required to satisfy the demands of structural reliability. Sn-Ag-Cu (SAC) solders are widely used as lead-free replacements but their coarse microstructure and formation of hard and brittle Inter-Metallic Compounds (IMCs) have limited their use in high temperature applications. Many additives are studied to refine the microstructure and improve the mechanical properties of SAC solders including iron (Fe), bismuth (Bi), antimony (Sb) and indium (In) etc. Whereas many researchers studied the impact of novel rare earth (RE) elements like lanthanum (La), cerium (Ce) and lutetium (Lu) on SAC solders. These RE elements are known as “vitamins of metals” because of their special surface active properties. They reduce the surface free energy, refine the grain size and improve the mechanical properties of many lead free solder alloys like Sn-Ag, Sn-Cu and SAC but still a systematic study is required to explore the special effects of “La” on the eutectic SAC alloys. The objective of this PhD thesis is to extend the current knowledge about lead free solders of SAC alloys towards lanthanum doping with varying environmental conditions implemented during service. This thesis is divided into six main parts.

Conversion from solvent rinsable fluxes to aqueous rinsable fluxes for hot oil solder leveling

NASA Astrophysics Data System (ADS)

1992-03-01

A water rinsable flux was evaluated for hot oil solder leveling of printed wiring boards. The previously used rosin-activated flux required a solvent containing a chlorinated hydrocarbon for removing the flux residues after soldering. The water rinsable flux requires hot water or a solution of hot detergent for removing flux residues after smoldering. The water rinsable flux produced an acceptable soldered surface. Flux residues were removed by either hot water (120 F) or a solution of hot detergent (120 F).

Method for forming hermetic seals

NASA Technical Reports Server (NTRS)

Gallagher, Brian D.

1987-01-01

The firmly adherent film of bondable metal, such as silver, is applied to the surface of glass or other substrate by decomposing a layer of solution of a thermally decomposable metallo-organic deposition (MOD) compound such as silver neodecanoate in xylene. The MOD compound thermally decomposes into metal and gaseous by-products. Sealing is accomplished by depositing a layer of bonding metal, such as solder or a brazing alloy, on the metal film and then forming an assembly with another high melting point metal surface such as a layer of Kovar. When the assembly is heated above the temperature of the solder, the solder flows, wets the adjacent surfaces and forms a hermetic seal between the metal film and metal surface when the assembly cools.

Development of Cu Clad Cu-Zr Based Metallic Glass and Its Solderability

NASA Astrophysics Data System (ADS)

Terajima, Takeshi; Kimura, Hisamichi; Inoue, Akihisa

Soldering is a candidate technique for joining metallic glasses. It can be processed far below the crystallization temperatures of the various metallic glasses so that there is no possibility of crystallization. However, wettability of Cu-Zr based metallic glass by Pb free solder is poor because a strong surface oxide film interferes direct contact between them. To overcome the problem, Cu thin film clad metallic glass was developed. It was preliminary produced by casting a melt of Cu36Zr48Al8Ag8 pre-alloy into Cu mold cavity, inside which Cu thin film with 2 mm in thickness was set on the wall. Cu36Zr48Al8Ag8 metallic glass, whose surface Cu thin film was welded to, was successfully produced. From the microstructure analyses, it was found that reaction layer was formed at the interface between Cu and Cu36Zr48Al8Ag8 metallic glass, however, there was no oxide in the Cu clad layer. Solderability to the metallic glass was drastically increased. The Cu clad layer played an important role to prevent the formation of surface oxide film and consequently improved the solderability.

Die Soldering in Aluminium Die Casting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Q.; Kenik, E.A.; Viswanathan, S.

2000-03-15

Two types of tests, dipping tests and dip-coating tests were carried out on small steel cylinders using pure aluminum and 380 alloy to investigate the mechanism of die soldering during aluminum die casting. Optical and scanning electron microscopy were used to study the morphology and composition of the phases formed during soldering. A soldering mechanism is postulated based on experimental observations. A soldering critical temperature is postulated at which iron begins to react with aluminum to form an aluminum-rich liquid phase and solid intermetallic compounds. When the temperature at the die surface is higher than this critical temperature, the aluminum-richmore » phase is liquid and joins the die with the casting during the subsequent solidification. The paper discusses the mechanism of soldering for the case of pure aluminum and 380 alloy casting in a steel mold, the factors that promote soldering, and the strength of the bond formed when soldering occurs. conditions, an aluminum-rich soldering layer may also form over the intermetallic layer. Although a significant amount of research has been conducted on the nature of these intermetallics, little is known about the conditions under which soldering occurs.« less

Real-time wetting dynamics and interfacial chemistry in low-melting 57Bi-42Sn-1Ag solder paste on Ni-Au

NASA Astrophysics Data System (ADS)

Bozack, M. J.

2004-11-01

We report the observation of real-time, in situ, wetting and spreading dynamics for 57Bi-42Sn-1Ag solder paste on Ni-Au surfaces during melting in a scanning electron microscope. The 57Bi-42Sn-1Ag is a low melting (139 °C) Pb-free eutectic alloy currently under consideration by automobile manufacturers for use in instrument displays. We find that, while there is excellent wetting of 57Bi-42Sn-1Ag solder paste on Ni-Au, there is almost no spreading. A large amount of Bi segregates to the surface of 57Bi-42Sn-1Ag solder balls during the sintering process. At melting, excessive flux outgassing and pooling are observed, several melted solder balls float on top of the flux, and substantial elemental segregation occurs during the first minutes of wetting. Neither Ni nor Au fully intermixes throughout the alloy at the interface within seconds of wetting. Bi does not move outward with the expanding alloy front. This combination of detrimental effects forms voids in the solder paste, contributes to low reliability of solder joints, and complicates the materials science at the solder-substrate interface as shown by Auger electron spectroscopy. Reliability work in progress (3000 cycles) shows that 57Bi-42Sn-1Ag on Ni-Au is less reliable than eutectic Sn-37Pb on Ni-Au for 2512 chip resistors cycled from -40 to 125 °C.

Robust solder joint attachment of coaxial cable leads to piezoelectric ceramic electrodes.

PubMed

Vianco, P T

1993-01-01

A technique was developed for the solder attachment of coaxial cable leads to silver-bearing thick-film electrodes on piezoelectric ceramics. Soldering the cable leads directly to the thick film caused bonds with low mechanical strength due to poor solder joint geometry. A barrier coating of 1.5 mum Cu/1.5 mum Ni/1.0 mum Sn deposited on the thick-film layer improved the strength of the solder joints by eliminating the adsorption of Ag from the thick film, which was responsible for the improper solder joint geometry. The procedure does not require special preparation of the electrode surface and is cost effective due to the use of nonprecious metal films and the batch processing capabilities of the electron beam deposition technique.

Ab initio surface properties of Ag-Sn alloys: implications for lead-free soldering.

PubMed

Saleh, Gabriele; Xu, Chen; Sanvito, Stefano

2018-02-07

Ag and Sn are the major components of solder alloys adopted to assemble printed circuit boards. The qualities that make them the alloys of choice for the modern electronic industry are related to their physical and chemical properties. For corrosion resistance and solderability, surface properties are particularly important. Yet, atomic-level information about the surfaces of these alloys is not known. Here we fill this gap by presenting an extensive ab initio investigation of composition, energetics, structure and reactivity of Ag-Sn alloy surfaces. The structure and stability of various surfaces is evaluated, and the main factors determining the energetics of surface formation are uncovered. Oxygen and sulphur chemisorptions are studied and discussed in the framework of corrosion tendency, an important issue for printed circuit boards. Adsorption energy trends are rationalized based on the analysis of structural and electronic features.

Evaluation of Electrochemical Migration on Printed Circuit Boards with Lead-Free and Tin-Lead Solder

NASA Astrophysics Data System (ADS)

He, Xiaofei; Azarian, Michael H.; Pecht, Michael G.

2011-09-01

To evaluate the current leakage and electrochemical migration behavior on printed circuit boards with eutectic tin-lead and lead-free solder, IPC B-24 comb structures were exposed to 65°C and 88% relative humidity conditions under direct-current (DC) bias for over 1500 h. These boards were processed with either Sn-3.0Ag-0.5Cu solder or Sn-37Pb solder. In addition to solder alloy, board finish (organic solderability preservative versus lead-free hot air solder leveling), spacing (25 mil versus 12.5 mil), and voltage (40 V versus 5 V bias) were also assessed by using in situ measurements of surface insulation resistance (SIR) and energy-dispersive spectroscopy after testing. It was shown that an initial increase of SIR was caused by consumption of electroactive species on the surface, intermittent drops of SIR were caused by dendritic growth, and a long-term SIR decline was caused by electrodeposition of a metallic layer. The prolonged SIR decline of Sn-3.0Ag-0.5Cu boards was simulated by three-dimensional (3D) progressive and instantaneous nucleation models, whose predictions were compared with experimental data. Sn-37Pb boards exhibited comigration of Sn, Pb, and Cu, while Sn-3.0Ag-0.5Cu boards incurred comigration of Sn, Ag, and Cu. Among the migrated species, Sn always dominated and was observed as either a layer or in polyhedral deposits, Pb was the most common element found in the dendrites, Cu was a minor constituent, and Ag migrated only occasionally. Compared with solder alloy, board finishes played a secondary role in affecting SIR due to their complexation with or dissolution into the solder. The competing effect between electric field and spacing was also investigated.

Liver repair and hemorrhage control by using laser soldering of liquid albumin in a porcine model.

PubMed

Wadia, Y; Xie, H; Kajitani, M

2000-01-01

We evaluated laser soldering by using liquid albumin for welding liver injuries. Major liver trauma has a high mortality because of immediate exsanguination and a delayed morbidity from septicemia, peritonitis, biliary fistulae, and delayed secondary hemorrhage. Eight laceration (6 x 2 cm) and eight nonanatomic resection injuries (raw surface, 6 x 2 cm) were repaired. An 805-nm laser was used to weld 50% liquid albumin-indocyanine green solder to the liver surface, reinforcing it with a free autologous omental scaffold. The animals were heparinized and hepatic inflow occlusion was used for vascular control. All 16 soldering repairs were evaluated at 3 hours. All 16 laser mediated liver repairs had minimal blood loss as compared with the suture controls. No dehiscence, hemorrhage, or bile leakage was seen in any of the laser repairs after 3 hours. Laser fusion repair of the liver is a reliable technique to gain hemostasis on the raw surface as well as weld lacerations. Copyright 2000 Wiley-Liss, Inc.

Whisker Formation Induced by Component and Assembly Ionic Contamination

NASA Astrophysics Data System (ADS)

Snugovsky, Polina; Meschter, Stephan; Bagheri, Zohreh; Kosiba, Eva; Romansky, Marianne; Kennedy, Jeffrey

2012-02-01

This paper describes the results of an intensive whisker formation study on Pb-free assemblies with different levels of cleanliness. Thirteen types of as-received surface-mount and pin-through-hole components were cleaned and intentionally contaminated with solutions containing chloride, sulfate, bromide, and nitrate. Then the parts were assembled on double-sided boards that were also cleaned or intentionally contaminated with three fluxes having different halide contents. The assemblies were subjected to high-temperature/high-humidity testing (85°C/85% RH). Periodic examination found that contamination triggered whisker formation on both exposed tin and solder fillets. Whisker occurrence and parameters depending on the type and level of contamination are discussed. Cross-sections were used to assess the metallurgical aspects of whisker formation and the microstructural changes occurring during corrosion.

Influence of multi-walled carbon nanotubes on melting temperature and microstructural evolution of Pb-free Sn-5Sb/Cu solder joint

NASA Astrophysics Data System (ADS)

Dele-Afolabi, T. T.; Azmah Hanim, M. A.; Norkhairunnisa, M.; Suraya, M. T.; Yusoff, H. M.

2017-09-01

In this study, the effects of multi-walled carbon nanotubes on the melting temperature and microstructural evolution of the Sn-5Sb/Cu joints are evaluated. Plain and carbon nanotubes (CNTs) reinforced Sn-5Sb solder systems with solder formulations Sn-5Sb, Sn-5Sb-0.01CNT, Sn-5Sb-0.05CNT and Sn-5Sb-0.1CNT were prepared through the powder metallurgy route and thereafter samples were subjected to thermal and microstructural evaluation. As retrieved from the DSC scans, a slight decline in the peak temperature was observed in the composite solders which is indicative of the CNTs role in exciting surface instability in the host Sn matrix. In order to prepare the solder joints and analyze the interfacial intermetallic compound (IMC) evolution, respective solder systems were placed on copper (Cu) substrate and subjected to both reflow soldering and isothermal aging (170°C) conditions. From the IMC thickness result, considerable retardation in the IMC layer growth was observed in the CNTs reinforced solder joints, especially the 0.05wt.% CNTs solder system owing to the inhibition of Sn atoms diffusion by reinforcement material.

Soldering-induced Cu diffusion and intermetallic compound formation between Ni/Cu under bump metallization and SnPb flip-chip solder bumps

NASA Astrophysics Data System (ADS)

Huang, Chien-Sheng; Jang, Guh-Yaw; Duh, Jenq-Gong

2004-04-01

Nickel-based under bump metallization (UBM) has been widely used as a diffusion barrier to prevent the rapid reaction between the Cu conductor and Sn-based solders. In this study, joints with and without solder after heat treatments were employed to evaluate the diffusion behavior of Cu in the 63Sn-37Pb/Ni/Cu/Ti/Si3N4/Si multilayer structure. The atomic flux of Cu diffused through Ni was evaluated from the concentration profiles of Cu in solder joints. During reflow, the atomic flux of Cu was on the order of 1015-1016 atoms/cm2s. However, in the assembly without solder, no Cu was detected on the surface of Ni even after ten cycles of reflow. The diffusion behavior of Cu during heat treatments was studied, and the soldering-process-induced Cu diffusion through Ni metallization was characterized. In addition, the effect of Cu content in the solder near the solder/intermetallic compound (IMC) interface on interfacial reactions between the solder and the Ni/Cu UBM was also discussed. It is evident that the (Cu,Ni)6Sn5 IMC might form as the concentration of Cu in the Sn-Cu-Ni alloy exceeds 0.6 wt.%.

Laser-tissue soldering with biodegradable polymer films in vitro: film surface morphology and hydration effects.

PubMed

Sorg, B S; Welch, A J

2001-01-01

Previous research introduced the concept of using biodegradable polymer film reinforcement of a liquid albumin solder for improvement of the tensile strength of repaired incisions in vitro. In this study, the effect of creating small pores in the PLGA films on the weld breaking strength is studied. Additionally, the effect of hydration on the strength of the reinforced welds is investigated. A 50%(w/v) bovine serum albumin solder with 0.5 mg/mL Indocyanine Green dye was used to repair an incision in bovine aorta. The solder was coagulated with an 806-nm CW diode laser. A poly(DL-lactic-co-glycolic acid) (PLGA) film was used to reinforce the solder (the controls had solder but no reinforcement). Breaking strengths were measured acutely and after hydration in saline for 1 and 2 days. The data were analyzed by ANOVA (P < 0.05) and multiple comparisons of means were performed using the Newman-Keuls test. The creation of pores in the PLGA films qualitatively improved the film flexibility without having an apparent adverse effect on the breaking strength, while the actual technique of applying the film and solder had more of an effect. The acute maximum average breaking strengths of some of the film reinforced specimens (114.7 g-134.4 g) were significantly higher (P < 0.05) than the acute maximum average breaking strength of the unreinforced control specimens (68.3 g). Film reinforced specimens were shown to have a statistically significantly higher breaking strength than unreinforced controls after 1- and 2-day hydration. Reinforcement of liquid albumin solders in laser-assisted incision repair appears to have advantages over conventional methods that do not reinforce the cohesive strength of the solder in terms of acute breaking strength and after immersion in moist environments for short periods of time. Using a film with the solder applied to one surface only may be advantageous over other techniques.

Soldering of Carbon Materials Using Transition Metal Rich Alloys.

PubMed

Burda, Marek; Lekawa-Raus, Agnieszka; Gruszczyk, Andrzej; Koziol, Krzysztof K K

2015-08-25

Joining of carbon materials via soldering has not been possible up to now due to lack of wetting of carbons by metals at standard soldering temperatures. This issue has been a severely restricting factor for many potential electrical/electronic and mechanical applications of nanostructured and conventional carbon materials. Here we demonstrate the formation of alloys that enable soldering of these structures. By addition of several percent (2.5-5%) of transition metal such as chromium or nickel to a standard lead-free soldering tin based alloy we obtained a solder that can be applied using a commercial soldering iron at typical soldering temperatures of approximately 350 °C and at ambient conditions. The use of this solder enables the formation of mechanically strong and electrically conductive joints between carbon materials and, when supported by a simple two-step technique, can successfully bond carbon structures to any metal terminal. It has been shown using optical and scanning electron microscope images as well as X-ray diffraction patterns and energy dispersive X-ray mapping that the successful formation of carbon-solder bonds is possible, first, thanks to the uniform nonreactive dispersion of transition metals in the tin-based matrix. Further, during the soldering process, these free elements diffuse into the carbon-alloy border with no formation of brazing-like carbides, which would damage the surface of the carbon materials.

Effect of Electromigration on the Type of Drop Failure of Sn-3.0Ag-0.5Cu Solder Joints in PBGA Packages

NASA Astrophysics Data System (ADS)

Huang, M. L.; Zhao, N.

2015-10-01

Board-level drop tests of plastic ball grid array (PBGA) packages were performed in accordance with the Joint Electron Devices Engineering Council standard to investigate the effect of electromigration (EM) on the drop reliability of Sn-3.0Ag-0.5Cu solder joints with two substrate surface finishes, organic solderability preservative (OSP) and electroless nickel electroless palladium immersion gold (ENEPIG). In the as-soldered state, drop failures occurred at the substrate sides only, with cracks propagating within the interfacial intermetallic compound (IMC) layer for OSP solder joints and along the IMC/Ni-P interface for ENEPIG solder joints. The drop lifetime of OSP solder joints was approximately twice that of ENEPIG joints. EM had an important effect on crack formation and drop lifetime of the PBGA solder joints. ENEPIG solder joints performed better in drop reliability tests after EM, that is, the drop lifetime of ENEPIG joints decreased by 43% whereas that of OSP solder joints decreased by 91%, compared with the as-soldered cases. The more serious polarity effect, i.e., excessive growth of the interfacial IMC at the anode, was responsible for the sharper decrease in drop lifetime. The different types of drop failure of PBGA solder joints before and after EM, including the position of initiation and the propagation path of cracks, are discussed on the basis of the growth behavior of interfacial IMC.

Ultrasonic-assisted soldering of fine-grained 7034 aluminum alloy using Sn-Zn solders below 300°C.

PubMed

Guo, Weibing; Luan, Tianmin; He, Jingshan; Yan, Jiuchun

2018-01-01

The fine-grained Al alloys prefer to be soldered at as low as temperature to keep their mechanical properties. Solders of Sn-4Zn, Sn-9Zn, and Sn-20Zn alloys were used to solder fine-grained 7034 Al alloy pieces by ultrasonic-assisted soldering below 300°C in air. The joint using Sn-4Zn solder had the highest tensile strength of 201MPa and the fractures occurred in both β-Sn and Sn-Zn eutectic phases. Such joint was much stronger than the 1060 Al joint using Sn-4Zn solder, and its strength had approached the strength of 7034 Al joint using Zn-5Al solder. The strength of the joints using Sn-9Zn and Sn-20Zn solders dropped to∼160MPa due to the appearance of weak interfaces between η-Zn and eutectic phases in the bond layers. All the joints using Sn-Zn solders had very strong interfacial bonding, and alumina interlayers were identified at all the interfaces. Al dissolved in the bond layer reacted with the O rapidly to form alumina interlayers at the interfaces under the ultrasonic action. Zn segregated at the interface and formed strong bonds with both the Al terminated surface of alumina and the bond layer, resulting in strong interfacial bonding between Sn-Zn solders and Al alloys. Copyright © 2017 Elsevier B.V. All rights reserved.

Sn-Ag-Cu Nanosolders: Solder Joints Integrity and Strength

NASA Astrophysics Data System (ADS)

Roshanghias, Ali; Khatibi, Golta; Yakymovych, Andriy; Bernardi, Johannes; Ipser, Herbert

2016-08-01

Although considerable research has been dedicated to the synthesis and characterization of lead-free nanoparticle solder alloys, only very little has been reported on the reliability of the respective joints. In fact, the merit of nanoparticle solders with depressed melting temperatures close to the Sn-Pb eutectic temperature has always been challenged when compared with conventional solder joints, especially in terms of inferior solderability due to the oxide shell commonly present on the nanoparticles, as well as due to compatibility problems with common fluxing agents. Correspondingly, in the current study, Sn-Ag-Cu (SAC) nanoparticle alloys were combined with a proper fluxing vehicle to produce prototype nanosolder pastes. The reliability of the solder joints was successively investigated by means of electron microscopy and mechanical tests. As a result, the optimized condition for employing nanoparticles as a competent nanopaste and a novel procedure for surface treatment of the SAC nanoparticles to diminish the oxide shell prior to soldering are being proposed.

Low-stress soldering technique used to assemble an optical system for aerospace missions

NASA Astrophysics Data System (ADS)

Ribes-Pleguezuelo, P.; Koechlin, C.; Burkhardt, T.; Hornaff, M.; Kamm, A.; Gramens, S.; Beckert, E.; Fiault, G.; Eberhardt, R.; Tünnermann, A.

2017-09-01

A high-precision opto-mechanical breadboard for a lens mount has been assembled by means of a laserbased soldering process called Solderjet Bumping; which thanks to its localized and minimized input of thermal energy, is well suited for the joining of optical components made of fragile and brittle materials such as glasses. An optical element made of a silica lens and a titanium barrel has been studied to replicate the lens mounts of the afocal beam expander used in the LIDAR instrument (ATLID) of the ESA EarthCare Mission, whose aim is to monitor molecular and particle-based back-scattering in order to analyze atmosphere composition. Finally, a beam expander optical element breadboard with a silica lens and a titanium barrel was assembled using the Solderjet Bumping technology with Sn96.5Ag3Cu0.5 SAC305 alloy resulting in a low residual stress (<1 MPa) on the joining areas, a low light-depolarization (<0.2 %) and low distortion (wave-front error measurement < 5 nm rms) on the assemblies. The devices also successfully passed humidity, thermal-vacuum, vibration, and shock tests with conditions similar to the ones expected for the ESA EarthCare mission and without altering their optical performances.

Solder glass sealing technology for use in packaging of fiber optic sensors

NASA Astrophysics Data System (ADS)

Kreutzmann, Gerd

1990-08-01

The solder glass sealing technology is an alternative to the direct sealing method of the socalled hboptocansu. Using solder glass for the junction of glass and the metal can the temperature at about 500 °C does not destroy the optical quality of the precision glass components. The glass can also be coated with an antireflective layer and even the sealing of filterglass is possible. In cases where coupling losses can't be tolerated, the fiber has to be fed directly through the wall into the housing. Fiber feedthroughs, using solder glass for the sealing of the fiber into a metal tube, are commonly metal soldered or welded into the wall and the fiber surface is directly leading to the semiconductor.

Effect of Interfacial Microstructures on the Bonding Strength of Sn-3.0Ag-0.5Cu Pb-Free Solder Bump

NASA Astrophysics Data System (ADS)

Kim, Jae-Myeong; Jeong, Myeong-Hyeok; Yoo, Sehoon; Park, Young-Bae

2012-05-01

The effect of interfacial microstructures on the bonding strength of Sn-3.0Ag-0.5Cu Pb-free solder bumps with respect to the loading speed, annealing time, and surface finish was investigated. The shear strength increased and the ductility decreased with increasing shear speed, primarily because of the time-independent plastic hardening and time-dependent strain-rate sensitivity of the solder alloy. The shear strength and toughness decreased for all surface finishes under the high-speed shear test of 500 mm/s as a result of increasing intermetallic compound (IMC) growth and pad interface weakness associated with increased annealing time. The immersion Sn and organic solderability preservative (OSP) finishes showed lower shear strength compared to the electroless nickel immersion gold (ENIG) finish. With increasing annealing time, the ENIG finish exhibited the pad open fracture mode, whereas the immersion Sn and OSP finishes exhibited the brittle fracture mode. In addition, the shear strength of the solder joints was correlated with each fracture mode.

Comparative Study of ENIG and ENEPIG as Surface Finishes for a Sn-Ag-Cu Solder Joint

NASA Astrophysics Data System (ADS)

Yoon, Jeong-Won; Noh, Bo-In; Jung, Seung-Boo

2011-09-01

Interfacial reactions and joint reliability of Sn-3.0Ag-0.5Cu solder with two different surface finishes, electroless nickel-immersion gold (ENIG) and electroless nickel-electroless palladium-immersion gold (ENEPIG), were evaluated during a reflow process. We first compared the interfacial reactions of the two solder joints and also successfully revealed a connection between the interfacial reaction behavior and mechanical reliability. The Sn-Ag-Cu/ENIG joint exhibited a higher intermetallic compound (IMC) growth rate and a higher consumption rate of the Ni(P) layer than the Sn-Ag-Cu/ENEPIG joint. The presence of the Pd layer in the ENEPIG suppressed the growth of the interfacial IMC layer and the consumption of the Ni(P) layer, resulting in the superior interfacial stability of the solder joint. The shear test results show that the ENIG joint fractured along the interface, exhibiting indications of brittle failure possibly due to the brittle IMC layer. In contrast, the failure of the ENEPIG joint only went through the bulk solder, supporting the idea that the interface is mechanically reliable. The results from this study confirm that the Sn-Ag-Cu/ENEPIG solder joint is mechanically robust and, thus, the combination is a viable option for a Pb-free package system.

Electromigration induced high fraction of compound formation in SnAgCu flip chip solder joints with copper column

NASA Astrophysics Data System (ADS)

Xu, Luhua; Han, Jung-Kyu; Liang, Jarrett Jun; Tu, K. N.; Lai, Yi-Shao

2008-06-01

To overcome the effect of current crowding on electromigration-induced pancake-type void formation in flip chip solder joints, two types of Cu column in 90μm flip chip SnAgCu solder joints have been studied. They were (1) the solder contacts the Cu column at bottom and side walls and (2) the solder wets only the bottom surface of the copper column. With a current density of 1.6×104A/cm2 at 135°C, no failure was detected after 1290h. However, the resistance increased by about 10% due to the formation of a large fraction of intermetallic compounds. We found that electromigration has accelerated the consumption rate of copper column and converted almost the entire solder joint into intermetallic compound. Mechanically, drop impact test indicates a brittle fracture failure in the intermetallic. The electromigration critical product for the intermetallic is discussed.

Evaluating print performance of Sn-Ag-Cu lead-free solder pastes used in electronics assembly process

NASA Astrophysics Data System (ADS)

Mallik, S.; Bauer, R.; Hübner, F.; Ekere, N. N.

2011-01-01

Solder paste is the most widely used interconnection material in the electronic assembly process for attaching electronic components/devices directly onto the surface of printed circuit boards, using stencil printing process. This paper evaluates the performance of three different commercially available Sn-Ag-Cu solder pastes formulated with different particle size distributions (PSD), metal content and alloy composition. A series of stencil printing tests were carried out using a specially designed stencil of 75 μm thickness and apertures of 300×300 μm2 dimension and 500 μm pitch sizes. Solder paste printing behaviors were found related to attributes such as slumping and surface tension and printing performance was correlated with metal content and PSD. The results of the study should benefit paste manufacturers and SMT assemblers to improve their products and practices.

New Coating Technique of Ceramic Implants with Different Glass Solder Matrices for Improved Osseointegration-Mechanical Investigations.

PubMed

Mick, Enrico; Markhoff, Jana; Mitrovic, Aurica; Jonitz, Anika; Bader, Rainer

2013-09-11

Ceramics are a very popular material in dental implant technology due to their tribological properties, their biocompatibility and their esthetic appearance. However, their natural surface structure lacks the ability of proper osseointegration, which constitutes a crucial process for the stability and, thus, the functionality of a bone implant. We investigated the application of a glass solder matrix in three configurations-consisting mainly of SiO₂, Al₂O₃, K₂O and Na₂O to TZP-A ceramic specimens. The corresponding adhesive strength and surface roughness of the coatings on ceramic specimens have been analyzed. Thereby, high adhesive strength (70.3 ± 7.9 MPa) was found for the three different coatings. The obtained roughness (R z ) amounted to 18.24 ± 2.48 µm in average, with significant differences between the glass solder configurations. Furthermore, one configuration was also tested after additional etching which did not lead to significant increase of surface roughness (19.37 ± 1.04 µm) or adhesive strength (57.2 ± 5.8 MPa). In conclusion, coating with glass solder matrix seems to be a promising surface modification technique that may enable direct insertion of ceramic implants in dental and orthopaedic surgery.

Simple, low-cost fabrication of semi-circular channel using the surface tension of solder paste and its application to microfluidic valves.

PubMed

Yan, Sheng; Li, Yuxing; Zhu, Yuanqing; Liu, Minsu; Zhao, Qianbin; Yuan, Dan; Yun, Guolin; Zhang, Shiwu; Wen, Weijia; Tang, Shi-Yang; Li, Weihua

2018-06-01

This work presents a simple, low-cost method to fabricate semi-circular channels using solder paste, which can amalgamate the cooper surface to form a half-cylinder mold using the surface tension of Sn-Pd alloy (the main component in solder paste). This technique enables semi-circular channels to be manufactured with different dimensions. These semi-circular channels will then be integrated with a polymethylmethacrylate frame and machine screws to create miniaturized, portable microfluidic valves for sequential liquid delivery and particle synthesis. This approach avoids complicated fabrication processes and expensive facilities and thus has the potential to be a useful tool for lab-on-a-chip applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method and apparatus for jetting, manufacturing and attaching uniform solder balls

DOEpatents

Yost, F.G.; Frear, D.R.; Schmale, D.T.

1999-01-05

An apparatus and process are disclosed for jetting molten solder in the form of balls directly onto all the metallized interconnects lands for a ball grid array package in one step with no solder paste required. Molten solder is jetted out of a grid of holes using a piston attached to a piezoelectric crystal. When voltage is applied to the crystal it expands forcing the piston to extrude a desired volume of solder through holes in the aperture plate. When the voltage is decreased the piston reverses motion creating an instability in the molten solder at the aperture plate surface and thereby forming spherical solder balls that fall onto a metallized substrate. The molten solder balls land on the substrate and form a metallurgical bond with the metallized lands. The size of the solder balls is determined by a combination of the size of the holes in the aperture plate, the duration of the piston pulse, and the displacement of the piston. The layout of the balls is dictated by the location of the hooks in the grid. Changes in ball size and layout can be easily accomplished by changing the grid plate. This invention also allows simple preparation of uniform balls for subsequent supply to BGA users. 7 figs.

Method and apparatus for jetting, manufacturing and attaching uniform solder balls

DOEpatents

Yost, Frederick G.; Frear, Darrel R.; Schmale, David T.

1999-01-01

An apparatus and process for jetting molten solder in the form of balls directly onto all the metallized interconnects lands for a ball grid array package in one step with no solder paste required. Molten solder is jetted out of a grid of holes using a piston attached to a piezoelectric crystal. When voltage is applied to the crystal it expands forcing the piston to extrude a desired volume of solder through holes in the aperture plate. When the voltage is decreased the piston reverses motion creating an instability in the molten solder at the aperture plate surface and thereby forming spherical solder balls that fall onto a metallized substrate. The molten solder balls land on the substrate and form a metallurgical bond with the metallized lands. The size of the solder balls is determined by a combination of the size of the holes in the aperture plate, the duration of the piston pulse, and the displacement of the piston. The layout of the balls is dictated by the location of the hooks in the grid. Changes in ball size and layout can be easily accomplished by changing the grid plate. This invention also allows simple preparation of uniform balls for subsequent supply to BGA users.

Sutureless liver repair and hemorrhage control using laser-mediated fusion of human albumin as a solder.

PubMed

Wadia, Y; Xie, H; Kajitani, M

2001-07-01

Major liver trauma has a high mortality because of immediate exsanguination and a delayed morbidity from septicemia, peritonitis, biliary fistulae, and delayed secondary hemorrhage. We evaluated laser soldering using liquid albumin for welding liver injuries. Fourteen lacerations (6 x 2 cm) and 13 nonanatomic resection injuries (raw surface, 8 x 2 cm) were repaired. An 805-nm laser was used to weld 53% liquid albumin-indocyanine green solder to the liver surface, reinforcing it by welding a free autologous omental scaffold. The animals were heparinized and hepatic inflow occlusion was used for vascular control. For both laceration and resection injuries, 16 soldering repairs were evaluated acutely at 3 hours. Eleven animals were evaluated chronically, two at 2 weeks and nine at 4 weeks. All 27 laser mediated-liver repairs had minimal blood loss compared with the suture controls. No dehiscence, hemorrhage, or bile leakage was seen in any of the laser repairs after 3 hours. All 11 chronic repairs healed without complication. This modality effectively seals the liver surface, joins lacerations with minimal thermal injury, and works independently of the patient's coagulation status.

Effects of soldering methods on tensile strength of a gold-palladium metal ceramic alloy.

PubMed

Ghadhanfari, Husain A; Khajah, Hasan M; Monaco, Edward A; Kim, Hyeongil

2014-10-01

The tensile strength obtained by conventional postceramic application soldering and laser postceramic welding may require more energy than microwave postceramic soldering, which could provide similar tensile strength values. The purpose of the study was to compare the tensile strength obtained by microwave postceramic soldering, conventional postceramic soldering, and laser postceramic welding. A gold-palladium metal ceramic alloy and gold-based solder were used in this study. Twenty-seven wax specimens were cast in gold-palladium noble metal and divided into 4 groups: laser welding with a specific postfiller noble metal, microwave soldering with a postceramic solder, conventional soldering with the same postceramic solder used in the microwave soldering group, and a nonsectioned control group. All the specimens were heat treated to simulate a normal porcelain sintering sequence. An Instron Universal Testing Machine was used to measure the tensile strength for the 4 groups. The means were analyzed statistically with 1-way ANOVA. The surface and fracture sites of the specimens were subjectively evaluated for fracture type and porosities by using a scanning electron microscope. The mean (standard deviation) ultimate tensile strength values were as follows: nonsectioned control 818 ±30 MPa, microwave 516 ±34 MPa, conventional 454 ±37 MPa, and laser weld 191 ±39 MPa. A 1-way ANOVA showed a significant difference in ultimate tensile strength among the groups (F3,23=334.5; P<.001). Follow-up multiple comparisons showed a significant difference among all the groups. Microwave soldering resulted in a higher tensile strength for gold and palladium noble metals than either conventional soldering or laser welding. Conventional soldering resulted in a higher tensile strength than laser welding. Under the experimental conditions described, either microwave or conventional postceramic soldering would appear to satisfy clinical requirements related to tensile strength. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Bond strength of luting cement to casting and soldering alloy.

PubMed

Kumbuloglu, O; Lassila, L V J; User, A; Toksavul, S; Vallittu, P K

2006-03-01

Adjustment of metal alloy framework of the porcelain-fused-to-metal crown by soldering minor marginal deficiences prior insertion may sometimes be needed. The aim of this study was to compare shear bond strengths of four luting cements to casting metal alloy and soldering metal alloy. A total of 64 flame cast non-precious metal alloy and flame soldered metal alloy samples were used. Durelon, Panavia F, RelyX Unicem Applicap and RelyX ARC stubs were bonded to the alloy substrate surface. After stored in water at 37 degrees C for 1 week, shear bond strength of the cement to the alloy was measured. Differences were analyzed using one way ANOVA (p<0.05). There were no difference between the cast metal alloy and soldering metal alloy substrate.

A review on solder reflow and flux application for flip chip

NASA Astrophysics Data System (ADS)

Suppiah, Sarveshvaran; Ong, Nestor Rubio; Sauli, Zaliman; Sarukunaselan, Karunavani; Alcain, Jesselyn Barro; Visvanathan, Susthitha Menon; Retnasamy, Vithyacharan

2017-09-01

This paper encompassed of the evolution and key findings, critical technical challenges, solutions and bonding equipment of solder reflow in flip chip bonding. Upon scrutinizing researches done by others, it can be deduced that peak temperature, time above liquidus, soak temperature, soak time, cooling rate and reflow environment played a vital role in achieving the desired bonding profile. In addition, flux is also needed with the purpose of removing oxides/contaminations on bump surface as well as to promote wetting of solder balls. Electromigration and warpage are the two main challenges faced by solder reflow process which can be overcome by the advancement in under bump metallization (UBM) and substrate technology. The review is ended with a brief description of the current equipment used in solder reflow process.

Synthesis and characterization of lead-free tin silver nanosolders and their application to halogen free nanosolder pastes

NASA Astrophysics Data System (ADS)

Wernicki, Evan

Solder paste is a key material used in attaching electronic components to printed circuit boards (PCBs). Commonly used lead-based solders, such as eutectic Sn/37Pb, are currently being replaced by lead-free alloy materials due to health and environmental concerns associated with lead. Many solder pastes, both lead-containing and lead-free, contain halogens which act as activators to remove surface oxide and enhance surface wetting, posing further environmental concern from the halogen species. Difficulties in obtaining reliable joints can occur since lead-free solder material candidates have higher melting temperatures (30-50 °C) than that of lead-based solders. Differences in material properties between the numerous materials used in assembly and packaging processes can lead to component damage during manufacturing. Furthermore, designs that include more electrical interconnects in smaller areas give rise for the need for new materials to allow this trend to continue. A surfactant-assisted chemical reduction method was used to synthesize Sn/Ag alloy nanoparticles with a target composition range of 3.5-5 wt% Ag that served as the lead-free solder material within a nanosolder paste. Structure and size characterization via SEM and TEM showed Sn-Ag nanosolders size average approximately 19 nm. Differential scanning calorimetry (DSC) measurements of the nanosolder samples containing 4.5 wt% Ag showed an endothermic peak at 222.5 °C and an onset of 219.2 °C, indicating up to 17.5 °C melting temperature depression when compared to the bulk liquidus value of 240 °C. Composition of the nanosolder material was confirmed using energy dispersive x-ray spectroscopy (EDS) and structures formed were analyzed via x-ray diffraction (XRD). Both halogen-free and halogen-containing flux materials were combined with the nanosolder material, respectively, with varying preparation parameters to form a design of experiments (DoE) for nanosolder paste preparation. Solder pastes prepared with 55, 70, and 85 wt% nanosolder material have been successfully printed and reflowed on Cu substrates to imitate current manufacturing process. Different peak reflow temperatures of 245 °C and 265 °C were used to observe the effect on solder paste spreading and wetting angle of reflowed solder features. Two different flux chemistries, halogen-free and halogen-based, were also studied. Statistical analysis indicated nanosolder loading had a strong impact on both the wetting angle and paste spreading after the reflow process. The wetting angles of the samples, from the highest to lowest weight percentage, resulted in values of 69.7°, 26.2°, and 0°. A 55 wt% nanosolder paste formed multiple reflowed solder bumps, compared to the single bumps obtained with 70 and 85 wt% nanosolders. The highest loading sample was found to spread the least. This can be attributed to a combination of factors such as higher paste viscosity and lower solder-solder surface tension interactions. A larger peak temperature resulted in larger paste spreading values proving to be significant, however it was not found to affect the resulting wetting angle significantly. Flux chemistry was found to statistically have no profound impact on either the wetting angle or the solder spread. Therefore, it was found that the halogen-free solder paste can act as a suitable replacement for the tested halogen-containing nanosolder paste samples. KEYWORDS : solder paste, nanoparticles, paste printing, lead-free, reflow.

Solder extrusion pressure bonding process and bonded products produced thereby

DOEpatents

Beavis, Leonard C.; Karnowsky, Maurice M.; Yost, Frederick G.

1992-01-01

Production of soldered joints which are highly reliable and capable of surviving 10,000 thermal cycles between about -40.degree. C. and 110.degree. C. Process involves interposing a thin layer of a metal solder composition between the metal surfaces of members to be bonded and applying heat and up to about 1000 psi compression pressure to the superposed members, in the presence of a reducing atmosphere, to extrude the major amount of the solder composition, contaminants including fluxing gases and air, from between the members being bonded, to form a very thin, strong intermetallic bonding layer having a thermal expansion tolerant with that of the bonded members.

Solder extrusion pressure bonding process and bonded products produced thereby

NASA Astrophysics Data System (ADS)

Beavis, L. C.; Karnowsky, M. M.; Yost, F. G.

1990-04-01

The production of soldered joints are highly reliable and capable of surviving 10,000 thermal cycles between about -40 and 110 C. The process involves interposing a thin layer of a metal solder composition between the metal surfaces of members to be bonded and applying heat up to about 1000 psi compression pressure to the superposed members, in the presence of a reducing atmosphere, to extrude the major amount of the solder composition, contaminants including fluxing gases and air, from between the members being bonded, to form a very thin, strong intermetallic bonding layer having a thermal expansion tolerant with that of the bonded members.

Capacitor bonding techniques and reliability. [thermal cycling tests

NASA Technical Reports Server (NTRS)

Kinser, D. L.; Graff, S. M.; Allen, R. V.; Caruso, S. V.

1974-01-01

The effect of thermal cycling on the mechanical failure of bonded ceramic chip capacitors mounted on alumina substrates is studied. It is shown that differential thermal expansion is responsible for the cumulative effects which lead to delayed failure of the capacitors. Harder or higher melting solders are found to be less susceptible to thermal cycling effects, although they are more likely to fail during initial processing operations.

Influence of Co and W powders on viscosity of composite solders during soldering of specially shaped diamond-abrasive tools

NASA Astrophysics Data System (ADS)

Sokolov, E. G.; Aref’eva, S. A.; Svistun, L. I.

2018-03-01

The influence of Co and W powders on the structure and the viscosity of composite solders Sn-Cu-Co-W used for the manufacture of the specially shaped diamond tools has been studied. The solders were obtained by mixing the metallic powders with an organic binder. The mixtures with and without diamonds were applied to steel rollers and shaped substrates. The sintering was carried out in a vacuum at 820 ° C with time-exposure of 40 minutes. The influence of Co and W powders on the viscosity solders was evaluated on the basis of the study of structures and according to the results of sintering specially shaped diamond tools. It was found that to provide the necessary viscosity and to obtain the uniform diamond-containing layers on the complex shaped surfaces, Sn-Cu-Co-W solder should contain 27–35 vol % of solid phase. This is achieved with a total solder content of 24–32 wt % of cobalt powder and 7 wt % of tungsten powder.

Effects of soldering and laser welding on bond strength of ceramic to metal.

PubMed

Aladağ, Akin; Cömlekoğlu, M Erhan; Dündar, Mine; Güngör, M Ali; Artunç, Celal

2011-01-01

Welding or soldering of metal frameworks negatively affects the overall bond strength between the veneering ceramic and metal. The purpose of this study was to evaluate the effect of soldering and laser-welding procedures on the bond strength between ceramic and metal. Thirty Ni-based metal specimens (Wiron 99) (8 × 4 × 4 mm) were fabricated and divided into 3 groups; soldered (S), laser welded (L), and control (untreated cast alloy) (n=10). In S and L specimens, a notch (1 × 1.5 mm) was prepared longitudinally on the surface of each specimen and filled with compatible alloy (Wiron soldering rods and Wiroweld NC, respectively). Vickers hardness measurements were made after polishing the surfaces with a metallographic polishing kit. A veneering ceramic (VITA VMK 95) was vibrated, condensed in a mold, and fired on the metal frameworks. The specimens were sectioned in 2 axes to obtain nontrimmed bar specimens with a bonding area of approximately 1 mm². Forty bars per block were obtained. Each bar was subjected to microtensile bond strength (μTBS) testing with a crosshead speed of 1 mm/min. The μTBS data (MPa) were recorded, and SEM was used for failure analysis of the tested bars. The measurements were statistically analyzed using a 1-way ANOVA and Tamhane tests (α=.05). The mean differences in μTBS of veneering ceramic to soldered (10.4 ±2.4 MPa) and laser-welded (11.7 ±1.3 MPa) metal surfaces were not significantly different and were significantly lower than that of the cast alloy (25.4 ±3.6 MPa) (P<.05). The mean Vickers hardness of cast alloy was significantly higher (236 ±17 HV) than soldered (114 ±9 HV) and laser-welded groups (129 ±11 HV) (P<.05). Soldering and laser welding significantly decreased the μTBS of a veneering ceramic to a base metal alloy. Copyright © 2011 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Intermetallic Compound Growth between Electroless Nickel/Electroless Palladium/Immersion Gold Surface Finish and Sn-3.5Ag or Sn-3.0Ag-0.5Cu Solder

NASA Astrophysics Data System (ADS)

Oda, Yukinori; Fukumuro, Naoki; Yae, Shinji

2018-04-01

Using an electroless nickel/electroless palladium/immersion gold (ENEPIG) surface finish with a thick palladium-phosphorus (Pd-P) layer of 1 μm, the intermetallic compound (IMC) growth between the ENEPIG surface finish and lead-free solders Sn-3.5Ag (SA) or Sn-3.0Ag-0.5Cu (SAC) after reflow soldering and during solid-state aging at 150°C was investigated. After reflow soldering, in the SA/ENEPIG and SAC/ENEPIG interfaces, thick PdSn4 layers of about 2 μm to 3 μm formed on the residual Pd-P layers ( 0.5 μm thick). On the SA/ENEPIG interface, Sn was detected on the upper side of the residual Pd-P layer. On the SAC/ENEPIG interface, no Sn was detected in the residual Pd-P layer, and Cu was detected in the interface between the Pd-P and PdSn4 layers. After 300 h of aging at 150°C, the residual Pd-P layers had diffused completely into the solders. In the SA/ENEPIG interface, an IMC layer consisting of Ni3Sn4 and Ni3SnP formed between the PdSn4 layer and the nickel-phosphorus (Ni-P) layer, and a (Pd,Ni)Sn4 layer formed on the lower side of the PdSn4 layer. On the SAC/ENEPIG interface, a much thinner (Pd,Ni)Sn4 layer was observed, and a (Cu,Ni)6Sn5 layer was observed between the PdSn4 and Ni-P layers. These results indicate that Ni diffusion from the Ni-P layer to the PdSn4 layer produced a thick (Pd,Ni)Sn4 layer in the SA solder case, but was prevented by formation of (Cu,Ni)6Sn5 in the SAC solder case. This causes the difference in solder joint reliability between SA/ENEPIG and SAC/ENEPIG interfaces in common, thin Pd-P layer cases.

METHOD FOR JOINING ALUMINUM TO STAINLESS STEEL

DOEpatents

Lemon, L.C.

1960-05-24

Aluminum may be joined to stainless steel without the use of flux by tinning the aluminum with a tin solder containing 1% silver and 1% lead, tinning the stainless steel with a 50% lead 50% tin solder, and then sweating the tinned surfaces together.

Effect of surface finish on the failure mechanisms of flip-chip solder joints under electromigration

NASA Astrophysics Data System (ADS)

Lin, Y. L.; Lai, Y. S.; Tsai, C. M.; Kao, C. R.

2006-12-01

Two substrate surface finishes, Au/Ni and organic solderable preservative (OSP), were used to study the effect of the surface finish on the reliability of flip-chip solder joints under electromigration at 150°C ambient temperature. The solder used was eutectic PbSn, and the applied current density was 5×103 A/cm2 at the contact window of the chip. The under bump metallurgy (UBM) on the chip was sputtered Cu/Ni. It was found that the mean-time-to-failure (MTTF) of the OSP joints was six times better than that of the Au/Ni joints (3080 h vs. 500 h). Microstructure examinations uncovered that the combined effect of current crowding and the accompanying local Joule heating accelerated the local Ni UBM consumption near the point of electron entrance. Once Ni was depleted at a certain region, this region became nonconductive, and the flow of the electrons was diverted to the neighboring region. This neighboring region then became the place where electrons entered the joint, and the local Ni UBM consumption was accelerated. This process repeated itself, and the Ni-depleted region extended further on, creating an ever-larger nonconductive region. The solder joint eventually, failed when the nonconductive region became too large, making the effective current density very high. Accordingly, the key factor determining the MTTF was the Ni consumption rate. The joints with the OSP surface finish had a longer MTTF because Cu released from the substrate was able to reduce the Ni consumption rate.

Morphology and Shear Strength of Lead-Free Solder Joints with Sn3.0Ag0.5Cu Solder Paste Reinforced with Ceramic Nanoparticles

NASA Astrophysics Data System (ADS)

Yakymovych, A.; Plevachuk, Yu.; Švec, P.; Švec, P.; Janičkovič, D.; Šebo, P.; Beronská, N.; Roshanghias, A.; Ipser, H.

2016-12-01

To date, additions of different oxide nanoparticles is one of the most widespread procedures to improve the mechanical properties of metals and metal alloys. This research deals with the effect of minor ceramic nanoparticle additions (SiO2, TiO2 and ZrO2) on the microstructure and mechanical properties of Cu/solder/Cu joints. The reinforced Sn3.0Ag0.5Cu (SAC305) solder alloy with 0.5 wt.% and 1.0 wt.% of ceramic nanoparticles was prepared through mechanically stirring. The microstructure of as-solidified Cu/solder/Cu joints was studied using scanning electron microscopy. The additions of ceramic nanoparticles suppressed the growth of the intermetallic compound layer Cu6Sn5 at the interface solder/Cu and improved the microstructure of the joints. Furthermore, measurements of mechanical properties showed improved shear strength of Cu/composite solder/Cu joints compared to joints with unreinforced solder. This fact related to all investigated ceramic nanoinclusions and should be attributed to the adsorption of nanoparticles on the grain surface during solidification. However, this effect is less pronounced on increasing the nanoinclusion content from 0.5 wt.% to 1.0 wt.% due to agglomeration of nanoparticles. Moreover, a comparison analysis showed that the most beneficial influence was obtained by minor additions of SiO2 nanoparticles into the SAC305 solder alloy.

Liver repair and hemorrhage control using laser soldering of liquid albumin in a porcine model

NASA Astrophysics Data System (ADS)

Wadia, Yasmin; Xie, Hua; Kajitani, Michio; Gregory, Kenton W.; Prahl, Scott A.

2000-05-01

The purpose of this study was to evaluate laser soldering using liquid albumin for welding liver lacerations and sealing raw surfaces created by segmental resection of a lobe. Major liver trauma has a high mortality due to immediate exsanguination and a delayed morbidity and mortality from septicemia, peritonitis, biliary fistulae and delayed secondary hemorrhage. Eight laceration injuries (6 cm long X 2 cm deep) and eight non-anatomical resection injuries (raw surface 6 cm X 2 cm) were repaired. An 805 nm laser was used to weld 53% liquid albumin-ICG solder to the liver surface, reinforcing it with a free autologous omental scaffold. The animals were heparinized to simulate coagulation failure and hepatic inflow occlusion was used for vascular control. For both laceration and resection injuries, eight soldering repairs each were evaluated at three hours. A single suture repair of each type was evaluated at three hours. All 16 laser mediated liver repairs were accompanied by minimal blood loss as compared to the suture controls. No dehiscence, hemorrhage or bile leakage was seen in any of the laser repairs after three hours. In conclusion laser fusion repair of the liver is a quick and reliable technique to gain hemostasis on the cut surface as well as weld lacerations.

