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1

Lead Free Piezoelectric Materials  

Microsoft Academic Search

Lead oxide based ferroelectrics, represented by lead zirconate titanate (Pb(Zr, Ti)O3) or PZT) are the most widely used materials for piezoelectric actuators, sensors and transducers due to their excellent piezoelectric properties. Considering lead toxicity, there is interest in developing piezoelectric materials that are biocompatible and environmentally friendlier. The low density of non-lead based materials can also be an advantage in

M. Demartin Maeder; D. Damjanovic; N. Setter

2004-01-01

2

Current Developments and Prospective of Lead-Free Piezoelectric Ceramics  

NASA Astrophysics Data System (ADS)

The dielectric, ferroelectric and piezoelectric properties of perovskite ferroelectric and bismuth layered-structured ferroelectric (BLSF) ceramics are described being superior candidates for lead-free piezoelectric materials to reduce environmental damage. Perovskite-type ceramics seem to be suitable for actuator and high-power applications that require a large piezoelectric constant, d33, and a high Curie temperature, Tc, or a depolarization temperature, Td (>200 C). For BaTiO3-based solid solutions, (1-x)BaTiO3-x(Bi0.5K0.5)TiO3 (BT-BKT100x) ceramics, Tc increases with increasing amount of x. The BT-BKT20 + MnCO3 (0.1 wt %) ceramic shows a high Tc greater than 200 C and an electromechanical coupling factor of k33 =0.35. In the case of a(Bi1/2Na1/2)TiO3-b(Bi1/2K1/2)TiO3-cBaTiO3 [BNBK (100a/100b/100c)] solid solution ceramics, d33 is 191 pC/N for BNBK (85.2/2.8/12). KNbO3 (KN)-based ceramics are also a candidate for lead-free piezoelectrics. In Mn-doped KN ceramics, a higher k33 of 0.507 is obtained for KN + MnCO3 (0.1 wt %). On the other hand, BLSF ceramics seem to be excellent candidates as piezoelectric sensors for high temperatures and ceramic resonators with a high mechanical quality factor, Qm, and a low temperature coefficient of resonance frequency, TC-f. The k33 value of the donor (Nb)-doped and grain-oriented (HF) Bi4Ti3-xNbxO12 (BITN-x) ceramic is 0.39 for x=0.08 and is able to keep the same stable value up to 350 C. Nd(0.01) and V(0.75) co-doped Bi4Ti3O12 ceramics, BNTV(0.01, 0.75), show a relatively low TC-f. Bi3TiTaO9 (BTT)-based solid solution, Srx-1Bi4-xTi2-xTaxO9 [SBTT2(x)] (1?q x?q 2), displays the high Qm value (=13500) in (p)-mode at x=1.25. For resonator applications, (Sr1-xCax)2Bi4Ti5O18 (SCBT) (0?q x?q 0.5) ceramics are suitable.

Takenaka, Tadashi; Nagata, Hajime; Hiruma, Yuji

2008-05-01

3

Domain evolution in lead-free thin film piezoelectric ceramics  

NASA Astrophysics Data System (ADS)

Due to environmental and health concerns lead-free piezoelectric systems are currently being evaluated for use as replacements for lead-based ceramics. (1-x)Na0.5Bi0.5TiO3 - xBaTiO3 (NBT-xBT) is a promising alternative. In order to develop materials with improved performance, it is necessary to understand local structure effects on the piezoelectric response at the grain level. Using piezoresponse force microscopy (PFM), we have studied the domain evolution under locally applied electric fields. Using pulsed laser deposition thin films are deposited on Pt/Ti/SiO2/Si substrates at a temperature of 650 C in a 150 mTorr O2 environment. In NBT-0.05BT films, domains are clearly visible after the application of a bias field and they relax after a period of time. After the films are exposed to ambient conditions for several weeks, they must be annealed before domains are again visible with PFM. Domain images after poling indicate that the polarization direction is rotating in the plane of the sample.

Rogers, Meredith E.; Fancher, Chris M.; Blendell, John E.