Surface Modifications of Dental Ceramic Implants with Different Glass Solder Matrices: In Vitro Analyses with Human Primary Osteoblasts and Epithelial Cells

PubMed Central

Mick, Enrico

2014-01-01

Ceramic materials show excellent esthetic behavior, along with an absence of hypersensitivity, making them a possible alternative implant material in dental surgery. However, their surface properties enable only limited osseointegration compared to titanium implants. Within this study, a novel surface coating technique for enhanced osseointegration was investigated biologically and mechanically. Specimens of tetragonal zirconia polycrystal (TZP) and aluminum toughened zirconia (ATZ) were modified with glass solder matrices in two configurations which mainly consisted of SiO2, Al2O3, K2O, and Na2O. The influence on human osteoblastic and epithelial cell viability was examined by means of a WST-1 assay as well as live/dead staining. A C1CP-ELISA was carried out to verify procollagen type I production. Uncoated/sandblasted ceramic specimens and sandblasted titanium surfaces were investigated as a reference. Furthermore, mechanical investigations of bilaterally coated pellets were conducted with respect to surface roughness and adhesive strength of the different coatings. These tests could demonstrate a mechanically stable implant coating with glass solder matrices. The coated ceramic specimens show enhanced osteoblastic and partly epithelial viability and matrix production compared to the titanium control. Hence, the new glass solder matrix coating could improve bone cell growth as a prerequisite for enhanced osseointegration of ceramic implants. PMID:25295270

Surface modifications of dental ceramic implants with different glass solder matrices: in vitro analyses with human primary osteoblasts and epithelial cells.

PubMed

Markhoff, Jana; Mick, Enrico; Mitrovic, Aurica; Pasold, Juliane; Wegner, Katharina; Bader, Rainer

2014-01-01

Ceramic materials show excellent esthetic behavior, along with an absence of hypersensitivity, making them a possible alternative implant material in dental surgery. However, their surface properties enable only limited osseointegration compared to titanium implants. Within this study, a novel surface coating technique for enhanced osseointegration was investigated biologically and mechanically. Specimens of tetragonal zirconia polycrystal (TZP) and aluminum toughened zirconia (ATZ) were modified with glass solder matrices in two configurations which mainly consisted of SiO2, Al2O3, K2O, and Na2O. The influence on human osteoblastic and epithelial cell viability was examined by means of a WST-1 assay as well as live/dead staining. A C1CP-ELISA was carried out to verify procollagen type I production. Uncoated/sandblasted ceramic specimens and sandblasted titanium surfaces were investigated as a reference. Furthermore, mechanical investigations of bilaterally coated pellets were conducted with respect to surface roughness and adhesive strength of the different coatings. These tests could demonstrate a mechanically stable implant coating with glass solder matrices. The coated ceramic specimens show enhanced osteoblastic and partly epithelial viability and matrix production compared to the titanium control. Hence, the new glass solder matrix coating could improve bone cell growth as a prerequisite for enhanced osseointegration of ceramic implants.

Vacuum encapsulated, high temperature diamond amplified cathode capsule and method for making same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rao, Triveni; Walsh, Josh; Gangone, Elizabeth

2015-12-29

A vacuum encapsulated, hermetically sealed cathode capsule for generating an electron beam of secondary electrons, which generally includes a cathode element having a primary emission surface adapted to emit primary electrons, an annular insulating spacer, a diamond window element comprising a diamond material and having a secondary emission surface adapted to emit secondary electrons in response to primary electrons impinging on the diamond window element, a first high-temperature solder weld disposed between the diamond window element and the annular insulating spacer and a second high-temperature solder weld disposed between the annular insulating spacer and the cathode element. The cathode capsulemore » is formed by a high temperature weld process under vacuum such that the first solder weld forms a hermetical seal between the diamond window element and the annular insulating spacer and the second solder weld forms a hermetical seal between the annular spacer and the cathode element whereby a vacuum encapsulated chamber is formed within the capsule.« less

Enhancement of Sn-Bi-Ag Solder Joints with ENEPIG Surface Finish for Low-Temperature Interconnection

NASA Astrophysics Data System (ADS)

Pun, Kelvin P. L.; Islam, M. N.; Rotanson, Jason; Cheung, Chee-wah; Chan, Alan H. S.

2018-05-01

Low-temperature soldering constitutes a promising solution in interconnect technology with the increasing trend of heat-sensitive materials in integrated circuit packaging. Experimental work was carried out to investigate the effect of electroless Ni/electroless Pd/immersion gold (ENEPIG) layer thicknesses on Sn-Bi-Ag solder joint integrity during extended reflow at peak temperatures as low as 175°C. Optimizations are proposed to obtain reliable solder joints through analysis of interfacial microstructure with the resulting joint integrity under extended reflow time. A thin Ni(P) layer with thin Pd led to diffusion of Cu onto the interface resulting in Ni3Sn4 intermetallic compound (IMC) spalling with the formation of thin interfacial (Ni,Cu)3Sn4 IMCs which enhance the robustness of the solder after extended reflow, while thick Ni(P) with thin Pd resulted in weakened solder joints with reflow time due to thick interfacial Ni3Sn4 IMCs with the entrapped brittle Bi-phase. With a suitable thin Ni(P), the Pd thickness has to be optimized to prevent excessive Ni-P consumption and early Cu outward diffusion to enhance the solder joint during extended reflow. Based on these findings, suitable Ni(P) and Pd thicknesses of ENEPIG are recommended for the formation of robust low-temperature solder joints.

Effect of the Silver Content of SnAgCu Solder on the Interfacial Reaction and on the Reliability of Angle Joints Fabricated by Laser-Jet Soldering

NASA Astrophysics Data System (ADS)

Ji, Hongjun; Ma, Yuyou; Li, Mingyu; Wang, Chunqing

2015-02-01

The silver content of lead-free solders affects their microstructure, the interfacial reaction, and the performance of the joints in reliability tests. In this study, Sn3.0Ag0.5Cu (wt.%, SAC305) and Sn1.0Ag0.5Cu (wt.%, SAC105) solder balls of diameter 55 μm were reflowed on gold surface pads by laser-jet soldering. It was found that four types of layered intermetallic compound (IMC) were formed at the interfaces; these were Au5Sn/AuSn, AuSn, AuSn2, and AuSn4 from the pad side to the solder matrix. The Au5Sn/AuSn eutectic region, thickness 400 nm, formed because of the high cooling rate induced by the laser-jet soldering. During high-temperature storage tests, the silver became segregated at the interfaces between the Au-Sn IMC and the solder matrix, resulting in inhibition of IMC growth in SAC305 joints, the shear strengths of which were higher than those of SAC105 joints. In mechanical drop tests, however, percentage failure of the SAC305 joints was twice that of the SAC105 joints.

Solder extrusion pressure bonding process and bonded products produced thereby

DOEpatents

Beavis, L.C.; Karnowsky, M.M.; Yost, F.G.

1992-06-16

Disclosed is a process for production of soldered joints which are highly reliable and capable of surviving 10,000 thermal cycles between about [minus]40 C and 110 C. Process involves interposing a thin layer of a metal solder composition between the metal surfaces of members to be bonded and applying heat and up to about 1000 psi compression pressure to the superposed members, in the presence of a reducing atmosphere, to extrude the major amount of the solder composition, contaminants including fluxing gases and air, from between the members being bonded, to form a very thin, strong intermetallic bonding layer having a thermal expansion tolerant with that of the bonded members.

Laser-fiber coupling by means of a silicon micro-optical bench and a self-aligned soldering process

NASA Astrophysics Data System (ADS)

Schmidt, Jan P.; Cordes, A.; Mueller, Joerg; Burkhardt, Hans

1995-02-01

The alignment of laser diodes to monomode fibers has to meet extremely close tolerances for a low coupling loss. Typically < 0.5 micrometers in lateral and vertical direction and less than two degrees in angle deviation are allowed for a coupling loss below 2 dB. Presently such close tolerances can only be met by gluing or soldering both components on separate base plates and combining them via piezoactivated alignment monitoring the output of the circuit and then gluing them using UV-hardening epoxies. Such a procedure is not very economical and not useful for mass applications. This paper presents the principle and realization of a silicon micro-optical bench for laser-fiber-coupling, which avoids the above mentioned disadvantages. The micro-optical bench is realized using well controlled plasma etching processes to transfer the guiding patterns for the laser and the fiber into the silicon substrate, keeping geometry tolerances below +/- 0.5 micrometers in lateral and vertical direction. Mounting the laser diode by means of a self-aligned soldering process, an additional contribution to the precise alignment of the laser is further improved.

A novel method for direct solder bump pull testing using lead-free solders

NASA Astrophysics Data System (ADS)

Turner, Gregory Alan

This thesis focuses on the design, fabrication, and evaluation of a new method for testing the adhesion strength of lead-free solders, named the Isotraction Bump Pull method (IBP). In order to develop a direct solder joint-strength testing method that did not require customization for different solder types, bump sizes, specific equipment, or trial-and-error, a combination of two widely used and accepted standards was created. First, solder bumps were made from three types of lead free solder were generated on untreated copper PCB substrates using an in-house fabricated solder bump-on-demand generator, Following this, the newly developed method made use of a polymer epoxy to encapsulate the solder bumps that could then be tested under tension using a high precision universal vertical load machine. The tests produced repeatable and predictable results for each of the three alloys tested that were in agreement with the relative behavior of the same alloys using other testing methods in the literature. The median peak stress at failure for the three solders tested were 2020.52 psi, 940.57 psi, and 2781.0 psi, and were within one standard deviation of the of all data collected for each solder. The assumptions in this work that brittle fracture occurred through the Intermetallic Compound layer (IMC) were validated with the use of Energy-Dispersive X-Ray Spectrometry and high magnification of the fractured surface of both newly exposed sides of the test specimens. Following this, an examination of the process to apply the results from the tensile tests into standard material science equations for the fracture of the systems was performed..

Optimal parameters for laser tissue soldering

NASA Astrophysics Data System (ADS)

McNally-Heintzelman, Karen M.; Sorg, Brian S.; Chan, Eric K.; Welch, Ashley J.; Dawes, Judith M.; Owen, Earl R.

1998-07-01

Variations in laser irradiance, exposure time, solder composition, chromophore type and concentration have led to inconsistencies in published results of laser-solder repair of tissue. To determine optimal parameters for laser tissue soldering, an in vitro study was performed using an 808-nm diode laser in conjunction with an indocyanine green (ICG)- doped albumin protein solder to weld bovine aorta specimens. Liquid and solid protein solders prepared from 25% and 60% bovine serum albumin (BSA), respectively, were compared. The effects of laser irradiance and exposure time on tensile strength of the weld and temperature rise as well as the effect of hydration on bond stability were investigated. Optimum irradiance and exposure times were identified for each solder type. Increasing the BSA concentration from 25% to 60% greatly increased the tensile strength of the weld. A reduction in dye concentration from 2.5 mg/ml to 0.25 mg/ml was also found to result in an increase in tensile strength. The strongest welds were produced with an irradiance of 6.4 W/cm2 for 50 s using a solid protein solder composed of 60% BSA and 0.25 mg/ml ICG. Steady-state solder surface temperatures were observed to reach 85 plus or minus 5 degrees Celsius with a temperature gradient across the solid protein solder strips of between 15 and 20 degrees Celsius. Finally, tensile strength was observed to decrease significantly (20 to 25%) after the first hour of hydration in phosphate-buffered saline. No appreciable change was observed in the strength of the tissue bonds with further hydration.

Microstructural Evolution and Mechanical Behavior of High Temperature Solders: Effects of High Temperature Aging

NASA Astrophysics Data System (ADS)

Hasnine, M.; Tolla, B.; Vahora, N.

2018-04-01

This paper explores the effects of aging on the mechanical behavior, microstructure evolution and IMC formation on different surface finishes of two high temperature solders, Sn-5 wt.% Ag and Sn-5 wt.% Sb. High temperature aging showed significant degradation of Sn-5 wt.% Ag solder hardness (34%) while aging has little effect on Sn-5 wt.% Sb solder. Sn-5 wt.% Ag experienced rapid grain growth as well as the coarsening of particles during aging. Sn-5 wt.% Sb showed a stable microstructure due to solid solution strengthening and the stable nature of SnSb precipitates. The increase of intermetallic compound (IMC) thickness during aging follows a parabolic relationship with time. Regression analysis (time exponent, n) indicated that IMC growth kinetics is controlled by a diffusion mechanism. The results have important implications in the selection of high temperature solders used in high temperature applications.

Long-Term Effects of Soldering By-Products on Nickel-Coated Copper Wire

NASA Technical Reports Server (NTRS)

Rolin, T. D.; Hodge, R. E.

2008-01-01

An analysis of thirty-year-old, down graded flight cables was conducted to determine the makeup of a green material on the surface of the shielded wire near soldered areas and to ascertain if the green material had corroded the nickel-coated copper wire. Two likely candidates were possible due to the handling and environments to which these cables were exposed. The flux used to solder the cables is known to contain abietic acid, a carboxylic acid found in many pine rosins used for the soldering process. The resulting material copper abietate is green in color and is formed during the application of heat during soldering operations. Copper (II) chloride, which is also green in color is known to contaminate flight parts and is corrosive. Data is presented that shows the material is copper abietate, not copper (II) chloride, and more importantly that the abietate does not aggressively attack nickel-plated copper wire.

Wetting properties of Au/Sn solders for microelectronics

NASA Astrophysics Data System (ADS)

Peterson, K. A.; Williams, C. B.

Hermetic sealing of microelectronic packages with Au/Sn solder is critically dependent upon good wetting. In studying specific problems in hermetic sealing, a solderability test based on ASTM standard F-357-78 has proven useful. The test has helped isolate and quantify the effects of contamination due to epoxy die attach and related handling, thermal preconditioning of packages, gold plating thickness, time and temperature during sealing, and solder alloy composition as they affect wetting. Some differences in hardware have been documented between manufacturing lots, but the overriding factors have been contamination which occurs during packaging process flows and thermal preconditioning during processing. The paper includes a review of metallurgical aspects of soldering to a non-inert surface and an examination of microstructural differences in seal joints. The results also quantify the conventional wisdom that alloys which are on the tin-rich side of the eutectic composition offer superior wetting properties.

Interaction of intermetallic compound formation in Cu/SnAgCu/NiAu sandwich solder joints

NASA Astrophysics Data System (ADS)

Xia, Yanghua; Lu, Chuanyan; Chang, Junling; Xie, Xiaoming

2006-05-01

The interaction between Cu/solder interface and solder/Ni interface at a Cu/SnAgCu/NiAu sandwich solder joint with various surface finishes and solder heights was investigated. The interfacial microstructure and composition of intermetallic compounds (IMCs) were characterized by a scanning electron microscope (SEM) equipped with energy-dispersive x-ray spectroscopy (EDX). The phase structure of IMC was identified by x-ray diffraction (XRD). It is found that ternary (Cu,Ni)6Sn5 IMCs form at both interfaces. The composition, thickness, and morphology of the ternary IMCs depend not only on the interface itself, but also on the opposite interface. That is to say, strong coupling effects exist between the two interfaces. Lattice parameters of (Cu,Ni)6Sn5 shrink with increasing Ni content, in agreement with Vegard’s law. The mechanism of ternary IMC formation and interface coupling effects are discussed in this paper.

Materials chemistry. Composition-matched molecular "solders" for semiconductors.

PubMed

Dolzhnikov, Dmitriy S; Zhang, Hao; Jang, Jaeyoung; Son, Jae Sung; Panthani, Matthew G; Shibata, Tomohiro; Chattopadhyay, Soma; Talapin, Dmitri V

2015-01-23

We propose a general strategy to synthesize largely unexplored soluble chalcogenidometallates of cadmium, lead, and bismuth. These compounds can be used as "solders" for semiconductors widely used in photovoltaics and thermoelectrics. The addition of solder helped to bond crystal surfaces and link nano- or mesoscale particles together. For example, CdSe nanocrystals with Na2Cd2Se3 solder was used as a soluble precursor for CdSe films with electron mobilities exceeding 300 square centimeters per volt-second. CdTe, PbTe, and Bi2Te3 powders were molded into various shapes in the presence of a small additive of composition-matched chalcogenidometallate or chalcogel, thus opening new design spaces for semiconductor technologies. Copyright © 2015, American Association for the Advancement of Science.

Corrosion Behaviour of Sn-based Lead-Free Solders in Acidic Solution

NASA Astrophysics Data System (ADS)

Nordarina, J.; Mohd, H. Z.; Ahmad, A. M.; Muhammad, F. M. N.

2018-03-01

The corrosion properties of Sn-9(5Al-Zn), Sn-Cu and SAC305 were studied via potentiodynamic polarization method in an acidic solution of 1 M hydrochloric acid (HCl). Sn-9(5Al-Zn) produced different polarization profile compared with Sn-Cu and SAC305. The morphological analysis showed that small, deep grooves shaped of corrosion product formed on top of Sn-9(5Al-Zn) solder while two distinctive structures of closely packed and loosely packed corrosion product formed on top of Sn-Cu and SAC305 solder alloys. Phase analysis revealed the formations of various corrosion products such as SnO and SnO2 mainly dominant on surface of solder alloys after potentiodynamic polarization in 1 M hydrochloric acid (HCl).

Albumin-genipin solder for laser tissue repair.

PubMed

Lauto, A; Foster, L J R; Ferris, L; Avolio, A; Zwaneveld, N; Poole-Warren, L A

2004-01-01

Laser tissue soldering (LTS) is an alternative technique to suturing for tissue repair that avoids foreign body reaction and provides immediate sealing of the wound. One of the major drawbacks of LTS, however, is the weak tensile strength of the solder welds when compared to sutures. In this study, a crosslinking agent of low cytotoxicity was investigated for its ability to enhance the bond strength of albumin solders with sheep intestine. Solder strips were welded onto rectangular sections of sheep small intestine using a diode laser. The laser delivered in continuous mode a power of 170 +/- 10 mW at lambda = 808 nm, through a multimode optical fiber (core size = 200 microm) to achieve a dose of 10.8 +/- 0.5 J/mg. The solder thickness and surface area were kept constant throughout the experiment (thickness = 0.15 +/- 0.01 mm, area = 12 +/- 1.2 mm2). The solder was composed of 62% bovine serum albumin (BSA), 0.38% genipin, 0.25% indocyanin green dye (IG), and water. Tissue welding was also performed with a BSA solder without genipin, as a control group. The repaired tissue was tested for tensile strength by a calibrated tensiometer. Murine fibroblasts were also cultured in extracted media from heat-denatured genipin solder to assess cell growth inhibition in a 48 hours period. The tensile strength of the genipin solder was doubled that of the BSA solder (0.21 +/- 0.04 N and 0.11 +/- 0.04 N, respectively; P = 10(-15) unpaired t-test, N = 30). Media extracted from crosslinked genipin solder showed negligible toxicity to fibroblast cells under the culture conditions examined here. Addition of a chemical crosslinking agent, such as genipin, significantly increased the tensile strength of adhesive-tissue bonds. A proposed mechanism for this enhanced bond strength is the synergistic action of mechanical adhesion with chemical crosslinking by genipin.

Metallization of Large Silicon Wafers

NASA Technical Reports Server (NTRS)

Pryor, R. A.

1978-01-01

A metallization scheme was developed which allows selective plating of silicon solar cell surfaces. The system is comprised of three layers. Palladium, through the formation of palladium silicide at 300 C in nitrogen, makes ohmic contact to the silicon surface. Nickel, plated on top of the palladium silicide layer, forms a solderable interface. Lead-tin solder on the nickel provides conductivity and allows a convenient means for interconnection of cells. To apply this metallization, three chemical plating baths are employed.

Resin bleed improvement on surface mount semiconductor device

NASA Astrophysics Data System (ADS)

Rajoo, Indra Kumar; Tahir, Suraya Mohd; Aziz, Faieza Abdul; Shamsul Anuar, Mohd

2018-04-01

Resin bleed is a transparent layer of epoxy compound which occurs during molding process but is difficult to be detected after the molding process. Resin bleed on the lead on the unit from the focused package, SOD123, can cause solderability failure at end customer. This failed unit from the customer will be considered as a customer complaint. Generally, the semiconductor company has to perform visual inspection after the plating process to detect resin bleed. Mold chase with excess hole, split cavity & stepped design ejector pin hole have been found to be the major root cause of resin bleed in this company. The modifications of the mold chase, changing of split cavity to solid cavity and re-design of the ejector pin proposed were derived after a detailed study & analysis conducted to arrive at these solutions. The solutions proposed have yield good results during the pilot run with zero (0) occurrence of resin bleed for 3 consecutive months.

Planar triode pulser socket

DOEpatents

Booth, Rex

1994-01-01

A planar triode is mounted in a PC board orifice by means of a U-shaped capacitor housing and anode contact yoke removably attached to cathode leg extensions passing through and soldered to the cathode side of the PC board by means of a PC cathode pad. A pliant/flexible contact attached to the orifice make triode grid contact with a grid pad on the grid side of the PC board, permitting quick and easy replacement of bad triodes.

Development and Application of a Wireless, Networked Raspberry Pi Controlled Head Mounted Tactile Display (HMTD)

DTIC Science & Technology

2016-09-01

10 Fig. 8 Lithium ion polymer battery .................................................................. 11 Fig. 9 PowerBoost 1000C (right) and...7]. http://www.adafruit.com/products/1552. 7. Lithium Ion Polymer Battery –3.7v 2500mAh. [accessed Jul 7]. https://www.adafruit.com/products/328. 8...port directly) RealTek RT5370 Wi-Fi USB adapter 1 Wire-wrapping wires . . . Wire-wrap hand tool . . . Soldering kit . . . alipo: lithium - ion

Fundamental study of microelectronic chip response under laser ultrasonic-interferometric inspection using C-scan method

NASA Astrophysics Data System (ADS)

Yang, Lei; Gong, Jie; Ume, I. Charles

2014-02-01

In modern surface mount packaging technologies, such as flip chips, chip scale packages, and ball grid arrays(BGA), chips are attached to the substrates/printed wiring board (PWB) using solder bump interconnections. The quality of solder bumps between the chips and the substrate/board is difficult to inspect. Laser ultrasonic-interferometric technique was proved to be a promising approach for solder bump inspection because of its noncontact and nondestructive characteristics. Different indicators extracted from received signals have been used to predict the potential defects, such as correlation coefficient, error ratio, frequency shifting, etc. However, the fundamental understanding of the chip behavior under laser ultrasonic inspection is still missing. Specifically, it is not sure whether the laser interferometer detected out-of-plane displacements were due to wave propagation or structural vibration when the chip was excited by pulsed laser. Plus, it is found that the received signals are chip dependent. Both challenges impede the interpretation of acquired signals. In this paper, a C-scan method was proposed to study the underlying phenomenon during laser ultrasonic inspection. The full chip was inspected. The response of the chip under laser excitation was visualized in a movie resulted from acquired signals. Specifically, a BGA chip was investigated to demonstrate the effectiveness of this method. By characterizing signals using discrete wavelet transform(DWT), both ultrasonic wave propagation and vibration were observed. Separation of them was successfully achieved using ideal band-pass filter and visualized in resultant movies, too. The observed ultrasonic waves were characterized and their respective speeds were measured by applying 2-D FFT. The C-scan method, combined with different digital signal processing techniques, was proved to be an very effective methodology to learn the behavior of chips under laser excitation. This general procedure can be applied to any unknown chip before inspection. A wealth of information can be provided by this learning procedure, which greatly benefits the interpretation of inspection signals afterwards.

Impact of Fe powder sintering and soldering in production of porous heating surface on flow boiling heat transfer in minichannels

NASA Astrophysics Data System (ADS)

Depczyński, Wojciech; Piasecki, Artur; Piasecka, Magdalena; Strąk, Kinga

2017-10-01

This paper focuses on identification of the impact of porous heated surface on flow boiling heat transfer in a rectangular minichannel. The heated element for Fluorinert FC-72 was a thin plate made of Haynes-230. Infrared thermography was used to determine changes in the temperature on its outer smooth side. The porous surface in contact with the fluid in the minichannel was produced in two processes: sintering or soldering of Fe powder to the plate. The results were presented as relationships between the heat transfer coefficient and the distance from the minichannel inlet and as boiling curves. Results obtained for using a smooth heated plate at the saturated boiling region were also presented to compare. In the subcooled boiling region, at a higher heat flux, the heat transfer coefficient was slightly higher for the surface prepared via soldering. In the saturated boiling region, the local heat transfer coefficients obtained for the smooth plate surface were slightly higher than those achieved from the sintered plate surface. The porous structures formed have low thermal conductivity. This may induce noticeable thermal resistance at the diffusion bridges of the sintered structures, in particular within the saturated boiling region.

Joint Lead-Free Solder Test Program for High Reliability Military and Space Applications

NASA Technical Reports Server (NTRS)

Brown, Christina

2004-01-01

Current and future space and defense systems face potential risks from the continued use of tin-lead solder, including: compliance with current environmental regulations, concerns about potential environmental legislation banning lead-containing products, reduced mission readiness, and component obsolescence with lead surface finishes. For example, the United States Environmental Protection Agency (USEPA) has lowered the Toxic Chemical Release reporting threshold for lead to 100 pounds. Overseas, the Waste Electrical and Electronic Equipment (WEEE) and the Restriction on Hazardous Substances (RoHS) Dicctives in Europe and similar mandates in Japan have instilled concern that a legislative body will prohibit the use of lead in aerospace/military electronics soldering. Any potential banning of lead compounds could reduce the supplier base and adversely affect the readiness of missions led by the National Aeronautics and Space Administration (NASA) and the U.S. Department of Defense (DoD). Before considering lead-free electronics for system upgrades or future designs, however, it is important for the DoD and NASA to know whether lead-free solders can meet their systems' requirements. No single lead-free solder is likely to qualify for all defense and space applications. Therefore, it is important to validate alternative solders for discrete applications. As a result of the need for comprehensive test data on the reliability of lead-free solders, a partnership was formed between the DoD, NASA, and several original equipment manufactures (OEMs) to conduct solder-joint reliability (laboratory) testing of three lead-free solder alloys on newly manufactured and reworked circuit cards to generate performance data for high-reliability (IPC Class 3) applications.

Life testing of reflowed and reworked advanced CCGA surface mount packages in harsh thermal environments

NASA Astrophysics Data System (ADS)

Ramesham, Rajeshuni

2013-03-01

Life testing/qualification of reflowed (1st reflow) and reworked (1st reflow, 1st removal, and then 1st rework) advanced ceramic column grid array (CCGA) surface mount interconnect electronic packaging technologies for future flight projects has been studied to enhance the mission assurance of JPL-NASA projects. The reliability of reworked/reflowed surface mount technology (SMT) packages is very important for short-duration and long-duration deep space harsh extreme thermal environmental missions. The life testing of CCGA electronic packages under extreme thermal environments (for example: -185°C to +125°C) has been performed with reference to various JPL/NASA project requirements which encompass the temperature range studied. The test boards of reflowed and reworked CCGA packages (717 Xilinx package, 624, 1152, and 1272 column Actel Packages) were selected for the study to survive three times the total number of expected temperature cycles resulting from all environmental and operational exposures occurring over the life of the flight hardware including all relevant manufacturing, ground operations, and mission phases or cycles to failure to assess the life of the hardware. Qualification/life testing was performed by subjecting test boards to the environmental harsh temperature extremes and assessing any structural failures, mechanical failures or degradation in electrical performance solder-joint failures due to either overstress or thermal cycle fatigue. The large, high density, high input/output (I/O) electronic interconnect SMT packages such as CCGA have increased usage in avionics hardware of NASA projects during the last two decades. The test boards built with CCGA packages are expensive and often require a rework to replace a reflowed, reprogrammed, failed, redesigned, etc., CCGA packages. Theoretically speaking, a good rework process should have similar temperature-time profile as that used for the original manufacturing process of solder reflow. A multiple rework processes may be implemented with CCGA packaging technology to understand the effect of number of reworks on the reliability of this technology for harsh thermal environments. In general, reliability of the assembled electronic packages reduces as a function of number of reworks and the extent is not known yet. A CCGA rework process has been tried and implemented to design a daisy-chain test board consists of 624 and 717 packages. Reworked CCGA interconnect electronic packages of printed wiring polyimide boards have been assembled and inspected using non-destructive x-ray imaging and optical microscope techniques. The assembled boards after 1st rework and 1st reflow were subjected to extreme temperature thermal atmospheric cycling to assess their reliability for future deep space JPL/NASA for moderate to harsh thermal mission environments. The resistance of daisy-chained interconnect sections were monitored continuously during thermal cycling to determine intermittent failures. This paper provides the experimental reliability test results to failure of assemblies for the first time of reflowed and reworked CCGA packages under extreme harsh thermal environments.

Characterization of skin tissue soldering using diode laser and indocyanine green: in vitro studies.

PubMed

Khosroshahi, M E; Nourbakhsh, M S; Saremi, S; Tabatabaee, F

2010-03-01

Laser tissue soldering based on protein as biological glues and other compounds can provide greater bond strength and less collateral damage. Endogenous and exogenous materials such as indocyanine green (ICG) are often added to solders to enhance light absorption. The purpose of this in vitro study was to examine the impact of different parameters of laser soldering on the thermo-physical properties of the skin. A mixture of albumin solder and ICG was prepared, and then the coated samples were irradiated by an 810 nm diode laser under different conditions. The temperature rise, number of scans (N(s)), and scan velocity (V(s)) were investigated in this study. The results showed that, at each laser irradiance (I), the tensile strength (sigma) of incisions repaired in static mode was higher than in dynamic mode and that the sigma increased with both increasing N(s) and increasing I. It is therefore important to consider the trade off between scan velocity and surface temperature for achieving an optimum operating condition.

3D Printing of Ball Grid Arrays

NASA Astrophysics Data System (ADS)

Sinha, Shayandev; Hines, Daniel; Dasgupta, Abhijit; Das, Siddhartha

Ball grid arrays (BGA) are interconnects between an integrated circuit (IC) and a printed circuit board (PCB), that are used for surface mounting electronic components. Typically, lead free alloys are used to make solder balls which, after a reflow process, establish a mechanical and electrical connection between the IC and the PCB. High temperature processing is required for most of these alloys leading to thermal shock causing damage to ICs. For producing flexible circuits on a polymer substrate, there is a requirement for low temperature processing capabilities (around 150 C) and for reducing strain from mechanical stresses. Additive manufacturing techniques can provide an alternative methodology for fabricating BGAs as a direct replacement for standard solder bumped BGAs. We have developed aerosol jet (AJ) printing methods to fabricate a polymer bumped BGA. As a demonstration of the process developed, a daisy chain test chip was polymer bumped using an AJ printed ultra violet (UV) curable polymer ink that was then coated with an AJ printed silver nanoparticle laden ink as a conducting layer printed over the polymer bump. The structure for the balls were achieved by printing the polymer ink using a specific toolpath coupled with in-situ UV curing of the polymer which provided good control over the shape, resulting in well-formed spherical bumps on the order of 200 um wide by 200 um tall for this initial demonstration. A detailed discussion of the AJ printing method and results from accelerated life-time testing will be presented

Enhanced laser tissue soldering using indocyanine green chromophore and gold nanoshells combination.

PubMed

Khosroshahi, Mohammad E; Nourbakhsh, Mohammad S

2011-08-01

Gold nanoshells (GNs) are new materials that have an optical response dictated by the plasmon resonance. The wavelength at which the resonance occurs depends on the core and shell sizes. The purposes of this study were to use the combination of indocyanine green (ICG) and different concentration of gold nanoshells for skin tissue soldering and also to examine the effect of laser soldering parameters on the properties of repaired skin. Two mixtures of albumin solder and different combinations of ICG and gold nanoshells were prepared. A full thickness incision of 2 × 20 mm(2) was made on the surface and after addition of mixtures it was irradiated by an 810 nm diode laser at different power densities. The changes of tensile strength (σ(t)) due to temperature rise, number of scan (Ns), and scan velocity (Vs) were investigated. The results showed at constant laser power density (I), σ(t) of repaired incisions increases by increasing the concentration of gold nanoshells in solder, Ns, and decreasing Vs. It was demonstrated that laser soldering using combination of ICG + GNs could be practical provided the optothermal properties of the tissue are carefully optimized. Also, the tensile strength of soldered skin is higher than skins that soldered with only ICG or GNs. In our case, this corresponds to σ(t) = 1800 g cm(-2) at I ∼ 47 Wcm(-2), T ∼ 85 [ordinal indicator, masculine]C, Ns = 10, and Vs = 0.3 mms(-1).

Spatiotemporal modeling of laser tissue soldering using photothermal nanocomposites.

PubMed

Mushaben, Madaline; Urie, Russell; Flake, Tanner; Jaffe, Michael; Rege, Kaushal; Heys, Jeffrey

2018-02-01

Laser tissue soldering using photothermal solders is a technology that facilitates rapid sealing using heat-induced changes in the tissue and the solder material. The solder material is made of gold nanorods embedded in a protein matrix patch that can be placed over the tissue rupture site and heated with a laser. Although laser tissue soldering is an attractive approach for surgical repair, potential photothermal damage can limit the success of this approach. Development of predictive mathematical models of photothermal effects including cell death, can lead to more efficient approaches in laser-based tissue repair. We describe an experimental and modeling investigation into photothermal solder patches for sealing porcine and mouse cadaver intestine sections using near-infrared laser irradiation. Spatiotemporal changes in temperature were determined at the surface as well as various depths below the patch. A mathematical model, based on the finite element method, predicts the spatiotemporal temperature distribution in the patch and surrounding tissue, as well as concomitant cell death in the tissue is described. For both the porcine and mouse intestine systems, the model predicts temperatures that are quantitatively similar to the experimental measurements with the model predictions of temperature increase often being within a just a few degrees of experimental measurements. This mathematical model can be employed to identify optimal conditions for minimizing healthy cell death while still achieving a strong seal of the ruptured tissue using laser soldering. Lasers Surg. Med. 50:143-152, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Planar triode pulser socket

DOEpatents

Booth, R.

1994-10-25

A planar triode is mounted in a PC board orifice by means of a U-shaped capacitor housing and anode contact yoke removably attached to cathode leg extensions passing through and soldered to the cathode side of the PC board by means of a PC cathode pad. A pliant/flexible contact attached to the orifice make triode grid contact with a grid pad on the grid side of the PC board, permitting quick and easy replacement of bad triodes. 14 figs.

Intermetallic Compounds Formed in Sn-20In-2.8Ag Solder BGA Packages with Ag/Cu Pads

NASA Astrophysics Data System (ADS)

Jain, C. C.; Wang, S. S.; Huang, K. W.; Chuang, T. H.

2009-03-01

The interfacial reactions in a Sn-20In-2.8Ag solder ball grid array (BGA) package with immersion Ag surface finish are investigated. After reflow, the Ag thin film dissolves quickly into the solder matrix, and scallop-shaped intermetallic layers, with compositions of (Cu0.98Ag0.02)6(In0.59Sn0.41)5, appear at the interfaces between Sn-20In-2.8Ag solder ball and Cu pad. No evident growth of the (Cu0.98Ag0.02)6(Sn0.59In0.41)5 intermetallic compounds was observed after prolonged aging at 100 °C. However, the growth accelerated at 150 °C, with more intermetallic scallops floating into the solder matrix. The intermetallic thickness versus the square root of reaction time ( t 1/2) shows a linear relation, indicating that the growth of intermetallic compounds is diffusion-controlled. Ball shear tests show that the strength of Sn-20In-2.8Ag solder joints after reflow is 4.4 N, which increases to 5.18 N and 5.14 N after aging at 100 and 150 °C, respectively.

In Situ Monitoring of Pb2+ Leaching from the Galvanic Joint Surface in a Prepared Chlorinated Drinking Water.

PubMed

Ma, Xiangmeng; Armas, Stephanie M; Soliman, Mikhael; Lytle, Darren A; Chumbimuni-Torres, Karin; Tetard, Laurene; Lee, Woo Hyoung

2018-02-20

A novel method using a micro-ion-selective electrode (micro-ISE) technique was developed for in situ lead monitoring at the water-metal interface of a brass-leaded solder galvanic joint in a prepared chlorinated drinking water environment. The developed lead micro-ISE (100 μm tip diameter) showed excellent performance toward soluble lead (Pb 2+ ) with sensitivity of 22.2 ± 0.5 mV decade -1 and limit of detection (LOD) of 1.22 × 10 -6 M (0.25 mg L -1 ). The response time was less than 10 s with a working pH range of 2.0-7.0. Using the lead micro-ISE, lead concentration microprofiles were measured from the bulk to the metal surface (within 50 μm) over time. Combined with two-dimensional (2D) pH mapping, this work clearly demonstrated that Pb 2+ ions build-up across the lead anode surface was substantial, nonuniform, and dependent on local surface pH. A large pH gradient (ΔpH = 6.0) developed across the brass and leaded-tin solder joint coupon. Local pH decreases were observed above the leaded solder to a pH as low as 4.0, indicating it was anodic relative to the brass. The low pH above the leaded solder supported elevated lead levels where even small local pH differences of 0.6 units (ΔpH = 0.6) resulted in about four times higher surface lead concentrations (42.9 vs 11.6 mg L -1 ) and 5 times higher fluxes (18.5 × 10 -6 vs 3.5 × 10 -6 mg cm -2 s -1 ). Continuous surface lead leaching monitoring was also conducted for 16 h.

Temperature-controlled two-wavelength laser soldering of tissues.

PubMed

Gabay, Ilan; Abergel, Avraham; Vasilyev, Tamar; Rabi, Yaron; Fliss, Dan M; Katzir, Abraham

2011-11-01

Laser tissue soldering is a method for bonding of incisions in tissues. A biological solder is spread over the cut, laser radiation heats the solder and the underlying cut edges and the incision is bonded. This method offers many advantages over conventional techniques (e.g., sutures). Past researches have shown that laser soldering, using a single laser, does not provide sufficient strength for bonding of cuts in thick (>1 mm) tissues. This study introduces a novel method for laser soldering of thick tissues, under temperature control, using two lasers, emitting two different wavelengths. An experimental system was built, using two lasers: (i) a CO(2) laser, whose radiation heated the upper surface of the tissue and (ii) a GaAs laser that heated an albumin layer under the tissue. An infrared fiber-optic radiometer monitored the temperature of the tissue. All three devices were connected to a computer that controlled the process. A computer simulation was written to optimize the system parameters. The system was tested on tissue phantoms, to validate the simulation and ensure that both the upper and lower sides of the cut were heated, and that the temperature could be controlled on both sides. The system was then used ex vivo to bond longitudinal cuts of lengths ∼12 mm in the esophagi of large farm pigs. The theoretical simulations showed a good stabilization of the temperatures at the upper and lower tissue surfaces at the target values. Experiments on tissue phantom showed a good agreement with these simulations. Incisions in esophagi, removed from large farm pigs, were then successfully bonded. The mean burst pressure was ∼3.6 m of water. This study demonstrated the capability of soldering cuts in thick tissues, paving the way for new types of surgical applications. Copyright © 2010 Wiley Periodicals, Inc.

Integrated Flexible Electronic Devices Based on Passive Alignment for Physiological Measurement

PubMed Central

Ryu, Jin Hwa; Byun, Sangwon; Baek, In-Bok; Lee, Bong Kuk; Jang, Won Ick; Jang, Eun-Hye; Kim, Ah-Yung; Yu, Han Yung

2017-01-01

This study proposes a simple method of fabricating flexible electronic devices using a metal template for passive alignment between chip components and an interconnect layer, which enabled efficient alignment with high accuracy. An electrocardiogram (ECG) sensor was fabricated using 20 µm thick polyimide (PI) film as a flexible substrate to demonstrate the feasibility of the proposed method. The interconnect layer was fabricated by a two-step photolithography process and evaporation. After applying solder paste, the metal template was placed on top of the interconnect layer. The metal template had rectangular holes at the same position as the chip components on the interconnect layer. Rectangular hole sizes were designed to account for alignment tolerance of the chips. Passive alignment was performed by simply inserting the components in the holes of the template, which resulted in accurate alignment with positional tolerance of less than 10 µm based on the structural design, suggesting that our method can efficiently perform chip mounting with precision. Furthermore, a fabricated flexible ECG sensor was easily attachable to the curved skin surface and able to measure ECG signals from a human subject. These results suggest that the proposed method can be used to fabricate epidermal sensors, which are mounted on the skin to measure various physiological signals. PMID:28420219

Focal Plane Alignment Utilizing Optical CMM

NASA Technical Reports Server (NTRS)

Liebe, Carl Christian; Meras, Patrick L.; Clark, Gerald J.; Sedaka, Jack J.; Kaluzny, Joel V.; Hirsch, Brian; Decker, Todd A.; Scholtz, Christopher R.

2012-01-01

In many applications, an optical detector has to be located relative to mechanical reference points. One solution is to specify stringent requirements on (1) mounting the optical detector relative to the chip carrier, (2) soldering the chip carrier onto the printed circuit board (PCB), and (3) installing the PCB to the mechanical structure of the subsystem. Figure 1 shows a sketch of an optical detector mounted relative to mechanical reference with high positional accuracy. The optical detector is typically a fragile wafer that cannot be physically touched by any measurement tool. An optical coordinate measuring machine (CMM) can be used to position optical detectors relative to mechanical reference points. This approach will eliminate all requirements on positional tolerances. The only requirement is that the PCB is manufactured with oversized holes. An exaggerated sketch of this situation is shown in Figure 2. The sketch shows very loose tolerances on mounting the optical detector in the chip carrier, loose tolerance on soldering the chip carrier to the PCB, and finally large tolerance on where the mounting screws are located. The PCB is held with large screws and oversized holes. The PCB is mounted loosely so it can move freely around. The optical CMM measures the mechanical reference points. Based on these measurements, the required positions of the optical detector corners can be calculated. The optical CMM is commanded to go to the position where one detector corner is supposed to be. This is indicated with the cross-hairs in Figure 2(a). This figure is representative of the image of the optical CMM monitor. Using a suitable tapping tool, the PCB is manually tapped around until the corner of the optical detector is at the crosshairs of the optical CMM. The CMM is commanded to another corner, and the process is repeated a number of times until all corners of the optical detector are within a distance of 10 to 30 microns of the required position. The situation is sketched in Figure 2(b) (the figure also shows the tapping tool and where to tap). At this point the fasteners for the PCB are torqued slightly so the PCB can still move. The PCB location is adjusted again with the tapping tool. This process is repeated 3 to 4 times until the final torque is achieved. The oversized mounting holes are then filled with a liquid bonding agent to secure the board in position (not shown in the sketch). A 10- to 30-micron mounting accuracy has been achieved utilizing this method..

Process for reducing series resistance of solar-cell metal-contact systems with a soldering-flux etchant

DOEpatents

Coyle, R.T.; Barrett, J.M.

1982-05-04

Disclosed is a process for substantially reducing the series resistance of a solar cell having a thick film metal contact assembly thereon while simultaneously removing oxide coatings from the surface of the assembly prior to applying solder therewith. The process includes applying a flux to the contact assembly and heating the cell for a period of time sufficient to substantially remove the series resistance associated with the assembly by etching the assembly with the flux while simultaneously removing metal oxides from said surface of said assembly.

Process for reducing series resistance of solar cell metal contact systems with a soldering flux etchant

DOEpatents

Coyle, R. T.; Barrett, Joy M.

1984-01-01

Disclosed is a process for substantially reducing the series resistance of a solar cell having a thick film metal contact assembly thereon while simultaneously removing oxide coatings from the surface of the assembly prior to applying solder therewith. The process includes applying a flux to the contact assembly and heating the cell for a period of time sufficient to substantially remove the series resistance associated with the assembly by etching the assembly with the flux while simultaneously removing metal oxides from said surface of said assembly.

Effects of Surface Finishes and Current Stressing on Interfacial Reaction Characteristics of Sn-3.0Ag-0.5Cu Solder Bumps

NASA Astrophysics Data System (ADS)

Kim, Jae-Myeong; Jeong, Myeong-Hyeok; Yoo, Sehoon; Park, Young-Bae

2012-04-01

The effects of surface finishes on the in situ interfacial reaction characteristics of ball grid array (BGA) Sn-3.0Ag-0.5Cu lead-free solder bumps were investigated under annealing and electromigration (EM) test conditions of 130°C to 175°C with 5.0 × 103 A/cm2. During reflow and annealing, (Cu,Ni)6Sn5 intermetallic compound (IMC) formed at the interface of electroless nickel immersion gold (ENIG) finish. In the case of both immersion Sn and organic solderability preservative (OSP) finishes, Cu6Sn5 and Cu3Sn IMCs formed. Overall, the IMC growth velocity of ENIG was much lower than that of the other finishes. The activation energies of total IMCs were found to be 0.52 eV for ENIG, 0.78 eV for immersion Sn, and 0.72 eV for OSP. The ENIG finish appeared to present an effective diffusion barrier between the Cu substrate and the solder, which leads to better EM reliability in comparison with Cu-based pad systems. The failure mechanisms were explored in detail via in situ EM tests.

A non-contact measurement technique at the micro scale

NASA Astrophysics Data System (ADS)

Ghosh, Santaneel

During their production and normal use, electronic packages experience large temperature excursions, leading to high thermo-mechanical stress gradients that cause fatigue failure of the solder joints. In order to prevent premature failure and prolong the fatigue life of solder joints, there is a pressing need for the characterization of the solder, especially lead-free solder, at the micro-level (joint size). The characterization and modeling of solder behavior at the appropriate scale is a major issue. However, direct measurement techniques are not applicable to characterize the deformation response of solder joints because of their micro scale dimensions. Therefore, a non-contact measurement technique utilizing a Scanning Electron Microscope (SEM) in conjunction with Digital Image Correlation (DIC) has been developed. Validation was achieved by performing a four-point bending test in both an in-house optical system with DIC and inside the SEM. This non-contact measurement technique was then used to extract the stress-strain response of the solder. Mechanical tests were performed on solder joints that were created using the same type of solder balls used in the electronic industry and were representative of normal joint scales. The SEM-DIC technique has been proven to be applicable for the determining the stress-strain response of solder material at the micro-scale. This study resulted in a validated material characterization technique specifically designed for micro-scale material response. One of the main contributions of this study is that the method is a lot simpler and cheaper, yet highly effective, compared to the previous methods. This technique is also readily applicable to the measurement of the stress-strain response of any micro-scale specimen, such as other metals, polymers, etc. Also, the measured displacement field by obtained by DIC can be used as the base for calculating the strain field on the surface of a specimen.

Dry Sintering Meets Wet Silver-Ion "Soldering": Charge-Transfer Plasmon Engineering of Solution-Assembled Gold Nanodimers From Visible to Near-Infrared I and II Regions.

PubMed

Fang, Lingling; Wang, Yueliang; Liu, Miao; Gong, Ming; Xu, An; Deng, Zhaoxiang

2016-11-07

Achieving highly tunable and localized surface plasmon resonance up to near infrared (NIR) regions is a key target in nanoplasmonics. In particular, a self-assembly process capable of producing highly uniform and solution-processable nanomaterials with tailor-made plasmonic properties is lacking. We herein address this problem through a conjunctive use of wet Ag + soldering and dry thermal sintering to produce nanodimer-derived structures with precisely engineered charge-transfer plasmon (CTP). The sintered dimers are water soluble, featuring gradually shifted CTP spanning an 800 nm wavelength range (up to NIR II). Upon silica removal, the products are grafted by DNA to offer surface functionality. This process is also adaptable to DNA-linked AuNP dimers toward plasmonic meta-materials via DNA-guided soldering and sintering. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transabdominal preperitoneal herniorrhaphy using laser-assisted tissue soldering in a porcine model.

PubMed

Lanzafame, Raymond J; Soltz, Barbara A; Stadler, Istvan; Soltz, Robert

2009-01-01

Collagen solder is capable of fixation of surgical meshes during laparoscopic herniorrhaphy without compromising tissue integration, increasing adhesions or inflammation. This pilot study describes development of instrumentation and techniques for transabdominal preperitoneal (TAPP) herniorrhaphy using laser-assisted soldering technology. Anesthetized 20-kg to 25-kg female Yorkshire pigs underwent laparoscopy performed using a 3-trocar technique. Peritoneal incisions were made and pockets created in the preperitoneal space for mesh placement. Parietex TEC mesh segments embedded in 60% collagen-solder were soldered to the muscle surface by using a prototype laser (1.45micro, 4.5W CW, 5mm spot, and 55 degrees C set temperature) and custom laparoscopic handpiece. Parietex TEC mesh segments (Control) were affixed to the muscle with fibrin sealant (Tisseel). Peritoneal closure was with staples (Control) or by soldering collagen embedded Vicryl mesh segments over the peritoneal incision (Mesh/TAPP). Segments were inserted using a specially designed introducer. Animals were recovered and underwent second-look laparoscopy at 6 weeks postimplantation. Mesh sites were harvested after animals were euthanized. The mesh-solder constructs were easily inserted and affixed in the TAPP approach. Tisseel tended to drip during application, particularly in vertical and ventral locations. Postoperative healing was similar to Control segments in all cases. Mesh/TAPP closures healed without scarring or adhesion formation. Collagen-based tissue soldering permits normal wound healing and may mitigate or reduce use of staples for laparoscopic mesh fixation and peritoneal closure. Laser-assisted mesh fixation and peritoneal closure is a promising alternative for laparoscopic herniorrhaphy. Further development of this strategy is warranted.

A comparative evaluation of the tensile strength of silver soldered joints of stainless steel and cobalt chromium orthodontic wires with band material--an in vitro study.

PubMed

Dua, R; Nandlal, B

2004-03-01

The present study was conducted to compare and evaluate the tensile strength of silver soldered joints of stainless steel and cobalt-chromium orthodontic wires with band material. An attempt was made to observe the effect of joint site preparation by incorporation of tack welding and increasing metal to metal surface contact area by flattening an end of the wire prior to soldering along with the regularly used round wires without tack welding. A total of 180 wire specimens were soldered to 180 band specimens. Fifteen samples according to joint site preparation were included for each of the wire groups i.e. Gloria (S.S.), Remanium (S.S.) and Remaloy (Co-Cr) wires of 0.036" in diameter. The findings of the study were suggestive that all three wires may be used for preparing silver soldered joints irrespective of the quality of the wire. However, when subjecting the wire to joint site preparation, Gloria (S.S.) wire showed less tensile strength as compared to Remanium and Remaloy.