2012-09-01

4

Study of nickel inner electrode lead-free piezoelectric ceramics  

Microsoft Academic Search

A (K,Na)NbO3 (KNN)-based multilayer piezoelectric ceramic with nickel inner electrodes was successfully fabricated by co-firing in a reducing atmosphere. We studied the compositional modification of KNN in order to increase reducing resistance in the sintering process, and obtained a good composition by using a solid solution with CaZrO3. A multilayer ceramic specimen had a ratio between the strain and induced

S. Kawada; M. Kimura; H. Hayashi; K. Ogiso; T. Konoike; H. Takagi

2011-01-01

5

Sodium potassium niobate-based lead-free piezoelectric ceramics: Bulk and freestanding thick films  

NASA Astrophysics Data System (ADS)

Due to the toxicity of lead, there is an urgent need to develop lead-free alternatives to replace the currently dominant lead-based piezoelectrics such as lead zirconate titanate (PZT). (Na0.5K0.5)NbO 3 (NKN)-based piezoelectrics are promising because of their relatively high Curie temperatures and piezoelectric coefficients among the non-lead piezoelectrics. However, it is difficult to sinter. In this thesis study, a colloidal coating method was developed to improve the sintering of NKN. With this coating method, NKN with good piezoelectric properties can be produced without cold isostatic pressing. To improve the piezoelectric performance of NKN, we performed antimony (Sb) doping studies for a NKN-LN solid solution using the coating approach. It was found that Sb doping greatly improved the density and the piezoelectric properties of the NKN-LiNbO3 solid solution and optimized performance was found at 4%Sb. The reasons for the improved piezoelectric properties and density were discussed. Recently, a large enhancement in the piezoelectric performance under electric fields was discovered in polycrystalline lead magnesium niobate-lead titanate (PMN-PT) when the material was made into freestanding film geometry. Here, for the first time, we show a similar effect was also observed in a lead-free system, (Na0.5K0.5)0.945Li0.055Nb 0.96Sb0.04O3. At 6-8 kV/cm, a giant --d 31 value of 1700 pm/V was achieved, 20 times higher than the value of bulk counterpart. The enhancement was found to result from the ease of domain motion imparted by the freestanding film geometry, and the magnitude of the enhancement can be affected by the electrode layer (a non-piezoelectric) thickness. The freestanding geometry provides a new approach to greatly improve the piezoelectric performance of the current lead-free systems.

Li, Huidong

6

Structural, Dielectric, Piezoelectric and Ferroelectric Characterization of NBT-BT Lead-Free Piezoelectric Ceramics  

NASA Astrophysics Data System (ADS)

Lead free piezoelectric 0.94(Na0.5Bi0.5)TiO3-0.06BaTiO3 (NBT-BT) ceramics were synthesized in MPB composition by conventional solid state reaction method. The crystalline nature of NBT-BT ceramic was studied by XRD and the size of the grains are determined by SEM. The X- ray diffraction results reveal that Ba2+ diffuse into the Na0.5 Bi0.5TiO3 lattices to form a solid solution with a pure perovskite structure. Because of the strong ferroelectricity and MPB, the ceramics exhibit high piezoelectric properties: d33 = 206 pC/N. Td (depolarization temperature) and Tm (temperature at with the dielectric constant epsilonr reaches a maximum) were observed through the phase transition in dielectric studies. In addition, the prepared ceramic exhibits relaxor characteristic, which probably results from the cation disordering in the 12fold coordination sites. Pr and Ec of the prepared ceramics were determined from the P-E hysteresis loop.

Shanmuga Sundari, S.; Kumar, Binay; Dhanasekaran, R.

2013-05-01

7

Structure, microstructure, and piezoelectric properties of ytterbium-doped potassium sodium niobate lead-free ceramics  

NASA Astrophysics Data System (ADS)

The structure, microstructure, and piezoelectric properties of conventionally sintered Yb-doped K0.5Na0.5NbO3 (KNN) lead-free ceramics were investigated. Doping the KNN ceramics with Yb2O3 was effective in inhibiting the grain growth in the KNN ceramics and in densifying the ceramics. The 1.0 wt. % Yb-doped KNN ceramics showed the maximum density, about 96.8% of the theoretical density. X-ray diffraction analysis showed that a small number of Yb3+ ions could be incorporated into the matrix of the ceramicsto occupythe ?- or ?-sites in the crystal lattice, thereby significantly affecting the piezoelectric properties of the ceramics. Enhanced piezoelectric properties ( i.e., d 33= 135 pC/N, k p = 34.5%, and Q m = 80.2) were obtained for the 0.50 wt. % Yb-doped KNN ceramics.