Effect of Thermal Aging on the Mechanical Properties of Sn3.0Ag0.5Cu/Cu Solder Joints Under High Strain Rate Conditions

NASA Astrophysics Data System (ADS)

Nguyen, Van Luong; Kim, Ho-Kyung

2015-07-01

Shear tests with velocities between 0.5 m/s and 2.5 m/s were conducted to investigate the deformation characteristics of 0.76 mm lead-free Sn-3Ag-0.5Cu solder ball joints after thermal aging at 373 K up to 1000 h. A scanning electron microscope equipped with energy dispersive spectroscopy was then used to examine the fracture surfaces and microstructures of the solder joints. The results showed that the main failure mode of the solder joints was the brittle interfacial fracture mode with cleavage failure in the intermetallic compound (IMC). The maximum shear strength and the fracture toughness ( K C) of the solder joint decreased substantially after aging for the initial aging time, after which they decreased gradually with further aging or an increase in the strain rate. The evolution of the IMC layer when it was thicker and had coarser nodules due to thermal aging was the primary cause of the reduction in the shear strength and fracture toughness in this study.

Optimal parameters for arterial repair using light-activated surgical adhesives.

PubMed

Soller, Eric C; Hoffman, Grant T; McNally-Heintzelman, Karen M

2003-01-01

The clinical acceptance of laser-tissue repair techniques is dependent on the reproducibility of viable repairs. Reproducibility is dependent on two factors: (i) the choice of materials to be used as the adhesive; and (ii) obtaining temperatures high enough to cause protein denaturation at the vital tissue interface without causing excessive thermal damage to the surrounding tissue. The use of a polymer scaffold as a carrier for the protein solder provides for uniform application of the solder to the tissue, thus allowing for pre-selection of optimal laser parameters. The scaffold also facilitates precise tissue alignment and ease of clinical application. In addition, the scaffold can be doped with various pharmaceuticals such as hemostatic and thrombogenic agents to aid wound healing. An ex vivo study was performed to correlate solder and tissue temperature with the tensile strength of arterial repairs formed using scaffold-enhanced light-activated surgical adhesives. Previous studies by our group using solid protein solder without the scaffold indicate that a solder/tissue, interface temperature of 65 degrees C is optimal. Using this parameter as a benchmark, laser irradiance was varied and temperatures were recorded at the surface and at the tissue interface of scaffold-enhanced protein solder using an infrared temperature monitoring system, designed by the researchers, and a type-K thermocouple, respectively.

Effect of current crowding on whisker growth at the anode in flip chip solder joints

NASA Astrophysics Data System (ADS)

Ouyang, Fan-Yi; Chen, Kai; Tu, K. N.; Lai, Yi-Shao

2007-12-01

Owing to the line-to-bump configuration in flip chip solder joints, current crowding occurs when electrons enter into or exit from the solder bump. At the cathode contact, where electrons enter into the bump, current crowding induced pancake-type void formation has now been observed widely. At the anode contact, where electrons exit from the bump, we report here that whisker is formed. Results of both eutectic SnPb and SnAgCu solder joints are presented and compared. The cross-sectioned surface in SnPb showed dimple and bulge after electromigration, while that of SnAgCu remained flat. The difference is due to a larger back stress in the SnAgCu, consequently, electromigration in SnAgCu is slower than that in SnPb. Nanoindentation markers were used to measure the combined atomic fluxes of back stress and electromigration.

Transabdominal Preperitoneal Herniorrhaphy using Laser-Assisted Tissue Soldering in a Porcine Model

PubMed Central

Soltz, Barbara A.; Stadler, Istvan; Soltz, Robert

2009-01-01

Background and Objectives: Collagen solder is capable of fixation of surgical meshes during laparoscopic herniorrhaphy without compromising tissue integration, increasing adhesions or inflammation. This pilot study describes development of instrumentation and techniques for transabdominal preperitoneal (TAPP) herniorrhaphy using laser-assisted soldering technology. Methods: Anesthetized 20-kg to 25-kg female Yorkshire pigs underwent laparoscopy performed using a 3-trocar technique. Peritoneal incisions were made and pockets created in the preperitoneal space for mesh placement. Parietex TEC mesh segments embedded in 60% collagen-solder were soldered to the muscle surface by using a prototype laser (1.45µ, 4.5W CW, 5mm spot, and 55°C set temperature) and custom laparoscopic handpiece. Parietex TEC mesh segments (Control) were affixed to the muscle with fibrin sealant (Tisseel). Peritoneal closure was with staples (Control) or by soldering collagen embedded Vicryl mesh segments over the peritoneal incision (Mesh/TAPP). Segments were inserted using a specially designed introducer. Animals were recovered and underwent second-look laparoscopy at 6 weeks postimplantation. Mesh sites were harvested after animals were euthanized. Results: The mesh-solder constructs were easily inserted and affixed in the TAPP approach. Tisseel tended to drip during application, particularly in vertical and ventral locations. Postoperative healing was similar to Control segments in all cases. Mesh/TAPP closures healed without scarring or adhesion formation. Discussion and Conclusion: Collagen-based tissue soldering permits normal wound healing and may mitigate or reduce use of staples for laparoscopic mesh fixation and peritoneal closure. Laser-assisted mesh fixation and peritoneal closure is a promising alternative for laparoscopic herniorrhaphy. Further development of this strategy is warranted. PMID:19660214

Nanoindentation on SnAgCu lead-free solder joints and analysis

NASA Astrophysics Data System (ADS)

Xu, Luhua; Pang, John H. L.

2006-12-01

The lead-free SnAgCu (SAC) solder joint on copper pad with organic solderability preservative (Cu-OSP) and electroless nickel and immersion gold (ENIG) subjected to thermal testing leads to intermetallic growth. It causes corresponding reliability concerns at the interface. Nanoindentation characterization on SnAgCu solder alloy, intermetallic compounds (IMCs), and the substrates subjected to thermal aging is reported. The modulus and hardness of thin IMC layers were measured by nanoindentation continuous stiffness measurement (CSM) from planar IMC surface. When SAC/Ni(Au) solder joints were subject to thermal aging, the Young’s modulus of the NiCuSn IMC at the SAC/ENIG specimen changed from 207 GPa to 146 GPa with different aging times up to 500 h. The hardness decreased from 10.0 GPa to 7.3 GPa. For the SAC/Cu-OSP reaction couple, the Young’s modulus of Cu6Sn5 stayed constant at 97.0 GPa and hardness about 5.7 GPa. Electron-probe microanalysis (EPMA) was used to thermal aging. The creep effect on the measured result was analyzed when measuring SnAgCu solder; it was found that the indentation penetration, and thus the hardness, is loading rate dependent. With the proposed constant P/P experiment, a constant indentation strain rate h/h and hardness could be achieved. The log-log plot of indentation strain rate versus hardness for the data from the constant P/P experiments yields a slope of 7.52. With the optimized test method and CSM Technique, the Modulus of SAC387 solder alloy and all the layers in a solder joint were investigated.

Electronic waste disassembly with industrial waste heat.

PubMed

Chen, Mengjun; Wang, Jianbo; Chen, Haiyian; Ogunseitan, Oladele A; Zhang, Mingxin; Zang, Hongbin; Hu, Jiukun

2013-01-01

Waste printed circuit boards (WPCBs) are resource-rich but hazardous, demanding innovative strategies for post-consumer collection, recycling, and mining for economically precious constituents. A novel technology for disassembling electronic components from WPCBs is proposed, using hot air to melt solders and to separate the components and base boards. An automatic heated-air disassembling equipment was designed to operate at a heating source temperature at a maximum of 260 °C and an inlet pressure of 0.5 MPa. A total of 13 individual WPCBs were subjected to disassembling tests at different preheat temperatures in increments of 20 °C between 80 and 160 °C, heating source temperatures ranging from 220 to 300 °C in increments of 20 °C, and incubation periods of 1, 2, 4, 6, or 8 min. For each experimental treatment, the disassembly efficiency was calculated as the ratio of electronic components released from the board to the total number of its original components. The optimal preheat temperature, heating source temperature, and incubation period to disassemble intact components were 120 °C, 260 °C, and 2 min, respectively. The disassembly rate of small surface mount components (side length ≤ 3 mm) was 40-50% lower than that of other surface mount components and pin through hole components. On the basis of these results, a reproducible and sustainable industrial ecological protocol using steam produced by industrial exhaust heat coupled to electronic-waste recycling is proposed, providing an efficient, promising, and green method for both electronic component recovery and industrial exhaust heat reutilization.

The intermetallic formation and growth kinetics at the interface of near eutectic tin-silver-copper solder alloys and gold/nickel metallization

NASA Astrophysics Data System (ADS)

Gao, Mao

The formation of a one micron thick layer of an intermetallic compound between a solder alloy and a metallic substrate generally constitutes a good solder joint in an electronic device. However, if the compound grows too thick, and/or if multiple intermetallic compounds form, poor solder joint reliability may result. Thus significant interest has been focused on intermetallic compound phase selection and growth kinetics at such solder/metal interfaces. The present study focuses on one such specific problem, the formation and growth of intermetallic compounds at near eutectic Sn-Ag-Cu solder alloy/Ni interfaces. Sn-3.0Ag-0.5Cu solder was reflowed on Au/Ni substrates, resulting in the initial formation and growth of (CuNi)6Sn 5 at Sn-3.0Ag-0.5Cu /Ni interfaces. (NiCu)3Sn4 formed between the (CuNi)6Sn5 and the Ni substrate when the concentration of Cu in the liquid SnAgCu solder decreased to a critical value which depended upon temperature: 0.37, 0.31 and 0.3(wt.%) at reflow temperatures of 260°C, 245°C and 230°C respectively. The growth rate of (CuNi)6Sn5 was found to be consistent with extrapolations of a diffusion limited growth model formulated for lower temperature, solid state diffusion couples. The long range diffusion of Cu did not limit growth rates. The spalling of (CuNiAu)6Sn5 from (NiCu)3 Sn4 surfaces during reflow was also examined. When the Cu concentration in the solder decreased to approximately 0.28wt.%, the (Cu,Ni,Au) 6Sn5 was observed to spall. Compressive stress in (CuNiAu) 6Sn5 and weak adhesion between (CuNiAu)6Sn 5 and (NiCu)3Sn4 was found to cause this effect.

Solar cell array interconnects

DOEpatents

Carey, P.G.; Thompson, J.B.; Colella, N.J.; Williams, K.A.

1995-11-14

Electrical interconnects are disclosed for solar cells or other electronic components using a silver-silicone paste or a lead-tin (Pb-Sn) no-clean fluxless solder cream, whereby the high breakage of thin (<6 mil thick) solar cells using conventional solder interconnect is eliminated. The interconnects of this invention employs copper strips which are secured to the solar cells by a silver-silicone conductive paste which can be used at room temperature, or by a Pb-Sn solder cream which eliminates undesired residue on the active surfaces of the solar cells. Electrical testing using the interconnects of this invention has shown that no degradation of the interconnects developed under high current testing, while providing a very low contact resistance value. 4 figs.

Solar cell array interconnects

DOEpatents

Carey, Paul G.; Thompson, Jesse B.; Colella, Nicolas J.; Williams, Kenneth A.

1995-01-01

Electrical interconnects for solar cells or other electronic components using a silver-silicone paste or a lead-tin (Pb-Sn) no-clean fluxless solder cream, whereby the high breakage of thin (<6 mil thick) solar cells using conventional solder interconnect is eliminated. The interconnects of this invention employs copper strips which are secured to the solar cells by a silver-silicone conductive paste which can be used at room temperature, or by a Pb-Sn solder cream which eliminates undesired residue on the active surfaces of the solar cells. Electrical testing using the interconnects of this invention has shown that no degradation of the interconnects developed under high current testing, while providing a very low contact resistance value.

Process for electrically interconnecting electrodes

DOEpatents

Carey, Paul G.; Thompson, Jesse B.; Colella, Nicolas J.; Williams, Kenneth A.

2002-01-01

Electrical interconnects for solar cells or other electronic components using a silver-silicone paste or a lead-tin (Pb--Sn) no-clean fluxless solder cream, whereby the high breakage of thin (<6 mil thick) solar cells using conventional solder interconnect is eliminated. The interconnects of this invention employs copper strips which are secured to the solar cells by a silver-silicone conductive paste which can be used at room temperature, or by a Pb--Sn solder cream which eliminates undesired residue on the active surfaces of the solar cells. Electrical testing using the interconnects of this invention has shown that no degradation of the interconnects developed under high current testing, while providing a very low contact resistance value.

Structural Design and Analysis of a Light-Weight Laminated Composite Heat Sink for Spaceflight PWBs

NASA Technical Reports Server (NTRS)

Fan, Mark S.; Niemeyer, W. Lee

1997-01-01

In order to reduce the overall weight in spaceborne electronic systems, a conventional metallic heat sink typically used for double-sided printed wiring boards was suggested to be replaced by light-weight and high-strength laminated composite materials. Through technology validation assurance (TVA) approach, it has been successfully demonstrated that using laminated composite heat sink can not only reduce the weight of the heat sink by nearly 50%, but also significantly lower the internal thermally-induced stresses that are largely responsible for potential delamination under cyclic temperature variations. With composite heat sink, both thermal and dynamic performance of the double-sided printed wiring board (PWB) exceeds that of its counterpart with metallic heat sink. Also included in this work is the original contribution to the understanding of creep behavior of the worst-case leadless chip carrier (LCC) surface mount solder joint. This was identified as the interconnection most susceptible to thermal fatigue damage in the PWB assembly.

Fabrication of Cu-Ni mixed phase layer using DC electroplating and suppression of Kirkendall voids in Sn-Ag-Cu solder joints

NASA Astrophysics Data System (ADS)

Chee, Sang-Soo; Lee, Jong-Hyun

2014-05-01

A solderable layer concurrently containing Cu-rich and Ni-rich phases (mixed-phase layer, MPL) was fabricated by direct current electroplating under varying process conditions. Current density was considered as the main parameter to adjust the microstructure and composition of MPL during the electroplating process, and deposit thickness were evaluated as functions of plating time. As a result, it was observed that the coral-like structure that consisted of Cu-rich and Ni-rich phases grew in the thickness direction. The most desirable microstructure was obtained at a relatively low current density of 0.4 mA/cm2. In other words, the surface was the smoothest and defect-free at this current density. The electroplating rate was slightly enhanced with an increase in current density. Investigations of its solid-state reaction properties, including the formation of Kirkendall voids, were also carried out after reflow soldering with Sn-3.0 Ag-0.5 Cu solder balls. In the solid-state aging experiment at 125°C, Kirkendall voids at the normal Sn-3.0 Ag-0.5 Cu solder/Cu interface were easily formed after just 240 h. Meanwhile, the presence of an intermetallic compound (IMC) layer created in the solder/MPL interface indicated a slightly lower growth rate, and no Kirkendall voids were observed in the IMC layer even after 720 h.

Soldering Characteristics and Mechanical Properties of Sn-1.0Ag-0.5Cu Solder with Minor Aluminum Addition

PubMed Central

Leong, Yee Mei; Haseeb, A.S.M.A.

2016-01-01

Driven by the trends towards miniaturization in lead free electronic products, researchers are putting immense efforts to improve the properties and reliabilities of Sn based solders. Recently, much interest has been shown on low silver (Ag) content solder SAC105 (Sn-1.0Ag-0.5Cu) because of economic reasons and improvement of impact resistance as compared to SAC305 (Sn-3.0Ag-0.5Cu. The present work investigates the effect of minor aluminum (Al) addition (0.1–0.5 wt.%) to SAC105 on the interfacial structure between solder and copper substrate during reflow. The addition of minor Al promoted formation of small, equiaxed Cu-Al particle, which are identified as Cu3Al2. Cu3Al2 resided at the near surface/edges of the solder and exhibited higher hardness and modulus. Results show that the minor addition of Al does not alter the morphology of the interfacial intermetallic compounds, but they substantially suppress the growth of the interfacial Cu6Sn5 intermetallic compound (IMC) after reflow. During isothermal aging, minor alloying Al has reduced the thickness of interfacial Cu6Sn5 IMC but has no significant effect on the thickness of Cu3Sn. It is suggested that of atoms of Al exert their influence by hindering the flow of reacting species at the interface. PMID:28773645

Soldering Characteristics and Mechanical Properties of Sn-1.0Ag-0.5Cu Solder with Minor Aluminum Addition.

PubMed

Leong, Yee Mei; Haseeb, A S M A

2016-06-28

Driven by the trends towards miniaturization in lead free electronic products, researchers are putting immense efforts to improve the properties and reliabilities of Sn based solders. Recently, much interest has been shown on low silver (Ag) content solder SAC105 (Sn-1.0Ag-0.5Cu) because of economic reasons and improvement of impact resistance as compared to SAC305 (Sn-3.0Ag-0.5Cu. The present work investigates the effect of minor aluminum (Al) addition (0.1-0.5 wt.%) to SAC105 on the interfacial structure between solder and copper substrate during reflow. The addition of minor Al promoted formation of small, equiaxed Cu-Al particle, which are identified as Cu₃Al₂. Cu₃Al₂ resided at the near surface/edges of the solder and exhibited higher hardness and modulus. Results show that the minor addition of Al does not alter the morphology of the interfacial intermetallic compounds, but they substantially suppress the growth of the interfacial Cu₆Sn₅ intermetallic compound (IMC) after reflow. During isothermal aging, minor alloying Al has reduced the thickness of interfacial Cu₆Sn₅ IMC but has no significant effect on the thickness of Cu₃Sn. It is suggested that of atoms of Al exert their influence by hindering the flow of reacting species at the interface.

Hybrid framework with cobalt-chromium alloy and gold cylinder for implant superstructure: Bond strength and corrosion resistance.

PubMed

Yoshinari, Masao; Uzawa, Shinobu; Komiyama, Yataro

2016-10-01

The aim of this in vitro study was to evaluate tensile bond strengths and corrosion resistance of CoCr alloys joined with gold cylinder by a soldering system in comparison with the conventional cast-joining system. CoCr alloys joined with gold cylinder by a soldering system using a high-fusing gold solder (CoCr/Solder/Gold cylinder), gold alloy joined with gold cylinder by a cast joining system (Gold alloy/Gold cylinder) and CoCr castings were fabricated. The tensile bond strength and corrosion resistance in 0.9% NaCl solution (pH 7.4 and pH 2.3) were evaluated. Scanning electron microscopy (SEM) of the fractured surface and electron probe microanalysis (EPMA) of the joined interfaces were also performed. The tensile bond strengths of the CoCr/Solder/Gold cylinder specimens showed similar values as the Gold alloy/Gold cylinder specimens. SEM observation and EPMA analyses suggested firm bonding between the CoCr alloy and gold cylinder. The released elements from the CoCr/Solder/Gold cylinder specimens were similar to ones from CoCr castings. Results showed that superstructures made of CoCr alloys joined with the gold cylinder using a high-fusing gold solder had sufficient bond strength and high corrosion resistance. These hybrid frameworks with cobalt-chromium alloy and gold cylinder are promising prosthesis for implant superstructures with the low cost and favorable mechanical properties instead of conventional high-gold alloys. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Flip-chip replacement within the constraints imposed by multilayer ceramic (MLC) modules

NASA Astrophysics Data System (ADS)

Puttlitz, Karl J.

1984-01-01

Economics often dictates that suitable module rework procedures be established to replace solder bump devices (flip chips) reflowed to multichip carriers. These operations are complicated, owing to various constraints such as the substrate's physical and mechanical properties, close proximity of surface features, etc. This paper describes the constraints and the methods to circumvent them. An order of preference based upon the degree of constraint is recommended to achieve device removal and subsequent site dress of the residual solder left on the substrate. It has been determined that rework (device replacement) can be successfully achieved in even highly constricted situations. This is illustrated by the example of utilizing a localized heating technique, hot gas, to remove solder from microsockets from which chips were previously removed. Microsockets are areas to which chips are reflowed to the top surface of IBM's densely populated multilayer ceramic (MLC) modules, thus forming the so-called controlled collapse chip connection or C-4. The microsocket patterns are thus identical to the chip footprint.

Contributions of Stress and Oxidation on the Formation of Whiskers in Pb-free Solders

DTIC Science & Technology

2016-01-29

environmental factors influencing formation of tin whiskers on electrodeposited lead free, tin coatings over copper (or copper containing) substrates is the...Oxidation on the Formation of Whiskers in Pb‐free Solders,” WP-1754 15. SUBJECT TERMS Tin Whiskers, Residual Stress, Environmental Degradation 16...showing the surface of a tin film with whisker .................... 2 Figure 2: SEM Micrograph of Tin film on Copper Substrate cross-sectioned by FIB

Bonding Diamond To Metal In Electronic Circuits

NASA Technical Reports Server (NTRS)

Jacquez, Andrew E.

1993-01-01

Improved technique for bonding diamond to metal evolved from older technique of soldering or brazing and more suitable for fabrication of delicate electronic circuits. Involves diffusion bonding, developed to take advantage of electrically insulating, heat-conducting properties of diamond, using small diamond bars as supports for slow-wave transmission-line structures in traveling-wave-tube microwave amplifiers. No fillets or side coats formed because metal bonding strips not melted. Technique also used to mount such devices as transistors and diodes electrically insulated from, but thermally connected to, heat sinks.

Soviet Research and Development of High-Power Gap Switches

DTIC Science & Technology

1974-01-01

mounted between 5 and trigger electrode 7. The BaTi03 disc face on the side of electrode 7 is coated with silver , the coating extending over the...pressed by springs, coaxial with the cylinder body of the gap, against contacts 4, which are soldered to the silver coating of the cylinder representing...space. Fig. 3 — Gap switch 1 — BaTi03 disc 2 and 3 — electrodes 4 — silver coating 5 — air space The pulse repetition frequency is 3 x lO4 Hz up to

Laser tissue welding mediated with a protein solder

NASA Astrophysics Data System (ADS)

Small, Ward, IV; Heredia, Nicholas J.; Celliers, Peter M.; Da Silva, Luiz B.; Eder, David C.; Glinsky, Michael E.; London, Richard A.; Maitland, Duncan J.; Matthews, Dennis L.; Soltz, Barbara A.

1996-05-01

A study of laser tissue welding mediated with an indocyanine green dye-enhanced protein solder was performed. Freshly obtained sections of porcine artery were used for the experiments. Sample arterial wall thickness ranged from two to three millimeters. Incisions approximately four millimeters in length were treated using an 805 nanometer continuous- wave diode laser coupled to a one millimeter diameter fiber. Controlled parameters included the power delivered by the laser, the duration of the welding process, and the concentration of dye in the solder. A two-color infrared detection system was constructed to monitor the surface temperatures achieved at the weld site. Burst pressure measurements were made to quantify the strengths of the welds immediately following completion of the welding procedure.

Perpendicular Growth Characteristics of Cu-Sn Intermetallic Compounds at the Surface of 99Sn-1Cu/Cu Solder Interconnects

NASA Astrophysics Data System (ADS)

Chen, Zhiwen; Liu, Changqing; Wu, Yiping; An, Bing

2015-12-01

The growth of intermetallic compounds (IMCs) on the free surface of 99Sn-1Cu solder joints perpendicular to the interdiffusion direction has been investigated in this work. The specimens were specifically designed and polished to reveal a flat free surface at the solder/Cu interface for investigation. After aging at 175°C for progressively increased durations, the height of the perpendicular IMCs was examined and found to follow a parabolic law with aging duration that could be expressed as y = 0.11√ t, where t is the aging duration in hours and y is the height of the perpendicular IMCs in μm. For comparison, the planar growth of IMCs along the interdiffusion direction was also investigated in 99Sn-1Cu/Cu solder joints. After prolonged aging at 175°C, the thickness of the planar interfacial IMC layers also increased parabolically with aging duration and could be expressed as h_{{IMC}} = 0.27√ t + 4.6, where h is the thickness in μm and t is the time in hours. It was found that both the planar and perpendicular growth of the IMCs were diffusion-controlled processes, but the perpendicular growth of the IMCs was much slower than their planar growth due to the longer diffusion distance. It is proposed that Cu3Sn forms prior to the formation of Cu6Sn5 in the perpendicular IMCs, being the reverse order compared with the planar IMC growth.

An evaluation of the spring finger solder joints on SA1358-10 and SA2052-4 connector assemblies (MC3617,W87).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kilgo, Alice C.; Vianco, Paul Thomas; Hlava, Paul Frank

2006-08-01

The SA1358-10 and SA2052-4 circular JT Type plug connectors are used on a number of nuclear weapons and Joint Test Assembly (JTA) systems. Prototype units were evaluated for the following specific defects associated with the 95Sn-5Sb (Sn-Sb, wt.%) solder joint used to attach the beryllium-copper (BeCu) spring fingers to the aluminum (Al) connector shell: (1) extended cracking within the fillet; (2) remelting of the solder joint during the follow-on, soldering step that attached the EMR adapter ring to the connector shell (and/or soldering the EMR shell to the adapter ring) that used the lower melting temperature 63Sn-37Pb (Sn-Pb) alloy; andmore » (3) spalling of the Cd (Cr) layer overplating layer from the fillet surface. Several pedigrees of connectors were evaluated, which represented older fielded units as well as those assemblies that were recently constructed at Kansas City Plant. The solder joints were evaluated that were in place on connectors made with the current soldering process as well as an alternative induction soldering process for attaching the EMR adapter ring to the shell. Very similar observations were made, which crossed the different pedigrees of parts and processes. The extent of cracking in the top side fillets varied between the different connector samples and likely the EMR adapter ring to the shell. Very similar observations were made, which crossed the different pedigrees of parts and processes. The extent of cracking in the top side fillets varied between the different connector samples and likely reflected the different extents to which the connector was mated to its counterpart assembly. In all cases, the spring finger solder joints on the SA1358-10 connectors were remelted as a result of the subsequent EMR adapter ring attachment process. Spalling of the Cd (Cr) overplating layer was also observed for these connectors, which was a consequence of the remelting activity. On the other hand, the SA2052-4 connector did not exhibit evidence of remelting of the spring finger solder joint. The Cd (Cr) layer did not show signs of spalling. These results suggested that, due to the size of the SA1358-10 connector, any of the former or current soldering processes used to attach the EMR adapter ring and/or EMR shell to the connector shell, requires a level of heat energy that will always result in the remelting of the spring finger solder joint attached with either the Sn-Ag or the Sn-Sb alloy. Lastly, it was construed that the induction soldering process, which is used to attach the EMR adapter ring onto the shell, was more likely to have caused the remelting event rather than the more localized heat source of the hand soldering iron used to attach the EMR shell to the adapter ring.« less

Numerical prediction of mechanical properties of Pb-Sn solder alloys containing antimony, bismuth and or silver ternary trace elements

NASA Astrophysics Data System (ADS)

Gadag, Shiva P.; Patra, Susant

2000-12-01

Solder joint interconnects are mechanical means of structural support for bridging the various electronic components and providing electrical contacts and a thermal path for heat dissipation. The functionality of the electronic device often relies on the structural integrity of the solder. The dimensional stability of solder joints is numerically predicted based on their mechanical properties. Algorithms to model the kinetics of dissolution and subsequent growth of intermetallic from the complete knowledge of a single history of time-temperature-reflow profile, by considering equivalent isothermal time intervals, have been developed. The information for dissolution is derived during the heating cycle of reflow and for the growth process from cooling curve of reflow profile. A simple and quick analysis tool to derive tensile stress-strain maps as a function of the reflow temperature of solder and strain rate has been developed by numerical program. The tensile properties are used in modeling thermal strain, thermal fatigue and to predict the overall fatigue life of solder joints. The numerical analysis of the tensile properties as affected by their composition and rate of testing, has been compiled in this paper. A numerical model using constitutive equation has been developed to evaluate the interfacial fatigue crack growth rate. The model can assess the effect of cooling rate, which depends on the level of strain energy release rate. Increasing cooling rate from normalizing to water-quenching, enhanced the fatigue resistance to interfacial crack growth by up to 50% at low strain energy release rate. The increased cooling rates enhanced the fatigue crack growth resistance by surface roughening at the interface of solder joint. This paper highlights salient features of process modeling. Interfacial intermetallic microstructure is affected by cooling rate and thereby affects the mechanical properties.

Parametric Study of Solder Flux Hygroscopicity: Impact of Weak Organic Acids on Water Layer Formation and Corrosion of Electronics

NASA Astrophysics Data System (ADS)

Piotrowska, Kamila; Ud Din, Rameez; Grumsen, Flemming Bjerg; Jellesen, Morten Stendahl; Ambat, Rajan

2018-07-01

The presence of solder flux residues on the printed circuit board assembly surface is an important factor contributing to humidity-related reliability issues that affect device lifetime. This investigation focuses on understanding the hygroscopic nature of typical wave solder flux activators—weak organic acids—under varied temperature conditions. In situ x-ray diffraction measurements assessed the effect of high temperature on the crystal structure of organic activators. The hygroscopicity studies were carried out under relative humidity (RH) levels varying from 30% to ˜ 99% and at temperatures 25°C, 40°C, and 60°C. Water absorption levels were determined using the gravimetric method, and the influence on reliability was assessed using electrochemical impedance and leak current measurements performed on the surface insulation resistance comb patterns. The corrosion studies were correlated with the hygroscopicity results and solubility data. Corrosion morphology was analysed using the optical microscopy and scanning electron microscopy. The results show that the hygroscopic nature of typical solder flux residue depends on its chemical structure and temperature. An increase of temperature shifts the critical RH level for water vapour absorption towards lower RH range, accelerating the formation of a conductive electrolyte and the occurrence of ion transport-induced electrochemical migration. The overall ranking of flux activators with the increasing order of aggressivity is: palmitic < suberic < adipic < succinic < glutaric < dl-malic acid.

Parametric Study of Solder Flux Hygroscopicity: Impact of Weak Organic Acids on Water Layer Formation and Corrosion of Electronics

NASA Astrophysics Data System (ADS)

Piotrowska, Kamila; Ud Din, Rameez; Grumsen, Flemming Bjerg; Jellesen, Morten Stendahl; Ambat, Rajan

2018-04-01

The presence of solder flux residues on the printed circuit board assembly surface is an important factor contributing to humidity-related reliability issues that affect device lifetime. This investigation focuses on understanding the hygroscopic nature of typical wave solder flux activators—weak organic acids—under varied temperature conditions. In situ x-ray diffraction measurements assessed the effect of high temperature on the crystal structure of organic activators. The hygroscopicity studies were carried out under relative humidity (RH) levels varying from 30% to ˜ 99% and at temperatures 25°C, 40°C, and 60°C. Water absorption levels were determined using the gravimetric method, and the influence on reliability was assessed using electrochemical impedance and leak current measurements performed on the surface insulation resistance comb patterns. The corrosion studies were correlated with the hygroscopicity results and solubility data. Corrosion morphology was analysed using the optical microscopy and scanning electron microscopy. The results show that the hygroscopic nature of typical solder flux residue depends on its chemical structure and temperature. An increase of temperature shifts the critical RH level for water vapour absorption towards lower RH range, accelerating the formation of a conductive electrolyte and the occurrence of ion transport-induced electrochemical migration. The overall ranking of flux activators with the increasing order of aggressivity is: palmitic < suberic < adipic < succinic < glutaric < uc(dl)-malic acid.

Scanning electron microscopy observations of failures of implant overdenture bars: a case series report.

PubMed

Waddell, J Neil; Payne, Alan G T; Swain, Michael V; Kieser, Jules A

2010-03-01

Soldered or cast bars are used as a standard of care in attachment systems supporting maxillary and mandibular implant overdentures. When failures of these bars occur, currently there is a lack of evidence in relation to their specific etiology, location, or nature. To investigate the failure process of a case series of six failed soldered bars, four intact soldered bars, and one intact cast milled bar, which had been supporting implant overdentures. A total of 11 different overdenture bars were removed from patients with different configuration of opposing arches. A failed bar (FB) group (n = 6) had failed soldered overdenture bars, which were recovered from patients following up to 2 years of wear before requiring prosthodontic maintenance and repair. An intact bar (IB) group (n = 5) had both soldered bars and a single cast milled bar, which had been worn by patients for 2 to 5 years prior to receiving other aspects of prosthodontic maintenance. All bars were examined using scanning electron microscopy to establish the possible mode of failure (FB) or to identify evidence of potential failure in the future (IB). Evidence of a progressive failure mode of corrosion fatigue and creep were observed on all the FB and IB usually around the solder areas and nonoxidizing gold cylinder. Fatigue and creep were also observed in all the IB. Where the level of corrosion was substantial, there was no evidence of wear from the matrices of the attachment system. Evidence of an instantaneous failure mode, ductile and brittle overload, was observed on the fracture surfaces of all the FB, within the solder and the nonoxidizing gold cylinders, at the solder/cylinder interface. Corrosion, followed by corrosion fatigue, appears to be a key factor in the onset of the failure process for overdenture bars in this case series of both maxillary and mandibular overdentures. Limited sample size and lack of standardization identify trends only but prevent broad interpretation of the findings.

Metal ion release from silver soldering and laser welding caused by different types of mouthwash.

PubMed

Erdogan, Ayse Tuygun; Nalbantgil, Didem; Ulkur, Feyza; Sahin, Fikrettin

2015-07-01

To compare metal ion release from samples welded with silver soldering and laser welding when immersed into mouthwashes with different ingredients. A total of 72 samples were prepared: 36 laser welded and 36 silver soldered. Four samples were chosen from each subgroup to study the morphologic changes on their surfaces via scanning electron microscopy (SEM). Each group was further divided into four groups where the samples were submerged into mouthwash containing sodium fluoride (NaF), mouthwash containing sodium fluoride + alcohol (NaF + alcohol), mouthwash containing chlorhexidine (CHX), or artificial saliva (AS) for 24 hours and removed thereafter. Subsequently, the metal ion release from the samples was measured with inductively coupled plasma mass spectrometry (ICP-MS). The metal ion release among the solutions and the welding methods were compared. The Kruskal-Wallis and analysis of variance (ANOVA) tests were used for the group comparisons, and post hoc Dunn multiple comparison test was utilized for the two group comparisons. The level of metal ion release from samples of silver soldering was higher than from samples of laser welding. Furthermore, greater amounts of nickel, chrome, and iron were released from silver soldering. With regard to the mouthwash solutions, the lowest amounts of metal ions were released in CHX, and the highest amounts of metal ions were released in NaF + alcohol. SEM images were in accord with these findings. The laser welding should be preferred over silver soldering. CHX can be recommended for patients who have welded appliances for orthodontic reasons.

Interfacial Reaction and IMC Growth of an Ultrasonically Soldered Cu/SAC305/Cu Structure during Isothermal Aging

PubMed Central

Long, Weifeng; Hu, Xiaowu; Fu, Yanshu

2018-01-01

In order to accelerate the growth of interfacial intermetallic compound (IMC) layers in a soldering structure, Cu/SAC305/Cu was first ultrasonically spot soldered and then subjected to isothermal aging. Relatively short vibration times, i.e., 400 ms and 800 ms, were used for the ultrasonic soldering. The isothermal aging was conducted at 150 °C for 0, 120, 240, and 360 h. The evolution of microstructure, the IMC layer growth mechanism during aging, and the shear strength of the joints after aging were systemically investigated. Results showed the following. (i) Formation of intermetallic compounds was accelerated by ultrasonic cavitation and streaming effects, the thickness of the interfacial Cu6Sn5 layer increased with aging time, and a thin Cu3Sn layer was identified after aging for 360 h. (ii) The growth of the interfacial IMC layer of the ultrasonically soldered Cu/SAC305/Cu joints followed a linear function of the square root of the aging time, revealing a diffusion-controlled mechanism. (iii) The tensile shear strength of the joint decreased to a small extent with increasing aging time, owing to the combined effects of IMC grain coarsening and the increase of the interfacial IMC. (iv) Finally, although the fracture surfaces and failure locations of the joint soldered with 400 ms and 800 ms vibration times show similar characteristics, they are influenced by the aging time. PMID:29316625

Electromigration and thermomigration in lead-free tin-silver-copper and eutectic tin-lead flip chip solder joints

NASA Astrophysics Data System (ADS)

Ou Yang, Fan-Yi

Phase separation and microstructure change of eutectic SnPb and SnAgCu flip chip solder joint were investigated under thermomigration, electromigration, stressmigration and the combination of these effects. Different morphological behaviors under DC and AC electromigration were seen. Phase separation with Pb rich phase migration to the anode was observed when current density is below 1.6 x 104 A/cm2 at 100°C. For some cases, phase separation of Pb-rich phase and Su-rich phase as well as refinement of lamellar microstructure has also been observed. We propose that the refinement is due to recrystallization. On the other hand, time-dependent melting of eutectic SnPb flip chip solder joints has been observed to occur frequently with current density above 1.6 x 104 A/cm 2at 100°C. It has been found that it is due to joule heating of the on-chip Al interconnects. We found that electromigration has especially generated voids at the anode of the Al. This damage has greatly increased the resistance of the Al, which produces the heat needed to melt the solder joint. Owing to the line-to-bump configuration in flip chip solder joints, current crowding occurs when electrons enters into or exits from the solder bump. At the cathode contact, current crowding induced pancake-type void formation was observed widely. Furthermore, at the anode contact, we note that hillock or whisker forms. The cross-sectioned surface in SnPb showed dimple and bulge after electromigration, while that of SnAgCu remained flat. The difference is due to a larger back stress in the SnAgCu, consequently electromigration in SnAgCu is slower than that in SnPb. For thermomigration in eutectic SnPb flip chip solder joints, phase separation of Sn and Pb occurred, with Pb moving to the cold end. Both Sn and Pb have a stepwise concentration profile across solder bump. Refinement of lamellar microstructure was observed, indicating recrystallization. Also, thermomigration in eutectic SnAgCu flip chip solder joint were presented. It seems that vacancy flux plays a dominant role in thermomigration in Pb-free solder bumps; voids formed on the cold end and Sn moved to the hot end.

Platform technologies for hybrid optoelectronic integration and packaging

NASA Astrophysics Data System (ADS)

Datta, Madhumita

In order to bring fiber-optics closer to individual home and business services, the optical network components have to be inexpensive and reliable. Integration and packaging of optoelectronic devices holds the key to high-volume low-cost component manufacturing. The goal of this dissertation is to propose, study, and demonstrate various ways to integrate optoelectronic devices on a packaging platform to implement cost-effective, functional optical modules. Two types of hybrid integration techniques have been proposed: flip-chip solder bump bonding for high-density two-dimensional array packaging of surface-emitting devices, and solder preform bonding for fiber-coupled edge-emitting semiconductor devices. For flip-chip solder bump bonding, we developed a simple, inexpensive remetallization process called "electroless plating", which converts the aluminum bond pads of foundry-made complementary metal oxide semiconductor (CMOS) chips into solder-bondable and wire-bondable gold surfaces. We have applied for a patent on this remetallization technique. For fiber-pigtailed edge-emitting laser modules, we have studied the coupling characteristics of different types of lensed single-mode fibers including semispherically lensed fiber, cylindrically lensed fiber and conically lensed fiber. We have experimentally demonstrated 66% coupling efficiency with semispherically lensed fiber and 50% efficiency with conically lensed fibers. We have proposed and designed a packaging platform on which lensed fibers can be actively aligned to a laser and solder-attached reliably to the platform so that the alignment is retained. We have designed thin-film nichrome heaters on fused quartz platforms as local heat source to facilitate on-board solder alignment and attachment of fiber. The thermal performance of the heaters was simulated using finite element analysis tool ANSYS prior to fabrication. Using the heater's reworkability advantage, we have estimated the shift of the fiber due to solder shrinkage and introduced a pre-correction in the alignment process to restore optimum coupling efficiency close to 50% with conically lensed fibers. We have applied for a patent on this unique active alignment method through the University of Maryland's Technology Commercialization Office. Although we have mostly concentrated on active alignment platforms, we have proposed the idea of combining the passive alignment advantages of silicon optical benches to the on-board heater-assisted active alignment technique. This passive-active alignment process has the potential of cost-effective array packaging of edge-emitting devices.

High power laser diodes at 14xx nm wavelength range for industrial and medical applications

NASA Astrophysics Data System (ADS)

Telkkälä, Jarkko; Boucart, Julien; Krejci, Martin; Crum, Trevor; Lichtenstein, Norbert

2014-03-01

We report on the development of the latest generation of high power laser diodes at 14xx nm wavelength range suitable for industrial applications such as plastics welding and medical applications including acne treatment, skin rejuvenation and surgery. The paper presents the newest chip generation developed at II-VI Laser Enterprise, increasing the output power and the power conversion efficiency while retaining the reliability of the initial design. At an emission wavelength around 1440 nm we applied the improved design to a variety of assemblies exhibiting maximum power values as high as 7 W for broad-area single emitters. For 1 cm wide bars on conductive coolers and for bars on active micro channel coolers we have obtained 50 W and 72 W in continuous wave (cw) operation respectively. The maximum power measured for a 1 cm bar operated with 50 μs pulse width and 0.01% duty cycle was 184 W, demonstrating the potential of the chip design for optimized cooling. Power conversion efficiency values as high as 50% for a single emitter device and over 40% for mounted bars have been demonstrated, reducing the required power budget to operate the devices. Both active and conductive bar assembly configurations show polarization purity greater than 98%. Life testing has been conducted at 95 A, 50% duty cycle and 0.5 Hz hard pulsed operation for bars which were soldered to conductive copper CS mounts using our hard solder technology. The results after 5500 h, or 10 million "on-off" cycles show stable operation.

Electrical Nanocontact Between Bismuth Nanowire Edges and Electrodes

NASA Astrophysics Data System (ADS)

Murata, Masayuki; Nakamura, Daiki; Hasegawa, Yasuhiro; Komine, Takashi; Uematsu, Daisuke; Nakamura, Shinichiro; Taguchi, Takashi

2010-09-01

Three methods for attaching electrodes to a bismuth nanowire sample were investigated. In the first and second methods, thin layers of titanium and copper were deposited by ion plating under vacuum onto the edge surface of individual bismuth nanowire samples that were encapsulated in a quartz template. Good electrical contact between the electrodes and the nanowire was achieved using silver epoxy and conventional solder on the thin-film layers in the first and second methods, respectively. In the third method, a low-melting-point solder was utilized and was also successful in achieving good electrical contact in air atmosphere. The connection methods showed no difference in terms of resistivity temperature dependence or Seebeck coefficient. The third method has an advantage in that nanocontact is easily achieved; however, diffusion of the solder into the nanowire allows contamination near the melting point of the solder. In the first and second methods, the thin-film layer enabled electrical contact to be more safely achieved than the direct contact used in the third method, because the thin-film layer prevented diffusion of binder components.

Packaging of ferroelectric liquid crystal-on-silicon spatial light modulators

NASA Astrophysics Data System (ADS)

Lin, W.; Morozova, Nina D.; Ju, TehHua; Zhang, Weidong; Lee, Yung-Cheng; McKnight, Douglas J.; Johnson, Kristina M.

1996-11-01

A self-pulling soldering technology has been demonstrated for assembling liquid crystal on silicon (LCOS) spatial light modulators (SLMs). One of the major challenges in manufacturing the LCOS modules is to reproducibly control the thickness of the gap between the very large scale integrated circuit (VLSI) chip and the cover glass. The liquid crystal material is sandwiched between the VLSI chop and the cover glass which is coated with a transparent conductor. Solder joints with different profiles and sizes have been designed to provide surface tension forces to control the gap accommodating the ferroelectric liquid crystal layer in the range of a micron level with sub- micron uniformity. The optimum solder joint design is defined as a joint that results in the maximum pulling force. This technology provides an automatic, batch assembly process for a LCOS SLM through one reflow process. Fluxless soldering technology is used to assemble the module. This approach avoids residues from chemical of flux and oxides, and eliminates potential contamination to the device. Two different LCOS SLM designs and the process optimization are described.

Effect of temperature and flux concentration on soldering of base metal.

PubMed

Lee, S Y; Lin, C T; Wang, M H; Tseng, H; Huang, H M; Dong, D R; Pan, L C; Shih, Y H

2000-12-01

The present study used the acoustic emission (AE) technique to evaluate interactions among soldering temperature, flux treatment, and the resultant ultimate tensile strength (UTS). Scanning electron microscopy (SEM) was used to examine fracture surfaces of the solder joints. Specimens were cast from removable partial denture alloy and then placed in a jig with a gap distance of 1.0 mm. A high-frequency soldering machine with an optical pyrometer was used for soldering at 1150 degrees C and 1200 degrees C, respectively. The flux concentrations were 67% and 75%. The soldered specimens were subjected to tensile test at a crosshead speed of 0.05 mm/min. During testing, acoustic emissions in the frequency range of 100--1200 kHz were collected, filtered, recorded, and processed by a sensing device. The results were analysed by ANOVA and Tukey LSD test. UTS at different temperatures showed no significant difference according to either mechanical or acoustic results. But in the 1200 degrees C group, the UTSs and AE counts showed significant differences (P<0.05) at both flux concentrations. SEM showed that the 1200C group had better dendritic crystal structure than did the 1150 degrees C group. In the 1200 degrees C group specimens with 67% flux had fewer flux inclusion bodies and dendritic crystals than did specimens with 75% flux. The 75% flux subgroup produced high-amplitude (60--70 dB) acoustic signals within the elastic deformation zone, while the 67% flux subgroup produced similar signals within the plastic deformation zone, either beyond the 0.2% yield point or before fracture.

Transistor screening evaluation SJ6708H

NASA Technical Reports Server (NTRS)

Barton, J. L.

1978-01-01

A manufacturer was contracted to screen 125 transistors capable of withstanding the high level inductive voltages obtained when switching inductive loads. Planned differences included a change in die bonding to comply with NASA's desire for hard solder die attachment which further necessitated a change in package to conform to the required die mounting system. Evaluation of the electrical performance and recommended changes were made during the preliminary build phase of the program. The following sections are outlined: (1) narrative outline; (2) customer data summary and X-ray reports; (3) device specification; (4) failure analysis reports; (5) test facilities list; and (6) test measurement data.

Novel First-Level Interconnect Techniques for Flip Chip on MEMS Devices

PubMed Central

Sutanto, Jemmy; Anand, Sindhu; Patel, Chetan; Muthuswamy, Jit

2013-01-01

Flip-chip packaging is desirable for microelectro-mechanical systems (MEMS) devices because it reduces the overall package size and allows scaling up the number of MEMS chips through 3-D stacks. In this report, we demonstrate three novel techniques to create first-level interconnect (FLI) on MEMS: 1) Dip and attach technology for Ag epoxy; 2) Dispense technology for solder paste; 3) Dispense, pull, and attach technology (DPAT) for solder paste. The above techniques required no additional microfabrication steps, produced no visible surface contamination on the MEMS active structures, and generated high-aspect-ratio interconnects. The developed FLIs were successfully tested on MEMS moveable microelectrodes microfabricated by SUMMiTVTM process producing no apparent detrimental effect due to outgassing. The bumping processes were successfully applied on Al-deposited bond pads of 100 μm × 100 μm with an average bump height of 101.3 μm for Ag and 184.8 μm for solder (63Sn, 37Pb). DPAT for solder paste produced bumps with the aspect ratio of 1.8 or more. The average shear strengths of Ag and solder bumps were 78 MPa and 689 kPa, respectively. The electrical test on Ag bumps at 794 A/cm2 demonstrated reliable electrical interconnects with negligible resistance. These scalable FLI technologies are potentially useful for MEMS flip-chip packaging and 3-D stacking. PMID:24504168

Interfacial Reaction and Mechanical Properties of Sn-Bi Solder joints

PubMed Central

Huang, Ying; Zhang, Zhijie

2017-01-01

Sn-Bi solder with different Bi content can realize a low-to-medium-to-high soldering process. To obtain the effect of Bi content in Sn-Bi solder on the microstructure of solder, interfacial behaviors in solder joints with Cu and the joints strength, five Sn-Bi solders including Sn-5Bi and Sn-15Bi solid solution, Sn-30Bi and Sn-45Bi hypoeutectic and Sn-58Bi eutectic were selected in this work. The microstructure, interfacial reaction under soldering and subsequent aging and the shear properties of Sn-Bi solder joints were studied. Bi content in Sn-Bi solder had an obvious effect on the microstructure and the distribution of Bi phases. Solid solution Sn-Bi solder was composed of the β-Sn phases embedded with fine Bi particles, while hypoeutectic Sn-Bi solder was composed of the primary β-Sn phases and Sn-Bi eutectic structure from networked Sn and Bi phases, and eutectic Sn-Bi solder was mainly composed of a eutectic structure from short striped Sn and Bi phases. During soldering with Cu, the increase on Bi content in Sn-Bi solder slightly increased the interfacial Cu6Sn5 intermetallic compound (IMC)thickness, gradually flattened the IMC morphology, and promoted the accumulation of more Bi atoms to interfacial Cu6Sn5 IMC. During the subsequent aging, the growth rate of the IMC layer at the interface of Sn-Bi solder/Cu rapidly increased from solid solution Sn-Bi solder to hypoeutectic Sn-Bi solder, and then slightly decreased for Sn-58Bi solder joints. The accumulation of Bi atoms at the interface promoted the rapid growth of interfacial Cu6Sn5 IMC layer in hypoeutectic or eutectic Sn-Bi solder through blocking the formation of Cu6Sn5 in solder matrix and the transition from Cu6Sn5 to Cu3Sn. Ball shear tests on Sn-Bi as-soldered joints showed that the increase of Bi content in Sn-Bi deteriorated the shear strength of solder joints. The addition of Bi into Sn solder was also inclined to produce brittle morphology with interfacial fracture, which suggests that the addition of Bi increased the shear resistance strength of Sn-Bi solder. PMID:28792440

A comparison of two soldering techniques on the misfit of bar-retained implant-supported overdentures.

PubMed

Alvarez, Angel; Lafita, Pedro; de Llanos, Hector; Gago, Angel; Brizuela, Aritza; Ellacuria, Joseba J

2014-02-01

This study was conducted to measure and compare the effect of the soldering method (torch soldering or ceramic furnace soldering) used for soldering bars to bar-retained, implant-supported overdentures on the fit between the bar gold cylinder and implant transgingival abutment. Thirty-two overdenture implant bars were manufactured and screw retained into two Bränemark implants, which were attached to a cow rib. The bars were randomly distributed in two groups: a torch-soldering group and a porcelain-furnace soldering group. Then all bars were cut and soldered using a torch and a ceramic furnace. The fit between the bar gold cylinders and implant transgingival abutments was measured with a light microscope on the opposite side to the screw tightening side before and after the bar soldering procedure. The data obtained were statistically processed for paired and independent data. The average misfit for all bars before soldering was 33.83 to 54.04 μm. After cutting and soldering the bars, the misfit increased up to a range of 71.74 to 78.79 μm. Both before and after the soldering procedure, the bars soldered using a torch showed a higher misfit when compared to the bars soldered using a porcelain furnace. After the soldering procedure, the misfit was slightly lower on the left side of the bars, which had been soldered using a ceramic furnace. According to our data, the soldering of bars using the torch or furnace oven soldering techniques does not improve the misfit of one-piece cast bars on two implants. The lower misfit was obtained using the porcelain furnace soldering technique. © 2013 by the American College of Prosthodontists.

Laser soldering technique for sutureless urethral surgery.