Li, Huan; Yang, Wenlong; Zhou, Zhongxiang; Tian, Hao

2013-09-01

8

Preparation of lead free KNLNTS piezoelectric ceramics by molten salt synthesis and its application  

Microsoft Academic Search

Lead-free (K0.44Na0.52Li0.04)(Nb0.86Ta0.10Sb0.04)O3 (KNLNTS) piezoelectric ceramics were synthesized by the NaCl-KCl (NaCl\\/KCl=1\\/1) molten salt synthesis (MSS) method. The KNLNTS ceramics was fabricated successfully by sintering at 1100degC to 1200degC. The results show that the KNLNTS powder particle size increased form 50 nm to 200 nm and the shape changed from cubic structure to plated-like structure with time increasing. Compared to the

Xiang-cheng Chu; Jun-fei Wu; Long-tu Li; Liang Zhong; Shi-xi Zhao

2008-01-01

9

Lead-free piezoelectric ceramics and transducers in potassium sodium niobate-solid solution system  

NASA Astrophysics Data System (ADS)

Lead-free piezoelectric ceramic of (K0.44Na0.52Li 0.04)(Nb0.84Ta0.1Sb0.06)O 3; (KNN-LT-LS) was prepared by two processing routes, namely "Perovskite" and "Mixed oxide". The sensitivity of raw materials to relative humidity of laboratory environment indicated that the powders batching/handling had to be carried out in a controlled atmosphere (e.g. Ar). The electromechanical properties of bulk samples in which batching carried out in Ar atmosphere were significantly higher than those ceramics prepared in the laboratory environment. The electromechanical properties of ceramics were also very sensitive to the oxygen flow rate during sintering. It was realized that oxygen vacancies could be formed in low oxygen flow rate and deteriorate piezoelectric properties of such ceramics. Reduction in oxygen vacancies facilitated domain wall switching and led to higher remnant polarization with lower coercive field. The highest longitudinal coupling (k33) and piezoelectric charge (d33 ) coefficients for perovskite routes at optimized oxygen flow rate of 180cm3/min were 65% and 315pC/N, respectively. The substitution of Ba2+ (0, 0.5, 1, 1.5, and 2 mol%) ion as an A-site donor dopant to this system improved the relative permittivity, longitudinal coupling and piezoelectric charge coefficients. Increase in remnant polarization along with the decline of coercive field indicated that the addition of Ba2+ gave rise to soft characteristics in this ternary system. The effect of 0-2 mol% of copper oxide (CuO) addition to the base composition was increased the grain size and changed the morphology and growth behavior of the grains. Mechanical quality factor was remarkably improved (Qm = 350) upon addition of 2 mol% Cu2+ with dramatic decrease in amount of energy for switching the dipole moments. Single element air-backed transducers made of undoped and 1.0 mol% Ba 2+-KNN-LT-LS, and PZT-4 showed a measured -6dB fractional bandwidth of 36%, 50.4%, and 53.5%, respectively. High frequency lead-free transducer of KNN-LT-LS were also fabricated that showed the fractional bandwidth (-6dB) of 55.3% at center frequency of 23.5 MHz. This close acoustic performance of studied lead-free transducer in regards to PZT-4 transducer showed that the lead-free system could be a good candidate used for imaging and HIFU (High Focused Ultrasound) therapeutic applications.

Marandian-Hagh, Nader

10

Nanoscale characterization and local piezoelectric properties of lead-free KNN-LT-LS thin films  

NASA Astrophysics Data System (ADS)

We report the observation of domain structure and piezoelectric properties of pure and Mn-doped (K0.44,Na0.52,Li0.04)(Nb0.84,Ta0.1,Sb0.06)O3 (KNN-LT-LS) thin films on SrTiO3 substrates. It is revealed that, using piezoresponse force microscopy, ferroelectric domain structure in such 500 nm thin films comprised of primarily 180 domains. This was in accordance with the tetragonal structure of the films, confirmed by relative permittivity measurements and x-ray diffraction patterns. Effective piezoelectric coefficient (d33) of the films were calculated using piezoelectric displacement curves and shown to be ~53 pm V-1 for pure KNN-LT-LS thin films. This value is among the highest values reported for an epitaxial lead-free thin film and shows a great potential for KNN-LT-LS to serve as an alternative to PZT thin films in future applications.

Abazari, M.; Choi, T.; Cheong, S.-W.; Safari, A.

2010-01-01

11

High magnetoelectric effect in laminated composites of giant magnetostrictive alloy and lead-free piezoelectric ceramic  

NASA Astrophysics Data System (ADS)

Magnetoelectric (ME) laminated composites with all phases environmentally friendly were prepared by sandwiching one layer of thickness-polarized (Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-BaTiO3 lead-free piezoelectric ceramic disk between two layers of thickness-magnetized Tb0.3Dy0.7Fe1.92 giant magnetostrictive alloy disk along the thickness direction. The composites exhibited the maximum ME voltage coefficient of 40.7 mV/Oe with a flat response in the measured frequency range of 0.1-20 kHz under a dc magnetic bias of 5 kOe. The induced ME voltage showed an extremely linear relationship to the applied ac magnetic field with amplitude varying from 310-5 to 10 Oe over a broad range of dc magnetic bias of 0-5.5 kOe. The high ME effect was analyzed and found to be comparable to most major lead-based ME composites. The present study opens up possibilities for developing green ME devices.

Jia, Yanmin; Or, Siu Wing; Wang, Jie; Chan, Helen Lai Wa; Zhao, Xiangyong; Luo, Haosu

2007-05-01

12

High performance Aurivillius phase sodium-potassium bismuth titanate lead-free piezoelectric ceramics with lithium and cerium modification  

NASA Astrophysics Data System (ADS)

The piezoelectric properties of the lithium and cerium modified A-site vacancies sodium-potassium bismuth titanate (NKBT) lead-free piezoceramics are investigated. The piezoelectric activity of NKBT ceramics is significantly improved by the modification of lithium and cerium. The Curie temperature TC, piezoelectric coefficient d33, and mechanical quality factor Qm for the NKBT ceramics modified with 0.10 mol % (LiCe) are found to be 660 C, 25 pC/N, and 3135, respectively. The Curie temperature gradually decreases from 675 to 650 C with the increase of (LiCe) modification. The dielectric spectroscopy shows that all the samples possess stable piezoelectric properties, demonstrating that the (LiCe) modified NKBT-based ceramics are the promising candidates for high temperature applications.

Wang, Chun-Ming; Wang, Jin-Feng

2006-11-01

13

Phase transition and high piezoelectricity in (Ba,Ca)(Ti1-xSnx)O3 lead-free ceramics  

NASA Astrophysics Data System (ADS)

The phase structure in the (Ba,Ca)(Ti1-xSnx)O3 lead-free ceramics was evolved from inceptive orthorhombic (O) at 0 <= x <= 0.04 to a two-phase coexistence of pseudocubic-orthorhombic (PC-O) at 0.06 <= x <= 0.10 and further to a multiphase coexistence of rhombohedral-pseudocubic-orthorhombic (R-PC-O) at x = 0.11. Due to the multiphase coexistence of R-PC-O at room temperature proved by X-ray diffraction, dielectric constant ?r and differential scanning calorimetry, an ultrahigh piezoelectric coefficient d33 = 670 pC/N and electrostrain 0.061% were achieved. The high d33 over 520 pC/N was stabilized in a wide compositional range of 0.07 <= x <= 0.11, suggesting that (Ba,Ca)(Ti,Sn)O3 ceramics are a promising candidate for the lead-free piezoelectric ceramics.