PubMed

Kirsch, A J; Canning, D A; Zderic, S A; Hensle, T W; Duckett, J W

1997-01-01

Investigators have attempted sutureless surgery to decrease operative time, lessen the inflammatory response, maintain luminal continuity, and increase the ease of performing technically difficult surgery. Only recently has laser-tissue welding (LTW) been used for urologic reconstruction in humans. Herein, we present our technique of laser soldering with the half-watt diode laser and wavelength matched albumin-based solder. Our methodology of LTW relies on bonding between the outer surface of the wound edges and the solder. The 808-nm diode wavelength does not penetrate deep tissue, and thus relies on indocyanine green dye to localize photon absorption. Since 1994, we have performed LTW, as an adjunct to suturing (N = 25) and as a primary means of tissue closure (N = 11). Preoperative diagnoses included hypospadias, urethral stricture, urethral diverticulum, and urethral fistulae. Follow-up ranged between 3 months and 3 years to identify complications of wound healing, stricture, and fistula formation. In the 37 patients undergoing urethral surgery, no strictures or diverticula have resulted. None of the patients have had wound infections or poor wound healing. Overall, five patients have developed fistulas between 2 weeks and 6 months postoperatively. The location of the hypospadiac meatus was scrotal or penoscrotal in four of these patients. Two fistulas developed following sutureless urethroplasty (reoperative) after traumatic catheterization for urinary retention (one case for inadvertent catheter removal). In our initial experience, the overall complication rate using laser soldering was 19% compared to 24% in an historical control group. Half of the complications occurred in a reoperative situation. More recently, the overall fistula rate was 14%; however, for primary cases, the current fistula rate is only 6%. LTW is safe and easy to perform. The application of protein solders (+/-chromophores) have permitted far greater tensile strengths to be achieved than laser alone. Temperature-control and chromophore-control have permitted safety and efficacy to be achieved. Solder application site and technique are equally important in the success of the LTW process. A randomized, prospective study comparing LTW to suturing is ongoing.

Modifications to a Laboratory-Scale Confined Laser Ignition Chamber for Pressure Measurements to 70 MPa

DTIC Science & Technology

2017-09-01

which is then turned over and pressed by hand against a flat surface. The solder ring is removed from the flange using a flat blade mini screwdriver...densities of M10 propellant. This series of experiments was conducted to get an indication of how many experiments could be run with the same window...While we were able to run 6 experiments with a pair of solder rings as the window seat, we typically replace the seat after 4 experiments have been

Soldering tool heats workpieces and applies solder in one operation

NASA Technical Reports Server (NTRS)

Gudkese, V. W.

1966-01-01

Fountain-pen type soldering iron heats workpieces and applies solder to joints in densely packed electronics assemblies. The basic soldering tool is used with different-sized orifice tips, eliminating the need for an assortment of conventional soldering guns.

Microwave Tissue Soldering for Immediate Wound Closure

NASA Technical Reports Server (NTRS)

Arndt, G. Dickey; Ngo, Phong H.; Phan, Chau T.; Byerly, Diane; Dusl, John; Sognier, Marguerite A.; Carl, James

2011-01-01

A novel approach for the immediate sealing of traumatic wounds is under development. A portable microwave generator and handheld antenna are used to seal wounds, binding the edges of the wound together using a biodegradable protein sealant or solder. This method could be used for repairing wounds in emergency settings by restoring the wound surface to its original strength within minutes. This technique could also be utilized for surgical purposes involving solid visceral organs (i.e., liver, spleen, and kidney) that currently do not respond well to ordinary surgical procedures. A miniaturized microwave generator and a handheld antenna are used to deliver microwave energy to the protein solder, which is applied to the wound. The antenna can be of several alternative designs optimized for placement either in contact with or in proximity to the protein solder covering the wound. In either case, optimization of the design includes the matching of impedances to maximize the energy delivered to the protein solder and wound at a chosen frequency. For certain applications, an antenna could be designed that would emit power only when it is in direct contact with the wound. The optimum frequency or frequencies for a specific application would depend on the required depth of penetration of the microwave energy. In fact, a computational simulation for each specific application could be performed, which would then match the characteristics of the antenna with the protein solder and tissue to best effect wound closure. An additional area of interest with potential benefit that remains to be validated is whether microwave energy can effectively kill bacteria in and around the wound. Thus, this may be an efficient method for simultaneously sterilizing and closing wounds.

Effects of PCB Substrate Surface Finish, Flux, and Phosphorus Content on Ionic Contamination

NASA Astrophysics Data System (ADS)

Bacior, M.; Sobczak, N.; Siewiorek, A.; Kudyba, A.; Homa, M.; Nowak, R.; Dziula, M.; Masłoń, S.

2015-02-01

The ionic contamination on printed circuit boards (PCB) having different surface finishes was examined using ionograph. The study was performed at the RT on three types of PCBs covered with: (i) hot air solder leveling (HASL LF), (ii) electroless nickel immersion gold (ENIG), and (iii) organic surface protectant (OSP), all on Cu substrates, as well as two types of fluxes, namely EF2202 and RF800. In the group of boards without soldered components, the lowest average value of contamination was for the ENIG 18 µm surface (0.01 μg NaCl/cm2). Boards with soldered components were more contaminated (from 0.29 μg NaCl/cm2 for the HASL LF 18 µm surface). After spraying boards with fluxing agents, the values of contaminants were the highest. The influence of phosphorus content in Ni-P layer of ENIG finish on ionic contamination was examined. In the group of PCBs with Au coating, the smallest amount of surface contaminants (0.32 μg NaCl/cm2) was for Ni-2-5%P layer. PCBs with Ni-11%P layer were higher contaminated (0.47 μg NaCl/cm2), and another with Ni-8%P layer had 0.81 μg NaCl/cm2. PCBs without Au coating, had the lowest contamination (0.48 μg NaCl/cm2) at phosphorous content equal 11%P. Higher contamination (0.67 μg NaCl/cm2) was at 2-5%P, up to 1.98 μg NaCl/cm2 for 8% of P. Boards with Au finish have lower value of contamination than identical boards without Au layer thus contributing to better reliability of electronic assemblies, since its failures due to current leakage and corrosion can be caused by contaminants.

Fluxless eutectic bonding of GaAs-on-Si by using Ag/Sn solder

NASA Astrophysics Data System (ADS)

Eo, Sung-Hwa; Kim, Dae-Seon; Jeong, Ho-Jung; Jang, Jae-Hyung

2013-11-01

Fluxless GaAs-on-Si wafer bonding using Ag/Sn solder was investigated to realize uniform and void-free heterogeneous material integration. The effects of the diffusion barrier, Ag/Sn thickness, and Ar plasma treatment were studied to achieve the optimal fluxless bonding process. Pt on a GaAs wafer and Mo on a Si wafer act as diffusion barriers by preventing the flow of Ag/Sn solder into both the wafers. The bonding strength is closely related to the Ag/Sn thickness and Ar plasma treatment. A shear strength test was carried out to investigate the bonding strength. Under identical bonding conditions, the Ag/Sn thickness was optimized to achieve higher bonding strength and to avoid the formation of voids due to thermal stress. An Ar plasma pretreatment process improved the bonding strength because the Ar plasma removed carbon contaminants and metal-oxide bonds from the metal surface.

Modified Process Reduces Porosity when Soldering in Reduced Gravity Environments

NASA Technical Reports Server (NTRS)

Watson, Kevin; Struk, Peter; Pettegrew, Richard; Downs, Robert; Haylett, Daniel

2012-01-01

A modified process yields lower levels of internal porosity for solder joints produced in reduced-gravity environments. The process incorporates both alternative materials and a modified procedure. The process provides the necessary cleaning action to enable effective bonding of the applied solder alloy with the materials to be joined. The modified process incorporates a commercially available liquid flux that is applied to the solder joint before heating with the soldering iron. It is subsequently heated with the soldering iron to activate the cleaning action of the flux and to evaporate most of the flux, followed by application of solder alloy in the form of commercially available solid solder wire (containing no flux). Continued heating ensures adequate flow of the solder alloy around and onto the materials to be joined. The final step is withdrawal of the soldering iron to allow alloy solidification and cooling of the solder joint.

Effects of limited cu supply on soldering reactions between SnAgCu and Ni

NASA Astrophysics Data System (ADS)

Ho, C. E.; Lin, Y. W.; Yang, S. C.; Kao, C. R.; Jiang, D. S.

2006-05-01

The volume difference between the various types of solder joints in electronic devices can be enormous. For example, the volume difference between a 760-µm ball grid array solder joint and a 75-µm flip-chip solder joint is as high as 1000 times. Such a big difference in volume produces a pronounced solder volume effect. This volume effect on the soldering reactions between the Sn3AgxCu (x=0.4, 0.5, or 0.6 wt.%) solders and Ni was investigated. Three different sizes of solder spheres (300, 500, and 760 µm in diameter) were soldered onto Ni soldering pads. Both the Cu concentration and the solder volume had a strong effect on the type of the reaction products formed. In addition, (Cu,Ni)6Sn5 massively spalled from the interface under certain conditions, including smaller joints and those with lower Cu concentration. We attributed the massive spalling of (Cu,Ni)6Sn5 to the decrease of the available Cu in the solders. The results of this study suggest that Cu-rich SnAgCu solders can be used to prevent this massive spalling.

Leaching behaviour and environmental risk assessment of heavy metals from electronic solder in acidified soil.

PubMed

Lao, Xiaodong; Cheng, Congqian; Min, Xiaohua; Zhao, Jie; Zhou, Dayu; Li, Xiaogang

2015-11-01

The leaching behaviour of Sn and Pb elements from eutectic SnPb solder of electronic waste in acidic soil was investigated through acidification with HCl-H2SO4 solution and compared with saline solution. The amounts of Sn and Pb elements leached, when subjected to acidic soil, are higher than those with saline soil. Evidence for the significantly preferential release of Sn into the leachate is provided; the galvanic couple accelerated such preferential release. Surface product analysis reveals the slight damage of SnPb in saline soil. Serious dissolution due to electrochemical reaction and a thick, porous PbSO4 surface layer are observed in acidified soil, suggesting more severe toxicity potential of Pb in soil rather than in water.

Effect of Solder-Joint Geometry on the Low-Cycle Fatigue Behavior of Sn- xAg-0.7Cu

NASA Astrophysics Data System (ADS)

Lee, Hwa-Teng; Huang, Kuo-Chen

2016-12-01

Low-cycle fatigue tests of Sn-Ag-Cu (SAC) Pb-free solder joints under fixed displacement were performed to evaluate the influence of Ag content (0-3 wt.%) and solder-joint geometry (barrel and hourglass types) on solder-joint fatigue behavior and reliability. The solder joints were composed of fine particles of Ag3Sn and Cu6Sn5, which aggregated as an eutectic constituent at grain boundaries of the primary β-Sn phase and formed a dense network structure. A decrease in the Ag content resulted in coarsening of the β-Sn and eutectic phases, which, in turn, decreased the strength of the joint and caused earlier failure. Solder joints in the hourglass form exhibited better fatigue performance with longer life than barrel-type joints. The sharp contact angle formed between the solder and the Cu substrate by the barrel-type joints concentrated stress, which compromised fatigue reliability. The addition of Ag to the solder, however, enhanced fatigue performance because of strengthening caused by Ag3Sn formation. The cracks of the barrel-type SAC solder joints originated mostly at the contact corner and propagated along the interfacial layer between the interfacial intermetallic compound (IMC) and solder matrix. Hourglass-type solder joints, however, demonstrated both crack initiation and propagation in the solder matrix (solder mode). The addition of 1.5-2.0 wt.% Ag to SAC solder appears to enhance the fatigue performance of solder joints while maintaining sufficient strength.

Sutureless laparoscopic heminephrectomy using laser tissue soldering.

PubMed

Ogan, Kenneth; Jacomides, Lucas; Saboorian, Hossein; Koeneman, Kenneth; Li, Yingming; Napper, Cheryl; Hoopman, John; Pearle, Margaret S; Cadeddu, Jeffrey A

2003-06-01

Widespread application of laparoscopic partial nephrectomy has been limited by the lack of a reliable means of attaining hemostasis. We describe laser tissue welding using human albumin as a solder to control bleeding and seal the collecting system during laparoscopic heminephrectomy in a porcine model. Laparoscopic left lower-pole heminephrectomy was performed in five female domestic pigs after occluding the hilar vessels. Using an 810-nm pulsed diode laser (20 W), a 50% liquid albumin-indocyanine green solder was welded to the cut edge of the renal parenchyma to seal the collecting system and achieve hemostasis. Two weeks later, an identical procedure was performed on the right kidney, after which, the animals were sacrificed and both kidneys were harvested for ex vivo retrograde pyelograms and histopathologic analysis. All 10 heminephrectomies were performed without complication. The mean operative time was 82 minutes, with an average blood loss of 43.5 mL per procedure. The mean warm ischemia time was 11.7 minutes. For each heminephrectomy, a mean of 4.2 mL of solder was welded to the cut parenchymal surface. In three of the five acute kidneys and all five 2-week kidneys, ex vivo retrograde pyelograms demonstrated no extravasation. In addition, no animal had clinical evidence of urinoma or delayed hemorrhage. Histopathologic analysis showed preservation of the renal parenchyma immediately beneath the solder. Laser tissue welding provided reliable hemostasis and closure of the collecting system while protecting the underlying parenchyma from the deleterious effect of the laser during porcine laparoscopic heminephrectomy.

Novel solid protein solder designs for laser-assisted tissue repair.

PubMed

McNally, K M; Sorg, B S; Welch, A J

2000-01-01

Previous studies have shown that the application of chromophore-enhanced albumin protein solders to augment laser tissue repairs significantly improves repair strength, enhances edge co-optation, and reduces thermal tissue injury. These investigations are furthered with this in vitro study conducted to assess a new range of specially designed chromophore-enhanced solid protein solders manufactured and tested for application during laser-assisted tissue repair. The experimental study was divided into three parts. In the first part of the study, the creation of a chromophore concentration gradient across the thickness of the solid protein solder was investigated as a means to improve control of the heat source gradient through the solder during laser irradiation. In the second part of the study, predenaturation of the solid protein solder was investigated as a means for enhancing the stability of the solder in physiological fluids before irradiation. Finally, in the third part of the study, the feasibility of using synthetic polymers as a scaffold for traditional albumin protein solder mixes was investigated as a means of improving the flexibility of the solder. Uniform denaturation across the thickness of the solder was achieved by controlling the chromophore concentration gradient, thus ensuring stable solder-tissue fusion when the specimen was submerged in a hydrated environment. Predenaturation of the solid protein solder significantly reduced the solubility of the solder, and consequently, improved the handling characteristics of the solder. The solder-doped polymer membranes were flexible enough to be wrapped around tissue, whereas their solid nature avoided problems associated with "runaway" of the less viscous liquid solders currently used by researchers. In addition, the solder-doped polymer membranes could be easily tailored to a wide range of geometries suitable to many clinical applications. The novel solid protein solder designs presented here add a new dimension to tissue repair as their flexible, moldable, and absorption controllable nature, greatly improves the clinical applicability of laser-assisted tissue repair. Copyright 2000 Wiley-Liss, Inc.

Electromigration in solder joints and solder lines

NASA Astrophysics Data System (ADS)

Gan, H.; Choi, W. J.; Xu, G.; Tu, K. N.

2002-06-01

Electromigration may affect the reliability of flip-chip solder joints. Eutectic solder is a two-phase alloy, so its electromigration behavior is different from that in aluminum or copper interconnects. In addition, a flipchip solder joint has a built-in currentcrowding configuration to enhance electromigration failure. To better understand electromigration in SnPb and lead-free solder alloys, the authors prepared solder lines in v-grooves etched on Si (001). This article discusses the results of those tests and compares the electromigration failure modes of eutectic SnPb and SnAgCu flip-chip solder joints along with the mean-timeto-failure.

Alignment-enhancing feed-through conductors for stackable silicon-on-sapphire wafers

NASA Technical Reports Server (NTRS)

Anthony, Thomas R. (Inventor)

1983-01-01

Alignment-enhancing electrically conductive feed-through paths are provided for the high-speed low-loss transfer of electrical signals between integrated circuits of a plurality of silicon-on-sapphire bodies arrayed in a stack. The alignment-enhancing feed-throughs are made by a process involving the drilling of holes through the body, double-sided sputtering, electroplating, and the filling of the holes with solder by capillary action. The alignment-enhancing feed-throughs are activated by forming a stack of wafers and remelting the solder whereupon the wafers, and the feed-through paths, are pulled into alignment by surface tension forces.

Printability Optimization For Fine Pitch Solder Bonding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwon, Sang-Hyun; Lee, Chang-Woo; Yoo, Sehoon

2011-01-17

Effect of metal mask and pad design on solder printability was evaluated by DOE in this study. The process parameters were stencil thickness, squeegee angle, squeegee speed, mask separating speed, and pad angle of PCB. The main process parameters for printability were stencil thickness and squeegee angle. The response surface showed that maximum printability of 1005 chip was achieved at the stencil thickness of 0.12 mm while the maximum printability of 0603 and 0402 chip was obtained at the stencil thickness of 0.05 mm. The bonding strength of the MLCC chips was also directly related with the printability.

In Situ Optical Creep Observation of Joint-Scale Tin-Silver-Copper Solder Shear Samples

NASA Astrophysics Data System (ADS)

Herkommer, Dominik; Reid, Michael; Punch, Jeff

2009-10-01

In this paper the creep behavior of lead-free 96.5Sn-3.0Ag-0.5Cu solder is evaluated. A series of creep tests at different stress/temperature and strain rate/temperature pairs has been conducted. The tests were observed in situ with a high-magnification camera system. Optical observation results are presented from selected tests, showing the occurrence of surface effects such as shear bands, voiding, and rumpling. From these observations the main deformation mechanisms were derived and compiled in terms of their dependence on the test conditions.

Multiwire conductor having increased interwire resistance and good mechanical stability and method for making same

DOEpatents

Luhman, Thomas; Klamut, Carl

1984-02-14

An improved multiwire conductor of the type which is mechanically stabilized by a solder filler. A solder filled conductor is heated to a temperature sufficient to make the solder brittle, but below the melting point of the solder. While still hot, the conductor is flexed, causing the solder to separate from the wires comprising the conductor, thereby increasing the interwire resistance. In one embodiment the conductor may be heated to a temperature above the eutectic temperature of the solder so that a controlled amount of solder is removed. The subject invention is particularly suited for use with braided, ribbon-type, solder filled superconductors.

Multiwire conductor having increased interwire resistance and good mechanical stability and method for making same

DOEpatents

Luhman, T.; Klamut, C.

1982-03-15

An improved multiwire conductor of the type which is mechanically stabilized by a solder filler. A solder filled conductor is heated to a temperature sufficient to make the solder brittle, but below the melting point of the solder. While still hot, the conductor is flexed, causing the solder to separate from the wires comprising the conductor, thereby increasing the interwire resistance. In one embodiment the conductor may be heated to a temperature above the eutectic temperature of the solder so that a controlled amount of solder is removed. The subject invention is particularly suited for use with braided, ribbon-type, solder filled superconductors.

Effect of Multiple Reflow Cycles and Al2O3 Nanoparticles Reinforcement on Performance of SAC305 Lead-Free Solder Alloy

NASA Astrophysics Data System (ADS)

Tikale, Sanjay; Prabhu, K. Narayan

2018-05-01

The effect of Al2O3 nanoparticles reinforcement on melting behavior, microstructure evolution at the interface and joint shear strength of 96.5Sn3Ag0.5Cu (SAC305) lead-free solder alloy subjected to multiple reflow cycles was investigated. The reinforced SAC305 solder alloy compositions were prepared by adding Al2O3 nanoparticles in different weight fractions (0.05, 0.1, 0.3 and 0.5 wt.%) through mechanical dispersion. Cu/solder/Cu micro-lap-shear solder joint specimens were used to assess the shear strength of the solder joint. Differential scanning calorimetry was used to investigate the melting behavior of SAC305 solder nanocomposites. The solder joint interfacial microstructure was studied using scanning electron microscopy. The results showed that the increase in melting temperature (T L) and melting temperature range of the SAC305 solder alloy by addition of Al2O3 nanoparticles were not significant. In comparison with unreinforced SAC305 solder alloy, the reinforcement of 0.05-0.5 wt.% of Al2O3 nanoparticles improved the solder wettability. The addition of nanoparticles in minor quantity effectively suppressed the Cu6Sn5 IMC growth, improved the solder joint shear strength and ductility under multiple reflow cycles. However, the improvement in solder properties was less pronounced on increasing the nanoparticle content above 0.1 wt.% of the solder alloy.

The Effect of Copper Addition on the Properties of Sn-0.7Cu Solder Paste

NASA Astrophysics Data System (ADS)

Said, R. M.; Mohamad Johari, F. H.; Salleh, M. A. A. Mohd; Sandu, A. V.

2018-03-01

The effect of copper addition on the properties of Sn-Cu based solder paste were investigate through this study. The Sn-0.7Cu solder paste doped with different concentration of Cu were prepared using solder paste mixture. The bulk solder microstructure of assolidified solder paste was studied. Besides that, intermetallic compound (IMC) formation on Cu substrate and hardness of all solder paste also being investigated. Results shows that increasing Cu concentration cause formation of large Cu6Sn5 IMC at bulk solder and the size of the IMC grew larger at high temperature. In addition, β-Sn area reduce when Cu concentration was high. The IMC morphology for all solder paste almost remain unchanged. However, there are large Cu6Sn5 IMC form near the interfacial IMC in Sn-Cu solder paste with high amount of Cu (Sn-10Cu). The hardness value was decrease when processing temperature at 250 °C due to present of small void in the microstructure while hardness of solder material increased at high temperature.

Investigation of the interaction of the solder components for laser welding of biological tissues

NASA Astrophysics Data System (ADS)

Ryabki, Dmitrii I.; Gerasimenko, Alexander Yu.; Kvasnov, Bogdan A.; Pyankov, Evgeny S.; Pyanov, Ivan V.; Telyshev, Dmitry V.; Podgaetsky, Vitaly M.

2017-07-01

Increase the weld strength is main directions of development of laser welding technology. Laser solders are used to increase tensile strength of welds and reduce of tissue temperature necrosis. Soldering components interaction effect the solder tensile strength characteristics of laser welds. Tensile strengths for welds obtained using of solder various concentration BSA and SWCNT was measured. Dimensions laser solder aggregates were measured. The dependence between the dimensions of the aggregates of laser solder and the tensile strength of the weld has been revealed.

Reliability and Characteristics of Wafer-Level Chip-Scale Packages under Current Stress

NASA Astrophysics Data System (ADS)

Chen, Po-Ying; Kung, Heng-Yu; Lai, Yi-Shao; Hsiung Tsai, Ming; Yeh, Wen-Kuan

2008-02-01

In this work, we present a novel approach and method for elucidating the characteristics of wafer-level chip-scale packages (WLCSPs) for electromigration (EM) tests. The die in WLCSP was directly attached to the substrate via a soldered interconnect. The shrinking of the area of the die that is available for power, and the solder bump also shrinks the volume and increases the density of electrons for interconnect efficiency. The bump current density now approaches to 106 A/cm2, at which point the EM becomes a significant reliability issue. As known, the EM failure depends on numerous factors, including the working temperature and the under bump metallization (UBM) thickness. A new interconnection geometry is adopted extensively with moderate success in overcoming larger mismatches between the displacements of components during current and temperature changes. Both environments and testing parameters for WLCSP are increasingly demanded. Although failure mechanisms are considered to have been eliminated or at least made manageable, new package technologies are again challenging its process, integrity and reliability. WLCSP technology was developed to eliminate the need for encapsulation to ensure compatibility with smart-mount technology (SMT). The package has good handing properties but is now facing serious reliability problems. In this work, we investigated the reliability of a WLCSP subjected to different accelerated current stressing conditions at a fixed ambient temperature of 125 °C. A very strong correlation exists between the mean time to failure (MTTF) of the WLCSP test vehicle and the mean current density that is carried by a solder joint. A series of current densities were applied to the WLCSP architecture; Black's power law was employed in a failure mode simulation. Additionally, scanning electron microscopy (SEM) was adopted to determine the differences existing between high- and low-current-density failure modes.

Undercooling Behavior and Intermetallic Compound Coalescence in Microscale Sn-3.0Ag-0.5Cu Solder Balls and Sn-3.0Ag-0.5Cu/Cu Joints

NASA Astrophysics Data System (ADS)

Zhou, M. B.; Ma, X.; Zhang, X. P.

2012-11-01

The microstructure of microscale solder interconnects and soldering defects have long been known to have a significant influence on the reliability of electronic packaging, and both are directly related to the solidification behavior of the undercooled solder. In this study, the undercooling behavior and solidification microstructural evolution of Sn-3.0Ag-0.5Cu solder balls with different diameters (0.76 mm, 0.50 mm, and 0.30 mm) and the joints formed by soldering these balls on Cu open pads of two diameters (0.48 mm and 0.32 mm) on a printed circuit board (PCB) substrate were characterized by differential scanning calorimetry (DSC) incorporated into the reflow process. Results show that the decrease in diameter of the solder balls leads to an obvious increase in the undercooling of the balls, while the undercooling of the solder joints shows a dependence on both the diameter of the solder balls and the diameter ratio of solder ball to Cu pad (i.e., D s/ D p), and the diameter of the solder balls has a stronger influence on the undercooling of the joints than the dimension of the Cu pad. Coarse primary intermetallic compound (IMC) solidification phases were formed in the smaller solder balls and joints. The bulk Ag3Sn IMC is the primary solidification phase in the as-reflowed solder balls. Due to the interfacial reaction and dissolution of Cu atoms into the solder matrix, the primary Ag3Sn phase can be suppressed and the bulk Cu6Sn5 IMC is the only primary solidification phase in the as-reflowed solder joints.

Understanding the reliability of solder joints used in advanced structural and electronics applications: Part 1 - Filler metal properties and the soldering process

DOE PAGES

Vianco, Paul T.

2017-02-01

Soldering technology has made tremendous strides in the past half-century. Whether structural or electronic, all solder joints must provide a level of reliability that is required by the application. This Part 1 report examines the effects of filler metal properties and soldering process on joint reliability. Solder alloy composition must have the appropriate melting and mechanical properties that suit the product's assembly process(es) and use environment. The filler metal must also optimize solderability (wetting-and-spreading) to realize the proper joint geometry. Here, the soldering process also affects joint reliability. The choice of flux and thermal profile support the solderability performance ofmore » the molten filler metal to successfully fill the gap and complete the fillet.« less

Testing a high-power LED based light source for hyperspectral imaging microscopy

NASA Astrophysics Data System (ADS)

Klomkaew, Phiwat; Mayes, Sam A.; Rich, Thomas C.; Leavesley, Silas J.

2017-02-01

Our lab has worked to develop high-speed hyperspectral imaging systems that scan the fluorescence excitation spectrum for biomedical imaging applications. Hyperspectral imaging can be used in remote sensing, medical imaging, reaction analysis, and other applications. Here, we describe the development of a hyperspectral imaging system that comprised an inverted Nikon Eclipse microscope, sCMOS camera, and a custom light source that utilized a series of high-power LEDs. LED selection was performed to achieve wavelengths of 350-590 nm. To reduce scattering, LEDs with low viewing angles were selected. LEDs were surface-mount soldered and powered by an RCD. We utilized 3D printed mounting brackets to assemble all circuit components. Spectraradiometric calibration was performed using a spectrometer (QE65000, Ocean Optics) and integrating sphere (FOIS-1, Ocean Optics). Optical output and LED driving current were measured over a range of illumination intensities. A normalization algorithm was used to calibrate and optimize the intensity of the light source. The highest illumination power was at 375 nm (3300 mW/cm2), while the lowest illumination power was at 515, 525, and 590 nm (5200 mW/cm2). Comparing the intensities supplied by each LED to the intensities measured at the microscope stage, we found there was a great loss in power output. Future work will focus on using two of the same LEDs to double the power and finding more LED and/or laser diodes and chips around the range. This custom hyperspectral imaging system could be used for the detection of cancer and the identification of biomolecules.

Packaging Reliability Effect of ENIG and ENEPIG Surface Finishes in Board Level Thermal Test under Long-Term Aging and Cycling

PubMed Central

Shen, Chaobo; Hai, Zhou; Zhao, Cong; Zhang, Jiawei; Evans, John L.; Bozack, Michael J.; Suhling, Jeffrey C.

2017-01-01

This study illustrates test results and comparative literature data on the influence of isothermal aging and thermal cycling associated with Sn-1.0Ag-0.5Cu (SAC105) and Sn-3.0Ag-0.5Cu (SAC305) ball grid array (BGA) solder joints finished with ENIG and ENEPIG on the board side and ENIG on the package side compared with ImAg plating on both sides. The resulting degradation data suggests that the main concern for 0.4 mm pitch 10 mm package size BGA is package side surface finish, not board side. That is, ENIG performs better than immersion Ag for applications involving long-term isothermal aging. SAC305, with a higher relative fraction of Ag3Sn IMC within the solder, performs better than SAC105. SEM and polarized light microscope analysis show cracks propagated from the corners to the center or even to solder bulk, which eventually causes fatigue failure. Three factors are discussed: IMC, grain structure, and Ag3Sn particle. The continuous growth of Cu-Sn intermetallic compounds (IMC) and grains increase the risk of failure, while Ag3Sn particles seem helpful in blocking the crack propagation. PMID:28772811

Chemoresponsive Colloidosomes via Ag⁺ Soldering of Surface-Assembled Nanoparticle Monolayers.

PubMed

Liu, Miao; Tian, Qian; Li, Yulin; You, Bo; Xu, An; Deng, Zhaoxiang

2015-04-28

Colloidosomes with a hollow interior and a porous plasmonic shell are highly desired for many applications including nanoreactors, surface-enhanced Raman scattering (SERS), photothermal therapy, and controlled drug release. We herein report a silica nanosphere-templated electrostatic self-assembly in conjunction with a newly developed Ag(+) soldering to fabricate gold colloidosomes toward multifunctionality and stimuli-responsibility. The gold colloidosomes are capable of capturing a nanosized object and releasing it via structural dissociation upon responding to a biochemical input (GSH, glutathione) at a concentration close to its cellular level. In addition, the colloidosomes have a tunable nanoporous shell composed of strongly coupled gold nanoparticles, which exhibit broadened near-infrared plasmon resonance. These features along with the simplicity and high tunability of the fabrication process make the gold colloidosomes quite promising for applications in a chemical or cellular environment.

Study on the Tensile Creep Behavior of Carbon Nanotubes-Reinforced Sn-58Bi Solder Joints

NASA Astrophysics Data System (ADS)

Yang, Li; Liu, Haixiang; Zhang, Yaocheng

2018-01-01

The microstructure and tensile creep behavior of plain Sn-58Bi solder and carbon nanotubes (CNTs)-reinforced composite solder joints were investigated. The stress exponent n under different stresses and the creep activation energy Q c under different temperatures of solder joints were obtained by an empirical equation. The results reveal that the microstructure of the composite solder joint is refined and the tensile creep resistance is improved by CNTs. The improvement of creep behavior is due to the microstructural change of the composite solder joints, since the CNTs could provide more obstacles for dislocation pile-up, which enhances the values of the stress exponent and the creep activation energy. The steady-state tensile creep rates of plain solder and composite solder joints are increased with increasing temperature and applied stress. The tensile creep constitutive equations of plain solder and composite solder joints are written as \\dot{ɛ }_{s1} = 14.94( {σ /G} )^{3.7} \\exp ( { - 81444/RT} ) and \\dot{ɛ }_{s2} = 2.5( {σ /G} )^{4.38} \\exp ( { - 101582/RT} ) , respectively. The tensile creep mechanism of the solder joints is the effects of lattice diffusion determined by dislocation climbing.

Analysis of Al diffusion processes in TiN barrier layers for the application in silicon solar cell metallization

NASA Astrophysics Data System (ADS)

Kumm, J.; Samadi, H.; Chacko, R. V.; Hartmann, P.; Wolf, A.

2016-07-01

An evaporated Al layer is known as an excellent rear metallization for highly efficient solar cells, but suffers from incompatibility with a common solder process. To enable solar cell-interconnection and module integration, in this work the Al layer is complemented with a solder stack of TiN/Ti/Ag or TiN/NiV/Ag, in which the TiN layer acts as an Al diffusion barrier. X-ray photoelectron spectroscopy measurements prove that diffusion of Al through the stack and the formation of an Al2O3 layer on the stack's surface are responsible for a loss of solderability after a strong post-metallization anneal, which is often mandatory to improve contact resistance and passivation quality. An optimization of the reactive TiN sputter process results in a densification of the TiN layer, which improves its barrier quality against Al diffusion. However, measurements with X-ray diffraction and scanning electron microscopy show that small grains with vertical grain boundaries persist, which still offer fast diffusion paths. Therefore, the concept of stuffing is introduced. By incorporating oxygen into the grain boundaries of the sputtered TiN layer, Al diffusion is strongly reduced as confirmed by secondary ion mass spectroscopy profiles. A quantitative analysis reveals a one order of magnitude lower Al diffusion coefficient for stuffed TiN layers. This metallization system maintains its solderability even after strong post-metallization annealing at 425 °C for 15 min. This paper thus presents an industrially feasible, conventionally solderable, and long-term stable metallization scheme for highly efficient silicon solar cells.

The effect of intermetallic compound morphology on Cu diffusion in Sn-Ag and Sn-Pb solder bump on the Ni/Cu Under-bump metallization

NASA Astrophysics Data System (ADS)

Jang, Guh-Yaw; Duh, Jenq-Gong

2005-01-01

The eutectic Sn-Ag solder alloy is one of the candidates for the Pb-free solder, and Sn-Pb solder alloys are still widely used in today’s electronic packages. In this tudy, the interfacial reaction in the eutectic Sn-Ag and Sn-Pb solder joints was investigated with an assembly of a solder/Ni/Cu/Ti/Si3N4/Si multilayer structures. In the Sn-3.5Ag solder joints reflowed at 260°C, only the (Ni1-x,Cux)3Sn4 intermetallic compound (IMC) formed at the solder/Ni interface. For the Sn-37Pb solder reflowed at 225°C for one to ten cycles, only the (Ni1-x,Cux)3Sn4 IMC formed between the solder and the Ni/Cu under-bump metallization (UBM). Nevertheless, the (Cu1-y,Niy)6Sn5 IMC was observed in joints reflowed at 245°C after five cycles and at 265°C after three cycles. With the aid of microstructure evolution, quantitative analysis, and elemental distribution between the solder and Ni/Cu UBM, it was revealed that Cu content in the solder near the solder/IMC interface played an important role in the formation of the (Cu1-y,Niy)6Sn5 IMC. In addition, the diffusion behavior of Cu in eutectic Sn-Ag and Sn-Pb solders with the Ni/Cu UBM were probed and discussed. The atomic flux of Cu diffused through Ni was evaluated by detailed quantitative analysis in an electron probe microanalyzer (EPMA). During reflow, the atomic flux of Cu was on the order of 1016-1017 atoms/cm2sec in both the eutectic Sn-Ag and Sn-Pb systems.

Effects of Metallic Nanoparticles on Interfacial Intermetallic Compounds in Tin-Based Solders for Microelectronic Packaging

NASA Astrophysics Data System (ADS)

Haseeb, A. S. M. A.; Arafat, M. M.; Tay, S. L.; Leong, Y. M.

2017-10-01

Tin (Sn)-based solders have established themselves as the main alternative to the traditional lead (Pb)-based solders in many applications. However, the reliability of the Sn-based solders continues to be a concern. In order to make Sn-based solders microstructurally more stable and hence more reliable, researchers are showing great interest in investigating the effects of the incorporation of different nanoparticles into them. This paper gives an overview of the influence of metallic nanoparticles on the characteristics of interfacial intermetallic compounds (IMCs) in Sn-based solder joints on copper substrates during reflow and thermal aging. Nanocomposite solders were prepared by mechanically blending nanoparticles of nickel (Ni), cobalt (Co), zinc (Zn), molybdenum (Mo), manganese (Mn) and titanium (Ti) with Sn-3.8Ag-0.7Cu and Sn-3.5Ag solder pastes. The composite solders were then reflowed and their wetting characteristics and interfacial microstructural evolution were investigated. Through the paste mixing route, Ni, Co, Zn and Mo nanoparticles alter the morphology and thickness of the IMCs in beneficial ways for the performance of solder joints. The thickness of Cu3Sn IMC is decreased with the addition of Ni, Co and Zn nanoparticles. The thickness of total IMC layer is decreased with the addition of Zn and Mo nanoparticles in the solder. The metallic nanoparticles can be divided into two groups. Ni, Co, and Zn nanoparticles undergo reactive dissolution during solder reflow, causing in situ alloying and therefore offering an alternative route of alloy additions to solders. Mo nanoparticles remain intact during reflow and impart their influence as discrete particles. Mechanisms of interactions between different types of metallic nanoparticles and solder are discussed.

Correlation Between Surface Area and Dissolving Properties of Lead - A Step in the Investigation of Higher than Standard Lead Concentration in Drinking Water in Washington, D.C.

NASA Astrophysics Data System (ADS)

Hua, M.; Garduno, L.; Mondragon, J. D.; Cuff, K. E.

2004-12-01

Several recently published articles by the Washington Post exposing the alarming concentration of lead in drinking water from schools and homes in the Washington D.C. area sparked our interest in the correlation between lead-containing materials used in plumbing and rate of lead solubility. Elementary children who attend schools in various regions of the District were contacted by San Francisco Bay Area- based high school students who are participants in the NSF-sponsored Environmental Science Information Technology Activities (ESITA) project. After receiving a thorough explanation of required sampling procedures, the elementary school children sent 500 ml water samples from their homes and schools to Berkeley along with information on the locations from which the water samples were collected. These water samples were analyzed for lead content at the Environmental Science Research Program laboratory at Lawrence Hall of Science. The majority of the samples contained more than 15 ppb of lead, which is the EPA action level. We hypothesize that there are three possible sources of lead in the drinking water: 1) lead pipes in the water main; 2) lead pipes in the service main; and 3) lead soldering that was often previously used to connect piping. We chose to investigate the effect of lead-based solder on the overall lead concentration in water. Using a soldering iron, we melted lead solder to create discs ranging from one to five centimeter diameter and one to thirty-six grams of mass. These discs were then placed into a beaker with 500 ml of 7.1pH distilled water and allowed to stand for 48 hours. At the end of 48 hours, the water samples were prepared for analysis using the EPA approved lead-dithizone procedure. Results showed an exponential relationship between disc surface area and the concentration of dissolved lead measured in the sample. Therefore, lead-based solder can represent a possible major source of lead contamination.

Ultracompliant Heterogeneous Copper-Tin Nanowire Arrays Making a Supersolder.

PubMed

Gong, Wei; Li, Pengfei; Zhang, Yunheng; Feng, Xuhui; Major, Joshua; DeVoto, Douglas; Paret, Paul; King, Charles; Narumanchi, Sreekant; Shen, Sheng

2018-06-13

Due to the substantial increase in power density, thermal interface resistance that can constitute more than 50% of the total thermal resistance has generally become a bottleneck for thermal management in electronics. However, conventional thermal interface materials (TIMs) such as solder, epoxy, gel, and grease cannot fulfill the requirements of electronics for high-power and long-term operation. Here, we demonstrate a high-performance TIM consisting of a heterogeneous copper-tin nanowire array, which we term "supersolder" to emulate the role of conventional solders in bonding various surfaces. The supersolder is ultracompliant with a shear modulus 2-3 orders of magnitude lower than traditional solders and can reduce the thermal resistance by two times as compared with the state-of-the-art TIMs. This supersolder also exhibits excellent long-term reliability with >1200 thermal cycles over a wide temperature range. By resolving this critical thermal bottleneck, the supersolder enables electronic systems, ranging from microelectronics and portable electronics to massive data centers, to operate at lower temperatures with higher power density and reliability.

Soldering instrument safety improvements

DOEpatents

Kosslow, William J.; Giron, Ronald W.

1996-01-01

A safe soldering device includes a retractable heat shield which can be moved between a first position in which the solder tip of the device is exposed for soldering operation and a second position in which the solder tip is covered by the heat shield. Preferably, the heat shield is biased towards the second position and may be locked in the first position for ease of use. When the soldering device is equipped with a vacuum system, the heat shield may serve to guide the flow of gases and heat from the solder tip away from the work area. The heat shield is preferably made of non-heatsinking plastic.

Soldering In Space Investigation Video

NASA Technical Reports Server (NTRS)

2004-01-01

This video captures Mike Fincke melting solder during the first set of planned In-Space Soldering Investigation (ISSI) experiments onboard the International Space Station (ISS). In the video, Fincke touches the tip of the soldering iron to a wire wrapped with rosin-core solder. Review of the experiment video revealed melting kinetics, wetting characteristics, and equilibrium shape attainment of the solder charge. Samples returned to Earth were examined for porosity and flux distribution as well as microstructural development. ISSI's purpose was to find out how solder behaves in a weightless environment and promote our knowledge of fabrication and repair techniques that might be employed during extended space exploration missions.

The present triumphs and future problems with wave soldering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vianco, P.T.

1993-10-01

Nearly 40 years of experience with wave soldering have resulted in processes that routinely produce several thousand, defect-free solder joints per minute. However, the climate of electronics manufacturing has changed significantly over the past 10 to 15 years. Environmental restrictions as well as the high quality of products made offshore has placed new demands and challenges on the electronics industry, right down to the assembly process. The impact on wave soldering by environmental regulations and a need for more cost-competitive manufacturing processes has become a serious issue in terms of the economical well-being of the industry. In order to obtainmore » a clearer understanding of the situation, however, it is first most appropriate and necessary to examine the technology of wave soldering. Historically, wave soldering was developed as a refinement of the dip and drag soldering processes with the objective of reducing or eliminating many of the associated defects often present in these earlier processes. Wave soldering reduces the area of contact between the circuit board and the solder. This characteristic, coupled with the agitation generated in the solder, allows flux and its volatile by-products to readily escape from under the board, decreasing the number of skips, unfilled holes, and solder joint voids. The reduced contact area also lessens the potential for thermal damage to the circuit board laminate. Control of the wave profile at the exit point of the circuit board lessens the likelihood of icicles and bridges forming on the solder joints; this latitude is not available in the dip soldering process.« less

Laser-based rework in electronics production

NASA Astrophysics Data System (ADS)

Albert, Florian; Mys, Ihor; Schmidt, Michael

2007-02-01

Despite the electronic manufacturing is well-established mass production process for a long time, the problem of reworking, i.a. reject and replace of defect components, still exists. The rework operations (soldering, replacement and desoldering) are performed in most cases manually. However, this practice is characterized by an inconsistent quality of the reworked solder joints and a high degree of physiological stress for the employees. In this paper, we propose a novel full-automated laser based soldering and rework process. Our developed soldering system is a pick-and-place unit with an integrated galvanometer scanner, a fiber coupled diode laser for quasi-simultaneous soldering and a pyrometer-based process control. The developed system provides soldering and reworking processes taking into account a kind of defect, a type of electronic component and quality requirements from the IPC- 610 norm. The paper spends a great deal of efforts to analyze quality of laser reworked solder joints. The quality depends mainly on the type and thickness of intermetallic phases between solder, pads and leads; the wetting angles between pad, solder and lead; and finally, the joint microstructure with its mechanical properties. The influence of the rework soldering on these three factors is discussed and compared to conventional laser soldering results. In order to optimize the quality of reworked joints, the different strategies of energy input are applied.

Effects of Grain Orientation on Cu6Sn5 Growth Behavior in Cu6Sn5-Reinforced Composite Solder Joints During Electromigration

NASA Astrophysics Data System (ADS)

Han, Jing; Wang, Yan; Tan, Shihai; Guo, Fu

2018-02-01

Electromigration is a major reliability problem in composite solder joints. Due to the anisotropy of the β-Sn crystal structure, the Sn grain orientations present in the solder matrix dominate the principal failure mechanism in solder joints under electric current stressing. In this work, the Cu6Sn5 growth behavior in Cu6Sn5-reinforced composite solder joints with three different Sn grain orientations was investigated at current density of 104 A/cm2 at room temperature. Micron-sized Cu particles were added to Sn-3.5Ag solder at 2% volume fraction using an in situ method. After current stressing for 528 h, the polarity effect in the composite solder joint was greatest for an angle ( θ) between the c-axis and electron flow direction of 30°, resulting in higher growth rate of Cu6Sn5 in the solder matrix compared with composite solder joints with θ of 60° or 90°. There were no noticeable changes in the composite solder joint with θ of 90°. The growth behavior of Cu6Sn5, Cu atomic motion, and Cu diffusivity in the composite solder joints with different Sn grain orientations were analyzed in detail.

Recrystallization Behavior in Mixed Solder Joints of BGA Components during Thermal Shock

NASA Astrophysics Data System (ADS)

Tan, Shihai; Han, Jing; Guo, Fu

2018-03-01

Sn-37Pb and Sn-3.0Ag-0.5Cu solder pastes printed onto a board were attached to ball grid array (BGA) samples using Sn-3.0Ag-0.5Cu solder balls. Before thermal shock, the initial grain orientations on the cross-section were obtained by scanning electron microscopy equipped with an electron backscattered diffraction system. Three mixed solder joints (two from the corner and another from the middle of the BGA component) and three lead-free solder joints (at the same positions) were selected to investigate the recrystallization behavior under thermal shock (TS) cycling conditions. All of the mixed and lead-free solder joints were initially single crystal. The results showed that recrystallization occurred in both the mixed and lead-free solder joints after 200 TS. For the mixed solder joints, more recrystallization was observed and the location of samples had a significant influence on their recrystallization behavior, while location was not as important for the lead-free samples after 200 TS in this study. Both the mixed and lead-free solder joints at the corner of BGA components showed the poorest reliability. According to misorientation distribution maps and subgrain rotation behaviors, the reliability of mixed solder joints was much poorer than that of lead-free solder joints.

Method for making alignment-enhancing feed-through conductors for stackable silicon-on-sapphire

NASA Technical Reports Server (NTRS)

Anthony, Thomas R. (Inventor)

1985-01-01

Alignment-enhancing electrically conductive feed-through paths are provided for the high-speed low-loss transfer of electrical signals between integrated circuits of a plurality of silicon-on-sapphire bodies arrayed in a stack. The alignment-enhancing feed-throughs are made by a process of this invention involving the drilling of holes through the body, double-sided sputtering, electroplating, and the filling of the holes with solder by capillary action. The alignment-enhancing feed-throughs are activated by forming a stack of wafers and remelting the solder whereupon the wafers, and the feed-through paths, are pulled into alignment by surface tension forces.

Silicon solar cells with nickel/solder metallization

NASA Technical Reports Server (NTRS)

Petersen, R. C.; Muleo, A.

1981-01-01

The use of nickel plus solder is shown to be feasible for contact metallization for silicon solar cells by offering a relatively inexpensive method of making electrical contact with the cell surfaces. Nickel is plated on silicon solar cells using an electroless chemical deposition method to give contacts with good adhesion, and in some cases where adhesion is poor initially, sintering under relatively mild conditions will dramatically improve the quality of the bond without harming the p-n junction of the cell. The cells can survive terrestrial environment stresses, which is demonstrated by a 1000 hour test at 85 C and 85% relative humidity under constant forward bias of 0.45 volt.

Evaluation of test equipment for the detection of contamination on electronic circuits

NASA Astrophysics Data System (ADS)

Bergendahl, C. G.; Dunn, B. D.

1984-08-01

The reproducibility, sensitivity and ease of operation of test equipment for the detection of ionizable contaminants on the surface of printed circuit assemblies were assessed. The characteristics of the test equipment are described. Soldering fluxes were chosen as contaminants and were applied in controlled amounts to printed-circuit board assemblies possessing two different component populations. Results show that the relationship between equipment readings varies with flux type. Each kind of test equipment gives a good measure of board cleanliness, although reservations exist concerning the interpretation of such results. A test method for the analysis of total (organic and inorganic) halides in solder fluxes is presented.

IR DirectFET Extreme Environments Evaluation Final Report

NASA Technical Reports Server (NTRS)

Burmeister, Martin; Mottiwala, Amin

2008-01-01

In 2007, International Rectifier (IR) introduced a new version of its DirectFET metal oxide semiconductor field effect transistor (MOSFET) packaging. The new version (referred to as 'Version 2') enhances device moisture resistance, makes surface mount (SMT) assembly of these devices to printed wiring boards (PWBs) more repeatable, and subsequent assembly inspection simpler. In the present study, the National Aeronautics Space Administration (NASA) Jet Propulsion Laboratory (JPL), in collaboration with Stellar Microelectronics (Stellar), continued an evaluation of the DirectFET that they started together in 2006. The present study focused on comparing the two versions of the DirectFET and examining the suitability of the DirectFET devices for space applications. This study evaluated both versions of two DirectFET packaged devices that had both been shown in the 2006 study to have the best electrical and thermal properties: the IRF6635 and IRF6644. The present study evaluated (1) the relative electrical and thermal performance of both versions of each device, (2) the performance through high reliability testing, and (3) the performance of these devices in combination with a range of alternate solder alloys in the extreme thermal environments of deep space....

Microwave Tissue Soldering for Immediate Wound Closure

NASA Technical Reports Server (NTRS)

Arndt, G. Dickey; Ngo, Phong H.; Plan, Chau T.; Byerly, Diane; Dusl, John; Sognier, Marguerite A.

2011-01-01

A novel approach for the immediate sealing of traumatic wounds is under development. A portable microwave generator and handheld antenna are used to seal wounds, binding the edges of the wound together using a biodegradable protein sealant or solder. This method could be used for repairing wounds in emergency settings, by restoring the wound surface to its original strength within minutes. This technique could also be utilized for surgical purposes involving solid visceral organs (i.e., liver, spleen, and kidney) that currently do not respond well to ordinary surgical procedures. A miniaturized microwave generator and a handheld antenna are used to deliver microwave energy to the protein solder, which is applied to the wound. The antenna can be of several alternative designs optimized for placement either in contact with or proximity to the protein solder covering the wound. In either case, optimization of the design includes the matching of impedances to maximize the energy delivered to the protein solder and wound at a chosen frequency. For certain applications, an antenna could be designed that would emit power only when it is in direct contact with the wound. The optimum frequency or frequencies for a specific application would depend on the required depth of penetration of the microwave energy. In fact, a computational simulation for each specific application could be performed, which would then match the characteristics of the antenna with the protein solder and tissue to best effect wound closure. An additional area of interest with potential benefit that remains to be validated is whether microwave energy can effectively kill bacteria in and around the wound. Thus, this may be an efficient method for simultaneously sterilizing and closing wounds. Using microwave energy to seal wounds has a number of advantages over lasers, which are currently in experimental use in some hospitals. Laser tissue welding is unsuitable for emergency use because its large, bulky equipment cannot be easily moved between operating rooms, let alone relocated to field sites where emergencies often occur. In addition, this approach is highly dependent on the uniformity and thickness of the protein solder as well as the surgeon s skills. In contrast, the use of microwave energy is highly tolerant of the thickness of the protein solder, level of fluids in and around the wound, and other parameters that can adversely affect the outcome of laser welding. However, controlling the depth of penetration of the microwave energy into the wound is critical for achieving effective wound sealing without damaging the adjacent tissue. In addition, microspheres that encapsulate metallic cores could also be incorporated into the protein solder to further control the depth of penetration of the microwave energy.

High Performance Hermetic Package For LiNbO3 Electro-Optic Waveguide Devices

NASA Astrophysics Data System (ADS)

Preston, K. R.; Macdonald, B. M.; Harmon, R. A.; Ford, C. W.; Shaw, R. N.; Reid, I.; Davidson, J. H.; Beaumont, A. R.; Booth, R. C.

1989-02-01

A high performance fibre-tailed package for LiNbO3 electro-optic waveguide devices is described. The package is based around a hermetic metal submodule which contains no epoxy or other organic materials. The LiNbO3 chip is mounted using a soldering technique, and laser welding is used for fibre fixing to give stable, low loss optical coupling to single mode fibres. Optical reflections are minimised by the use of antireflective coatings on the fibre ends and waveguide facets. High speed electrical connections are made via coplanar glass-sealed leadthroughs to LiNb03 travelling wave devices, and packaged device operation to frequencies in excess of 4GHz is demonstrated.

Laser assisted soldering: microdroplet accumulation with a microjet device.

PubMed

Chan, E K; Lu, Q; Bell, B; Motamedi, M; Frederickson, C; Brown, D T; Kovach, I S; Welch, A J

1998-01-01

We investigated the feasibility of a microjet to dispense protein solder for laser assisted soldering. Successive micro solder droplets were deposited on rat dermis and bovine intima specimens. Fixed laser exposure was synchronized with the jetting of each droplet. After photocoagulation, each specimen was cut into two halves at the center of solder coagulum. One half was fixed immediately, while the other half was soaked in phosphate-buffered saline for a designated hydration period before fixation (1 hour, 1, 2, and 7 days). After each hydration period, all tissue specimens were prepared for scanning electron microscopy (SEM). Stable solder coagulum was created by successive photocoagulation of microdroplets even after the soldered tissue exposed to 1 week of hydration. This preliminary study suggested that tissue soldering with successive microdroplets is feasible even with fixed laser parameters without active feedback control.

Distortion of three-unit implant frameworks during casting, soldering, and simulated porcelain firings.

PubMed

Zervas, P J; Papazoglou, E; Beck, F M; Carr, A B

1999-09-01

The aim of this study was to assess distortion inherent in casting, soldering, and simulated porcelain firings of screw-retained, implant-supported three-unit fixed partial dentures (FPDs). Ten wax patterns were fabricated on a die-stone cast containing two implants, 20 mm apart from center to center. Five specimens were cast in a high-palladium alloy, exposed to simulated porcelain firings, sectioned, and then soldered with low-fusing solder. Five specimens were cast, sectioned, soldered with high-fusing solder, and then exposed to simulated porcelain firings. For each specimen, two horizontal and six vertical distances between appropriately scribed reference points were measured with a traveling microscope. Comparisons were made among the various measurements taken after wax-pattern fabrication, casting, high- and low-fusing soldering, and each porcelain firing. Data were analyzed using a repeated-measures factorial ANOVA (alpha = 0.05). Significant difference was detected in the amount of horizontal distortion during casting (53 +/- 24 microns) and high-fusing soldering (-49 +/- 50 microns), as well as in the amount of horizontal distortion during high-fusing soldering (-49 +/- 50 microns) and low-fusing soldering (17 +/- 26 microns). However, no clinically significant difference was found in the amount of horizontal distortion during casting, low-fusing, and high-fusing soldering. The greatest amount of distortion during the simulated porcelain firings took place during the oxidizing cycle. Soldering did not improve the casting misfit of a three-unit implant-retained FPD model. Metal-ceramic implant frameworks should be oxidized before intraoral fit evaluation.

Properties of Sn3.8Ag0.7Cu Solder Alloy with Trace Rare Earth Element Y Additions

NASA Astrophysics Data System (ADS)

Hao, H.; Tian, J.; Shi, Y. W.; Lei, Y. P.; Xia, Z. D.

2007-07-01

In the current research, trace rare earth (RE) element Y was incorporated into a promising lead-free solder, Sn3.8Ag0.7Cu, in an effort to improve the comprehensive properties of Sn3.8Ag0.7Cu solder. The range of Y content in Sn3.8Ag0.7Cu solder alloys varied from 0 wt.% to 1.0 wt.%. As an illustration of the advantage of Y doping, the melting temperature, wettability, mechanical properties, and microstructures of Sn3.8Ag0.7CuY solder were studied. Trace Y additions had little influence on the melting behavior, but the solder showed better wettability and mechanical properties, as well as finer microstructures, than found in Y-free Sn3.8Ag0.7Cu solder. The Sn3.8Ag0.7Cu0.15Y solder alloy exhibited the best comprehensive properties compared to other solders with different Y content. Furthermore, interfacial and microstructural studies were conducted on Sn3.8Ag0.7Cu0.15Y solder alloys, and notable changes in microstructure were found compared to the Y-free alloy. The thickness of an intermetallic compound layer (IML) was decreased during soldering, and the growth of the IML was suppressed during aging. At the same time, the growth of intermetallic compounds (IMCs) inside the solder was reduced. In particular, some bigger IMC plates were replaced by fine, granular IMCs.

GPS compound eye attitude and navigation sensor and method

NASA Technical Reports Server (NTRS)

Quinn, David A. (Inventor)

2003-01-01

The present invention is a GPS system for navigation and attitude determination, comprising a sensor array including a convex hemispherical mounting structure having a plurality of mounting surfaces, and a plurality of antennas mounted to the mounting surfaces for receiving signals from space vehicles of a GPS constellation. The present invention also includes a receiver for collecting the signals and making navigation and attitude determinations. In an alternate embodiment the present invention may include two opposing convex hemispherical mounting structures, each of the mounting structures having a plurality of mounting surfaces, and a plurality of antennas mounted to the mounting surfaces.

Evaluation on the characteristics of tin-silver-bismuth solder

NASA Astrophysics Data System (ADS)

Xia, Z.; Shi, Y.; Chen, Z.

2002-02-01

Tin-silver-bismuth solder is characterized by its lower melting point, good wetting behavior, and good mechanical property for which it is expected to be a new lead-free solder to replace tin-lead solder. In this article, Sn-3.33Ag-4.83Bi solder was investigated concerning its physical, spreading, and mechanical properties under specific conditions. Cooling curves and DSC results showed that it was close to eutectic composition (m.p. 210° 212 °C). Coefficiency of thermal expansion (CTE) of this solder, between that of PCBs and copper substrates, was beneficial to alleviate the thermal mismatch of the substrates. It was also a good electrical and thermal conductor. Using a rosin-based, mildly activated (RMA) flux, a spreading test indicated that SnAgBi solder paste had good solderability. Meanwhile, the solder had high tensile strength and fracture energy. Its fracture mechanism was a mixture of ductile and brittle fracture morphology. The metallographic and EDAX analyses indicated that it was composed of a tin-based solid solution and some intermetallic compound (IMC) that could strengthen the substrate. However, these large needle-like IMCs would cut the substrate and this resulted in the decreasing of the toughness of the solder.

Controlling intermetallic compound growth in SnAgCu/Ni-P solder joints by nanosized Cu6Sn5 addition

NASA Astrophysics Data System (ADS)

Kao, Szu-Tsung; Lin, Yung-Chi; Duh, Jenq-Gong

2006-03-01

Nanosized Cu6Sn5 dispersoids were incorporated into Sn and Ag powders and milled together to form Sn-3Ag-0.5Cu composite solders by a mechanical alloying process. The aim of this study was to investigate the interfacial reaction between SnAgCu composite solder and electroless Ni-P/Cu UBM after heating for 15 min. at 240°C. The growth of the IMCs formed at the composite solder/EN interface was retarded as compared to the commercial Sn3Ag0.5Cu solder joints. With the aid of the elemental distribution by x-ray color mapping in electron probe microanalysis (EPMA), it was revealed that the SnAgCu composite solder exhibited a refined structure. It is proposed that the Cu6Sn5 additives were pinned on the grain boundary of Sn after heat treatment, which thus retarded the movement of Cu toward the solder/EN interface to form interfacial compounds. In addition, wetting is an essential prerequisite for soldering to ensure good bonding between solder and substrate. It was demonstrated that the contact angles of composite solder paste was <25°, and good wettability was thus assured.

Effect of Embedding Cu-Graphene Hybrid Powder into 2-Phase In-Cu Solders on Its Suitability as Metallic Thermal Interface Material

NASA Astrophysics Data System (ADS)

Sharma, Deepak; Jain, Aman; Somaiah, Nalla; Narayanan, P. Ramesh; Kumar, Praveen

2018-05-01

The effect of embedding Cu-graphene hybrid powder, namely "graphene nano-sheet Cu" (GNS-Cu) powder, into In-40 vol.% Cu solder alloy on the electrical and mechanical properties of In-Cu solder is investigated. GNS-Cu hybrid powders were prepared by mixing reduced graphene oxide powders and CuSO4·5H2O, followed by reduction of the mixture with hydrazine. Subsequently, In-Cu solders with GNS-Cu powders were prepared using a 2-step process, comprising liquid phase sintering (LPS) of In and Cu powders followed by accumulative roll bonding (ARB). During ARB, the GNS-Cu powders were embedded as distinct layers into In-Cu composite solders. Electrical conductivity of the GNS-Cu embedded solders increased by > 20% as compared to pure In-Cu solders processed through the same combination of LPS-ARB steps. The yield strength of In-Cu solder increased by only 10% with the addition of GNS-Cu powders and thus retained the moderate strength often associated with pure In-Cu composite solders. Moreover, the thermal conductivity of GNS-Cu-embedded solders was estimated theoretically to increase by > 60%. These promising findings suggest that GNS-Cu-embedded In-Cu solders can be suitable for next-generation metallic thermal interface material and package-level interconnect applications.

ECM soldering technologies for small businesses. Final report/project accomplishments summary, project number 93-KCPP-015-E1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Becka, G.A.

1997-03-01

The purpose of this outreach project was to demonstrate, transfer, and educate multiple small and medium-sized US firms in the methodology and technology of environmentally conscious manufacturing soldering techniques. Consultation on replacement solvents for ozone-depleting chemicals, low residue/no clean soldering, and lead-free solder alloys were examples of available FM and T expertise. Depending upon the needs, materials engineering or process engineering help was made available under the program. Requesting businesses could obtain up to 250 hours of assistance from AlliedSignal FM and T on these efforts. The participating companies mainly requested assistance with their immediate needs. Examples of assistance providedmore » included specialized training for their particular product line. FM and T Solder Certification School has an excellent reputation and responded with solder training and help with course outlines for the requesters. One company reported problems soldering certain components. FM and T evaluations determined that the company was received components with solderability levels that did not meet specification rather than experiencing a soldering process problem. Other companies received assistance in incorporating lead-free soldering materials into their production lines and development assistance with fluxless soldering processes. The project was terminated when it was determined that this need could be served by FM and T`s current Technical Assistance Program.« less

Anand constitutive model of lead-free solder joints in 3D IC device

NASA Astrophysics Data System (ADS)

Zhang, Liang; Liu, Zhi-quan; Ji, Yu-tong

2016-08-01

Anand constitutive relation of SnAgCu and SnAgCu-nano Al solders were studied under uniaxial tension, and the constitutive model was used in the finite element simulation to analyze the stress-strain response of lead-free solder joints in 3D IC devices. The results showed that the nine parameters of the Anand model can be determined from separated constitutive relations and experimental results. Based on Anand model, the finite element method was selected to calculate the stress-strain response of lead-free solder joints, it was found that in the 3D IC device the maximum stress-strain concentrated in the concern solder joints, the stress-strain of SnAgCu-nano Al solder joints was lower than that of SnAgCu solder joints, which represented that the addition of nano Al particles can enhance the reliability of lead-free solder joints in 3D IC devices.

Preparing Solar Cells for Soldering

NASA Technical Reports Server (NTRS)

Hagerty, J. J.

1983-01-01

Solder paste and contact ribbon dispensed in synchronism. Solder-paste dispenser operates on one cell at a time. Ribbon fed up ramps and into positioned while solder paste is applied. When ramps are moved out of way, ribbon lies down onto cell.

Analysis of Al diffusion processes in TiN barrier layers for the application in silicon solar cell metallization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumm, J.; Samadi, H.; Chacko, R. V.

An evaporated Al layer is known as an excellent rear metallization for highly efficient solar cells, but suffers from incompatibility with a common solder process. To enable solar cell-interconnection and module integration, in this work the Al layer is complemented with a solder stack of TiN/Ti/Ag or TiN/NiV/Ag, in which the TiN layer acts as an Al diffusion barrier. X-ray photoelectron spectroscopy measurements prove that diffusion of Al through the stack and the formation of an Al{sub 2}O{sub 3} layer on the stack's surface are responsible for a loss of solderability after a strong post-metallization anneal, which is often mandatorymore » to improve contact resistance and passivation quality. An optimization of the reactive TiN sputter process results in a densification of the TiN layer, which improves its barrier quality against Al diffusion. However, measurements with X-ray diffraction and scanning electron microscopy show that small grains with vertical grain boundaries persist, which still offer fast diffusion paths. Therefore, the concept of stuffing is introduced. By incorporating oxygen into the grain boundaries of the sputtered TiN layer, Al diffusion is strongly reduced as confirmed by secondary ion mass spectroscopy profiles. A quantitative analysis reveals a one order of magnitude lower Al diffusion coefficient for stuffed TiN layers. This metallization system maintains its solderability even after strong post-metallization annealing at 425 °C for 15 min. This paper thus presents an industrially feasible, conventionally solderable, and long-term stable metallization scheme for highly efficient silicon solar cells.« less

An in-vitro investigation of skin tissue soldering using gold nanoshells and diode laser.

PubMed

Nourbakhsh, Mohammad S; Khosroshahi, Mohammad E

2011-01-01

Gold-coated silica core nanoparticles have an optical response dictated by the plasmon resonance (PR). The wavelength at which the resonance occurs depends on the core and shell size, allowing nanoshells to be tailored for particular applications. The purpose of this study is to synthesize and use different concentrations of gold nanoshells as exogenous material for in-vitro skin tissue soldering and also to examine the effect of laser-soldering parameters on the properties of repaired skin. Two mixtures of albumin solder and different concentrations of gold nanoshells were prepared. A full-thickness incision of 2 × 20 mm(2) was made on the surface and after addition of mixtures it was irradiated by an 810-nm diode laser at different power densities. The changes of tensile strength σ(t) due to temperature rise, number of scan (N(s)), and scan velocity (V(s)) were investigated. The results showed at constant laser power density (I), σ(t) of repaired incisions increases by increasing the concentration of gold nanoshells, N(s) and decreasing V(s). It is therefore important to consider the trade-off between the scan velocity and the skin temperature for achieving an optimum operating condition. In our case, this corresponds to σ(t) = 1,610 g/cm(2) at I ∼ 60 Wcm(-2), T ∼ 65°C, Ns = 10 and Vs = 0.2 mms(-1).

40 CFR 438.2 - General definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... chemical conversion coating operations. (d) Metal-bearing operations means one or more of the following... descaling; shot tower—lead shot manufacturing; soldering; solder flux cleaning; solder fusing; solder...) Oily operations means one or more of the following: abrasive blasting; adhesive bonding; alkaline...

40 CFR 438.2 - General definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... conversion coating operations. (d) Metal-bearing operations means one or more of the following: abrasive jet... descaling; shot tower—lead shot manufacturing; soldering; solder flux cleaning; solder fusing; solder...) Oily operations means one or more of the following: abrasive blasting; adhesive bonding; alkaline...

40 CFR 438.2 - General definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... chemical conversion coating operations. (d) Metal-bearing operations means one or more of the following... descaling; shot tower—lead shot manufacturing; soldering; solder flux cleaning; solder fusing; solder...) Oily operations means one or more of the following: abrasive blasting; adhesive bonding; alkaline...

40 CFR 438.2 - General definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... conversion coating operations. (d) Metal-bearing operations means one or more of the following: abrasive jet... descaling; shot tower—lead shot manufacturing; soldering; solder flux cleaning; solder fusing; solder...) Oily operations means one or more of the following: abrasive blasting; adhesive bonding; alkaline...

40 CFR 438.2 - General definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... chemical conversion coating operations. (d) Metal-bearing operations means one or more of the following... descaling; shot tower—lead shot manufacturing; soldering; solder flux cleaning; solder fusing; solder...) Oily operations means one or more of the following: abrasive blasting; adhesive bonding; alkaline...

An evaluation of the lap-shear test for Sn-rich solder/Cu couples: Experiments and simulation

NASA Astrophysics Data System (ADS)

Chawla, N.; Shen, Y.-L.; Deng, X.; Ege, E. S.

2004-12-01

The lap-shear technique is commonly used to evaluate the shear, creep, and thermal fatigue behavior of solder joints. We have conducted a parametric experimental and modeling study, on the effect of testing and geometrical parameters on solder/copper joint response in lap-shear. It was shown that the farfield applied strain is quite different from the actual solder strain (measured optically). Subtraction of the deformation of the Cu substrate provides a reasonable approximation of the solder strain in the elastic regime, but not in the plastic regime. Solder joint thickness has a profound effect on joint response. The solder response moves progressively closer to “true” shear response with increasing joint thickness. Numerical modeling using finite-element analyses were performed to rationalize the experimental findings. The same lap-shear configuration was used in the simulation. The input response for solder was based on the experimental tensile test result on bulk specimens. The calculated shear response, using both the commonly adopted far-field measure and the actual shear strain in solder, was found to be consistent with the trends observed in the lap-shear experiments. The geometric features were further explored to provide physical insight into the problem. Deformation of the substrate was found to greatly influence the shear behavior of the solder.

Effects of CuZnAl Particles on Properties and Microstructure of Sn-58Bi Solder

PubMed Central

Yang, Fan; Zhang, Liang; Liu, Zhi-quan; Zhong, Su Juan; Ma, Jia; Bao, Li

2017-01-01

With the purpose of improving the properties of the Sn-58Bi lead-free solder, micro-CuZnAl particles ranging from 0 to 0.4 wt % were added into the low temperature eutectic Sn-58Bi lead-free solder. After the experimental testing of micro-CuZnAl particles on the properties and microstructure of the Sn-58Bi solders, it was found that the wettability of the Sn-58Bi solders was obviously improved with addition of CuZnAl particles. When the addition of CuZnAl particles was 0.2 wt %, the wettability of the Sn-58Bi solder performed best. At the same time, excessive addition of CuZnAl particles led to poor wettability. However, the results showed that CuZnAl particles changed the melting point of the Sn-58Bi solder slightly. The microstructure of the Sn-58Bi solder was refined by adding CuZnAl particles. When the content of CuZnAl addition was between 0.1 and 0.2 wt %, the refinement was great. In addition, the interfacial IMC layer between new composite solder and Cu substrate was thinner than that between the Sn-58Bi solder and Cu substrate. PMID:28772917

Subgrain Rotation Behavior in Sn3.0Ag0.5Cu-Sn37Pb Solder Joints During Thermal Shock

NASA Astrophysics Data System (ADS)

Han, Jing; Tan, Shihai; Guo, Fu

2018-01-01

Ball grid array (BGA) samples were soldered on a printed circuit board with Sn37Pb solder paste to investigate the recrystallization induced by subgrain rotation during thermal shock. The composition of the solder balls was Sn3.0Ag0.5Cu-Sn37Pb, which comprised mixed solder joints. The BGA component was cross-sectioned before thermal shock. The microstructure and grain orientations were obtained by a scanning electron microscope equipped with an electron back-scattered diffraction system. Two mixed solder joints at corners of the BGA component were selected as the subjects. The results showed that recrystallization occurred at the corner of the solder joints after 200 thermal shock cycles. The recrystallized subgrains had various new grain orientations. The newly generated grain orientations were closely related to the initial grain orientations, which indicated that different subgrain rotation behaviors could occur in one mixed solder joint with the same initial grain orientation. When the misorientation angles were very small, the rotation axes were about Sn [100], [010] and [001], as shown by analyzing the misorientation angles and subgrain rotation axes, while the subgrain rotation behavior with large misorientation angles in the solder joints was much more complicated. As Pb was contained in the solder joints and the stress was concentrated on the corner of the mixed solder joints, concaves and cracks were formed. When the adjacent recrystallized subgrains were separated, and the process of the continuous recrystallization was limited.

Nanoshell assisted laser soldering of vascular tissue.

PubMed

Schöni, Daniel S; Bogni, Serge; Bregy, Amadé; Wirth, Amina; Raabe, Andreas; Vajtai, Istvan; Pieles, Uwe; Reinert, Michael; Frenz, Martin

2011-12-01

Laser tissue soldering (LTS) is a promising technique for tissue fusion but is limited by the lack of reproducibility particularly when the amount of indocyanine green (ICG) applied as energy absorber cannot be controlled during the soldering procedure. Nanotechnology enables the control over the quantitative binding of the ICG. The aim of this study was to establish a highly reproducible and strong tissue fusion using ICG packed nanoshells. By including the chromophore in the soldering scaffold, dilution of the energy absorber during the soldering procedure is prevented. The feasibility of this novel nanoshell soldering technique was studied by assessing the local heating of the area and tensile strength of the resulting fused tissue. Nanoshells with a diameter of 250-270 nm were loaded with ICG and included in a porous polycaprolactone (PCL) scaffold doped with albumin solder. The nanoshell scaffold was used in a flexible, semi-dry formulation suitable for surgical use. Heat development, tensile strength as well as tissue damage were assessed. Rabbit aortic arteries were successfully soldered using an ICG packed nanoshell scaffold. Tensile strengths of these nanoshell soldered anastomoses were found to be 734 ± 327 mN (median = 640 mN). Thermal damage was restricted to the adventitia at the irradiated area. In addition, absorber dilution was prevented during the soldering procedure resulting in significantly lower variance in maximum temperature (P = 0.03) compared to the classical liquid ICG soldering technique. Using nanoshells, controlled amounts of chromophore could successfully be bound into the polymer scaffold. Diode laser soldering of vascular tissue using ICG-nanoshell scaffolds leads to strong and reproducible tissue fusion. With optimally chosen settings of irradiation time, nanoshells coating and scaffold properties, our improved LTS procedure demonstrates the potential for a clinically applicable anastomosis technique. Copyright © 2011 Wiley Periodicals, Inc.

Effect of Sn-Ag-Cu on the Improvement of Electromigration Behavior in Sn-58Bi Solder Joint

NASA Astrophysics Data System (ADS)

Wang, Fengjiang; Zhou, Lili; Zhang, Zhijie; Wang, Jiheng; Wang, Xiaojing; Wu, Mingfang

2017-10-01

Reliability issues caused by the formation of a Bi-rich layer at the anode interface usually occurs in the Sn-58Bi eutectic solder joint during electromigration (EM). To improve the EM performance of a Sn-58Bi solder joint, Sn-3.0Ag-0.5Cu solder was introduced into it to produce SnBi-SnAgCu structural or compositional composite joints, and their EM behaviors were investigated with the current density of 1.0 × 104 A/cm2 for different stressing times. The structure of the compositional composite solder joint was obtained by the occurrence of partial or full mixing between Sn-Bi and Sn-Ag-Cu solder with a suitable soldering temperature. In the structural composite joint, melted Sn-Bi was partially mixed with Sn-Ag-Cu solder to produce a Cu/Sn-Bi/Sn-Ag-Cu/Sn-Bi/Cu structure. In the compositional composite joint, full melting and mixing between these two solders occurred to produce a Cu/Sn-Ag-Cu-Bi/Cu structure, in which the solder matrix was a homogeneous structure including Sn, Bi phases, Cu6Sn5 and Ag3Sn IMCs. After current stressing, the EM performance of Sn-Bi solder was obviously improved with the structural or the compositional composite joint. In Sn-58Bi joints, a thick Bi-rich layer was easily produced at the anode interface, and obviously increased with stressing time. However, after current stressing on the structural composite joints, the existence of s Sn-3.0Ag-0.5Cu interlayer between the two Sn-58Bi solders effectively acted as a diffusion barrier and significantly slowed the formation of the Bi-rich layer at the anode side and the IMC thicknesses at the interfaces.

Inspection criteria ensure quality control of parallel gap soldering

NASA Technical Reports Server (NTRS)

Burka, J. A.

1968-01-01

Investigation of parallel gap soldering of electrical leads resulted in recommendation on material preparation, equipment, process control, and visual inspection criteria to ensure reliable solder joints. The recommendations will minimize problems in heat-dwell time, amount of solder, bridging conductors, and damage of circuitry.

Composition-matched molecular “solders” for semiconductors

NASA Astrophysics Data System (ADS)

Dolzhnikov, Dmitriy S.; Zhang, Hao; Jang, Jaeyoung; Son, Jae Sung; Panthani, Matthew G.; Shibata, Tomohiro; Chattopadhyay, Soma; Talapin, Dmitri V.

2015-01-01

We propose a general strategy to synthesize largely unexplored soluble chalcogenidometallates of cadmium, lead, and bismuth. These compounds can be used as “solders” for semiconductors widely used in photovoltaics and thermoelectrics. The addition of solder helped to bond crystal surfaces and link nano- or mesoscale particles together. For example, CdSe nanocrystals with Na2Cd2Se3 solder was used as a soluble precursor for CdSe films with electron mobilities exceeding 300 square centimeters per volt-second. CdTe, PbTe, and Bi2Te3 powders were molded into various shapes in the presence of a small additive of composition-matched chalcogenidometallate or chalcogel, thus opening new design spaces for semiconductor technologies.

Influence of nanoparticle addition on the formation and growth of intermetallic compounds (IMCs) in Cu/Sn–Ag–Cu/Cu solder joint during different thermal conditions

PubMed Central

Ting Tan, Ai; Wen Tan, Ai; Yusof, Farazila

2015-01-01

Nanocomposite lead-free solders are gaining prominence as replacements for conventional lead-free solders such as Sn–Ag–Cu solder in the electronic packaging industry. They are fabricated by adding nanoparticles such as metallic and ceramic particles into conventional lead-free solder. It is reported that the addition of such nanoparticles could strengthen the solder matrix, refine the intermetallic compounds (IMCs) formed and suppress the growth of IMCs when the joint is subjected to different thermal conditions such as thermal aging and thermal cycling. In this paper, we first review the fundamental studies on the formation and growth of IMCs in lead-free solder joints. Subsequently, we discuss the effect of the addition of nanoparticles on IMC formation and their growth under several thermal conditions. Finally, an outlook on the future growth of research in the fabrication of nanocomposite solder is provided. PMID:27877786

Wetting reaction of Sn-Ag based solder systems on Cu substrates plated with Au and/or Pd layer

NASA Astrophysics Data System (ADS)

Liu, C. Y.; Li, Jian; Vandentop, G. J.; Choi, W. J.; Tu, K. N.

2001-05-01

The wetting behavior of SnAg based Pb-free solders on Cu and Cu substrates plated with Au, Pd, and Au/Pd thin films have been studied. The wetting angle and kinetics of interfacial reaction were measured. The Au-plated substrates exhibit better wetting than the Pd-plated substrates. In the case of SnAg on Pd-plated Cu, SEM observation revealed that the solder cap was surrounded by an innerring of Cu-Sn compound and an outer ring of Pd-Sn compound. This implies that the molten SnAg solder had removed the Pd and wetted the Cu directly in the equilibrium state. The effects of pre-doping Cu in the SnAg solder on wetting behavior were also investigated. We found that wettability decreases with increasing Cu content in the solder. We also observed that the SnAgCu solders have a lower Cu consumption rate than the SnAg solder.

Imaging and Analysis of Void-defects in Solder Joints Formed in Reduced Gravity using High-Resolution Computed Tomography

NASA Technical Reports Server (NTRS)

Easton, John W.; Struk, Peter M.; Rotella, Anthony

2008-01-01

As a part of efforts to develop an electronics repair capability for long duration space missions, techniques and materials for soldering components on a circuit board in reduced gravity must be developed. This paper presents results from testing solder joint formation in low gravity on a NASA Reduced Gravity Research Aircraft. The results presented include joints formed using eutectic tin-lead solder and one of the following fluxes: (1) a no-clean flux core, (2) a rosin flux core, and (3) a solid solder wire with external liquid no-clean flux. The solder joints are analyzed with a computed tomography (CT) technique which imaged the interior of the entire solder joint. This replaced an earlier technique that required the solder joint to be destructively ground down revealing a single plane which was subsequently analyzed. The CT analysis technique is described and results presented with implications for future testing as well as implications for the overall electronics repair effort discussed.

Lead-free solder

DOEpatents

Anderson, Iver E.; Terpstra, Robert L.

2001-05-15

A Sn--Ag--Cu eutectic alloy is modified with one or more low level and low cost alloy additions to enhance high temperature microstructural stability and thermal-mechanical fatigue strength without decreasing solderability. Purposeful fourth or fifth element additions in the collective amount not exceeding about 1 weight % (wt. %) are added to Sn--Ag--Cu eutectic solder alloy based on the ternary eutectic Sn--4.7%Ag--1.7%Cu (wt. %) and are selected from the group consisting essentially of Ni, Fe, and like-acting elements as modifiers of the intermetallic interface between the solder and substrate to improve high temperature solder joint microstructural stability and solder joint thermal-mechanical fatigue strength.

An Accelerated Method for Testing Soldering Tendency of Core Pins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Qingyou; Xu, Hanbing; Ried, Paul

2010-01-01

An accelerated method for testing die soldering has been developed. High intensity ultrasonic vibrations has been used to simulate the die casting conditions such as high pressure and high impingement speed of molten metal on the pin. Soldering tendency of steels and coated pins has been examined. The results indicate that in the low carbon steel/Al system, the onset of soldering is 60 times faster with ultrasonic vibration than that without ultrasonic vibration. In the H13/A380 system, the onset of soldering reaction is accelerated to 30-60 times. Coating significantly reduces the soldering tendency of the core pins.

Diode laser soldering using a lead-free filler material for electronic packaging structures

NASA Astrophysics Data System (ADS)

Chaminade, C.; Fogarassy, E.; Boisselier, D.

2006-04-01

As of today, several lead-free soldering pastes have been qualified for currently used soldering process. Regarding the new potential of laser-assisted soldering processes, the behaviour of the SnAgCu soldering paste requires, however, new investigations. In the first part of this study, the specific temperature profile of a laser soldering process is investigated using a high power diode laser (HPDL). These experimental results are compared to a thermal simulation developed for this specific application. The second part of this work deals with the diffusion of the tin-based filler material through the nickel barrier using the information extracted from the temperature simulations.

Laser-activated protein solder for peripheral nerve repair

NASA Astrophysics Data System (ADS)

Trickett, Rodney I.; Lauto, Antonio; Dawes, Judith M.; Owen, Earl R.

1995-05-01

A 100 micrometers core optical fiber-coupled 75 mW diode laser operating at a wavelength of 800 nm has been used in conjunction with a protein solder to stripe weld severed rat tibial nerves, reducing the long operating time required for microsurgical nerve repair. Welding is produced by selective laser denaturation of the albumin based solder which contains the dye indocyanine green. Operating time for laser soldering was 10 +/- 5 min. (n equals 20) compared to 23 +/- 9 min. (n equals 10) for microsuturing. The laser solder technique resulted in patent welds with a tensile strength of 15 +/- 5 g, while microsutured nerves had a tensile strength of 40 +/- 10 g. Histopathology of the laser soldered nerves, conducted immediately after surgery, displayed solder adhesion to the outer membrane with minimal damage to the inner axons of the nerves. An in vivo study is under way comparing laser solder repaired tibial nerves to conventional microsuture repair. At the time of submission 15 laser soldered nerves and 7 sutured nerves were characterized at 3 months and showed successful regeneration with compound muscle action potentials of 27 +/- 8 mV and 29 +/- 8 mW respectively. A faster, less damaging and long lasting laser based anastomotic technique is presented.

Effect of the Angle Between Sn Grain c-Axis and Electron Flow Direction on Cu-Reinforced Composite Solder Joints Under Current Stressing

NASA Astrophysics Data System (ADS)

Wang, Yan; Han, Jing; Wang, Yishu; Ma, Limin; Guo, Fu

2018-01-01

With a body-centered tetragonal crystal structure, Sn grains were demonstrated to have highly anisotropic behaviors in various properties. The electromigration behavior of lead-free solder was impacted by the grain orientations. In this paper, the angle between the c-axis and the electron flow direction in composite solder joints (angle θ) was proven to be an important factor during electromigration. The effects of angle θ on the electromigration of composite solder joints were investigated in this paper. Cu particle-reinforced Sn3.5Ag solder joints were stressed under a current density of 104 A/cm2 at room temperature. After 336 h current stressing time, different electromigration phenomena occurred at the two sides of the grain boundary in the composite solder joint which contained two Sn grains with different angle θ. The Sn grains with the larger angle θ had a smaller growth rate of Cu6Sn5. In addition, a composite solder joint with a single Sn grain was set as the contrast and its angle θ was smaller than that of the composite solder joint with two Sn grains. The growth rate of Cu6Sn5 in the composite solder joint with a single grain was faster than that of the composite solder joint with two Sn grains.

Understanding the Reliability of Solder Joints Used in Advanced Structural and Electronics Applications: Part 2 - Reliability Performance.

DOE PAGES

Vianco, Paul T.

2017-03-01

Whether structural or electronic, all solder joints must provide the necessary level of reliability for the application. The Part 1 report examined the effects of filler metal properties and the soldering process on joint reliability. Filler metal solderability and mechanical properties, as well as the extents of base material dissolution and interface reaction that occur during the soldering process, were shown to affect reliability performance. The continuation of this discussion is presented in this Part 2 report, which highlights those factors that directly affect solder joint reliability. There is the growth of an intermetallic compound (IMC) reaction layer at themore » solder/base material interface by means of solid-state diffusion processes. In terms of mechanical response by the solder joint, fatigue remains as the foremost concern for long-term performance. Thermal mechanical fatigue (TMF), a form of low-cycle fatigue (LCF), occurs when temperature cycling is combined with mismatched values of the coefficient of thermal expansion (CTE) between materials comprising the solder joint “system.” Vibration environments give rise to high-cycle fatigue (HCF) degradation. Although accelerated aging studies provide valuable empirical data, too many variants of filler metals, base materials, joint geometries, and service environments are forcing design engineers to embrace computational modeling to predict the long-term reliability of solder joints.« less

Evaluation of advanced microelectronic fluxless solder-bump contacts for hybrid microcircuits

NASA Technical Reports Server (NTRS)

Mandal, R. P.

1976-01-01

Technology for interconnecting monolithic integrated circuit chips with other components is investigated. The advantages and disadvantages of the current flip-chip approach as compared to other interconnection methods are outlined. A fluxless solder-bump contact technology is evaluated. Multiple solder-bump contacts were formed on silicon integrated circuit chips. The solder-bumps, comprised of a rigid nickel under layer and a compliant solder overlayer, were electroformed onto gold device pads with the aid of thick dry film photomasks. Different solder alloys and the use of conductive epoxy for bonding were explored. Fluxless solder-bump bond quality and reliability were evaluated by measuring the effects of centrifuge, thermal cycling, and high temperature storage on bond visual characteristics, bond electrical continuity, and bond shear tests. The applicability and suitability of this technology for hybrid microelectronic packaging is discussed.

30 CFR 77.1916 - Welding, cutting, and soldering; fire protection.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, and soldering; fire... OF UNDERGROUND COAL MINES Slope and Shaft Sinking § 77.1916 Welding, cutting, and soldering; fire protection. (a) One portable fire extinguisher shall be provided where welding, cutting, or soldering with...

Heat Lamps Solder Solar Array Quickly

NASA Technical Reports Server (NTRS)

Coyle, P. J.; Crouthamel, M. S.

1982-01-01

Interconnection tabs in a nine-solar-cell array have been soldered simultaneously with radiant heat. Cells and tabs are held in position for soldering by sandwiching them between compliant silicone-rubber vacuum platen and transparent polyimide sealing membrane. Heat lamps warm cells, producing smooth, flat solder joints of high quality.

Testing of printed circuit board solder joints by optical correlation

NASA Technical Reports Server (NTRS)

Espy, P. N.

1975-01-01

An optical correlation technique for the nondestructive evaluation of printed circuit board solder joints was evaluated. Reliable indications of induced stress levels in solder joint lead wires are achievable. Definite relations between the inherent strength of a solder joint, with its associated ability to survive stress, are demonstrable.

30 CFR 77.1916 - Welding, cutting, and soldering; fire protection.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Welding, cutting, and soldering; fire... OF UNDERGROUND COAL MINES Slope and Shaft Sinking § 77.1916 Welding, cutting, and soldering; fire protection. (a) One portable fire extinguisher shall be provided where welding, cutting, or soldering with...

30 CFR 77.1916 - Welding, cutting, and soldering; fire protection.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Welding, cutting, and soldering; fire... OF UNDERGROUND COAL MINES Slope and Shaft Sinking § 77.1916 Welding, cutting, and soldering; fire protection. (a) One portable fire extinguisher shall be provided where welding, cutting, or soldering with...

30 CFR 77.1916 - Welding, cutting, and soldering; fire protection.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Welding, cutting, and soldering; fire... OF UNDERGROUND COAL MINES Slope and Shaft Sinking § 77.1916 Welding, cutting, and soldering; fire protection. (a) One portable fire extinguisher shall be provided where welding, cutting, or soldering with...

30 CFR 77.1916 - Welding, cutting, and soldering; fire protection.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Welding, cutting, and soldering; fire... OF UNDERGROUND COAL MINES Slope and Shaft Sinking § 77.1916 Welding, cutting, and soldering; fire protection. (a) One portable fire extinguisher shall be provided where welding, cutting, or soldering with...

IRON COATED URANIUM AND ITS PRODUCTION

DOEpatents

Gray, A.G.

1960-03-15

A method of applying a protective coating to a metallic uranium article is given. The method comprises etching the surface of the article with an etchant solution containlng chloride ions, such as a solution of phosphoric acid and hydrochloric acid, cleaning the etched surface, electroplating iron thereon from a ferrous ammonium sulfate electroplating bath, and soldering an aluminum sheath to the resultant iron layer.

Effects of Transducer Installation on Unsteady Pressure Measurements on Oscillating Blades

NASA Technical Reports Server (NTRS)

Lepicovsky, Jan

2006-01-01

Unsteady pressures were measured above the suction side of a blade that was oscillated to simulate blade stall flutter. Measurements were made at blade oscillation frequencies up to 500 Hz. Two types of miniature pressure transducers were used: surface-mounted flat custom-made, and conventional miniature, body-mounted transducers. The signals of the surface-mounted transducers are significantly affected by blade acceleration, whereas the signals of body-mounted transducers are practically free of this distortion. A procedure was introduced to correct the signals of surface-mounted transducers to rectify the signal distortion due to blade acceleration. The signals from body-mounted transducers, and corrected signals from surface-mounted transducers represent true unsteady pressure signals on the surface of a blade subjected to forced oscillations. However, the use of body-mounted conventional transducers is preferred for the following reasons: no signal corrections are needed for blade acceleration, the conventional transducers are noticeably less expensive than custom-made flat transducers, the survival rate of body-mounted transducers is much higher, and finally installation of body-mounted transducers does not disturb the blade surface of interest.

Orbital Winch

NASA Technical Reports Server (NTRS)

Hoyt, Robert (Inventor); Slostad, Jeffrey T. (Inventor); Frank, Scott (Inventor); Barnes, Ian M. (Inventor)

2016-01-01

Orbital winch having: lower and upper frames; spool having upper and lower flanges with lower flange attached to lower frame; axial tether guide mounted to upper frame; secondary slewing ring coaxial with spool and rotatably mounted to upper frame, wherein secondary slewing ring's outer surface has gearing; upper tether guide mounted to inner surface of secondary slewing ring; linear translation means having upper end mounted to upper frame and lower end mounted on lower frame; primary slewing ring rotatably mounted within linear translation means allowing translation axially between flanges, wherein primary slewing ring's outer surface has gearing; lower tether guide mounted on primary slewing ring's inner surface; pinion rod having upper end mounted to upper frame and lower end mounted to lower frame, wherein pinion rod's teeth engage primary and secondary slewing rings' outer surface teeth; and tether passing through axial, upper, and lower tether guides and winding around spool.

Capacitor Test, Evaluation. and Modeling Within NASA Electronic Parts and Packaging (NEPP) Program. "Why Ceramic Capacitors Fracture During Manual Soldering and How to Avoid Failures"

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander

2011-01-01

Presentation discusses: (1) Why Multi-Layer Ceramic Capacitors(MLCCs) crack during manual soldering? Workmanship and parts issues. (2) Do existing qualification requirements assure crack-free soldering? MIL-spec Thermal Shock (TS) testing. MIL-spec Resistance to Soldering Heat (RSH) test. (3) What test can assure reliable soldering? Mechanical characteristics of ceramics. Comparison of three TS techniques: LND, TSD, and IWT. (4) Simulation of TS conditions.

Solderability of pre-tinned Cu sheet

NASA Astrophysics Data System (ADS)

Sunwoo, A. J.; Morris, J. W.; Lucey, G. K.

1992-05-01

The reliability and integrity of pre-tinned copper-clad printed circuit (PC) boards are serious concerns in the manufacture of electronic devices. The factors that influence the wetting during soldering of Cu are discussed. The results suggest that pre-tinning with a Pb-rich solder, such as 95Pb-5Sn, is preferred to pre-tinning with eutectic solder, since the latter can develop exposed intermetallics during aging that wet poorly. The results also confirm that the use of flux leads to carbon contamination in the solder.

Aspects of the structural evolution of lead-free solder joints

NASA Astrophysics Data System (ADS)

Zribi, A.; Kinyanjui, R.; Borgesen, P.; Zavalij, L.; Cotts, E. J.

2002-06-01

Studies of the formation of intermetallic compounds at some lead-free solder/metallization interfaces are briefly reviewed in this article. SnAgCu/Ni and SnAgCu/Cu interfaces are examined in particular. It has been found that (Cu,Ni)6Sn5 forms at SnAgCu/Ni interfaces until copper is depleted from the solder matrix. This article also contrasts the formation of (Au,Ni)Sn4 and related compounds in PbSn/Ni solder joints and lead-free solder joints.

Intraluminal laser light source and external solder: in vivo evaluation of a new technique for microvascular anastomosis.

PubMed

Ott, Beat; Constantinescu, Mihai A; Erni, Dominique; Banic, Andrej; Schaffner, Thomas; Frenz, Martin

2004-01-01

Current laser-assisted end-to-end anastomoses are performed by irradiating the vessel wall from outside after additional fixation with three to six sutures. These sutures are needed to provide adequate approximation of the vessel stumps. We present a new laser soldering technique that is based on an intraluminal laser light source centered in a balloon catheter, and external application of a solder. This technique was applied in vivo in order to test its feasibility under clinical conditions. Seven white pigs were treated with a total of fourteen end-to-end laser-anastomoses of their saphenous arteries having outer diameters of 2 mm. The vessels were stented over an intraluminal balloon catheter, which was maximally dilated and which allowed for a precise approximation of the vascular stumps. An 808 nm diode laser was coupled into a specially designed optical fiber producing a 360 degrees radiation ring inside the balloon catheter. An indocyanine green (ICG) doped liquid albumin solder was applied on the external surface of the vascular stumps. Laser soldering was achieved by irradiating with a 808 nm laser diode for 75 seconds. Tightness of the anastomoses was evaluated by clamping the artery distal to the anastomosis for 1 hour, and patency was tested over an observation period of 3 hours, during which the animals were heparinized. Thereafter, the anastomoses were harvested for histomorphological examination. All anastomoses remained patent over the entire observation period. Some leakage was observed in three anastomoses, which was explained by a deviation of the illumination fiber from the center of the balloon leading to an inhomogeneous irradiation of the vessel wall. Histology revealed perfect adaptation of the vascular stumps. A segment of denaturated vascular collagen was observed, that corresponded to the irradiated, solder-covered zone. Patent, maximally dilated and well adapted microvascular anastomoses could be obtained without the need of stay sutures. A well centered laser light source is indispensable for avoiding inhomogenous welding, thus causing leakage. (c) 2004 Wiley-Liss, Inc.

Laparoscopic laser soldering for repair of ureteropelvic junction obstruction in the porcine model.

PubMed

Shumalinsky, Dmitry; Lobik, Leonid; Cytron, Shmuel; Halpern, Marisa; Vasilyev, Tamar; Ravid, Avi; Katzir, Abraham

2004-03-01

Laparoscopic pyeloplasty is used for the repair of ureteropelvic junction (UPJ) obstruction. Our objective was to introduce laser soldering to this procedure. We developed a system based on a CO2 laser, an infrared detector, and two infrared transmitting optical fibers to obtain temperature-controlled laser soldering of cuts in tissues. The system was used for laparoscopic soldering of incisions in the kidneys of pigs. We carried out laparoscopic pyeloplasty successfully in a porcine model using fiberoptic laser soldering. Laparoscopic laser soldering was found to be faster than suturing. It was easier to use and provided watertight bonding. This technique will be useful in pyeloplasty as well as other laparoscopic surgical procedures.

Solder doped polycaprolactone scaffold enables reproducible laser tissue soldering.

PubMed

Bregy, Amadé; Bogni, Serge; Bernau, Vianney J P; Vajtai, Istvan; Vollbach, Felix; Petri-Fink, Alke; Constantinescu, Mihai; Hofmann, Heinrich; Frenz, Martin; Reinert, Michael

2008-12-01

In this in vitro feasibility study we analyzed tissue fusion using bovine serum albumin (BSA) and Indocyanine green (ICG) doped polycaprolactone (PCL) scaffolds in combination with a diode laser as energy source while focusing on the influence of irradiation power and albumin concentration on the resulting tensile strength and induced tissue damage. A porous PCL scaffold doped with either 25% or 40% (w/w) of BSA in combination with 0.1% (w/w) ICG was used to fuse rabbit aortas. Soldering energy was delivered through the vessel from the endoluminal side using a continuous wave diode laser at 808 nm via a 400 microm core fiber. Scaffold surface temperatures were analyzed with an infrared camera. Optimum parameters such as irradiation time, radiation power and temperature were determined in view of maximum tensile strength but simultaneously minimum thermally induced tissue damage. Differential scanning calorimetry (DSC) was performed to measure the influence of PCL on the denaturation temperature of BSA. Optimum parameter settings were found to be 60 seconds irradiation time and 1.5 W irradiation power resulting in tensile strengths of around 2,000 mN. Corresponding scaffold surface temperature was 117.4+/- 12 degrees C. Comparison of the two BSA concentration revealed that 40% BSA scaffold resulted in significant higher tensile strength compared to the 25%. At optimum parameter settings, thermal damage was restricted to the adventitia and its interface with the outermost layer of the tunica media. The DSC showed two endothermic peaks in BSA containing samples, both strongly depending on the water content and the presence of PCL and/or ICG. Diode laser soldering of vascular tissue using BSA-ICG-PCL-scaffolds leads to strong and reproducible tissue bonds, with vessel damage limited to the adventitia. Higher BSA content results in higher tensile strengths. The DSC-measurements showed that BSA denaturation temperature is lowered by addition of water and/or ICG-PCL. (c) 2008 Wiley-Liss, Inc.

Concentrated autologous plasma protein: a biochemically neutral solder for tissue welding.

PubMed

Stewart, R B; Bleustein, C B; Petratos, P B; Chin, K C; Poppas, D P; Kung, R T

2001-01-01

Xenographic or allographic serum protein solders used for laser welding may have immunologic and/or pathogenic complications. The objective of these studies was to develop a safe, autologous solder. Five methods of preparing concentrated autologous plasma protein solder (CAPPS) were evaluated. Next, the CAPPS was evaluated via (1) thermal denaturation studies using differential scanning calorimetry, (2) tissue welding studies to characterize both acute and healing properties. The optimal concentration method to produce CAPPS rapidly was a dialysis method using chemical (osmotic) forces. The CAPPS showed similar denaturation profiles to serum albumin (SA) solders. Acutely, CAPPS provided comparable breaking strengths to SA solders. At 7 days, there was no significant difference in breaking strength or histology between 50% human SA solder and CAPPS (using a porcine skin model). These studies demonstrate that the CAPPS system provides acceptable acute and chronic properties for laser welding. Copyright 2001 Wiley-Liss, Inc.

Modeling the Rate-Dependent Durability of Reduced-Ag SAC Interconnects for Area Array Packages Under Torsion Loads

NASA Astrophysics Data System (ADS)

Srinivas, Vikram; Menon, Sandeep; Osterman, Michael; Pecht, Michael G.

2013-08-01

Solder durability models frequently focus on the applied strain range; however, the rate of applied loading, or strain rate, is also important. In this study, an approach to incorporate strain rate dependency into durability estimation for solder interconnects is examined. Failure data were collected for SAC105 solder ball grid arrays assembled with SAC305 solder that were subjected to displacement-controlled torsion loads. Strain-rate-dependent (Johnson-Cook model) and strain-rate-independent elastic-plastic properties were used to model the solders in finite-element simulation. Test data were then used to extract damage model constants for the reduced-Ag SAC solder. A generalized Coffin-Manson damage model was used to estimate the durability. The mechanical fatigue durability curve for reduced-silver SAC solder was generated and compared with durability curves for SAC305 and Sn-Pb from the literature.

Composition of low-strength solder joints in solar-concentrator-cell arrays

NASA Astrophysics Data System (ADS)

Chamberlain, M. B.; Nordstrom, T. V.

Bond strengths of Cu strips soldered to the backside metallization of solar concentrator cells were found to be unacceptably low. To determine whether contaminants in the cell metallization caused these low strengths, unsoldered cells and soldered cells were characterized by scanning Auger microscopy. The backside metallization consisted of a 5 micrometers Ag conductor layer, a 150 nm Pd diffusion barrier and a 150 nm Ti adhesion layer next to an Al ohmic contact layer on the Si cell. The analysis showed that the Ti layer are partially oxidized during soldering, that Pb from the Pb-5 wt % Sn - 2.5 wt % Ag solder segregated during soldering to the Pd-oxidized Ti interface, and that low strength fractures occurred in this Pb layer at the Pd-oxidized Ti interface. The problem was solved by changing the ambient gas used during soldering from N2 to forming gas (80% N2 + 20% H2).

30 CFR 77.1112 - Welding, cutting, or soldering with arc or flame; safeguards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, or soldering with arc or... WORK AREAS OF UNDERGROUND COAL MINES Fire Protection § 77.1112 Welding, cutting, or soldering with arc or flame; safeguards. (a) When welding, cutting, or soldering with arc or flame near combustible...

30 CFR 77.1112 - Welding, cutting, or soldering with arc or flame; safeguards.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Welding, cutting, or soldering with arc or... WORK AREAS OF UNDERGROUND COAL MINES Fire Protection § 77.1112 Welding, cutting, or soldering with arc or flame; safeguards. (a) When welding, cutting, or soldering with arc or flame near combustible...

30 CFR 77.1112 - Welding, cutting, or soldering with arc or flame; safeguards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Welding, cutting, or soldering with arc or... WORK AREAS OF UNDERGROUND COAL MINES Fire Protection § 77.1112 Welding, cutting, or soldering with arc or flame; safeguards. (a) When welding, cutting, or soldering with arc or flame near combustible...

30 CFR 77.1112 - Welding, cutting, or soldering with arc or flame; safeguards.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Welding, cutting, or soldering with arc or... WORK AREAS OF UNDERGROUND COAL MINES Fire Protection § 77.1112 Welding, cutting, or soldering with arc or flame; safeguards. (a) When welding, cutting, or soldering with arc or flame near combustible...

30 CFR 77.1112 - Welding, cutting, or soldering with arc or flame; safeguards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Welding, cutting, or soldering with arc or... WORK AREAS OF UNDERGROUND COAL MINES Fire Protection § 77.1112 Welding, cutting, or soldering with arc or flame; safeguards. (a) When welding, cutting, or soldering with arc or flame near combustible...

Method for optical and mechanically coupling optical fibers

DOEpatents

Toeppen, J.S.

1996-10-01

A method and apparatus are disclosed for splicing optical fibers. A fluorescing solder glass frit having a melting point lower than the melting point of first and second optical fibers is prepared. The solder glass frit is then attached to the end of the first optical fiber and/or the end of the second optical fiber. The ends of the optical fibers are aligned and placed in close proximity to each other. The solder glass frit is then heated to a temperature which is lower than the melting temperature of the first and second optical fibers, but which is high enough to melt the solder glass frit. A force is applied to the first and second optical fibers pushing the ends of the fibers towards each other. As the solder glass flit becomes molten, the layer of molten solder glass is compressed into a thin layer between the first and second optical fibers. The thin compressed layer of molten solder glass is allowed to cool such that the first and second optical fibers are bonded to each other by the hardened layer of solder glass. 6 figs.

Method for optical and mechanically coupling optical fibers

DOEpatents

Toeppen, John S.

1996-01-01

A method and apparatus for splicing optical fibers. A fluorescing solder glass frit having a melting point lower than the melting point of first and second optical fibers is prepared. The solder glass frit is then attached to the end of the first optical fiber and/or the end of the second optical fiber. The ends of the optical fibers are aligned and placed in close proximity to each other. The solder glass frit is then heated to a temperature which is lower than the melting temperature of the first and second optical fibers, but which is high enough to melt the solder glass frit. A force is applied to the first and second optical fibers pushing the ends of the fibers towards each other. As the solder glass flit becomes molten, the layer of molten solder glass is compressed into a thin layer between the first and second optical fibers. The thin compressed layer of molten solder glass is allowed to cool such that the first and second optical fibers are bonded to each other by the hardened layer of solder glass.

The failure analysis and lifetime prediction for the solder joint of the magnetic head

NASA Astrophysics Data System (ADS)

Xiao, Xianghui; Peng, Minfang; Cardoso, Jaime S.; Tang, Rongjun; Zhou, YingLiang

2015-02-01

Micro-solder joint (MSJ) lifetime prediction methodology and failure analysis (FA) are to assess reliability by fatigue model with a series of theoretical calculations, numerical simulation and experimental method. Due to shortened time of solder joints on high-temperature, high-frequency sampling error that is not allowed in productions may exist in various models, including round-off error. Combining intermetallic compound (IMC) growth theory and the FA technology for the magnetic head in actual production, this thesis puts forward a new growth model to predict life expectancy for solder joint of the magnetic head. And the impact of IMC, generating from interface reaction between slider (magnetic head, usually be called slider) and bonding pad, on mechanical performance during aging process is analyzed in it. By further researching on FA of solder ball bonding, thesis chooses AuSn4 growth model that affects least to solder joint mechanical property to indicate that the IMC methodology is suitable to forecast the solder lifetime. And the diffusion constant under work condition 60 °C is 0.015354; the solder lifetime t is 14.46 years.

Temperature-controlled laser-soldering system and its clinical application for bonding skin incisions

NASA Astrophysics Data System (ADS)

Simhon, David; Gabay, Ilan; Shpolyansky, Gregory; Vasilyev, Tamar; Nur, Israel; Meidler, Roberto; Hatoum, Ossama Abu; Katzir, Abraham; Hashmonai, Moshe; Kopelman, Doron

2015-12-01

Laser tissue soldering is a method of repairing incisions. It involves the application of a biological solder to the approximated edges of the incision and heating it with a laser beam. A pilot clinical study was carried out on 10 patients who underwent laparoscopic cholecystectomy. Of the four abdominal incisions in each patient, two were sutured and two were laser soldered. Cicatrization, esthetical appearance, degree of pain, and pruritus in the incisions were examined on postoperative days 1, 7, and 30. The soldered wounds were watertight and healed well, with no discharge from these wounds or infection. The total closure time was equal in both methods, but the net soldering time was much shorter than suturing. There was no difference between the two types of wound closure with respect to the pain and pruritus on a follow-up of one month. Esthetically, the soldered incisions were estimated as good as the sutured ones. The present study confirmed that temperature-controlled laser soldering of human skin incisions is clinically feasible, and the results obtained were at least equivalent to those of standard suturing.

Temperature-controlled laser-soldering system and its clinical application for bonding skin incisions.

PubMed

Simhon, David; Gabay, Ilan; Shpolyansky, Gregory; Vasilyev, Tamar; Nur, Israel; Meidler, Roberto; Hatoum, Ossama Abu; Katzir, Abraham; Hashmonai, Moshe; Kopelman, Doron

2015-01-01

Laser tissue soldering is a method of repairing incisions. It involves the application of a biological solder to the approximated edges of the incision and heating it with a laser beam. A pilot clinical study was carried out on 10 patients who underwent laparoscopic cholecystectomy. Of the four abdominal incisions in each patient, two were sutured and two were laser soldered. Cicatrization, esthetical appearance, degree of pain, and pruritus in the incisions were examined on postoperative days 1, 7, and 30. The soldered wounds were watertight and healed well, with no discharge from these wounds or infection. The total closure time was equal in both methods, but the net soldering time was much shorter than suturing. There was no difference between the two types of wound closure with respect to the pain and pruritus on a follow-up of one month. Esthetically, the soldered incisions were estimated as good as the sutured ones. The present study confirmed that temperature-controlled laser soldering of human skin incisions is clinically feasible, and the results obtained were at least equivalent to those of standard suturing.

New multicomponent solder alloys of low melting pointfor low-cost commercial electronic assembly

NASA Astrophysics Data System (ADS)

Al-Ganainy, G. S.; Sakr, M. S.

2003-09-01

The requirements of the telecommunications, automobile, electronics and aircraft industries for non-toxic solders with melting points close to that of near-eutectic Pb-Sn alloys has led to the development of new Sn-Zn-In solder alloys. Differential thermal analysis (DTA) shows melting points of 198, 195, 190 and 185 +/- 2 °C for the alloys Sn-9Zn, Sn-9Zn-2In, Sn-9Zn-4In and Sn-9Zn-6In, respectively. An equation that fits the data relating the melting point to the In content in the solders is derived. The X-ray diffraction patterns are analyzed to determine the phases that exist in each solder. The stress-strain curves are studied in the temperature range from 90 to 130 °C for all the solders except for those that contain 4 wt% of In, where the temperature range continues to 150 °C. The work-hardening parameters, y (the yield stress), f (the fracture stress), and the parabolic work-hardening coefficient X, increase with increasing indium content in the solders at all working temperatures. They decrease with increasing working temperature for each solder, and show two relaxation stages only for the Sn-9Zn-4In solder around a temperature of 120 °C. (

The automated system for technological process of spacecraft's waveguide paths soldering

NASA Astrophysics Data System (ADS)

Tynchenko, V. S.; Murygin, A. V.; Emilova, O. A.; Bocharov, A. N.; Laptenok, V. D.

2016-11-01

The paper solves the problem of automated process control of space vehicles waveguide paths soldering by means of induction heating. The peculiarities of the induction soldering process are analyzed and necessity of information-control system automation is identified. The developed automated system makes the control of the product heating process, by varying the power supplied to the inductor, on the basis of information about the soldering zone temperature, and stabilizing the temperature in a narrow range above the melting point of the solder but below the melting point of the waveguide. This allows the soldering process automating to improve the quality of the waveguides and eliminate burn-troughs. The article shows a block diagram of a software system consisting of five modules, and describes the main algorithm of its work. Also there is a description of the waveguide paths automated soldering system operation, for explaining the basic functions and limitations of the system. The developed software allows setting of the measurement equipment, setting and changing parameters of the soldering process, as well as view graphs of temperatures recorded by the system. There is shown the results of experimental studies that prove high quality of soldering process control and the system applicability to the tasks of automation.

Tissue soldering with biodegradable polymer films: in-vitro investigation of hydration effects on weld strength

NASA Astrophysics Data System (ADS)

Sorg, Brian S.; Welch, Ashley J.

2001-05-01

Previous work demonstrated increased breaking strengths of tissue repaired with liquid albumin solder reinforced with a biodegradable polymer film compared to unreinforced control specimens. It was hypothesized that the breaking strength increase was due to reinforcement of the liquid solder cohesive strength. Immersion in a moist environment can decrease the adhesion of solder to tissue and negate any strength benefits gained from reinforcement. The purpose of this study was to determine if hydrated specimens repaired with reinforced solder would still be stronger than unreinforced controls. A 50%(w/v) bovine serum albumin solder with 0.5 mg/mL Indocyanine Green dye was used to repair an incision in bovine aorta. The solder was coagulated with 806-nm diode laser light. A poly(DL-lactic- co-glycolic acid) film was used to reinforce the solder (the controls had no reinforcement). The repaired tissues were immersed in phosphate buffered saline for time periods of 1 and 2 days. The breaking strengths of all of the hydrated specimens decreased compared to the acute breaking strengths. However, the reinforced specimens still had larger breaking strengths than the unreinforced controls. These results indicate that reinforcement of a liquid albumin solder may have the potential to improve the breaking strength in a clinical setting.

Nanocomposite SAC Solders: The Effect of Adding Ni and Ni-Sn Nanoparticles on Morphology and Mechanical Properties of Sn-3.0Ag-0.5Cu Solders

NASA Astrophysics Data System (ADS)

Yakymovych, A.; Švec, P.; Orovcik, L.; Bajana, O.; Ipser, H.

2018-01-01

This study investigates the effect of minor additions of Ni, Ni3Sn or Ni3Sn2 nanoparticles on the microstructure and mechanical properties of Cu/solder/Cu joints. The nanocomposite Sn-3.0Ag-0.5Cu (SAC305) solders with 0.5, 1.0 and 2.0 wt.% metallic nanoparticles were prepared through a paste mixing method. The employed Ni and Ni-Sn nanoparticles were produced via a chemical reduction method. The microstructure of as-solidified Cu/solder/Cu joints was studied by x-ray diffraction and scanning electron microscopy. The results showed that additions of Ni and Ni-Sn nanoparticles to the SAC305 solder paste lead initially to a decrease in the average thickness of the intermetallic compound layer in the interface between solder and substrate, while further additions up to 2.0 wt.% did not induce any significant changes. In addition, shear strength and microhardness tests were performed to investigate the relationship between microstructure and mechanical properties of the investigated solder joints. The results indicated an increase in both of these properties which was most significant for the solder joints using SAC305 with 0.5 wt.% Ni or Ni-Sn nanoparticles.

Effect of ultrasonic vibration time on the Cu/Sn-Ag-Cu/Cu joint soldered by low-power-high-frequency ultrasonic-assisted reflow soldering.

PubMed

Tan, Ai Ting; Tan, Ai Wen; Yusof, Farazila

2017-01-01

Techniques to improve solder joint reliability have been the recent research focus in the electronic packaging industry. In this study, Cu/SAC305/Cu solder joints were fabricated using a low-power high-frequency ultrasonic-assisted reflow soldering approach where non-ultrasonic-treated samples were served as control sample. The effect of ultrasonic vibration (USV) time (within 6s) on the solder joint properties was characterized systematically. Results showed that the solder matrix microstructure was refined at 1.5s of USV, but coarsen when the USV time reached 3s and above. The solder matrix hardness increased when the solder matrix was refined, but decreased when the solder matrix coarsened. The interfacial intermetallic compound (IMC) layer thickness was found to decrease with increasing USV time, except for the USV-treated sample with 1.5s. This is attributed to the insufficient USV time during the reflow stage and consequently accelerated the Cu dissolution at the joint interface during the post-ultrasonic reflow stage. All the USV-treated samples possessed higher shear strength than the control sample due to the USV-induced-degassing effect. The shear strength of the USV-treated sample with 6s was the lowest among the USV-treated samples due to the formation of plate-like Ag 3 Sn that may act as the crack initiation site. Copyright © 2016 Elsevier B.V. All rights reserved.

Al and Si Alloying Effect on Solder Joint Reliability in Sn-0.5Cu for Automotive Electronics

NASA Astrophysics Data System (ADS)

Hong, Won Sik; Oh, Chulmin; Kim, Mi-Song; Lee, Young Woo; Kim, Hui Joong; Hong, Sung Jae; Moon, Jeong Tak

2016-12-01

To suppress the bonding strength degradation of solder joints in automotive electronics, we proposed a mid-temperature quaternary Pb-free Sn-0.5Cu solder alloy with minor Pd, Al, Si and Ge alloying elements. We manufactured powders and solder pastes of Sn-0.5Cu-(0.01,0.03)Al-0.005Si-(0.006-0.007)Ge alloys ( T m = 230°C), and vehicle electronic control units used for a flame-retardant-4 printed circuit board with an organic solderability preservative finish were assembled by a reflow soldering process. To investigate the degradation properties of solder joints used in engine compartments, thermal cycling tests were conducted from -40°C to 125°C (10 min dwell) for 1500 cycles. We also measured the shear strength of the solder joints in various components and observed the microstructural evolution of the solder joints. Based on these results, intermetallic compound (IMC) growth at the solder joints was suppressed by minor Pd, Al and Si additions to the Sn-0.5Cu alloy. After 1500 thermal cycles, IMC layers thicknesses for 100 parts per million (ppm) and 300 ppm Al alloy additions were 6.7 μm and 10 μm, compared to the as-reflowed bonding thicknesses of 6 μm and 7 μm, respectively. Furthermore, shear strength degradation rates for 100 ppm and 300 ppm Al(Si) alloy additions were at least 19.5%-26.2%. The cause of the improvement in thermal cycling reliability was analyzed using the (Al,Cu)-Sn, Si-Sn and Al-Sn phases dispersed around the Cu6Sn5 intermetallic at the solder matrix and bonding interfaces. From these results, we propose the possibility of a mid-temperature Sn-0.5Cu(Pd)-Al(Si)-Ge Pb-free solder for automotive engine compartment electronics.

30 CFR 75.1106 - Welding, cutting, or soldering with arc or flame underground.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, or soldering with arc or... Protection § 75.1106 Welding, cutting, or soldering with arc or flame underground. [Statutory Provisions] All welding, cutting, or soldering with arc or flame in all underground areas of a coal mine shall, whenever...

Efforts to Develop a 300°C Solder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norann, Randy A

2015-01-25

This paper covers the efforts made to find a 300°C electrical solder solution for geothermal well monitoring and logging tools by Perma Works LLC. This paper covers: why a high temperature solder is needed, what makes for a good solder, testing flux, testing conductive epoxy and testing intermetallic bonds. Future areas of research are suggested.

Anomalous creep in Sn-rich solder joints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Ho Geon; Morris Jr., John W.; Hua, Fay

2002-03-15

This paper discusses the creep behavior of example Sn-rich solders that have become candidates for use in Pb-free solder joints. The specific solders discussed are Sn-3.5Ag, Sn-3Ag-0.5Cu, Sn-0.7Cu and Sn-10In-3.1Ag, used in thin joints between Cu and Ni-Au metallized pads.

30 CFR 75.1106 - Welding, cutting, or soldering with arc or flame underground.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Welding, cutting, or soldering with arc or... Protection § 75.1106 Welding, cutting, or soldering with arc or flame underground. [Statutory Provisions] All welding, cutting, or soldering with arc or flame in all underground areas of a coal mine shall, whenever...

30 CFR 75.1106 - Welding, cutting, or soldering with arc or flame underground.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Welding, cutting, or soldering with arc or... Protection § 75.1106 Welding, cutting, or soldering with arc or flame underground. [Statutory Provisions] All welding, cutting, or soldering with arc or flame in all underground areas of a coal mine shall, whenever...

30 CFR 75.1106 - Welding, cutting, or soldering with arc or flame underground.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Welding, cutting, or soldering with arc or... Protection § 75.1106 Welding, cutting, or soldering with arc or flame underground. [Statutory Provisions] All welding, cutting, or soldering with arc or flame in all underground areas of a coal mine shall, whenever...

30 CFR 75.1106 - Welding, cutting, or soldering with arc or flame underground.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Welding, cutting, or soldering with arc or... Protection § 75.1106 Welding, cutting, or soldering with arc or flame underground. [Statutory Provisions] All welding, cutting, or soldering with arc or flame in all underground areas of a coal mine shall, whenever...

Thermo-Mechanical Response of Monolithic and NiTi Shape Memory Alloy Fiber Reinforced Sn-3.8Ag-0.7Cu Solder

DTIC Science & Technology

2005-09-01

novel adaptive Tin-Silver-Copper ( SnAgCu ) solder reinforced with NiTi shape-memory alloy (particles or fiber) developed. An experimental...to meet the demands of miniaturization and enhanced performance in severe environments, a novel adaptive Tin-Silver-Copper ( SnAgCu ) solder...4. Crack region of SnAgCu solder after TMF, from reference [1] ............. 5 Figure 5. Phase diagram of 95.5Sn-3.8Ag-0.7Cu solder, from reference

An Accelerated Method for Soldering Testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Qingyou; Xu, Hanbing; Ried, Paul

2007-01-01

An accelerated method for testing die soldering has been developed. High intensity ultrasonic vibrations have been applied to simulate the die casting conditions such as high pressure and high molten metal velocity on the pin. The soldering tendency of steels and coated pins has been examined. The results suggest that in the low carbon steel/Al system, the onset of soldering is 60 times faster with ultrasonic vibration than that without ultrasonic vibration. In the H13/A380 system, the onset of soldering reaction is accelerated to between 30-60 times. Coatings significantly reduce the soldering tendency. For purposes of this study, several commercialmore » coatings from Balzers demonstrated the potential for increasing the service life of core pins between 15 and 180 times.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sloan, J.M.; Pergantis, C.G.

Organic and organo-metallic coatings are presently being applied over bare copper as an approach to improve the co-planarity of circuit boards. Conformal organic solderability preservative coatings (OSP) are environmentally and economically advantageous over the more commonly used lead based coatings. Problems arise in assessing the solderability of the bare copper and the integrity of the organic coating. Specular reflectance Fourier transform infrared spectroscopy (FT-IR) was utilized to monitor and evaluate the formation of Cu oxides occurring on copper substrates used in the manufacturing of electronic circuit boards. Previous studies reported the utility of this technique. By measuring the oxide andmore » protective coating characteristics of these surfaces, their solderability performance can rapidly be evaluated in a manufacturing environment. OSP coated test specimens were subjected to hot-dry and hot-wet environmental conditions using MIL-STD-202F and MIL-STD-883E as guides. The resultant FT-IR spectra provided clear evidence for the formation of various Cu oxides at the Cu/OSP interface over exposure time, for the samples subjected to the hot-dry environment. IR spectral bands consistent with O-Cu-O and Cu{sub 2}O{sub 2} formation appear, while very minimal deterioration to the OSP coating was observed. The appearance of the Cu oxide layers grew steadily with increased environmental exposure. Specimens subjected to the hot-wet conditions showed no significant signs of deterioration. The IR data can be directly correlated to solderability performance as evaluated by wet balance testing.« less

Soldering Tool for Integrated Circuits

NASA Technical Reports Server (NTRS)

Takahashi, Ted H.

1987-01-01

Many connections soldered simultaneously in confined spaces. Improved soldering tool bonds integrated circuits onto printed-circuit boards. Intended especially for use with so-called "leadless-carrier" integrated circuits.

Array automated assembly task, phase 2. Low cost silicon solar array project

NASA Technical Reports Server (NTRS)

Rhee, S. S.; Jones, G. T.; Allison, K. T.

1978-01-01

Several modifications instituted in the wafer surface preparation process served to significantly reduce the process cost to 1.55 cents per peak watt in 1975 cents. Performance verification tests of a laser scanning system showed a limited capability to detect hidden cracks or defects, but with potential equipment modifications this cost effective system could be rendered suitable for applications. Installation of electroless nickel plating system was completed along with an optimization of the wafer plating process. The solder coating and flux removal process verification test was completed. An optimum temperature range of 500-550 C was found to produce uniform solder coating with the restriction that a modified dipping procedure is utilized. Finally, the construction of the spray-on dopant equipment was completed.

Evaluation of Cleanliness Test Methods for Spacecraft PCB Assemblies

NASA Astrophysics Data System (ADS)

Tegehall, P.-E.; Dunn, B. D.

2006-10-01

Ionic contamination on printed-circuit-board assemblies may cause current leakage and short-circuits. The present cleanliness requirement in ECSS-Q-70-08, "The manual soldering of high-reliability electrical connections", is that the ionic contamination shall be less than 1.56 fl-glcm2 NaCI equivalents. The relevance of the method used for measurement of the ionic contamination level, resistivity of solvent extract, has been questioned. Alternative methods are ion chromatography and measurement of surface insulation resistance, but these methods also have their drawbacks. These methods are first described and their advantages and drawbacks are discussed. This is followed by an experimental evaluation of the three methods. This was done by soldering test vehicles at four manufacturers of space electronics using their ordinary processes for soldering and cleaning printed board assemblies. The experimental evaluation showed that the ionic contamination added by the four assemblers was very small and well below the acceptance criterion in ECSS-Q-70-80. Ion-chromatography analysis showed that most of the ionic contamination on the cleaned assembled boards originated from the hot-oil fusing of the printed circuit boards. Also, the surface insulation resistance was higher on the assembled boards compared to the bare printed circuit boards. Since strongly activated fluxes are normally used when printed circuit boards are hot-oil fused, it is essential that they are thoroughly cleaned in order to achieve low contamination levels on the final printed-board assemblies.

KNOWING CHEMISTRY CAN HELP GET THE LEAD OUT

EPA Science Inventory

Lead in tap water comes from the materials used in plumbing such as from leaded solder, lead pipe, and lead-containing brass found in fittings and faucets. Fortunately, the surface of brass eventually becomes passivated when in contact with most waters. Oxidants in water (usually...

Mechanical Deformation Behavior of Sn-Ag-Cu Solders with Minor Addition of 0.05 wt.% Ni

NASA Astrophysics Data System (ADS)

Hammad, A. E.; El-Taher, A. M.

2014-11-01

The aim of the present work is to develop a comparative evaluation of the microstructural and mechanical deformation behavior of Sn-Ag-Cu (SAC) solders with the minor addition of 0.05 wt.% Ni. Test results showed that, by adding 0.05Ni element into SAC solders, generated mainly small rod-shaped (Cu,Ni)6Sn5 intermetallic compounds (IMCs) inside the β-Sn phase. Moreover, increasing the Ag content and adding Ni could result in the change of the shape and size of the IMC precipitate. Hence, a significant improvement is observed in the mechanical properties of SAC solders with increasing Ag content and Ni addition. On the other hand, the tensile results of Ni-doped SAC solders showed that both the yield stress and ultimate tensile strengths decrease with increasing temperature and with decreasing strain rate. This behavior was attributed to the competing effects of work hardening and dynamic recovery processes. The Sn-2.0Ag-0.5Cu-0.05Ni solder displayed the highest mechanical properties due to the formation of hard (Cu,Ni)6Sn5 IMCs. Based on the obtained stress exponents and activation energies, it is suggested that the dominant deformation mechanism in SAC (205)-, SAC (0505)- and SAC (0505)-0.05Ni solders is pipe diffusion, and lattice self-diffusion in SAC (205)-0.05Ni solder. In view of these results, the Sn-2.0Ag-0.5Cu-0.05Ni alloy is a more reliable solder alloy with improved properties compared with other solder alloys tested in the present work.

A Study on the Physical Properties and Interfacial Reactions with Cu Substrate of Rapidly Solidified Sn-3.5Ag Lead-Free Solder

NASA Astrophysics Data System (ADS)

Ma, Hai-Tao; Wang, Jie; Qu, Lin; Zhao, Ning; Kunwar, A.

2013-08-01

A rapidly solidified Sn-3.5Ag eutectic alloy produced by the melt-spinning technique was used as a sample in this research to investigate the microstructure, thermal properties, solder wettability, and inhibitory effect of Ag3Sn on Cu6Sn5 intermetallic compound (IMC). In addition, an as-cast Sn-3.5Ag solder was prepared as a reference. Rapidly solidified and as-cast Sn-3.5Ag alloys of the same size were soldered at 250°C for 1 s to observe their instant melting characteristics and for 3 s with different cooling methods to study the inhibitory effect of Ag3Sn on Cu6Sn5 IMC. Experimental techniques such as scanning electron microscopy, differential scanning calorimetry, and energy-dispersive spectrometry were used to observe and analyze the results of the study. It was found that rapidly solidified Sn-3.5Ag solder has more uniform microstructure, better wettability, and higher melting rate as compared with the as-cast material; Ag3Sn nanoparticles that formed in the rapidly solidified Sn-3.5Ag solder inhibited the growth of Cu6Sn5 IMC during aging significantly much strongly than in the as-cast material because their number in the rapidly solidified Sn-3.5Ag solder was greater than in the as-cast material with the same soldering process before aging. Among the various alternative lead-free solders, this study focused on comparison between rapidly solidified and as-cast solder alloys, with the former being observed to have better properties.

Finite Element-Assisted Assessment of the Thermo-cyclic Characteristics of Leads Soldered with SnAgCu(+Bi,In) Alloys

NASA Astrophysics Data System (ADS)

Lis, Adrian; Nakanishi, Kohei; Matsuda, Tomoki; Sano, Tomokazu; Minagawa, Madoka; Okamoto, Masahide; Hirose, Akio

2017-07-01

Solder joints between leads and printed circuit boards in thin small outline packages were produced with conventional Sn1.0Ag0.7Cu (SAC107) and Sn3.0Ag0.7Cu (SAC305) solders as well as various solder alloys with gradually increasing amounts of Bi (up to 3.0 wt.%) and In (up to 1.0 wt.%) within the SAC107 base solder. The reliability of soldered leads in temperature cycle (TC) tests improved most with solder alloys containing both Bi (1.6 wt.%) and In (0.5 wt.%). Microindentation and electron probe microanalysis mappings revealed that the effect originates from a combination of solution and precipitation strengthening of the initial SAC alloy. The distribution of inelastic strain accumulation (ISA), as a measure for degradation, was determined in the solder joints by finite element calculations. It was shown that defects in the solder proximal to the lead (<60-75 μm) strongly impact the reliability and provoke crack initiation around the defect where the highest ISA is located. In particular, similar TC performance can be expected for defect-free joints and for those whose defects exceed the threshold distance from the lead (>60-75 μm), which was underpinned by similar cracking characteristics along the lead-solder interface. The ISA was confirmed to be lower in SAC+Bi/In alloys owing to their enhanced elasto-plastic properties. Moreover, the addition of a thin Cu coating on the leads could improve the joint reliability, as suggested by the calculation of the ISA and the acceleration factor.

Recrystallization Behavior in SAC305 and SAC305 + 3.0POSS Solder Joints Under Thermal Shock

NASA Astrophysics Data System (ADS)

Han, Jing; Gu, Penghao; Ma, Limin; Guo, Fu; Liu, Jianping

2018-04-01

Sn-3.0Ag-0.5Cu (SAC305) and SAC305 + 3.0 polyhedral oligomeric silsesquioxanes (POSS) ball grid array (BGA) assemblies have been prepared, observed, and subjected to thermal shock. The microstructure and grain orientation evolution of the solder joints located at the same position of the package were characterized by scanning electron microscopy and electron backscattering diffraction, respectively. The results showed that the microstructure of the solder joints was refined by addition of POSS particles. In addition, compared with the single-grained or tricrystal joints normally observed in SAC305 BGA solder joints, the frequency of single-grained as-reflowed SAC305 + 3.0POSS BGA joints was greatly reduced, and the solder joints were typically composed of multicrystals with orientations separated by high-angle grain boundaries. These multicrystal joints appear to be obtained by dominant tricrystals or double tricrystals with deviation of the preferred [110] and [1\\bar{1}0] growth directions of Sn dendrites in Sn-Ag-based solder alloys during solidification from the melt. After 928 thermal shock cycles, the SAC305 solder joint had large-area recrystallization and cracks in contrast to the SAC305 + 3.0POSS solder joint located at the same position of the package, indicating that addition of POSS to SAC305 solder joints may contribute to postponement of recrystallization and subsequent crack initiation and propagation along recrystallized grain boundaries by pinning grain boundaries and movement of dislocations. This finding also confirms the double tricrystal solidification twinning nucleation behavior in Pb-free solder joints.

Dural reconstruction by fascia using a temperature-controlled CO2 laser soldering system

NASA Astrophysics Data System (ADS)

Forer, Boaz; Vasilyev, Tamar; Brosh, Tamar; Kariv, Naam; Gil, Ziv; Fliss, Dan M.; Katzir, Abraham

2005-04-01

Conventional methods for dura repair are normally based on sutures or stitches. These methods have several disadvantages: (1) The dura is often brittle, and the standard procedures are difficult and time consuming. (2) The seal is leaky. (3) The introduction of a foreign body (e.g. sutures) may cause an inflammatory response. In order to overcome these difficulties we used a temperature controlled fiber optic based CO2 laser soldering system. In a set of in vitro experiments we generated a hole of diameter 10 mm in the dura of a pig corpse, covered the hole with a segment of fascia, and soldered the fascia to the edges of the hole, using 47% bovine albumin as a solder. The soldering was carried out spot by spot, and each spot was heated to 65° C for 3-6 seconds. The soldered dura was removed and the burst pressure of the soldered patch was measured. The average value for microscopic muscular side soldering was 194 mm Hg. This is much higher than the maximal physiological pressure of the CSF fluid in the brain, which is 15 mm Hg. In a set of in vivo experiments, fascia patches were soldered on holes in five farm pigs. The long term results of these experiments were very promising. In conclusion, we have developed an advanced technique for dural reconstruction, which will find important clinical applications.

Failure Mechanisms of SAC/Fe-Ni Solder Joints During Thermal Cycling

NASA Astrophysics Data System (ADS)

Gao, Li-Yin; Liu, Zhi-Quan; Li, Cai-Fu

2017-08-01

Thermal cycling tests have been conducted on Sn-Ag-Cu/Fe- xNi ( x = 73 wt.% or 45 wt.%) and Sn-Ag-Cu/Cu solder joints according to the Joint Electron Device Engineering Council industrial standard to study their interfacial reliability under thermal stress. The interfacial intermetallic compounds formed for solder joints on Cu, Fe-73Ni, and Fe-45Ni were 4.5 μm, 1.7 μm, and 1.4 μm thick, respectively, after 3000 cycles, demonstrating excellent diffusion barrier effect of Fe-Ni under bump metallization (UBM). Also, two deformation modes, viz. solder extrusion and fatigue crack formation, were observed by scanning electron microscopy and three-dimensional x-ray microscopy. Solder extrusion dominated for solder joints on Cu, while fatigue cracks dominated for solder joints on Fe-45Ni and both modes were detected for those on Fe-73Ni. Solder joints on Fe-Ni presented inferior reliability during thermal cycling compared with those on Cu, with characteristic lifetime of 3441 h, 3190 h, and 1247 h for Cu, Fe-73Ni, and Fe-45Ni UBM, respectively. This degradation of the interfacial reliability for solder joints on Fe-Ni is attributed to the mismatch in coefficient of thermal expansion (CTE) at interconnection level. The CTE mismatch at microstructure level was also analyzed by electron backscatter diffraction for clearer identification of recrystallization-related deformation mechanisms.

The Shear Strength and Fracture Behavior of Sn-Ag- xSb Solder Joints with Au/Ni-P/Cu UBM

NASA Astrophysics Data System (ADS)

Lee, Hwa-Teng; Hu, Shuen-Yuan; Hong, Ting-Fu; Chen, Yin-Fa

2008-06-01

This study investigates the effects of Sb addition on the shear strength and fracture behavior of Sn-Ag-based solders with Au/Ni-P/Cu underbump metallization (UBM) substrates. Sn-3Ag- xSb ternary alloy solder joints were prepared by adding 0 wt.% to 10 wt.% Sb to a Sn-3.5Ag alloy and joining them with Au/Ni-P/Cu UBM substrates. The solder joints were isothermally stored at 150°C for up to 625 h to study their microstructure and interfacial reaction with the UBM. Single-lap shear tests were conducted to evaluate the mechanical properties, thermal resistance, and failure behavior. The results show that UBM effectively suppressed intermetallic compound (IMC) formation and growth during isothermal storage. The Sb addition helped to refine the Ag3Sn compounds, further improving the shear strength and thermal resistance of the solders. The fracture behavior evolved from solder mode toward the mixed mode and finally to the IMC mode with increasing added Sb and isothermal storage time. However, SnSb compounds were found in the solder with 10 wt.% Sb; they may cause mechanical degradation of the solder after long-term isothermal storage.

Root Cause Investigation of Lead-Free Solder Joint Interfacial Failures After Multiple Reflows

NASA Astrophysics Data System (ADS)

Li, Yan; Hatch, Olen; Liu, Pilin; Goyal, Deepak

2017-03-01

Solder joint interconnects in three-dimensional (3D) packages with package stacking configurations typically must undergo multiple reflow cycles during the assembly process. In this work, interfacial open joint failures between the bulk solder and the intermetallic compound (IMC) layer were found in Sn-Ag-Cu (SAC) solder joints connecting a small package to a large package after multiple reflow reliability tests. Systematic progressive 3D x-ray computed tomography experiments were performed on both incoming and assembled parts to reveal the initiation and evolution of the open failures in the same solder joints before and after the reliability tests. Characterization studies, including focused ion beam cross-sections, scanning electron microscopy, and energy-dispersive x-ray spectroscopy, were conducted to determine the correlation between IMC phase transformation and failure initiation in the solder joints. A comprehensive failure mechanism, along with solution paths for the solder joint interfacial failures after multiple reflow cycles, is discussed in detail.

Microstructure and mechanical behavior of low-melting point Bi-Sn-In solder joints

NASA Astrophysics Data System (ADS)

Nguyen, Van Luong; Kim, Sang Hoon; Jeong, Jae Won; Lim, Tae-Soo; Yang, Dong-Yeol; Kim, Ki Bong; Kim, Young Ja; Lee, Jun Hong; Kim, Yong-Jin; Yang, Sangsun

2017-09-01

Ternary Bi-31.5Sn-25.0In solder has been proposed and studied for application in temperature-sensitive electronic components. In a Bi-31.5Sn- 25.0In solder joint, In was detected in an intermetallic compound (IMC) layer formed at the solder/Cu substrate interface with a thickness of 4.8 μm. The microstructure of the bulk solder consisted of Sn-rich phases distributed in Bi-rich phases with dispersion of In in both phases. Meanwhile, the nanomechanical properties of the Bi-31.5Sn-25.0In solder showed great strain rate sensitivity. To be specific, hardness increased from 9.91 MPa to 56.84 MPa as the strain rate increased in the range of (0.0005-0.125) s-1. The strain-rate sensitivity exponent ( m) was found to be 0.28, indicating that the excellent ductility was shown for the solder tested under the present conditions. [Figure not available: see fulltext.

Interfacial Phenomena in Al/Al, Al/Cu, and Cu/Cu Joints Soldered Using an Al-Zn Alloy with Ag or Cu Additions

NASA Astrophysics Data System (ADS)

Pstruś, Janusz; Gancarz, Tomasz

2014-05-01

The studies of soldered joints were carried out in systems: Al/solder/Al, Al/solder/Cu, Cu/solder/Cu, where the solder was (Al-Zn)EUT, (Al-Zn)EUT with 0.5, 1.0, and 1.5 at.% of Ag and (Al-Zn)EUT with 0.5, 1.0, and 1.5 at.% of Cu addition. Brazing was performed at 500 °C for 3 min. The EDS analysis indicated that the composition of the layers starting from the Cu pad was CuZn, Cu5Zn8, and CuZn4, respectively. Wetting tests were performed at 500 °C for 3, 8, 15, and 30 min, respectively. Thickness of the layers and their kinetics of growth were measured based on the SEM micrographs. The formation of interlayers was not observed from the side of Al pads. On the contrary, dissolution of the Al substrate and migration of Al-rich particles into the bulk of the solder were observed.

Microstructural evolution and IMCs growth behavior of Sn-58Bi-0.25Mo solder joint during aging treatment

NASA Astrophysics Data System (ADS)

Yang, Li; Zhu, Lu; Zhang, Yaocheng; Zhou, Shiyuan; Xiong, Yifeng; Wu, Pengcheng

2018-02-01

The microstructural evolution and IMCs growth behavior of Sn-58Bi and Sn-58Bi-0.25Mo solder joints were investigated. The results showed that the microstructure is coarsened, the IMCs layer thickness is increased and the tensile strength of Sn-58Bi and Sn-58Bi-0.25Mo solder joints is decreased with increasing aging time and temperature. Aging temperature is the key factor that causes the excessive IMCs growth of the solder joint compared with aging time, and the activation energy of IMCs layer growth of Sn-58Bi and Sn-58Bi-0.25Mo solder joints is 48.94 kJ mol-1 and 53.79 kJ mol-1, respectively. During the aging treatment, the microstructure of Sn-58Bi solder joint is refined by adding Mo nanoparticles, and the appropriate IMCs layer thickness and improved mechanical properties are obtained by Sn-58Bi-0.25Mo solder joint.

Histologic assessment of mesh fixation following laser-assisted tissue soldering in a lapine model.

PubMed

Lanzafame, Raymond J; Brondon, Philip; Stadler, Istvan; DeVore, Dale P; Soltz, Robert; Soltz, Barbara A

2005-08-01

Wound histology and mesh bioincorporation following intraperitoneal fixation using laser-assisted soldering was evaluated. 2.8-3.2 kg NZW rabbits underwent laparotomy. Controls had 2x2 cm segments of Mersilene stapled to peritoneum. Group 2 segments were affixed with 55% collagen solder onlay by fiber-coupled diode laser (1.43 +/- 10 micro, 2.5 W CW, 4 mm spot, 60 degrees C set temperature). Group 4 had Mersilene inlaid into melted solder. Group 3 had solder-embedded Vicryl mesh affixed. Animals were euthanized at 0, 2, 4, 6 weeks. Fixed sections were assessed for integrity, inflammation, and fibrosis using H & E, Masson's Trichrome and Evans Van Gieson staining. Histology demonstrated cell types, local mesh reaction, and progressive evidence of solder reabsorption mimicking normal healing and bioincorporation. Mersilene groups demonstrated normal arrangement of collagen-rich layers around mesh. Collagen-based tissue soldering permits normal wound healing and may mitigate use of staples. Further development of this strategy is warranted. (c) 2005 Wiley-Liss, Inc.

An analysis of the pull strength behaviors of fine-pitch, flip chip solder interconnections using a Au-Pt-Pd thick film conductor on Low-Temperature, Co-fired Ceramic (LTCC) substrates.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uribe, Fernando R.; Kilgo, Alice C.; Grazier, John Mark

2008-09-01

The assembly of the BDYE detector requires the attachment of sixteen silicon (Si) processor dice (eight on the top side; eight on the bottom side) onto a low-temperature, co-fired ceramic (LTCC) substrate using 63Sn-37Pb (wt.%, Sn-Pb) in a double-reflow soldering process (nitrogen). There are 132 solder joints per die. The bond pads were gold-platinum-palladium (71Au-26Pt-3Pd, wt.%) thick film layers fired onto the LTCC in a post-process sequence. The pull strength and failure modes provided the quality metrics for the Sn-Pb solder joints. Pull strengths were measured in both the as-fabricated condition and after exposure to thermal cycling (-55/125 C; 15more » min hold times; 20 cycles). Extremely low pull strengths--referred to as the low pull strength phenomenon--were observed intermittently throughout the product build, resulting in added program costs, schedule delays, and a long-term reliability concern for the detector. There was no statistically significant correlation between the low pull strength phenomenon and (1) the LTCC 'sub-floor' lot; (2) grit blasting the LTCC surfaces prior to the post-process steps; (3) the post-process parameters; (4) the conductor pad height (thickness); (5) the dice soldering assembly sequence; or (5) the dice pull test sequence. Formation of an intermetallic compound (IMC)/LTCC interface caused by thick film consumption during either the soldering process or by solid-state IMC formation was not directly responsible for the low-strength phenomenon. Metallographic cross sections of solder joints from dice that exhibited the low pull strength behavior, revealed the presence of a reaction layer resulting from an interaction between Sn from the molten Sn-Pb and the glassy phase at the TKN/LTCC interface. The thick film porosity did not contribute, explicitly, to the occurrence of reaction layer. Rather, the process of printing the very thin conductor pads was too sensitive to minor thixotropic changes to ink, which resulted in inconsistent proportions of metal and glassy phase particles present during the subsequent firing process. The consequences were subtle, intermittent changes to the thick film microstructure that gave rise to the reaction layer and, thus, the low pull strength phenomenon. A mitigation strategy would be the use of physical vapor deposition (PVD) techniques to create thin film bond pads; this is multi-chip module, deposited (MCM-D) technology.« less

Intermetallic compounds in 3D integrated circuits technology: a brief review

NASA Astrophysics Data System (ADS)

Annuar, Syahira; Mahmoodian, Reza; Hamdi, Mohd; Tu, King-Ning

2017-12-01

The high performance and downsizing technology of three-dimensional integrated circuits (3D-ICs) for mobile consumer electronic products have gained much attention in the microelectronics industry. This has been driven by the utilization of chip stacking by through-Si-via and solder microbumps. Pb-free solder microbumps are intended to replace conventional Pb-containing solder joints due to the rising awareness of environmental preservation. The use of low-volume solder microbumps has led to crucial constraints that cause several reliability issues, including excessive intermetallic compounds (IMCs) formation and solder microbump embrittlement due to IMCs growth. This article reviews technologies related to 3D-ICs, IMCs formation mechanisms and reliability issues concerning IMCs with Pb-free solder microbumps. Finally, future outlook on the potential growth of research in this area is discussed.

Intermetallic compounds in 3D integrated circuits technology: a brief review.

PubMed

Annuar, Syahira; Mahmoodian, Reza; Hamdi, Mohd; Tu, King-Ning

2017-01-01

The high performance and downsizing technology of three-dimensional integrated circuits (3D-ICs) for mobile consumer electronic products have gained much attention in the microelectronics industry. This has been driven by the utilization of chip stacking by through-Si-via and solder microbumps. Pb-free solder microbumps are intended to replace conventional Pb-containing solder joints due to the rising awareness of environmental preservation. The use of low-volume solder microbumps has led to crucial constraints that cause several reliability issues, including excessive intermetallic compounds (IMCs) formation and solder microbump embrittlement due to IMCs growth. This article reviews technologies related to 3D-ICs, IMCs formation mechanisms and reliability issues concerning IMCs with Pb-free solder microbumps. Finally, future outlook on the potential growth of research in this area is discussed.

Ultrasonic-assisted soldering of Cu/Ti joints

NASA Astrophysics Data System (ADS)

Cui, Wei; Wang, Chunyu; Li, Yuhang; Zhong, Tongtong; Yang, Jianguo; Bao, Yefeng

2018-03-01

Cu/Ti joints are expected to be used in various applications, while reliable joining method is still to be developed. It is commonly not possible to solder Ti alloys using Sn-based solder alloys because of their poor wettability. In this study, Sn-Ag-Cu soldering filler metal was used to joining TC4 titanium alloy and pure copper using ultrasonic-assisted soldering. The influence of different temperature and different ultrasonic time on the welded joint is studied and explored. Microstructure of the joints was investigated. Shear strength of the joints reached the maximum value, i.e. 38.2MPa. Relationship between the sonication parameters and the microstructure and strength of the joints was discussed. Thus, it is verified that dissimilar metal brazing of TC4 and copper is suitable for low temperature soldering.

Effect of varying chromophores used in light-activated protein solders on tensile strength and thermal damage profile of repairs.

PubMed

Hoffman, Grant T; Byrd, Brian D; Soller, Eric C; Heintzelman, Douglas L; McNally-Heintzelman, Karen M

2003-01-01

Clinical adoption of laser tissue welding (LTW) techniques has been beleaguered by problems associated with thermal damage of tissue and insufficient strength of the resulting tissue bond. The magnitude of these problems has been significantly reduced with the incorporation of indocyanine green (ICG)-doped protein solders into the LTW procedure to form a new technique known as laser tissue soldering (LTS). With the addition of ICG, a secondary concern has arisen relating to the potential harmful effects of the degradation products of the chromophore upon thermal denaturation of the protein solder with a laser. In this study, two different food colorings were investigated, including blue #1 and green consisting of yellow #5 and blue #1, as alternative chromophores for use in LTS techniques. Food coloring has been found to have a suitable stability and safety profile for enteral use when heated to temperatures above 200 degrees C; thus, it is a promising candidate chromophore for LTS which typically requires temperatures between 50 degrees C and 100 degrees C. Experimental investigations were conducted to test the tensile strength of ex vivo repairs formed using solders doped with these alternative chromophores in a bovine model. Two commonly used chromophores, ICG and methylene blue (MB), were investigated as a reference. In addition, the temperature rise, depth of thermal coagulation in the protein solder, and the extent of thermal damage in the surrounding tissue were measured. Temperature rise at the solder/tissue interface, and consequently the degree of solder coagulation and collateral tissue thermal damage, was directly related to the penetration depth of laser light in the protein solder. Variation of the chromophore concentration such that the laser light penetrated to a depth approximately equal to half the thickness of the solder resulted in uniform results between each group of chromophores investigated. Optimal tensile strength of repairs was achieved by optimizing laser and solder parameters to obtain a temperature of approximately 65 degrees C at the solder/tissue interface. The two alternative chromophores tested in this study show considerable promise for application in LTS techniques, with equivalent tensile strength to solders doped with ICG or MB, and the potential advantage of eliminating the risks associated with harmful byproducts.

Investigation of corrosion and stress corrosion cracking susceptibility of S30400 and S31600 stainless steels exposed to commercial soldering flux containing zinc chloride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, D.T.

1995-10-01

A corrosion investigation was conducted to determine corrosion behavior and stress corrosion cracking (SCC) susceptibility of S30400 and S31600 stainless steel exposed to soldering flux paste containing 25 wt% zinc chloride. Electrochemical test results indicated that soldering flux paste was not corrosive to S30400 and S31600 at room temperature. The wax phase (light phase) of soldering flux was also not corrosive to S30400 and S31600. However, the heavy phase of solder flux was corrosive to S30400 and S31600 at elevated temperatures. In heavy phase, S30400 did not passivate, while S31600 passivated at temperatures up to 80 C while no passivitymore » was observed at 85 C and above. AC impedance test results showed that S30400 and S31600 corroded at rates of less than 0.1 mpy in solder flux pastes at room temperature. In the soldering flux heavy phase, corrosion rates were about 2 mpy or less for S30400 at temperatures up to 75 C and S31600 at temperatures up to 70 C. However, corrosion rates of S30400 in the soldering flux heavy phase increased to 5, 8, 10, and 22 mpy at 80, 85, 90, and 95 C while corrosion rates of S31600 sst in the soldering flux heavy phase increased to 4, 5, 7, and 11, and 30 mpy at 75, 80, 85, 90 and 95 C, respectively. CERT results revealed that no SCC susceptibility when S30400 and S31600 were exposed to soldering flux paste at room temperature and wax phase at 65 and 95 C. However, both test alloys were susceptible to transgranular SCC when exposed to the soldering flux heavy phase at temperatures of 65+ C. Severity of SCC increased with temperature increase. SCC fractures were characterized by reduction of ductility and numerous SCC secondary cracks on the specimen gage length. The most severe SCC fracture was observed on a S30400 specimen partially submersed in the soldering flux heavy phase and partially submersed in the soldering flux wax phase at 95 C. No similar cracking was observed on S31600.« less

Processing of NiTi Reinforced Adaptive Solder for Electronic Packaging

DTIC Science & Technology

2004-03-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS PROCESSING OF NITI REINFORCED ADAPTIVE SOLDER FOR ELECTRONIC PACKAGING...March 2004 3. REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE: Processing of NiTi Reinforced Adaptive Solder for Electronic...reports in the development a process to fabricate solder joints with a fine distribution of shape memory alloys (SMA) NiTi particulates. The

49 CFR 393.67 - Liquid fuel tanks.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., by brazing, by silver soldering, or by techniques which provide heat resistance and mechanical... soldering with a lead-based or other soft solder. (2) Fittings. The fuel tank body must have flanges or...

49 CFR 393.67 - Liquid fuel tanks.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., by brazing, by silver soldering, or by techniques which provide heat resistance and mechanical... soldering with a lead-based or other soft solder. (2) Fittings. The fuel tank body must have flanges or...

49 CFR 393.67 - Liquid fuel tanks.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., by brazing, by silver soldering, or by techniques which provide heat resistance and mechanical... soldering with a lead-based or other soft solder. (2) Fittings. The fuel tank body must have flanges or...

Acid soldering flux poisoning

MedlinePlus

Acid soldering flux is a chemical used to clean and protect the area where two pieces of metal are ... The harmful substances in soldering fluxes are called hydrocarbons. They include: Ammonium chloride Rosin Hydrochloric acid Zinc chloride

49 CFR 393.67 - Liquid fuel tanks.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., by brazing, by silver soldering, or by techniques which provide heat resistance and mechanical... soldering with a lead-based or other soft solder. (2) Fittings. The fuel tank body must have flanges or...

The Influence of Processing on Strengthening Mechanisms in Pb-Free Solder Joints

NASA Astrophysics Data System (ADS)

Mutuku, Francis; Arfaei, Babak; Cotts, Eric J.

2017-04-01

The number, and the spacing, of Ag3Sn precipitates in Sn-Ag-Cu/Cu solder joints were related to separate processing parameters. The mechanical properties of an individual solder joint were directly related to the resulting distribution of different dispersoids in the joint. As the number of Ag3Sn precipitates increased, so did solder joint strength and shear fatigue lifetime. The room-temperature shear fatigue lifetime was inversely correlated with the separation between Ag3Sn precipitates. Bi and Sb solid solution strengthening was found to result in significantly larger values of shear strength and shear fatigue lifetime for one Pb-free solder. Room-temperature shear fatigue lifetime tests were identified as a relatively straightforward, yet sensitive means to gain insight into the reliability of Sn-Ag-Cu (SAC) solder joints.

Intermetallic compounds in 3D integrated circuits technology: a brief review

PubMed Central

Annuar, Syahira; Mahmoodian, Reza; Hamdi, Mohd; Tu, King-Ning

2017-01-01

Abstract The high performance and downsizing technology of three-dimensional integrated circuits (3D-ICs) for mobile consumer electronic products have gained much attention in the microelectronics industry. This has been driven by the utilization of chip stacking by through-Si-via and solder microbumps. Pb-free solder microbumps are intended to replace conventional Pb-containing solder joints due to the rising awareness of environmental preservation. The use of low-volume solder microbumps has led to crucial constraints that cause several reliability issues, including excessive intermetallic compounds (IMCs) formation and solder microbump embrittlement due to IMCs growth. This article reviews technologies related to 3D-ICs, IMCs formation mechanisms and reliability issues concerning IMCs with Pb-free solder microbumps. Finally, future outlook on the potential growth of research in this area is discussed. PMID:29057024

Ductile fracture mechanism of low-temperature In-48Sn alloy joint under high strain rate loading.

PubMed

Kim, Jong-Woong; Jung, Seung-Boo

2012-04-01

The failure behaviors of In-48Sn solder ball joints under various strain rate loadings were investigated with both experimental and finite element modeling study. The bonding force of In-48Sn solder on an Ni plated Cu pad increased with increasing shear speed, mainly due to the high strain-rate sensitivity of the solder alloy. In contrast to the cases of Sn-based Pb-free solder joints, the transition of the fracture mode from a ductile mode to a brittle mode was not observed in this solder joint system due to the soft nature of the In-48Sn alloy. This result is discussed in terms of the relationship between the strain-rate of the solder alloy, the work-hardening effect and the resulting stress concentration at the interfacial regions.

The effects of additives to SnAgCu alloys on microstructure and drop impact reliability of solder joints

NASA Astrophysics Data System (ADS)

Liu, Weiping; Lee, Ning-Cheng

2007-07-01

The impact reliability of solder joints in electronic packages is critical to the lifetime of electronic products, especially those portable devices using area array packages such as ball-grid array (BGA) and chip-scale packages (CSP). Currently, SnAgCu (SAC) solders are most widely used for lead-free applications. However, BGA and CSP solder joints using SAC alloys are fragile and prone to premature interfacial failure, especially under shock loading. To further enhance impact reliability, a family of SAC alloys doped with a small amount of additives such as Mn, Ce, Ti, Bi, and Y was developed. The effects of doping elements on drop test performance, creep resistance, and microstructure of the solder joints were investigated, and the solder joints made with the modified alloys exhibited significantly higher impact reliability.

Development of n+-in-p planar pixel quadsensor flip-chipped with FE-I4 readout ASICs

NASA Astrophysics Data System (ADS)

Unno, Y.; Kamada, S.; Yamamura, K.; Yamamoto, H.; Hanagaki, K.; Hori, R.; Ikegami, Y.; Nakamura, K.; Takubo, Y.; Takashima, R.; Tojo, J.; Kono, T.; Nagai, R.; Saito, S.; Sugibayashi, K.; Hirose, M.; Jinnouchi, O.; Sato, S.; Sawai, H.; Hara, K.; Sato, Kz.; Sato, Kj.; Iwabuchi, S.; Suzuki, J.

2017-01-01

We have developed flip-chip modules applicable to the pixel detector for the HL-LHC. New radiation-tolerant n+-in-p planar pixel sensors of a size of four FE-I4 application-specific integrated circuits (ASICs) are laid out in a 6-in wafer. Variation in readout connection for the pixels at the boundary of ASICs is implemented in the design of quadsensors. Bump bonding technology is developed for four ASICs onto one quadsensor. Both sensors and ASICs are thinned to 150 μm before bump bonding, and are held flat with vacuum chucks. Using lead-free SnAg solder bumps, we encounter deficiency with large areas of disconnected bumps after thermal stress treatment, including irradiation. Surface oxidation of the solder bumps is identified as a critical source of this deficiency after bump bonding trials, using SnAg bumps with solder flux, indium bumps, and SnAg bumps with a newly-introduced hydrogen-reflow process. With hydrogen-reflow, we establish flux-less bump bonding technology with SnAg bumps, appropriate for mass production of the flip-chip modules with thin sensors and thin ASICs.

Studies of material and process compatibility in developing compact silicon vapor chambers

NASA Astrophysics Data System (ADS)

Cai, Qingjun; Bhunia, Avijit; Tsai, Chialun; Kendig, Martin W.; DeNatale, Jeffrey F.

2013-06-01

The performance and long-term reliability of a silicon vapor chamber (SVC) developed for thermal management of high-power electronics critically depend on compatibility of the component materials. A hermetically sealed SVC presented in this paper is composed of bulk silicon, glass-frit as a bonding agent, lead/tin solder as an interface sealant and a copper charging tube. These materials, in the presence of a water/vapor environment, may chemically react and release noncondensable gas (NCG), which can weaken structural strength and degrade the heat transfer performance with time. The present work reports detailed studies on chemical compatibility of the components and potential solutions to avoid the resulting thermal performance degradation. Silicon surface oxidation and purification of operating liquid are necessary steps to reduce performance degradation in the transient period. A lead-based solder with its low reflow temperature is found to be electrochemically stable in water/vapor environment. High glazing temperature solidifies molecular bonding in glass-frit and mitigates PbO precipitation. Numerous liquid flushes guarantee removal of chemical residual after the charging tube is soldered to SVC. With these improvements on the SVC material and process compatibility, high effective thermal conductivity and steady heat transfer performance are obtained.

A Comparative Study on the Microstructure and Mechanical Properties of Cu6Sn5 and Cu3Sn Joints Formed by TLP Soldering With/Without the Assistance of Ultrasonic Waves

NASA Astrophysics Data System (ADS)

Zhao, H. Y.; Liu, J. H.; Li, Z. L.; Song, X. G.; Zhao, Y. X.; Niu, H. W.; Tian, H.; Dong, H. J.; Feng, J. C.

2018-07-01

In this study, the microstructure and mechanical properties of Cu6Sn5 and Cu3Sn intermetallic joints, formed by the transient liquid phase (TLP) soldering process with and without the assistance of ultrasonic waves (USWs), were compared. After the application of USWs in the TLP soldering process, Cu-Sn intermetallic compounds (IMCs) exhibited a novel noninterfacial growth pattern in the molten solder interlayer. The resulting Cu6Sn5 and Cu3Sn joints consisted of refined equiaxed IMC grains with average sizes of 3 and 2.3 µm, respectively. The Cu6Sn5 grains in the ultrasonically soldered intermetallic joints demonstrated uniform mechanical properties with elastic modulus and hardness values of 123.0 and 5.98 GPa, respectively, while those of Cu3Sn grains were 133.9 and 5.08 GPa, respectively. The shear strengths of ultrasonically soldered Cu6Sn5 and Cu3Sn joints were measured to be 60 and 65 MPa, respectively, higher than that for reflow-soldered intermetallic joints. Ultrasonically soldered Cu6Sn5 and Cu3Sn joints both exhibited a combination of transgranular and intergranular fractures during shear testing.

Detection of micro solder balls using active thermography and probabilistic neural network

NASA Astrophysics Data System (ADS)

He, Zhenzhi; Wei, Li; Shao, Minghui; Lu, Xingning

2017-03-01

Micro solder ball/bump has been widely used in electronic packaging. It has been challenging to inspect these structures as the solder balls/bumps are often embedded between the component and substrates, especially in flip-chip packaging. In this paper, a detection method for micro solder ball/bump based on the active thermography and the probabilistic neural network is investigated. A VH680 infrared imager is used to capture the thermal image of the test vehicle, SFA10 packages. The temperature curves are processed using moving average technique to remove the peak noise. And the principal component analysis (PCA) is adopted to reconstruct the thermal images. The missed solder balls can be recognized explicitly in the second principal component image. Probabilistic neural network (PNN) is then established to identify the defective bump intelligently. The hot spots corresponding to the solder balls are segmented from the PCA reconstructed image, and statistic parameters are calculated. To characterize the thermal properties of solder bump quantitatively, three representative features are selected and used as the input vector in PNN clustering. The results show that the actual outputs and the expected outputs are consistent in identification of the missed solder balls, and all the bumps were recognized accurately, which demonstrates the viability of the PNN in effective defect inspection in high-density microelectronic packaging.

Fast formation and growth of high-density Sn whiskers in Mg/Sn-based solder/Mg joints by ultrasonic-assisted soldering: Phenomena, mechanism and prevention.

PubMed

Li, M Y; Yang, H F; Zhang, Z H; Gu, J H; Yang, S H

2016-06-08

A universally applicable method for promoting the fast formation and growth of high-density Sn whiskers on solders was developed by fabricating Mg/Sn-based solder/Mg joints using ultrasonic-assisted soldering at 250 °C for 6 s and then subjected to thermal aging at 25 °C for 7 d. The results showed that the use of the ultrasonic-assisted soldering could produce the supersaturated dissolution of Mg in the liquid Sn and lead to the existence of two forms of Mg in Sn after solidification. Moreover, the formation and growth of the high-density whiskers were facilitated by the specific contributions of both of the Mg forms in the solid Sn. Specifically, interstitial Mg can provide the persistent driving force for Sn whisker growth, whereas the Mg2Sn phase can increase the formation probability of Sn whiskers. In addition, we presented that the formation and growth of Sn whiskers in the Sn-based solders can be significantly restricted by a small amount of Zn addition (≥3 wt.%), and the prevention mechanisms are attributed to the segregation of Zn atoms at grain or phase boundaries and the formation of the lamellar-type Zn-rich structures in the solder.

A Comparative Study on the Microstructure and Mechanical Properties of Cu6Sn5 and Cu3Sn Joints Formed by TLP Soldering With/Without the Assistance of Ultrasonic Waves

NASA Astrophysics Data System (ADS)

Zhao, H. Y.; Liu, J. H.; Li, Z. L.; Song, X. G.; Zhao, Y. X.; Niu, H. W.; Tian, H.; Dong, H. J.; Feng, J. C.

2018-05-01

In this study, the microstructure and mechanical properties of Cu6Sn5 and Cu3Sn intermetallic joints, formed by the transient liquid phase (TLP) soldering process with and without the assistance of ultrasonic waves (USWs), were compared. After the application of USWs in the TLP soldering process, Cu-Sn intermetallic compounds (IMCs) exhibited a novel noninterfacial growth pattern in the molten solder interlayer. The resulting Cu6Sn5 and Cu3Sn joints consisted of refined equiaxed IMC grains with average sizes of 3 and 2.3 µm, respectively. The Cu6Sn5 grains in the ultrasonically soldered intermetallic joints demonstrated uniform mechanical properties with elastic modulus and hardness values of 123.0 and 5.98 GPa, respectively, while those of Cu3Sn grains were 133.9 and 5.08 GPa, respectively. The shear strengths of ultrasonically soldered Cu6Sn5 and Cu3Sn joints were measured to be 60 and 65 MPa, respectively, higher than that for reflow-soldered intermetallic joints. Ultrasonically soldered Cu6Sn5 and Cu3Sn joints both exhibited a combination of transgranular and intergranular fractures during shear testing.

Low temperature electrical properties of some Pb-free solders

NASA Astrophysics Data System (ADS)

Kisiel, Ryszard; Pekala, Marek

2006-03-01

The electronic industry is engaged in developing Pb-free technologies for more than ten years. However till now not all properties of new solders are described. The aim of the paper is to present some electrical properties of new series of Pb-free solders (eutectic SnAg, near eutectic SnAgCu with and without Bi) in low temperature ranges 10 K to 273K. The following parameters were analyzed: electrical resistivity, temperature coefficient of resistance and thermoelectric power. The electrical resistivity at temperatures above 50 K is a monotonically rising function of temperature for Pb-free solders studied. The electrical resistivity of the Bi containing alloys is higher as compared to the remaining ones. The thermoelectric power values at room temperature are about -8 μV/K to -6 μV/K for Pb-free solders studied, being higher as compared to typical values -3 μVK of SnPb solder. The relatively low absolute values as well as the smooth and weak temperature variation of electrical resistivity in lead free solders enable the possible low temperature application. The moderate values of thermoelectric power around and above the room temperature show that when applying the solders studied the temperature should be kept as uniform as possible, in order to avoid spurious or noise voltages.

The failure models of Sn-based solder joints under coupling effects of electromigration and thermal cycling

NASA Astrophysics Data System (ADS)

Ma, Limin; Zuo, Yong; Liu, Sihan; Guo, Fu; Wang, Xitao

2013-01-01

Currently, the main concerns of Pb-free solder joints are focusing on electromigration (EM) and thermomechanical fatigue (TMF) problems. Many models have been established to understand the failure mechanisms of the joint under such single test conditions. Based on the fact that almost all microelectronic devices serve in combination conditions of fluctuated temperature and electric current stressing, the coupling effects of EM and TMF on evolution of microstructure and resistance of solder joint had been investigated. The failure models of binary SnBi alloy and ternary SnAgCu (SAC) solder under the coupling stressing were divided into four and three different stages, respectively. The failure mechanisms were dominant by the relationship of phase segregation, polarity effect, phase coarsening, and the coefficient of thermal expansion mismatch. Cracks tend to form and propagate along the interface between intermetallic compound layers and solder matrix in SAC solder. However, grain boundary was considered as the nucleation sites for microcracks in SnBi solder. High current density alleviates the deterioration of solder at the beginning stage of coupling stressing through Joule heating effect. An abrupt jump of resistance could be observed before the failure of the joint. The failure molds were determined by interactions of EM behaviors and TMF damages.

Survivability of soldered leadless chip carriers after temperature cycling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zawicki, L.R.; Lenhardt, B.W.; Smith, F.R.

Temperature cycling evaluations were conducted on leadless chip carriers (LCCs) soldered to thick film networks (TKNs). Various temperature ranges, rates of change, cycle times, number of cycles, and sizes of LCCs were used. The TKNs were attached to metal backing plates with 63Sn/37Pb solder preforms using an infrared vacuum soldering process. The LCCs were attached to Pt/Au TKNs with 63Sn/37Pb solder paste using a belt reflow process. Visual examination and cross-sectional analysis were used to evaluate the survivability. Results were also correlated with finite elemental analysis. Considering the initial results, possible solutions included changing the solder from 63Sn/37Pb to 50Pb/50In,more » deleting the metal backplate, changing the rate of change in the temperature cycle, and/or adding leads to the large LCCs. Because of a system requirement, the rate of change in the temperature cycle could not be changed. Since there was no long term reliability information on the Pt/Au TKN with 50Pb/50In solder, this option was also dropped. Additional evaluations showed little difference in the survivability of large LCC solder joints with or without the metal backing plate. The final results indicated that LCCs beyond a certain physical size required compliant leads to survive the temperature cycle requirements.« less

Lead-Free Electronics: Impact for Space Electronics

NASA Technical Reports Server (NTRS)

Sampson, Michael J.

2010-01-01

Pb is used as a constituent in solder alloys used to connect and attach electronic parts to printed wiring boards (PWBs). Similar Pbbearing alloys are electroplated or hot dipped onto the terminations of electronic parts to protect the terminations and make them solderable. Changing to Pb-free solders and termination finishes has introduced significant technical challenges into the supply chain. Tin/lead (Sn/Pb) alloys have been the solders of choice for electronics for more than 50 years. Pb-free solder alloys are available but there is not a plug-in replacement for 60/40 or 63/37 (Sn/Pb) alloys, which have been the industry workhorses.

Working with Consortia - Advanced Packaging Reliability

NASA Technical Reports Server (NTRS)

Blanche, Jim; Strickland, Mark

2010-01-01

Description: Support the responsible NASA official for lead-free solder evaluation. Serve as the NASA technical liaison to the NASA/DoD Pb-free Project. Assure NASA areas of interest are included in JG-PP follow-on work. Support NASA/DoD telcons and face-to-face meetings. Update MSFC lead-free solder lessons learned report. FY10 plans: - Reliability data on lead-free solder applications for various part lead finishes and board finishes. - Update lead-free solder risks and risk mitigation strategies for NASA. - Evaluate lead-free alloy/lead-free finish reliability in design application. - Status CAVE project on Pb-free solder aging effects. - Compile the LTESE flight and bench data.

Multiwire conductor having greatly increased interwire resistance and method for making same

DOEpatents

Luhman, Thomas; Suenaga, Masaki

1984-01-17

An improved multiwire conductor of the type which is mechanically stabilized by a tin based solder filler. A solder filled conductor is heated to a temperature above its melting point for a period long enough to allow a substantial amount of copper to be dissolved from the wires comprising the conductor. The copper forms the brittle intermetallic compound Cu.sub.5 Sn.sub.6 with tin in the solder. After cooling the conductor is flexed causing a random cracking of the solder, and thereby increasing the interwire resistance of the conductor. The subject invention is particularly adapted for use with braided, ribbon-type solder filled superconductors.

Characteristics of solder joints under fatigue loads using piezomechanical actuation

NASA Astrophysics Data System (ADS)

Shim, Dong-Jin; Spearing, S. Mark

2003-07-01

Crack initiation and growth characteristics of solder joints under fatigue loads are investigated using piezomechanical actuation. Cracks in solder joints, which can cause failure in microelectronics components, are induced via piezoelectricity in piezo-ceramic bonded joints. Lead-zirconate-titanate ceramic plates and eutectic Sn-Pb solder bonded in a double-lap shear configuration are used in the investigation. Electric field across each piezo-ceramic plate is applied such that shear stresses/strains are induced in the solder joints. The experiments show that cracks initiate in the solder joints around defects such as voids and grow in length until they coalesce with other cracks from adjacent voids. These observations are compared with the similar thermal cycling tests from the literature to show feasibility and validity of the current method in investigating the fatigue characteristics of solder joints. In some specimens, cracks in the piezo-ceramic plates are observed, and failure in the specimens generally occurred due to piezo-ceramic plate fracture. The issues encountered in implementing this methodology such as low actuation and high processing temperatures are further discussed.

A maximum entropy fracture model for low and high strain-rate fracture in TinSilverCopper alloys

NASA Astrophysics Data System (ADS)

Chan, Dennis K.

SnAgCu solder alloys exhibit significant rate-dependent constitutive behavior. Solder joints made of these alloys exhibit failure modes that are also rate-dependent. Solder joints are an integral part of microelectronic packages and are subjected to a wide variety of loading conditions which range from thermo-mechanical fatigue to impact loading. Consequently, there is a need for non-empirical rate-dependent failure theory that is able to accurately predict fracture in these solder joints. In the present thesis, various failure models are first reviewed. But, these models are typically empirical or are not valid for solder joints due to limiting assumptions such as elastic behavior. Here, the development and validation of a maximum entropy fracture model (MEFM) valid for low strain-rate fracture in SnAgCu solders is presented. To this end, work on characterizing SnAgCu solder behavior at low strain-rates using a specially designed tester to estimate parameters for constitutive models is presented. Next, the maximum entropy fracture model is reviewed. This failure model uses a single damage accumulation parameter and relates the risk of fracture to accumulated inelastic dissipation. A methodology is presented to extract this model parameter through a custom-built microscale mechanical tester for Sn3.8Ag0.7Cu solder. This single parameter is used to numerically simulate fracture in two solder joints with entirely different geometries. The simulations are compared to experimentally observed fracture in these same packages. Following the simulations of fracture at low strain rate, the constitutive behavior of solder alloys across nine decades of strain rates through MTS compression tests and split-Hopkinson bar are presented. Preliminary work on using orthogonal machining as novel technique of material characterization at high strain rates is also presented. The resultant data from the MTS compression and split-Hopkinson bar tester is used to demonstrate the localization of stress to the interface of solder joints at high strain rates. The MEFM is further extended to predict failure in brittle materials. Such an extension allows for fracture prediction within intermetallic compounds (IMCs) in solder joints. It has been experimentally observed that the failure mode shifts from bulk solder to the IMC layer with increasing loading rates. The extension of the MEFM would allow for prediction of the fracture mode within the solder joint under different loading conditions. A fracture model capable of predicting failure modes at higher strain rates is necessary, as mobile electronics are becoming ubiquitous. Mobile devices are prone to being dropped which can induce loading rates within solder joints that are much larger than experienced under thermo-mechanical fatigue. A range of possible damage accumulation parameters for Cu6Sn 5 is determined for the MEFM. A value within the aforementioned range is used to demonstrate the increasing likelihood of IMC fracture in solder joints with larger loading rates. The thesis is concluded with remarks about ongoing work that include determining a more accurate damage accumulation parameter for Cu6Sn 5 IMC, and on using machining as a technique for extracting failure parameters for the MEFM.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez, R.O.

Voltage breakdowns become a major concern in reducing the size of high-voltage power converter transformers. Even the smallest of voids can provide a path for corona discharge which can cause a dielectric breakdown leading to a transformer failure. A method of encapsulating small high voltage transformers has been developed. The method virtually eliminates voids in the impregnation material, provides an exceptional dielectric between windings and provides a mechanically rugged package. The encapsulation material is a CTBN modified mica filled epoxy. The method requires heat/vacuum to impregnate the coil and heat/pressure to cure the encapsulant. The transformer package utilizes a Diallylmore » Phthalate (DAP) contact assembly in which a coated core/coil assembly is mounted and soldered. This assembly is then loaded into an RTV mold and the encapsulation process begins.« less

Enabling two-phase microfluidic thermal transport systems using a novel thermal-flux degassing and fluid charging approach

NASA Astrophysics Data System (ADS)

Singh Dhillon, Navdeep; Pisano, Albert P.

2014-03-01

A novel two-port thermal-flux method has been proposed and demonstrated for degassing and charging two-phase microfluidic thermal transport systems with a degassed working fluid. In microscale heat pipes and loop heat pipes (mLHPs), small device volumes and large capillary forces associated with smaller feature sizes render conventional vacuum pump-based degassing methods quite impractical. Instead, we employ a thermally generated pressure differential to purge non-condensable gases from these devices before charging them with a degassed working fluid in a two-step process. Based on the results of preliminary experiments studying the effectiveness and reliability of three different high temperature-compatible device packaging approaches, an optimized compression packaging technique was developed to degas and charge a mLHP device using the thermal-flux method. An induction heating-based noninvasive hermetic sealing approach for permanently sealing the degassed and charged mLHP devices has also been proposed. To demonstrate the efficacy of this approach, induction heating experiments were performed to noninvasively seal 1 mm square silicon fill-hole samples with donut-shaped solder preforms. The results show that the minimum hole sealing induction heating time is heat flux limited and can be estimated using a lumped capacitance thermal model. However, further continued heating of the solder uncovers the hole due to surface tension-induced contact line dynamics of the molten solder. It was found that an optimum mass of the solder preform is required to ensure a wide enough induction-heating time window for successful sealing of a fill-hole.

Synthesis of tin, silver and their alloy nanoparticles for lead-free interconnect applications

NASA Astrophysics Data System (ADS)

Jiang, Hongjin

SnPb solders have long been used as interconnect materials in microelectronic packaging. Due to the health threat of lead to human beings, the use of lead-free interconnect materials is imperative. Three kinds of lead-free interconnect materials are being investigated, namely lead-free metal solders (SnAg, SnAgCu, etc.), electrically conductive adhesives (ECAs) and carbon nanotubes (CNTs). However, there are still limitations for the full utilization of these lead-free interconnect materials in the microelectronic packaging, such as higher melting point of lead-free metal solders, lower electrical conductivity of the ECAs and poor adhesion of CNTs to substrates. This thesis is devoted to the research and development of low processing temperature lead-free interconnect materials for microelectronic packaging applications with an emphasis on fundamental studies of nanoparticles synthesis, dispersion and oxidation prevention, and nanocomposites fabrication. Oxide-free tin (Sn), tin/silver (96.5Sn3.5Ag) and tin/silver/copper (96.5Sn3.0Ag0.5Cu) alloy nanoparticles with different sizes were synthesized by a low temperature chemical reduction method. Both size dependent melting point and latent heat of fusion of the synthesized nanoparticles were obtained. The nano lead-free solder pastes/composites created by dispersing the SnAg or SnAgCu alloy nanoparticles into an acidic type flux spread and wet on the cleaned copper surface at 220 to 230°C. This study demonstrated the feasibility of nano sized SnAg or SnAgCu alloy particle pastes for low processing temperature lead-free interconnect applications in microelectronic packaging.

Prediction of Phase Formation in Nanoscale Sn-Ag-Cu Solder Alloy

NASA Astrophysics Data System (ADS)

Wu, Min; Lv, Bailin

2016-01-01

In a dynamic nonequilibrium process, the effective heat of formation allows the heat of formation to be calculated as a function of concentrations of the reacting atoms. In this work, we used the effective heat of formation rule to predict the formation and size of compound phases in a nanoscale Sn-Ag-Cu lead-free solder. We calculated the formation enthalpy and effective formation enthalpy of compounds in the Sn-Ag, Sn-Cu, and Ag-Cu systems by using the Miedema model and effective heat of formation. Our results show that, considering the surface effect of the nanoparticle, the effective heat of formation rule successfully predicts the phase formation and sizes of Ag3Sn and Cu6Sn5 compounds, which agrees well with experimental data.

Numerical simulation of CTE mismatch and thermal-structural stresses in the design of interconnects

NASA Astrophysics Data System (ADS)

Peter, Geoffrey John M.

With the ever-increasing chip complexity, interconnects have to be designed to meet the new challenges. Advances in optical lithography have made chip feature sizes available today at 70 nm dimensions. With advances in Extreme Ultraviolet Lithography, X-ray Lithography, and Ion Projection Lithography it is expected that the line width will further decrease to 20 nm or less. With the decrease in feature size, the number of active devices on the chip increases. With higher levels of circuit integration, the challenge is to dissipate the increased heat flux from the chip surface area. Thermal management considerations include coefficient of thermal expansion (CTE) matching to prevent failure between the chip and the board. This in turn calls for improved system performance and reliability of the electronic structural systems. Experience has shown that in most electronic systems, failures are mostly due to CTE mismatch between the chip, board, and the solder joint (solder interconnect). The resulting high thermal-structural stress and strain due to CTE mismatch produces cracks in the solder joints with eventual failure of the electronic component. In order to reduce the thermal stress between the chip, board, and the solder joint, this dissertation examines the effect of inserting wire bundle (wire interconnect) between the chip and the board. The flexibility of the wires or fibers would reduce the stress at the rigid joints. Numerical simulations of two, and three-dimensional models of the solder and wire interconnects are examined. The numerical simulation is linear in nature and is based on linear isotropic material properties. The effect of different wire material properties is examined. The effect of varying the wire diameter is studied by changing the wire diameter. A major cause of electronic equipment failure is due to fatigue failure caused by thermal cycling, and vibrations. A two-dimensional modal and harmonic analysis was simulated for the wire interconnect and the solder interconnect. The numerical model simulated using ANSYS program was validated with the numerical/experimental results of other published researchers. In addition the results were cross-checked by IDEAS program. A prototype non-working wire interconnect is proposed to emphasize practical application. The numerical analysis, in this dissertation is based on a U.S. Patent granted to G. Peter(42).

Vertically aligned multiwalled carbon nanotubes as electronic interconnects

NASA Astrophysics Data System (ADS)

Gopee, Vimal Chandra

The drive for miniaturisation of electronic circuits provides new materials challenges for the electronics industry. Indeed, the continued downscaling of transistor dimensions, described by Moore’s Law, has led to a race to find suitable replacements for current interconnect materials to replace copper. Carbon nanotubes have been studied as a suitable replacement for copper due to its superior electrical, thermal and mechanical properties. One of the advantages of using carbon nanotubes is their high current carrying capacity which has been demonstrated to be three orders of magnitude greater than that of copper. Most approaches in the implementation of carbon nanotubes have so far focused on the growth in vias which limits their application. In this work, a process is described for the transfer of carbon nanotubes to substrates allowing their use for more varied applications. Arrays of vertically aligned multiwalled carbon nanotubes were synthesised by photo-thermal chemical vapour deposition with high growth rates. Raman spectroscopy was used to show that the synthesised carbon nanotubes were of high quality. The carbon nanotubes were exposed to an oxygen plasma and the nature of the functional groups present was determined using X-ray photoelectron spectroscopy. Functional groups, such as carboxyl, carbonyl and hydroxyl groups, were found to be present on the surface of the multiwalled carbon nanotubes after the functionalisation process. The multiwalled carbon nanotubes were metallised after the functionalisation process using magnetron sputtering. Two materials, solder and sintered silver, were chosen to bind carbon nanotubes to substrates so as to enable their transfer and also to make electrical contact. The wettability of solder to carbon nanotubes was investigated and it was demonstrated that both functionalisation and metallisation were required in order for solder to bond with the carbon nanotubes. Similarly, functionalisation followed by metallisation was critical for bonding carbon nanotubes to sintered silver. A step by step process is described that allows the production of solder-carbon nanotubes and silver-carbon nanotubes interconnects. 4-point probe electrical characterisation of the interconnects was performed and the interconnects were shown to have a resistivity of 5.0 x 10-4 Ωcm for solder-carbon nanotubes and 5.2 x 10-4 Ωcm for silver-carbon nanotubes interconnects. Ramp to failure tests carried out on solder-carbon nanotubes interconnects showed current carrying capacity of 0.75 MA/cm2, only one order of magnitude lower than copper.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rejent, J.A.; Vianco, P.T.; Woodrum, R.A.

Aging analyses were performed on solder joints from two radar units: (1) a laboratory, N57 tube-type radar unit and (2) a field-returned, B61-0, tube-type radar unit. The cumulative temperature environments experienced by the units during aging were calculated from the intermetallic compound layer thickness and the mean Pb-rich phase particle size metrics for solder joints in the units, assuming an aging time of 35 years for both radars. Baseline aging metrics were obtained from a laboratory test vehicle assembled at AS/FM and T; the aging kinetics of both metrics were calculated from isothermal aging experiments. The N57 radar unit interconnectmore » board solder joints exhibited very little aging. The eyelet solder joints did show cracking that most likely occurred at the time of assembly. The eyelet, SA1126 connector solder joints, showed some delamination between the Cu pad and underlying laminate. The B61 field-returned radar solder joints showed a nominal degree of aging. Cracking of the eyelet solder joints was observed. The Pb-rich phase particle measurements indicated additional aging of the interconnects as a result of residual stresses. Cracking of the terminal pole connector, pin-to-pin solder joint was observed; but it was not believed to jeopardize the electrical functionality of the interconnect. Extending the stockpile lifetime of the B61 tube-type radar by an additional 20 years would not be impacted by the reliability of the solder joints with respect to further growth of the intermetallic compound layer. Additional coarsening of the Pb-rich phase will increase the joints' sensitivity to thermomechanical fatigue.« less

Microstructure and Mechanical Properties of Tin-Bismuth Solder Reinforced by Aluminum Borate Whiskers

NASA Astrophysics Data System (ADS)

Wang, Jun; Wei, Hongmei; He, Peng; Lin, Tiesong; Lu, Fengjiao

2015-10-01

Tin-bismuth solder has emerged as a promising lead-free alternative to tin-lead solder, especially for low-temperature packaging applications. However, the intrinsic brittleness of tin-bismuth solder alloy, aggravated by the coarse bismuth-rich phase and the thick interfacial intermetallic layer, notably limits the mechanical performance of the bonded joints. In this work, the microstructure and mechanical performance of solder joints were improved by adding 3.2 vol.% aluminum borate whiskers to the tin-bismuth solder alloy. This whisker-reinforced composite solder was fabricated through a simple process. Typically, 25- μm to 75- μm tin-bismuth particles were mixed with a small amount of aluminum borate whiskers with diameter of 0.5 μm to 1.5 μm and length of 5 μm to 15 μm. The addition of whiskers restrained the formation of coarse brittle bismuth-rich phase and decreased the lamellar spacing from 0.84 μm to 7.94 μm to the range of 0.22 μm to 1.80 μm. Moreover, the growth rate of the interfacial intermetallic layer during the remelting treatment decreased as well. The joint shear strength increased from 19.4 MPa to 24.7 MPa, and only declined by 4.9% (average, -5.9% to 15.8%) after the tenth remelting, while the shear strength of the joint without whiskers declined by 31.5% (average, 10.1-44.1%). The solder alloy was reinforced because of their high strength and high modulus and also the refinement effect on the solder alloy microstructure.

Dye-enhanced protein solders and patches in laser-assisted tissue welding.

PubMed

Small, W; Heredia, N J; Maitland, D J; Da Silva, L B; Matthews, D L

1997-01-01

This study examines the use of dye-enhanced protein bonding agents in 805 nm diode laser-assisted tissue welding. A comparison of an albumin liquid solder and collagen solid-matrix patches used to repair arteriotomies in an in vitro porcine model is presented. Extrinsic bonding media in the form of solders and patches have been used to enhance the practice of laser tissue welding. Preferential absorption of the laser wavelength has been achieved by the incorporation of chromophores. Both the solder and the patch included indocyanine green dye (ICG) to absorb the 805 nm continuous-wave diode laser light used to perform the welds. Solder-mediated welds were divided into two groups (high power/short exposure and low power/long exposure), and the patches were divided into three thickness groups ranging from 0.1 to 1.3 mm. The power used to activate the patches was constant, but the exposure time was increased with patch thickness. Burst pressure results indicated that solder-mediated and patched welds yielded similar average burst strengths in most cases, but the patches provided a higher success rate (i.e., more often exceeded 150 mmHg) and were more consistent (i.e., smaller standard deviation) than the solder. The strongest welds were obtained using 1.0-1.3 mm thick patches, while the high power/short exposure solder group was the weakest. Though the solder and patches yielded similar acute weld strengths, the solid-matrix patches facilitated the welding process and provided consistently strong welds. The material properties of the extrinsic agents influenced their performance.

Electromigration Critical Product to Measure Effect of Underfill Material in Suppressing Bi Segregation in Sn-58Bi Solder

NASA Astrophysics Data System (ADS)

Zhao, Xu; Takaya, Satoshi; Muraoka, Mikio

2017-08-01

Recently, we detected length-dependent electromigration (EM) behavior in Sn-58Bi (SB) solder and revealed the existence of Bi back-flow, which retards EM-induced Bi segregation and is dependent on solder length. The cause of the back-flow is attributed to an oxide layer formed on the SB solder. At present, underfill (UF) material is commonly used in flip-chip packaging as filler between chip and substrate to surround solder bumps. In this study, we quantitatively investigated the effect of UF material as a passivation layer on EM in SB solder strips. EM tests on SB solder strips with length of 50 μm, 100 μm, and 150 μm were conducted simultaneously. Some samples were coated with commercial thermosetting epoxy UF material, which acted as a passivation layer on the Cu-SB-Cu interconnections. The value of the critical product for SB solder was estimated to be 38 A/cm to 43 A/cm at 353 K to 373 K without UF coating and 59 A/cm at 373 K with UF coating. The UF material acting as a passivation layer suppressed EM-induced Bi segregation and increased the threshold current density by 37% to 55%. However, at very high current density, this effect became very slight. In addition, Bi atoms can diffuse to the anode side through the Sn phase, hence addition of microelements to the Sn phase to form obstacles, such as intermetallic compounds, may retard Bi segregation in SB solder.

Reliability of High I/O High Density CCGA Interconnect Electronic Packages under Extreme Thermal Environment

NASA Technical Reports Server (NTRS)

Ramesham, Rajeshuni

2012-01-01

This paper provides the experimental test results of advanced CCGA packages tested in extreme temperature thermal environments. Standard optical inspection and x-ray non-destructive inspection tools were used to assess the reliability of high density CCGA packages for deep space extreme temperature missions. Ceramic column grid array (CCGA) packages have been increasing in use based on their advantages such as high interconnect density, very good thermal and electrical performances, compatibility with standard surface-mount packaging assembly processes, and so on. CCGA packages are used in space applications such as in logic and microprocessor functions, telecommunications, payload electronics, and flight avionics. As these packages tend to have less solder joint strain relief than leaded packages or more strain relief over lead-less chip carrier packages, the reliability of CCGA packages is very important for short-term and long-term deep space missions. We have employed high density CCGA 1152 and 1272 daisy chained electronic packages in this preliminary reliability study. Each package is divided into several daisy-chained sections. The physical dimensions of CCGA1152 package is 35 mm x 35 mm with a 34 x 34 array of columns with a 1 mm pitch. The dimension of the CCGA1272 package is 37.5 mm x 37.5 mm with a 36 x 36 array with a 1 mm pitch. The columns are made up of 80% Pb/20%Sn material. CCGA interconnect electronic package printed wiring polyimide boards have been assembled and inspected using non-destructive x-ray imaging techniques. The assembled CCGA boards were subjected to extreme temperature thermal atmospheric cycling to assess their reliability for future deep space missions. The resistance of daisy-chained interconnect sections were monitored continuously during thermal cycling. This paper provides the experimental test results of advanced CCGA packages tested in extreme temperature thermal environments. Standard optical inspection and x-ray non-destructive inspection tools were used to assess the reliability of high density CCGA packages for deep space extreme temperature missions. Keywords: Extreme temperatures, High density CCGA qualification, CCGA reliability, solder joint failures, optical inspection, and x-ray inspection.

Albumin solder covalently bound to a polymer membrane: New approach to improve binding strength in laser tissue soldering in-vitro.

PubMed

Hiebl, B; Ascher, L; Luetzow, K; Kratz, K; Gruber, C; Mrowietz, C; Nehring, M E; Lendlein, A; Franke, R-P; Jung, F

2018-01-01

Laser tissue soldering (LTS) based on indocyanine green (ICG)-mediated heat-denaturation of proteins might be a promising alternative technique for micro-suturing, but up to now the problem of too weak shear strength of the solder welds in comparison to sutures is not solved. Earlier reports gave promising results showing that solder supported by carrier materials can enhance the cohesive strength of the liquid solder. In these studies, the solder was applied to the carriers by dip coating. Higher reliability of the connection between the solder and the carrier material is expected when the solder is bound covalently to the carrier material. In the present study a poly(ether imide) (PEI) membrane served as carrier material and ICG-supplemented albumin as solder substrate. The latter was covalently coupled to the carrier membrane under physiological conditions to prevent structural protein changes. As laser source a diode continuous-wave laser emitting at 808 nm with intensities between 250 mW and 1500 mW was utilized. The albumin functionalized carrier membrane was placed onto the tunica media of explanted pig thoracic aortae forming an overlapping area of approximately 0.5×0.5 cm2. All tests were performed in a dry state to prevent laser light absorption by water. Infrared spectroscopy, spectro-photometrical determination of the secondary and primary amine groups after acid orange II staining, contact angle measurements, and atomic force microscopy proved the successful functionalization of the PEI membrane with albumin. A laser power of 450 mW LTS could generate a membrane-blood vessel connection which was characterized by a shear strength of 0.08±0.002 MPa, corresponding to 15% of the tensile strength of the native blood vessel. Theoretically, an overlapping zone of 4.1 mm around the entire circumference of the blood vessel could have provided shear strength of the PEI membrane-blood vessel compound identical to the tensile strength of the native blood vessel. These in-vitro results confirmed the beneficial effects of solder reinforcement by carrier membranes, and suggest LTS with covalently bound solders on PEI substrates for further studies in animal models.

Multiwire conductor having greatly increased interwire resistance and method for making same

DOEpatents

Luhman, T.; Suenaga, M.

1982-03-15

An improved multiwire conductor of the type which is mechanically stabilized by a tin based solder filler is described. A solder filled conductor is heated to a temperature above its melting point for a period long enough to allow a substantial amount of copper to be dissolved from the wires comprising the conductor. The copper forms the brittle intermetallic compound Cu/sub 5/Sn/sub 6/ with tin in the solder. After cooling the conductor is flexed causing a random cracking of the solder, and thereby increasing the interwire resistance of the conductor. The subject invention is particularly adapted for use with braided, ribbon-type solder filled superconductors.

Induction soldering of photovoltaic system components

DOEpatents

Kumaria, Shashwat; de Leon, Briccio

2015-11-17

A method comprises positioning a pair of photovoltaic wafers in a side-by-side arrangement. An interconnect is placed on the pair of wafers such that the interconnect overlaps both wafers of the pair, solder material being provided between the interconnect and the respective wafers. A solder head is then located adjacent the interconnect, and the coil is energized to effect inductive heating of the solder material. The solder head comprises an induction coil shaped to define an eye, and a magnetic field concentrator located at least partially in the eye of the coil. The magnetic field concentrator defines a passage extending axially through the eye of the coil, and may be of a material with a high magnetic permeability.

The Failure Models of Lead Free Sn-3.0Ag-0.5Cu Solder Joint Reliability Under Low-G and High-G Drop Impact

NASA Astrophysics Data System (ADS)

Gu, Jian; Lei, YongPing; Lin, Jian; Fu, HanGuang; Wu, Zhongwei

2017-02-01

The reliability of Sn-3.0Ag-0.5Cu (SAC 305) solder joint under a broad level of drop impacts was studied. The failure performance of solder joint, failure probability and failure position were analyzed under two shock test conditions, i.e., 1000 g for 1 ms and 300 g for 2 ms. The stress distribution on the solder joint was calculated by ABAQUS. The results revealed that the dominant reason was the tension due to the difference in stiffness between the print circuit board and ball grid array, and the maximum tension of 121.1 MPa and 31.1 MPa, respectively, under both 1000 g or 300 g drop impact, was focused on the corner of the solder joint which was located in the outmost corner of the solder ball row. The failure modes were summarized into the following four modes: initiation and propagation through the (1) intermetallic compound layer, (2) Ni layer, (3) Cu pad, or (4) Sn-matrix. The outmost corner of the solder ball row had a high failure probability under both 1000 g and 300 g drop impact. The number of failures of solder ball under the 300 g drop impact was higher than that under the 1000 g drop impact. The characteristic drop values for failure were 41 and 15,199, respectively, following the statistics.

Fast formation and growth of high-density Sn whiskers in Mg/Sn-based solder/Mg joints by ultrasonic-assisted soldering: Phenomena, mechanism and prevention

PubMed Central

Li, M. Y.; Yang, H. F.; Zhang, Z. H.; Gu, J. H.; Yang, S. H.

2016-01-01

A universally applicable method for promoting the fast formation and growth of high-density Sn whiskers on solders was developed by fabricating Mg/Sn-based solder/Mg joints using ultrasonic-assisted soldering at 250 °C for 6 s and then subjected to thermal aging at 25 °C for 7 d. The results showed that the use of the ultrasonic-assisted soldering could produce the supersaturated dissolution of Mg in the liquid Sn and lead to the existence of two forms of Mg in Sn after solidification. Moreover, the formation and growth of the high-density whiskers were facilitated by the specific contributions of both of the Mg forms in the solid Sn. Specifically, interstitial Mg can provide the persistent driving force for Sn whisker growth, whereas the Mg2Sn phase can increase the formation probability of Sn whiskers. In addition, we presented that the formation and growth of Sn whiskers in the Sn-based solders can be significantly restricted by a small amount of Zn addition (≥3 wt.%), and the prevention mechanisms are attributed to the segregation of Zn atoms at grain or phase boundaries and the formation of the lamellar-type Zn-rich structures in the solder. PMID:27273421

Interfacial reactions and compound formation of Sn-Ag-Cu solders by mechanical alloying on electroless Ni-P/Cu under bump metallization

NASA Astrophysics Data System (ADS)

Kao, Szu-Tsung; Duh, Jenq-Gong

2005-08-01

Electroless Ni-P under bump metallization (UBM) has been widely used in electronic interconnections due to the good diffusion barrier between Cu and solder. In this study, the mechanical alloying (MA) process was applied to produce the SnAgCu lead-free solder pastes. Solder joints after annealing at 240°C for 15 min were employed to investigate the evolution of interfacial reaction between electroless Ni-P/Cu UBM and SnAgCu solder with various Cu concentrations ranging from 0.2 to 1.0 wt.%. After detailed quantitative analysis with an electron probe microanalyzer, the effect of Cu content on the formation of intermetallic compounds (IMCs) at SnAgCu solder/electroless Ni-P interface was evaluated. When the Cu concentration in the solder was 0.2 wt.%, only one (Ni, Cu)3Sn4 layer was observed at the solder/electroless Ni-P interface. As the Cu content increased to 0.5 wt.%, (Cu, Ni)6Sn5 formed along with (Ni, Cu)3Sn4. However, only one (Cu, Ni)6Sn5 layer was revealed, if the Cu content was up to 1 wt.%. With the aid of microstructure evolution, quantitative analysis, and elemental distribution by x-ray color mapping, the presence of the Ni-Sn-P phase and P-rich layer was evidenced.

Thermomechanical fatigue life prediction for several solders

NASA Astrophysics Data System (ADS)

Wen, Shengmin

Since solder connections operate at high homologous temperature, solders are high temperature materials. This feature makes their mechanical behavior and fatigue phenomena unique. Based on experimental findings, a physical damage mechanism is introduced for solders. The mechanism views the damage process as a series of independent local damage events characterized by the failure of individual grains, while the structural damage is the eventual percolation result of such local events. Fine's dislocation energy density concept and Mura's microcrack initiation theory are adopted to derive the fatigue formula for an individual grain. A physical damage metric is introduced to describe the material with damage. A unified creep and plasticity constitutive model is adopted to simulate the mechanical behavior of solders. The model is cast into a continuum damage mechanics framework to simulate material with damage. The model gives good agreement with the experimental results of 96.5Pb-3.5Sn and 96.5Sn-3.5Ag solders under uniaxial strain-controlled cyclic loading. The model is convenient for implementation into commercial computational packages. Also presented is a fatigue theory with its failure criterion for solders based on physical damage mechanism. By introducing grain orientation into the fatigue formula, an m-N curve (m is Schmid factor) at constant loading condition is suggested for fatigue of grains with different orientations. A solder structure is defined as fatigued when the damage metric reaches a critical threshold, since at this threshold the failed grains may form a cluster and percolate through the structure according to percolation theory. Fatigue data of 96.5Pb-3.5Sn solder bulk specimens under various uniaxial tension tests were analyzed. Results show that the theory gives consistent predictions under broad conditions, while inelastic strain theory does not. The theory is anisotropic with no size limitation to its application, which could be suitable for anisotropic small-scale (micron or nano scale) solder joints. More importantly, the theory is materials science based so that the parameters of the fatigue formula can be worked out by testing of bulk specimens while the formula can be applicable to small-scale structures. The theory suggests metallurgical control in the manufacturing process to optimize the fatigue life of solder structures.

Single-Crystal Material on Non-Single-Crystalline Substrate

DTIC Science & Technology

1999-02-01

point frit or solder glass can be deposited on a surface and bonded to a second surface using pressure and temperature. A sodium silicate material...interface. A metal or silicide at the bonding interface may be advantageous fQr electrical current conduction across the interface. 10 Applications...substrate, or a silicide or metal to aid bonding and vertical electrical current conduction. In some cases, it is difficult to polish the non- single

New Failure Mode of Flip-Chip Solder Joints Related to the Metallization of an Organic Substrate

NASA Astrophysics Data System (ADS)

Jang, J. W.; Yoo, S. J.; Hwang, H. I.; Yuk, S. Y.; Kim, C. K.; Kim, S. J.; Han, J. S.; An, S. H.

2015-10-01

We report a new failure phenomenon during flip-chip die attach. After reflow, flip-chip bumps were separated between the Al and Ti layers on the Si die side. This was mainly observed at the Si die corner. Transmission electron microscopy images revealed corrosion of the Al layer at the edge of the solder bump metallization. The corrosion at the metallization edge exhibited a notch shape with high stress concentration factor. The organic substrate had Cu metallization with an organic solderable preservative (OSP) coating layer, where a small amount of Cl ions were detected. A solder bump separation mechanism is suggested based on the reaction between Al and Cl, related to the flow of soldering flux. During reflow, the flux will dissolve the Cl-containing OSP layer and flow up to the Al layer on the Si die side. Then, the Cl-dissolved flux will actively react with Al, forming AlCl3. During cooling, solder bumps at the Si die corner will separate through the location of Al corrosion. This demonstrated that the chemistry of the substrate metallization can affect the thermomechanical reliability of flip-chip solder joints.

Whisker Formation on SAC305 Soldered Assemblies

NASA Astrophysics Data System (ADS)

Meschter, S.; Snugovsky, P.; Bagheri, Z.; Kosiba, E.; Romansky, M.; Kennedy, J.; Snugovsky, L.; Perovic, D.

2014-11-01

This article describes the results of a whisker formation study on SAC305 assemblies, evaluating the effects of lead-frame materials and cleanliness in different environments: low-stress simulated power cycling (50-85°C thermal cycling), thermal shock (-55°C to 85°C), and high temperature/high humidity (85°C/85% RH). Cleaned and contaminated small outline transistors, large leaded quad flat packs (QFP), plastic leaded chip carrier packages, and solder balls with and without rare earth elements (REE) were soldered to custom designed test boards with Sn3Ag0.5Cu (SAC305) solder. After assembly, all the boards were cleaned, and half of them were recontaminated (1.56 µg/cm2 Cl-). Whisker length, diameter, and density were measured. Detailed metallurgical analysis on components before assembly and on solder joints before and after testing was performed. It was found that whiskers grow from solder joint fillets, where the thickness is less than 25 µm, unless REE was present. The influence of lead-frame and solder ball material, microstructure, cleanliness, and environment on whisker characteristics is discussed. This article provides detailed metallurgical observations and select whisker length data obtained during this multiyear testing program.

Digital Soldering-Iron Tester

NASA Technical Reports Server (NTRS)

Buggle, R. N.; Metka, W. H., Jr

1984-01-01

Instrument reads tip temperature and contact potential in seconds. Tinned soldering tip touched to temperature sensitive button for 4 seconds and to voltage probe for 1 to 3 seconds. Tip temperature and voltage appear on digital displays. Instrument quickly gives assurance conditions are correct for reliable soldering.

Handling fixture for soldering round wires to FCC

NASA Technical Reports Server (NTRS)

Loggins, R.; Martineck, H. G.

1971-01-01

Fixture holds flat conductor cable and wires in position until after soldering of contacting conductor ends and potting of junctions. Device provides for proper spacing of wires and adequate access for soldered joints during fabrication, and positions mold halves during potting operation.

Requirements for soldered electrical connections

NASA Technical Reports Server (NTRS)

1992-01-01

This publication is applicable to NASA programs involving solder connections for flight hardware, mission essential support equipment, and elements thereof. This publication sets forth hand and wave soldering requirements for reliable electrical connections. The prime consideration is the physical integrity of solder connections. Special requirements may exist which are not in conformance with the requirements of this publication. Design documentation contains the detail for these requirements, and they take precedence over conflicting portions of this publication when they are approved in writing by the procuring NASA installation.

Microstructural evolution of SiC joints soldered using Zn-Al filler metals with the assistance of ultrasound.

PubMed

Wu, Bingzhi; Leng, Xuesong; Xiu, Ziyang; Yan, Jiuchun

2018-06-01

SiC ceramics were successfully soldered with the assistance of ultrasound. Two kinds of filler metals, namely non-eutectic Zn-5Al-3Cu and eutectic Zn-5Al alloys, were used. The effects of ultrasonic action on the microstructure and mechanical properties of the soldered joints were investigated. The results showed that ultrasound could promote the wetting and bonding between the SiC ceramic and filler metals within tens of seconds. For the Zn-5Al-3Cu solder, a fully grain-refined structure in the bond layer was obtained as the ultrasonic action time increased. This may lead to a substantial enhancement in the strength of the soldered joints. For the Zn-5Al solder, the shear strength of the soldered joints was only ∼102 MPa when the ultrasonic action time was shorter, and fractures occurred in the brittle lamellar eutectic phases in the center of the bond layer. With increasing ultrasonic action time, the lamellar eutectic phase in the bond layer of SiC joints could be completely transformed to a fine non-lamellar eutectic structure. Meanwhile, the grains in the bond layer were obviously refined. Those results led to the remarkable enhancement of the shear strength of the joints (∼138 MPa) using the Zn-5Al solder, which had approached that enhancement using the Zn-5Al-3Cu solder. The enhanced mechanical properties of the joints were attributed to the significant refinement of the grains and the change in the eutectic structure in the bond layer. Prolonged enhanced heterogeneous nucleation triggered by ultrasonic cavitation is the predominant refinement mechanism of the bond metals of the SiC joints. Copyright © 2018 Elsevier B.V. All rights reserved.

The growth of intermetallic compounds at Sn-Ag-Cu solder/Cu and Sn-Ag-Cu solder/Ni interfaces and the associated evolution of the solder microstructure

NASA Astrophysics Data System (ADS)

Zribi, A.; Clark, A.; Zavalij, L.; Borgesen, P.; Cotts, E. J.

2001-09-01

The evolution of intermetallics at and near SnAgCu/Cu and SnAgCu/Ni interfaces was examined, and compared to the behavior, near PbSn/metal and Sn/metal interfaces. Two different solder compositions were considered, Sn93.6Ag4.7Cu1.7 and Sn95.5Ag3.5Cu1.0 (Sn91.8Ag5.1 Cu3.1 and Sn94.35Ag3.8Cu1.85 in atomic percent). In both cases, phase formation and growth at interfaces with Cu were very similar to those commonly observed for eutectic SnPb solder. However, the evolution of intermetallics at SnAgCu/Ni interfaces proved much more complex. The presence of the Cu in the solder dramatically altered the phase selectivity at the solder/Ni interface and affected the growth kinetics of intermetallics. As long as sufficient Cu was available, it would combine with Ni and Sn to form (Cu,Ni)6)Sn5 which grew instead of the Ni3Sn4 usually observed in PbSn/Ni and Sn/Ni diffusion couples. This growing phase would, however, eventually consume essentially all of the available Cu in the solder. Because the mechanical properties of Sn-Ag-Cu alloys, depend upon the Cu content, this consumption can be expected to alter the mechanical properties of these Pb-free solderjoints. After depletion of the Cu from the solder, further annealing then gradually transformed the (Cu,Ni)6Sn5 phase into a (Ni,Cu)3Sn4 phase.

Reliability analysis of different structure parameters of PCBA under drop impact

NASA Astrophysics Data System (ADS)

Liu, P. S.; Fan, G. M.; Liu, Y. H.

2018-03-01

The establishing process of PCBA is modelled by finite element analysis software ABAQUS. Firstly, introduce the Input-G method and the fatigue life under drop impact are introduced and the mechanism of the solder joint failure in the process of drop is analysed. The main reason of solder joint failure is that the PCB component is suffering repeated tension and compression stress during the drop impact. Finally, the equivalent stress and peel stress of different solder joint and plate-level components under different impact acceleration are also analysed. The results show that the reliability of tin-silver copper joint is better than that of tin- lead solder joint, and the fatigue life of solder joint expectancy decrease as the impact pulse amplitude increases.

Solder creep-fatigue interactions with flexible leaded parts

NASA Technical Reports Server (NTRS)

Ross, R. G., Jr.; Wen, L. C.; Mon, G. R.; Jetter, E.

1992-01-01

With flexible leaded parts, the solder-joint failure process involves a complex interplay of creep and fatigue mechanisms. To better understand the role of creep in typical multi-hour cyclic loading conditions, a specialized non-linear finite-element creep simulation computer program has been formulated. The numerical algorithm includes the complete part-lead-solder-PWB system, accounting for strain-rate dependence of creep on applied stress and temperature, and the role of the part-lead dimensions and flexibility that determine the total creep deflection (solder strain range) during stress relaxation. The computer program has been used to explore the effects of various solder creep-fatigue parameters such as lead height and stiffness, thermal-cycle test profile, and part/board differential thermal expansion properties. One of the most interesting findings is the strong presence of unidirectional creep-ratcheting that occurs during thermal cycling due to temperature dominated strain-rate effects. To corroborate the solder fatigue model predictions, a number of carefully controlled thermal-cycle tests have been conducted using special bimetallic test boards.

Ab initio-aided CALPHAD thermodynamic modeling of the Sn-Pb binary system under current stressing

PubMed Central

Lin, Shih-kang; Yeh, Chao-kuei; Xie, Wei; Liu, Yu-chen; Yoshimura, Masahiro

2013-01-01

Soldering is an ancient process, having been developed 5000 years ago. It remains a crucial process with many modern applications. In electronic devices, electric currents pass through solder joints. A new physical phenomenon – the supersaturation of solders under high electric currents – has recently been observed. It involves (1) un-expected supersaturation of the solder matrix phase, and (2) the formation of unusual “ring-shaped” grains. However, the origin of these phenomena is not yet understood. Here we provide a plausible explanation of these phenomena based on the changes in the phase stability of Pb-Sn solders. Ab initio-aided CALPHAD modeling is utilized to translate the electric current-induced effect into the excess Gibbs free energies of the phases. Hence, the phase equilibrium can be shifted by current stressing. The Pb-Sn phase diagrams with and without current stressing clearly demonstrate the change in the phase stabilities of Pb-Sn solders under current stressing. PMID:24060995

Massive spalling of intermetallic compounds in solder-substrate reactions due to limited supply of the active element

NASA Astrophysics Data System (ADS)

Yang, S. C.; Ho, C. E.; Chang, C. W.; Kao, C. R.

2007-04-01

Massive spalling of intermetallic compounds has been reported in the literature for several solder/substrate systems, including SnAgCu soldered on Ni substrate, SnZn on Cu, high-Pb PbSn on Cu, and high-Pb PbSn on Ni. In this work, a unified thermodynamic argument is proposed to explain this rather unusual phenomenon. According to this argument, two necessary conditions must be met. The number one condition is that at least one of the reactive constituents of the solder must be present in a limited amount, and the second condition is that the soldering reaction has to be very sensitive to its concentration. With the growth of intermetallic, more and more atoms of this constituent are extracted out of the solder and incorporated into the intermetallic. As the concentration of this constituent decreases, the original intermetallic at the interface becomes a nonequilibrium phase, and the spalling of the original intermetallic occurs.

Massive spalling of intermetallic compounds in solder-substrate reactions due to limited supply of the active element

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, S. C.; Ho, C. E.; Chang, C. W.

2007-04-15

Massive spalling of intermetallic compounds has been reported in the literature for several solder/substrate systems, including SnAgCu soldered on Ni substrate, SnZn on Cu, high-Pb PbSn on Cu, and high-Pb PbSn on Ni. In this work, a unified thermodynamic argument is proposed to explain this rather unusual phenomenon. According to this argument, two necessary conditions must be met. The number one condition is that at least one of the reactive constituents of the solder must be present in a limited amount, and the second condition is that the soldering reaction has to be very sensitive to its concentration. With themore » growth of intermetallic, more and more atoms of this constituent are extracted out of the solder and incorporated into the intermetallic. As the concentration of this constituent decreases, the original intermetallic at the interface becomes a nonequilibrium phase, and the spalling of the original intermetallic occurs.« less

Predicting the Drop Performance of Solder Joints by Evaluating the Elastic Strain Energy from High-Speed Ball Pull Tests

NASA Astrophysics Data System (ADS)

You, Taehoon; Kim, Yunsung; Kim, Jina; Lee, Jaehong; Jung, Byungwook; Moon, Jungtak; Choe, Heeman

2009-03-01

Despite being expensive and time consuming, board-level drop testing has been widely used to assess the drop or impact resistance of the solder joints in handheld microelectronic devices, such as cellphones and personal digital assistants (PDAs). In this study, a new test method, which is much simpler and quicker, is proposed. The method involves evaluating the elastic strain energy and relating it to the impact resistance of the solder joint by considering the Young’s modulus of the bulk solder and the fracture stress of the solder joint during a ball pull test at high strain rates. The results show that solder joints can be ranked in order of descending elastic strain energy as follows: Sn-37Pb, Sn-1Ag-0.5Cu, Sn-3Ag-0.5Cu, and Sn-4Ag-0.5Cu. This order is consistent with the actual drop performances of the samples.

On-Chip Out-of-Plane High-Q Inductors

DTIC Science & Technology

2002-01-01

and leaves the substrate available for circuits. Magnetic forces [2] and the surface tension of a molten dot of solder [3] or polymer [4] have been...and P. Renaud, "High aspect ratio planar coils embedded in SU8 photoepoxy for MEMS applications," Tech. Digest Eurosensors XII, Southampton, Sep. 13-16

Characteristics of shear damage for 60Sn-40Pb solder material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, H.E.; Chow, C.L.; Wei, Y.

This paper presents an investigation of the development of a continuum damage model capable of accurately analyzing shear damage in 60Sn-40Pb solder material. Based on the theory of damage mechanics, an internal state variable known as the damage variable is introduced to characterize material degradation caused by the change of material microstructures under load. A damage surface in stress space is proposed to quantify damage initiation and its successive expanding surfaces to represent damage hardening. With the aid of irreversible thermodynamics, the damage-coupled constitutive equations and the damage evolution equations are established. A failure criterion is proposed based on themore » accumulation of overall damage in the material. The damage model is implemented in a general purpose finite element program ABAQUS through its user-defined material subroutine UMAT. The program is applied to predict shear deformation in a notched specimen. The predicted failure mode and maximum load agree well with those measured experimentally. The effect of finite element meshing on the numerical results is also examined and discussed.« less

Effect of gap distance on tensile strength of preceramic base metal solder joints.

PubMed

Fattahi, Farnaz; Motamedi, Milad

2011-01-01

In order to fabricate prostheses with high accuracy and durability, soldering techniques have been introduced to clinical dentistry. However, these prostheses always fail at their solder joints. The purpose of this study was to evaluate the effect of gap distance on the tensile strength of base metal solder joints. Based on ADA/ISO 9693 specifications for tensile test, 40 specimens were fabricated from a Ni-Cr alloy and cut at the midpoint of 3-mm diameter bar and placed at desired positions by a specially designed device. The specimens were divided into four groups of 10 samples according to the desired solder gap distance: Group1: 0.1mm; Group2: 0.25mm; Group3: 0.5mm; and Group4: 0.75mm. After soldering, specimens were tested for tensile strength by a universal testing machine at a cross-head speed of 0.5mm/min with a preload of 10N. The mean tensile strength values of the groups were 162, 307.8, 206.1 and 336.7 MPa, respectively. The group with 0.75-mm gap had the highest and the group with 0.1-mm gap had the lowest tensile strength. Bonferroni test showed that Group1 and Group4 had statistically different values (P=0.023), but the differences between other groups were not sig-nificant at a significance level of 0.05. There was no direct relationship between increasing soldering gap distance and tensile strength of the solder joints.

Laser-activated protein bands for peripheral nerve repair

NASA Astrophysics Data System (ADS)

Lauto, Antonio; Trickett, Rodney I.; Malik, Richard; Dawes, Judith M.; Owen, Earl R.

1996-01-01

A 100 micrometer core optical fiber-coupled 75 mW diode laser operating at a wavelength of 800 nm has been used in conjunction with a protein solder to stripe weld severed rat tibial nerves, reducing the long operating time required for microsurgical nerve repair. Welding is produced by selective laser denaturation of the protein based solder which contains the dye indocyanine green. Operating time for laser soldering was 10 plus or minus 5 min. (n equals 24) compared to 23 plus or minus 9 min (n equals 13) for microsuturing. The laser solder technique resulted in patent welds with a tensile strength of 15 plus or minus 5 g, while microsutured nerves had a tensile strength of 40 plus or minus 10 g. Histopathology of the laser soldered nerves, conducted immediately after surgery, displayed solder adhesion to the outer membrane with minimal damage to the inner axons of the nerves. An in vivo study, with a total of fifty-seven adult male wistar rats, compared laser solder repaired tibial nerves to conventional microsuture repair. Twenty-four laser soldered nerves and thirteen sutured nerves were characterized at three months and showed successful regeneration with average compound muscle action potentials (CMAP) of 2.4 plus or minus 0.7 mV and 2.7 plus or minus 0.8 mV respectively. Histopathology of the in vivo study, confirmed the comparable regeneration of axons in laser and suture operated nerves. A faster, less damaging and long lasting laser based anastomotic technique is presented.

Closure of skin incisions in rabbits by laser soldering II: Tensile strength.

PubMed

Brosh, Tamar; Simhon, David; Halpern, Marisa; Ravid, Avi; Vasilyev, Tamar; Kariv, Naam; Nevo, Zvi; Katzir, Abraham

2004-01-01

The basic characteristic property of wound closure is the immediate and long-term tensile strength (LTS). The objective of the current study was to compare tissue laser soldering to other available methods (i.e., cyanoacrylate glues and sutures) in the performance and outcome of wound closure and reparative healing process, with an emphasis on the immediate and LTS. The animals were divided into three groups according to the type and details of the closure procedure. Group A: laser treatments at different temperatures were compared to sutured incisions, emphasizing the LTS after 10 days. Group B: laser soldering at 65 +/- 5 degrees C was compared to chemical glues (i.e., Histoacryl and Dermabond), emphasizing the immediate tensile strength (ITS). Group C: LTS of laser soldered incisions was compared to that of sutured incisions at various time intervals emphasizing LTS (3, 7, 14, 28 days). Group A: LTS at 60 degrees C exhibited the highest values (0.48 MPa). Group B: no ITS difference was detected between laser soldering and chemical glues. Group C: soldered incisions at 65 degrees C exhibited higher LTS (1.81 MPa) than that of sutured incisions (1.08 MPa) (P < 0.043). Temperature-controlled laser soldering at 65 degrees C provided sufficient ITS and higher bonding LTS values compared with sutures, resulting in better wound healing characteristics. The laser soldering system presented here should be tested on larger animal models before adopting it for clinical usage.

Orthodontic soldering techniques: aspects of quality assurance in the dental laboratory.

PubMed

Heidemann, Jutta; Witt, Emil; Feeg, Martin; Werz, Rainer; Pieger, Klaus

2002-07-01

In Germany, the dental technician is required by the Medical Products Act (MPG) to produce workpieces of high safety and quality and to document these properties. Soldering continues to be the prevailing joining technique in the dental laboratory, although problems arise from the susceptibility to corrosion and the low strength of soldered joints. This study aimed to reveal sources of defects in dental laboratory workpieces in order to achieve optimization in terms of quality assurance. The joints were produced by various dental technicians using three different soldering techniques. These joining techniques were investigated for their quality and their corrosion properties during immersion in ferric chloride, orthodontic appliance cleanser, and artificial saliva. Observance of the soldering instructions by the dental technicians was checked. Corrosion attack was confirmed by scanning electron microscopy and by measuring the ion concentrations of copper, silver and zinc in the corrosive agents, using atomic emission spectroscopy with stimulation by inductively coupled plasma (ICP-AES analysis). Incomplete filling of the soldering gap, porosities resulting from the production process, poor corrosion properties, and in particular a high variability of the measured values point to insufficient reliability of two soldering techniques. Variations in quality were also detected among the technicians' modes of operation. The analyses confirm the need for quality assurance of soldering techniques and for increased support for alternative joining techniques such as laser welding in the future. The results of the studies on laser welding are presented in a separate publication.

Safer Soldering Guidelines and Instructional Resources

ERIC Educational Resources Information Center

Love, Tyler S.; Tomlinson, Joel

2018-01-01

Soldering is a useful and necessary process for many classroom, makerspace, Fab Lab, technology and engineering lab, and science lab activities. As described in this article, soldering can pose many safety risks without proper engineering controls, standard operating procedures, and direct instructor supervision. There are many safety hazards…

A simple, efficient resistance soldering apparatus

NASA Technical Reports Server (NTRS)

Vermillion, C. M.

1972-01-01

Multiple resistance soldering device for attaching electric leads to multiple terminal block connectors uses power source with one terminal connected to working probe, and other terminal attached to connector carrying common pins for lead insertion. Mating of male and female connectors solders each lead to individual cup pin.

Experiments and Demonstrations with Soldering Guns.

ERIC Educational Resources Information Center

Henry, Dennis C.; Danielson, Sarah A.

1993-01-01

Discusses the essential electrical characteristics of a particular model of soldering gun. Presents four classroom demonstrations that utilize the soldering gun to test the following geometrics of wire loops as electromagnets: (1) the original tip; (2) a single circular loop; (3) a Helmholtz coil; and (4) the solenoid. (MDH)

Water Ingress Failure Analysis of Whistler II Unit

DTIC Science & Technology

2014-08-01

contaminants getting in the water, possibly from the batteries, the solder flux, some other means, or some combination. The Whistler Unit was...White residue was present on many of the solder joints. Per Art Harrison, this is consistent with exposure of solder flux to moisture. c

Evaluation of alternative cleaners for solder flux and mold release removal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lopez, E.P.; Peebles, D.E.; Reich, J.E.

1991-01-01

As part of a solvent substitution program, an evaluation of selected alternative cleaners for solder flux and mold release removal has been performed. Six cleaners were evaluated for their efficiency in removing a rosin mildly activated flux and a silicone mold release from copper, 17-4PH stainless steel, polyimide quartz glass and tin-lead surfaces. A parallel effort also studied deionized water removal of organic acid fluxes. Auger electron spectroscopy and X-ray photoelectron spectroscopy were used to determine relative elemental cleanliness of the outermost atomic layers. An Omega Meter Test was used to measure residual ionic contamination. Water drop contact angles weremore » used to measure the effectiveness of silicone removal from Cu substrates. In most cases, the cleanliness levels were good to excellent. 10 refs., 8 figs., 19 tabs.« less

30 CFR 77.1111 - Welding, cutting, soldering; use of fire extinguisher.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, soldering; use of fire... OF UNDERGROUND COAL MINES Fire Protection § 77.1111 Welding, cutting, soldering; use of fire extinguisher. One portable fire extinguisher shall be provided at each location where welding, cutting, or...

30 CFR 77.1111 - Welding, cutting, soldering; use of fire extinguisher.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Welding, cutting, soldering; use of fire... OF UNDERGROUND COAL MINES Fire Protection § 77.1111 Welding, cutting, soldering; use of fire extinguisher. One portable fire extinguisher shall be provided at each location where welding, cutting, or...

30 CFR 77.1111 - Welding, cutting, soldering; use of fire extinguisher.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Welding, cutting, soldering; use of fire... OF UNDERGROUND COAL MINES Fire Protection § 77.1111 Welding, cutting, soldering; use of fire extinguisher. One portable fire extinguisher shall be provided at each location where welding, cutting, or...

30 CFR 77.1111 - Welding, cutting, soldering; use of fire extinguisher.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Welding, cutting, soldering; use of fire... OF UNDERGROUND COAL MINES Fire Protection § 77.1111 Welding, cutting, soldering; use of fire extinguisher. One portable fire extinguisher shall be provided at each location where welding, cutting, or...

30 CFR 77.1111 - Welding, cutting, soldering; use of fire extinguisher.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Welding, cutting, soldering; use of fire... OF UNDERGROUND COAL MINES Fire Protection § 77.1111 Welding, cutting, soldering; use of fire extinguisher. One portable fire extinguisher shall be provided at each location where welding, cutting, or...

Thermodynamic Description of the Quaternary Ag-Bi-Cu-Sn System

NASA Astrophysics Data System (ADS)

Gierlotka, Wojciech

2018-01-01

Lead-free soldering is an important part of electronic devices production. New lead-free solders that replace classical Sn-37Pb solder are still under development. Thermodynamic modeling makes the development process faster, cheaper and more environmentally friendly due to predictions of phases stabilities and phases transformations. In this work, the thermodynamic description of quaternary Ag-Bi-Cu-Sn system is presented. The thermodynamic assessment of promising lead-free quaternary solder was prepared using the Calphad approach. A good agreement between available experimental data and calculation was found.

Phase diagrams for lead-free solder alloys

NASA Astrophysics Data System (ADS)

Kattner, Ursula R.

2002-12-01

The need for new, improved solder alloys and a better understanding of reactions during the soldering process grows steadily as the need for smaller and more reliable electronic products increases. Information obtained from phase equilibria data and thermodynamic calculations has proven to be an important tool in the design and understanding of new lead-free solder alloys. A wide range of candidate alloys can be rapidly evaluated for proper freezing ranges, susceptibility to contamination effects, and reactions with substrate materials before the expensive process of preparing and testing candidate alloys is initiated.

Microstructural Evolution and Tensile Properties of SnAgCu Mixed with Sn-Pb Solder Alloys (Preprint)

DTIC Science & Technology

2009-03-01

AFRL-RX-WP-TP-2009-4132 MICROSTRUCTURAL EVOLUTION AND TENSILE PROPERTIES OF SnAgCu MIXED WITH Sn-Pb SOLDER ALLOYS (PREPRINT...PROPERTIES OF SnAgCu MIXED WITH Sn-Pb SOLDER ALLOYS (PREPRINT) 5a. CONTRACT NUMBER FA8650-04-C-5704 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...ANSI Std. Z39-18 Microstructural evolution and tensile properties of SnAgCu mixed with Sn-Pb solder alloys Fengjiang Wang,1 Matthew O’Keefe,1,2 and

Proceedings of the Annual Soldering/Manufacturing Seminar (10th) Held in China Lake, California on 19-20 February 1986

DTIC Science & Technology

1986-02-19

solderability testing what it wants it to be. We might be preparing to be too demanding. We cannot demand what is unattain- able, but must first determine what ...warehouse environment. We earlier pointed out the lack of IMC growth with the solder-dipped parts. So what is the mechanism for solder consumption...the vendors’ facilities, insight was gained into * what was or was not possible for them to do. In turn, it was then possible to offer suggestions and

Electromigration effect on intermetallic growth and Young's modulus in SAC solder joint

NASA Astrophysics Data System (ADS)

Xu, Luhua; Pang, John H. L.; Ren, Fei; Tu, K. N.

2006-12-01

Solid-state intermetallic compound (IMC) growth behavior plays and important role in solder joint reliability of electronic packaging assemblies. The directional impact of electromigration (EM) on the growth of interfacial IMCs in Ni/SAC/Ni, Cu/SAC/Ni single BGA ball solder joint, and fine pitch ball-grid-array (FPBGA) at the anode and cathode sides is reported in this study. When the solder joint was subjected to a current density of 5,000 A/cm2 at 125°C or 150°C, IMC layer growth on the anode interface was faster than that on the cathode interface, and both were faster than isothermal aging due to the Joule heating effect. The EM affects the IMC growth rate, as well as the composition and mechanical properties. The Young’s modulus and hardness were measured by the nanoindentation continuous stiffness measurement (CSM) from planar IMC surfaces after EM exposure. Different values were observed at the anode and cathode. The energy-dispersive x-ray (EDX) line scan analysis was conducted at the interface from the cathode to anode to study the presence of species; Ni was found in the anode IMC at SAC/Cu in the Ni/SAC/Cu joint, but not detected when the current was reverse. Electron-probe microanalysis (EPMA) measurement on the Ni/SAC/Ni specimen also confirmed the polarized Ni and Cu distributions in cathode and anode IMCs, which were (Ni0.57Cu0.43)3Sn4 and (Cu0.73Ni0.27)6Sn5, respectively. Thus, the Young’s moduli of the IMC are 141 and 175 GPa, respectively.

A Probabilistic Approach to Predict Thermal Fatigue Life for Ball Grid Array Solder Joints

NASA Astrophysics Data System (ADS)

Wei, Helin; Wang, Kuisheng

2011-11-01

Numerous studies of the reliability of solder joints have been performed. Most life prediction models are limited to a deterministic approach. However, manufacturing induces uncertainty in the geometry parameters of solder joints, and the environmental temperature varies widely due to end-user diversity, creating uncertainties in the reliability of solder joints. In this study, a methodology for accounting for variation in the lifetime prediction for lead-free solder joints of ball grid array packages (PBGA) is demonstrated. The key aspects of the solder joint parameters and the cyclic temperature range related to reliability are involved. Probabilistic solutions of the inelastic strain range and thermal fatigue life based on the Engelmaier model are developed to determine the probability of solder joint failure. The results indicate that the standard deviation increases significantly when more random variations are involved. Using the probabilistic method, the influence of each variable on the thermal fatigue life is quantified. This information can be used to optimize product design and process validation acceptance criteria. The probabilistic approach creates the opportunity to identify the root causes of failed samples from product fatigue tests and field returns. The method can be applied to better understand how variation affects parameters of interest in an electronic package design with area array interconnections.

A Novel Technique for the Connection of Ceramic and Titanium Implant Components Using Glass Solder Bonding

PubMed Central

Mick, Enrico; Tinschert, Joachim; Mitrovic, Aurica; Bader, Rainer

2015-01-01

Both titanium and ceramic materials provide specific advantages in dental implant technology. However, some problems, like hypersensitivity reactions, corrosion and mechanical failure, have been reported. Therefore, the combining of both materials to take advantage of their pros, while eliminating their respective cons, would be desirable. Hence, we introduced a new technique to bond titanium and ceramic materials by means of a silica-based glass ceramic solder. Cylindrical compound samples (Ø10 mm × 56 mm) made of alumina toughened zirconia (ATZ), as well as titanium grade 5, were bonded by glass solder on their end faces. As a control, a two-component adhesive glue was utilized. The samples were investigated without further treatment, after 30 and 90 days of storage in distilled water at room temperature, and after aging. All samples were subjected to quasi-static four-point-bending tests. We found that the glass solder bonding provided significantly higher bending strength than adhesive glue bonding. In contrast to the glued samples, the bending strength of the soldered samples remained unaltered by the storage and aging treatments. Scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analyses confirmed the presence of a stable solder-ceramic interface. Therefore, the glass solder technique represents a promising method for optimizing dental and orthopedic implant bondings. PMID:28793440

Soldering in prosthodontics--an overview, part I.

PubMed

Byrne, Gerard

2011-04-01

The fit of fixed multiunit dental prostheses (FDP), traditionally termed fixed partial dentures (FPDs), is an ongoing problem. Poorly fitting restorations may hasten mechanical failure, due to abutment caries or screw failure. Soldering and welding play an important role in trying to overcome misfit of fixed multiunit prostheses. The term FPD will be used to denote multiunit fixed dental prostheses in this review. This is the first of a series of articles that review the state of the art and science of soldering and welding in relation to the fit of cemented or screw-retained multiunit prostheses. A comprehensive archive of background information and scientific findings is presented. Texts in dental materials and prosthodontics were reviewed. Scientific data were drawn from the numerous laboratory studies up to and including 2009. The background, theory, terminology, and working principles, along with the applied research, are presented. This first article focuses on soldering principles and dimensional accuracy in soldering. There is some discussion and suggestions for future research and development. Soldering may improve dimensional accuracy or reduce the distortion of multiunit fixed prostheses. Many variables can affect the outcome in soldering technique. Research science has developed some helpful guidelines. Research projects are disconnected and limited in scope. © 2011 by The American College of Prosthodontists.

Solder Flux Residues and Humidity-Related Failures in Electronics: Relative Effects of Weak Organic Acids Used in No-Clean Flux Systems

NASA Astrophysics Data System (ADS)

Verdingovas, Vadimas; Jellesen, Morten Stendahl; Ambat, Rajan

2015-04-01

This paper presents the results of humidity testing of weak organic acids (WOAs), namely adipic, succinic, glutaric, dl-malic, and palmitic acids, which are commonly used as activators in no-clean solder fluxes. The study was performed under humidity conditions varying from 60% relative humidity (RH) to ˜99%RH at 25°C. The following parameters were used for characterization of WOAs: mass gain due to water adsorption and deliquescence of the WOA (by quartz crystal microbalance), resistivity of the water layer formed on the printed circuit board (by impedance spectroscopy), and leakage current measured using the surface insulation resistance pattern in the potential range from 0 V to 10 V. The combined results indicate the importance of the WOA chemical structure for the water adsorption and therefore conductive water layer formation on the printed circuit board assembly (PCBA). A substantial increase of leakage currents and probability of electrochemical migration was observed at humidity levels above the RH corresponding to the deliquescence point of WOAs present as contaminants on the printed circuit boards. The results suggest that use of solder fluxes with WOAs having higher deliquescence point could improve the reliability of electronics operating under circumstances in which exposure to high humidity is likely to occur.

A method for encapsulating high voltage power transformers

NASA Astrophysics Data System (ADS)

Sanchez, Robert O.

Voltage breakdowns become a major concern in reducing the size of high-voltage power converter transformers. Even the smallest of voids can provide a path for corona discharge which can cause a dielectric breakdown leading to a transformer failure. A method of encapsulating small high voltage transformers has been developed. The method virtually eliminates voids in the impregnation material, provides an exceptional dielectric between windings and provides a mechanically rugged package. The encapsulation material is a carboxyl terminated butadiene nitril (CTBN) modified mica filled epoxy. The method requires heat/vacuum to impregnate the coil and heat/pressure to cure the encapsulant. The transformer package utilizes a diallyl phthalate (DAP) contact assembly in which a coated core/coil assembly is mounted and soldered. This assembly is then loaded into an RTV mold and the encapsulation process begins.

Polarity effect of electromigration on mechanical properties of lead-free solder joints

NASA Astrophysics Data System (ADS)

Ren, Fei

The trend of electronic packaging is to package the chips and the associated interconnections in a compact way that allows high speed operation; that allows for sufficient heat removal; that can withstand the thermal cycling associated with the turning on and turning off of the circuits; and that protects the circuits from environmental attack. These goals require that flip chip solder joints have higher resistance to electromigration, stronger mechanical property to sustain thermal mechanical stress, and are lead-free materials to satisfy environment and health concern. With lots of work on chemical reaction, electromigration and mechanical study in flip chip solder joints, however, the interaction between different driving forces is still little known. As a matter of fact, the combination study of chemical, electrical and mechanical is more and more significant to the understanding of the behavior of flip chip solder joints. In this dissertation, I developed one dimensional Cu (wire)-eutectic SnAgCu(ball)-Cu(wire) structure to investigate the interaction between electrical and mechanical force in lead-free solder joints. Electromigration was first conducted. The mechanical behaviors of solder joints before, after, and during electromigration were examined. Electrical current and mechanical stress were applied either in serial or in parallel to the solder joints. Tensile, creep, and drop tests, combined with different electrical current densities (1˜5x10 3A/cm2) and different stressing time (3˜144 hours), have been performed to study the effect of electromigration on the mechanical behavior of solder joints. Nano-indentation test was conducted to study the localized mechanical property of IMC at both interfaces in nanometer scale. Fracture images help analyze the failure mechanism of solder joints driven by both electrical and mechanical forces. The combination study shows a strain build-up during electromigration. Furthermore, a ductile-to-brittle transition in flip chip solder joints induced by electromigration is observed, in which the fracture position migrates from the middle to the cathode interface of the joint with increasing current density and time. The transition is explained by the polarity effect of electromigration, particular due to the accumulation of vacancies at the cathode interface.

Packaging system with cleaning channel and method of making the same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fang, Lu

A packaging structure and method for surface mount integrated circuits reduces electrochemical migration (ECM) problems by including one or more cleaning channels to effectively and efficiently remove flux residue that may otherwise remain lodged in gaps between the surface mount package and the printed circuit board. A cleaning channel may be formed along a bottom surface of the surface mount package (i.e., the surface facing the printed circuit board), or along a portion of a top surface of the printed circuit board. In either case, the inclusion of a cleaning channel enlarges the gap between the bottom surface of themore » surface mount package and the printed circuit board and creates a path for contaminants to be flushed out during a cleaning process.« less

Comparison of Extensive Thermal Cycling Effects on Microstructure Development in Micro-alloyed Sn-Ag-Cu Solder Joints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Iver E.; Boesenberg, Adam; Harringa, Joel

2011-09-28

Pb-free solder alloys based on the Sn-Ag-Cu (SAC) ternary eutectic have promise for widespread adoption across assembly conditions and operating environments, but enhanced microstructural control is needed. Micro-alloying with elements such as Zn was demonstrated for promoting a preferred solidification path and joint microstructure earlier in simple (Cu/Cu) solder joints studies for different cooling rates. This beneficial behavior now has been verified in reworked ball grid array (BGA) joints, using dissimilar SAC305 (Sn-3.0Ag-0.5Cu, wt.%) solder paste. After industrial assembly, BGA components joined with Sn-3.5Ag-0.74Cu-0.21Zn solder were tested in thermal cycling (-55 C/+125 C) along with baseline SAC305 BGA joints beyondmore » 3000 cycles with continuous failure monitoring. Weibull analysis of the results demonstrated that BGA components joined with SAC + Zn/SAC305 have less joint integrity than SAC305 joints, but their lifetime is sufficient for severe applications in consumer, defense, and avionics electronic product field environments. Failure analysis of the BGA joints revealed that cracking did not deviate from the typical top area (BGA component side) of each joint, in spite of different Ag3Sn blade content. Thus, SAC + Zn solder has not shown any advantage over SAC305 solder in these thermal cycling trials, but other characteristics of SAC + Zn solder may make it more attractive for use across the full range of harsh conditions of avionics or defense applications.« less

Effect of Gap Distance on Tensile Strength of Preceramic Base Metal Solder Joints

PubMed Central

Fattahi, Farnaz; Motamedi, Milad

2011-01-01

Background and aims In order to fabricate prostheses with high accuracy and durability, soldering techniques have been introduced to clinical dentistry. However, these prostheses always fail at their solder joints. The purpose of this study was to evaluate the effect of gap distance on the tensile strength of base metal solder joints. Materials and methods Based on ADA/ISO 9693 specifications for tensile test, 40 specimens were fabricated from a Ni-Cr alloy and cut at the midpoint of 3-mm diameter bar and placed at desired positions by a specially designed device. The specimens were divided into four groups of 10 samples according to the desired solder gap distance: Group1: 0.1mm; Group2: 0.25mm; Group3: 0.5mm; and Group4: 0.75mm. After soldering, specimens were tested for tensile strength by a universal testing machine at a cross-head speed of 0.5mm/min with a preload of 10N. Results The mean tensile strength values of the groups were 162, 307.8, 206.1 and 336.7 MPa, respectively. The group with 0.75-mm gap had the highest and the group with 0.1-mm gap had the lowest tensile strength. Bonferroni test showed that Group1 and Group4 had statistically different values (P=0.023), but the differences between other groups were not sig-nificant at a significance level of 0.05. Conclusion There was no direct relationship between increasing soldering gap distance and tensile strength of the solder joints. PMID:22991610

Computer simulation of solder joint failure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burchett, S.N.; Frear, D.R.; Rashid, M.M.

The thermomechanical fatigue failure of solder joints is increasingly becoming an important reliability issue for electronic packages. The purpose of this Laboratory Directed Research and Development (LDRD) project was to develop computational tools for simulating the behavior of solder joints under strain and temperature cycling, taking into account the microstructural heterogeneities that exist in as-solidified near eutectic Sn-Pb joints, as well as subsequent microstructural evolution. The authors present two computational constitutive models, a two-phase model and a single-phase model, that were developed to predict the behavior of near eutectic Sn-Pb solder joints under fatigue conditions. Unique metallurgical tests provide themore » fundamental input for the constitutive relations. The two-phase model mathematically predicts the heterogeneous coarsening behavior of near eutectic Sn-Pb solder. The finite element simulations with this model agree qualitatively with experimental thermomechanical fatigue tests. The simulations show that the presence of an initial heterogeneity in the solder microstructure could significantly degrade the fatigue lifetime. The single-phase model was developed to predict solder joint behavior using materials data for constitutive relation constants that could be determined through straightforward metallurgical experiments. Special thermomechanical fatigue tests were developed to give fundamental materials input to the models, and an in situ SEM thermomechanical fatigue test system was developed to characterize microstructural evolution and the mechanical behavior of solder joints during the test. A shear/torsion test sample was developed to impose strain in two different orientations. Materials constants were derived from these tests. The simulation results from the two-phase model showed good fit to the experimental test results.« less

Soldering iron temperature is automatically reduced

NASA Technical Reports Server (NTRS)

Lum, J. Y.

1966-01-01

Hinged cradle-microswitch arrangement maintains a soldering iron at less than peak temperature when not in use. The microswitch introduces a voltage reducing element into the soldering iron power circuit when the iron is placed on the cradle. The iron, when removed from the cradle, returns to operating temperature in 15 to 30 seconds.

A microstructurally based model of solder joints under conditions of thermomechanical fatigue

NASA Astrophysics Data System (ADS)

Frear, D. R.; Burchett, S. N.; Rashid, M. M.

The thermomechanical fatigue failure of solder joints is increasingly becoming an important reliability issue. We present two computational methodologies that have been developed to predict the behavior of near eutectic Sn-Pb solder joints under fatigue conditions that are based on metallurgical tests as fundamental input for constitutive relations. The two-phase model mathematically predicts the heterogeneous coarsening behavior of near eutectic Sn-Pb solder. The finite element simulations from this model agree well with experimental thermomechanical fatigue tests. The simulations show that the presence of an initial heterogeneity in the solder microstructure could significantly degrade the fatigue lifetime. The single phase model is a computational technique that was developed to predict solder joint behavior using materials data for constitutive relation constants that could be determined through straightforward metallurgical experiments. A shear/torsion test sample was developed to impose strain in two different orientations. Materials constants were derived from these tests and the results showed an adequate fit to experimental results. The single-phase model could be very useful for conditions where microstructural evolution is not a dominant factor in fatigue.

Effect of Preconditioning and Soldering on Failures of Chip Tantalum Capacitors

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander A.

2014-01-01

Soldering of molded case tantalum capacitors can result in damage to Ta205 dielectric and first turn-on failures due to thermo-mechanical stresses caused by CTE mismatch between materials used in the capacitors. It is also known that presence of moisture might cause damage to plastic cases due to the pop-corning effect. However, there are only scarce literature data on the effect of moisture content on the probability of post-soldering electrical failures. In this work, that is based on a case history, different groups of similar types of CWR tantalum capacitors from two lots were prepared for soldering by bake, moisture saturation, and longterm storage at room conditions. Results of the testing showed that both factors: initial quality of the lot, and preconditioning affect the probability of failures. Baking before soldering was shown to be effective to prevent failures even in lots susceptible to pop-corning damage. Mechanism of failures is discussed and recommendations for pre-soldering bake are suggested based on analysis of moisture characteristics of materials used in the capacitors' design.

Repair of pig dura in vivo using temperature controlled CO(2) laser soldering.

PubMed

Forer, Boaz; Vasilyev, Tamar; Brosh, Tamar; Kariv, Noam; Gil, Ziv; Fliss, Dan M; Katzir, Abraham

2005-10-01

The purpose of this study was to demonstrate that laser soldering might be successfully used for closing holes or cuts in the dura layer, which encapsulates the brain. A temperature controlled fiberoptic CO(2) laser system and albumin solder were used for spot soldering of fascia patches to holes in the dura of farm pigs, in vitro and in vivo. The mean burst pressure of the soldered patches in the in vitro experiments was 190 +/- 88 mm Hg-significantly higher than typical maximum CSF pressure of 15 mm Hg. In the in vivo experiments the pigs showed no postoperative complications. Histopathological studies exhibited an accepted level of inflammatory reaction and showed no thermal damage to the underlying brain tissue. It has been clearly demonstrated that temperature controlled laser soldering is a very useful technique for the repair of the dura. It provides significant advantages over standard closure techniques: it is easy to apply, the bond is strong and watertight and the procedure is likely to be much faster than suturing. This research work will lead to clinical trials.

Nano-soldering of magnetically aligned three-dimensional nanowire networks.

PubMed

Gao, Fan; Gu, Zhiyong

2010-03-19

It is extremely challenging to fabricate 3D integrated nanostructures and hybrid nanoelectronic devices. In this paper, we report a simple and efficient method to simultaneously assemble and solder nanowires into ordered 3D and electrically conductive nanowire networks. Nano-solders such as tin were fabricated onto both ends of multi-segmented nanowires by a template-assisted electrodeposition method. These nanowires were then self-assembled and soldered into large-scale 3D network structures by magnetic field assisted assembly in a liquid medium with a high boiling point. The formation of junctions/interconnects between the nanowires and the scale of the assembly were dependent on the solder reflow temperature and the strength of the magnetic field. The size of the assembled nanowire networks ranged from tens of microns to millimeters. The electrical characteristics of the 3D nanowire networks were measured by regular current-voltage (I-V) measurements using a probe station with micropositioners. Nano-solders, when combined with assembling techniques, can be used to efficiently connect and join nanowires with low contact resistance, which are very well suited for sensor integration as well as nanoelectronic device fabrication.

Thermal model for optimization of vascular laser tissue soldering.

PubMed

Bogni, Serge; Stumpp, Oliver; Reinert, Michael; Frenz, Martin

2010-06-01

Laser tissue soldering (LTS) is a promising technique for tissue fusion based on a heat-denaturation process of proteins. Thermal damage of the fused tissue during the laser procedure has always been an important and challenging problem. Particularly in LTS of arterial blood vessels strong heating of the endothelium should be avoided to minimize the risk of thrombosis. A precise knowledge of the temperature distribution within the vessel wall during laser irradiation is inevitable. The authors developed a finite element model (FEM) to simulate the temperature distribution within blood vessels during LTS. Temperature measurements were used to verify and calibrate the model. Different parameters such as laser power, solder absorption coefficient, thickness of the solder layer, cooling of the vessel and continuous vs. pulsed energy deposition were tested to elucidate their impact on the temperature distribution within the soldering joint in order to reduce the amount of further animal experiments. A pulsed irradiation with high laser power and high absorbing solder yields the best results. (c) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Three Dimensional Characterization of Tin Crystallography and Cu6Sn5 Intermetallics in Solder Joints by Multiscale Tomography

NASA Astrophysics Data System (ADS)

Kirubanandham, A.; Lujan-Regalado, I.; Vallabhaneni, R.; Chawla, N.

2016-11-01

Decreasing pitch size in electronic packaging has resulted in a drastic decrease in solder volumes. The Sn grain crystallography and fraction of intermetallic compounds (IMCs) in small-scale solder joints evolve much differently at the smaller length scales. A cross-sectional study limits the morphological analysis of microstructural features to two dimensions. This study utilizes serial sectioning technique in conjunction with electron backscatter diffraction to investigate the crystallographic orientation of both Sn grains and Cu6Sn5 IMCs in Cu/Pure Sn/Cu solder joints in three dimensional (3D). Quantification of grain aspect ratio is affected by local cooling rate differences within the solder volume. Backscatter electron imaging and focused ion beam serial sectioning enabled the visualization of morphology of both nanosized Cu6Sn5 IMCs and the hollow hexagonal morphology type Cu6Sn5 IMCs in 3D. Quantification and visualization of microstructural features in 3D thus enable us to better understand the microstructure and deformation mechanics within these small scale solder joints.

Integrated Electrode Arrays for Neuro-Prosthetic Implants

NASA Technical Reports Server (NTRS)

Brandon, Erik; Mojarradi, Mohammede

2003-01-01

Arrays of electrodes integrated with chip-scale packages and silicon-based integrated circuits have been proposed for use as medical electronic implants, including neuro-prosthetic devices that might be implanted in brains of patients who suffer from strokes, spinal-cord injuries, or amyotrophic lateral sclerosis. The electrodes of such a device would pick up signals from neurons in the cerebral cortex, and the integrated circuit would perform acquisition and preprocessing of signal data. The output of the integrated circuit could be used to generate, for example, commands for a robotic arm. Electrode arrays capable of acquiring electrical signals from neurons already exist, but heretofore, there has been no convenient means to integrate these arrays with integrated-circuit chips. Such integration is needed in order to eliminate the need for the extensive cabling now used to pass neural signals to data-acquisition and -processing equipment outside the body. The proposed integration would enable progress toward neuro-prostheses that would be less restrictive of patients mobility. An array of electrodes would comprise a set of thin wires of suitable length and composition protruding from and supported by a fine-pitch micro-ball grid array or chip-scale package (see figure). The associated integrated circuit would be mounted on the package face opposite the probe face, using the solder bumps (the balls of the ball grid array) to make the electrical connections between the probes and the input terminals of the integrated circuit. The key innovation is the insertion of probe wires of the appropriate length and material into the solder bumps through a reflow process, thereby fixing the probes in place and electrically connecting them with the integrated circuit. The probes could be tailored to any distribution of lengths and made of any suitable metal that could be drawn into fine wires. Furthermore, the wires could be coated with an insulating layer using anodization or other processes, to achieve the correct electrical impedance. The probe wires and the packaging materials must be biocompatible using such materials as lead-free solders. For protection, the chip and package can be coated with parylene.

Effect of Grain Boundary Misorientation on Electromigration in Lead-Free Solder Joints

NASA Astrophysics Data System (ADS)

Tasooji, Amaneh; Lara, Leticia; Lee, Kyuoh

2014-12-01

Reduction in microelectronic interconnect size gives rise to solder bumps consisting of few grains, approaching a single- or bicrystal grain morphology in C4 bumps. Single grain anisotropy, individual grain orientation, presence of easy diffusion paths along grain boundaries, and the increased current density in these small solder bumps aggravate electromigration. This reduces the reliability of the entire microelectronic system. This paper focuses on electromigration behavior in Pb-free solder, specifically the Sn-0.7 wt.%Cu alloy. We discuss the effects of texture, grain orientation, and grain boundary misorientation angle on electromigration (EM) and intermetallic compound formation in EM-tested C4 bumps. The detailed electron backscatter diffraction (EBSD) analysis used in this study reveals the greater influence of grain boundary misorientation on solder bump electromigration compared with the effect associated with individual grain orientation.

Solder joint aging characteristics from the MC2918 firing set of a B61 accelerated aging unit (AAU)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vianco, P.T.; Rejent, J.A.

1997-10-01

The B61 accelerated aging unit (AAU) provided a unique opportunity to document the effects of a controlled, long-term thermal cycling environment on the aging of materials used in the device. This experiment was of particular interest to solder technologists because thermal cycling environments are a predominant source of solder joint failures in electronic assemblies. Observations of through hole solder joints in the MC2918 Firing Set from the B61 AAU did not reveal signs of catastrophic failure. Quantitative analyses of the microstructural metrics of intermetallic compound layer thickness and Pb-rich phase particle distributions indicated solder joint aging that was commensurate withmore » the accelerated aging environment. The effects of stress-enhanced coarsening of the Pb-rich phase were also documented.« less

Human albumin solders for clinical application during laser tissue welding.

PubMed

Poppas, D P; Wright, E J; Guthrie, P D; Shlahet, L T; Retik, A B

1996-01-01

Fifty percent human albumin solder significantly improves weld strength when compared to lower concentrations [Wright et al., ASLMS meeting, April, 1995]. We developed a method for preparing 50% human albumin that may be considered compatible for clinical applications. Fifty percent human albumin solder was prepared from 25% commercially available human albumin using a lyophilization technique. Assessment of sterility, viscosity, pH, and peak absorption wavelength were performed. This report describes the methodology used to prepare a 50% human albumin solder that is compatible with clinical use. Maintenance of the structural integrity of the albumin was confirmed by polyacrylamide gel electrophoresis. This solder preparation can be used alone or with the addition of exogenous chromophores. The final product is sterile, incorporates viral free protocols, maintains high viscosity, and can be applied easily during open or laparoscopic procedures.

Ultrasonic semi-solid coating soldering 6061 aluminum alloys with Sn-Pb-Zn alloys.

PubMed

Yu, Xin-ye; Xing, Wen-qing; Ding, Min

2016-07-01

In this paper, 6061 aluminum alloys were soldered without a flux by the ultrasonic semi-solid coating soldering at a low temperature. According to the analyses, it could be obtained that the following results. The effect of ultrasound on the coating which promoted processes of metallurgical reaction between the components of the solder and 6061 aluminum alloys due to the thermal effect. Al2Zn3 was obtained near the interface. When the solder was in semi-solid state, the connection was completed. Ultimately, the interlayer mainly composed of three kinds of microstructure zones: α-Pb solid solution phases, β-Sn phases and Sn-Pb eutectic phases. The strength of the joints was improved significantly with the minimum shear strength approaching 101MPa. Copyright © 2016. Published by Elsevier B.V.

STS-57 Pilot Duffy uses TDS soldering tool in SPACEHAB-01 aboard OV-105

NASA Technical Reports Server (NTRS)

1993-01-01

STS-57 Pilot Brian J. Duffy, at a SPACEHAB-01 (Commercial Middeck Augmentation Module (CMAM)) work bench, handles a soldering tool onboard the Earth-orbiting Endeavour, Orbiter Vehicle (OV) 105. Duffy is conducting a soldering experiment (SE) which is part of the Tools and Diagnostic Systems (TDS) project. He is soldering on a printed circuit board, positioned in a specially designed holder, containing 45 connection points and will later de-solder 35 points on a similar board. TDS' sponsor is the Flight Crew Support Division, Space and Life Sciences Directorate, JSC. It represents a group of equipment selected from tools and diagnostic hardware to be supported by the Space Station program. TDS was designed to demonstrate the maintenance of experiment hardware on-orbit and to evaluate the adequacy of its design and the crew interface.

Microstructural evolution and mechanical properties of SnAgCu alloys

NASA Astrophysics Data System (ADS)

Fouassier, O.; Heintz, J.-M.; Chazelas, J.; Geffroy, P.-M.; Silvain, J.-F.

2006-08-01

Lead containing solder paste is now considered as an environmental threat. In order to eliminate this undesirable environmental impact associated to their production, a family of lead-free solder joint, Sn-3.8Ag-0.7Cu, is proposed. Microstructural and mechanical data of this solder joint have been acquired and compared with the most common used SnPb solder paste. The evolution of the microstructure as well as the failure mode and the mechanical properties of SnAgCu solder joint are discussed as a function of strain rate, annealing treatments, and testing temperature. Tensile tests have been performed, at temperatures ranging from -50to+150°C, on bulk samples. Changes of the mechanical properties of bulk tested samples are actually correlated with microstructural changes, as shown by transmission electronic microscopy investigations.