Zhu, Li-Feng; Zhang, Bo-Ping; Zhao, Xiao-Kun; Zhao, Lei; Yao, Fang-Zhou; Han, Xi; Zhou, Peng-Fei; Li, Jing-Feng

2013-08-01

14

Effect of Dopant on Piezoelectric Properties of Lead-Free BiFeO3--BaTiO3 Film  

Microsoft Academic Search

To realize high-performance lead-free piezoelectric materials, we have selected BiFeO3 as the rhomboheral phase material and BaTiO3 as the tetragonal phase material, following the MPB mechanism of PZT. To further improve the piezoelectric properties of BiFeO3--BaTiO3 (BFBT) thin films, we investigated the effect of dopant on the piezoelectric properties of BFBT. Considering both Shanon effective ionic radii and valence number,

Tsutomu Sasaki; Yasutoshi Hirabayashi; Hiroyuki Kobayashi; Yukio Sakashita

2011-01-01

15

Lead free (K,Na)NbO3-based piezoelectric ceramics and transducers  

Microsoft Academic Search

Recent advances in (K,Na)NbO3-based ferroelectrics is reviewed, with special emphasis on the (K,Na)NbO3-LiTaO3-LiSbO3 system. Processing issues are elaborated on. The importance of precursor purity, moisture sensitivity and oxygen content on the dielectric and piezoelectric properties will be shown. Properties of prototype transducers are given and it will be shown that high performance metrics reminiscent to PZT-4 based transducers can be

K. Kerman; M. Abazari; N. Marandian-Hagh; E. K. Akdogan; A. Safari

2008-01-01

16

Piezoelectric Properties of LiSbO3-Modified (K0.48Na0.52)NbO3 Lead-Free Ceramics  

NASA Astrophysics Data System (ADS)

Lead-free piezoelectric (1-x)(K0.48Na0.52)NbO3-xLiSbO3 [(1-x)KNN-xLS] ceramics were prepared by conventional sintering. A morphotropic phase boundary (MPB) between the orthorhombic and tetragonal phases was identified in the composition range of 0.04piezoelectric properties, temperature stability, and aging characteristics. It was found that the samples with 5 mol % LS exhibited enhanced electrical properties (d33 262 pC/N, kp 46%, Tc 373 C, To--t 60 C). These results show that (1-x)KNN-xLS ceramic is a promising lead-free piezoelectric material.

Wu, Jiagang; Wang, Yuanyu; Xiao, Dingquan; Zhu, Jianguo; Yu, Ping; Wu, Lang; Wu, Wenjuan

2007-11-01

17

Correlation between Phase Transitions and Piezoelectric Properties in Lead-Free (K,Na,Li)NbO3-BaTiO3 Ceramics  

NASA Astrophysics Data System (ADS)

In this manuscript, we report the polymorphic phase transitions, structural changes and piezoelectric properties of alkali niobate based lead-free ceramics. The phase transitions were characterized as a function of alkali niobate content at room temperature. The results clearly demonstrate that in this system high piezoelectric properties are achieved for a specific fraction of ferroelectric orthorhombic (O) and tetragonal (T) phases. Using Rietveld and powder diffraction analysis, a correlation was established among the piezoelectric response, the fraction of O and T phases, and KNN ratio for three different systems of (K,Na)NbO3-BaTiO3 (KNN-BT), KNN-LiNbO3 (LN), and (K,Na,Li)NbO3 (KNLN)-BT.

Ahn, Cheol-Woo; Park, Chee-Sung; Viehland, Dwight; Nahm, Sahn; Kang, Dong-Heon; Bae, Kyoo-Sik; Priya, Shashank

2008-12-01

18

Temperature Dependence of Creep and Hardness of Sn-Ag-Cu Lead-Free Solder  

NASA Astrophysics Data System (ADS)

The creep behavior and hardness of Sn-3.5Ag-0.7Cu solder were studied using Berkovich depth-sensing indentation at temperatures of 25C to 125C. Assuming a power-law relationship between the creep strain rate and stress, an activation energy of 40 kJ/mol and stress exponents of 7.4, 5.5, and 3.7 at 25C, 75C, and 125C, respectively, were obtained. The results revealed that, with increasing temperature, the creep penetration and steady-state creep strain rate increased whereas the stress exponent decreased. The stress exponent and activation energy results also suggested that the creep mechanism is dislocation climb, assisted by diffusion through dislocation cores in Sn. Furthermore, the hardness results exhibited a decreasing trend with increasing temperature, which is attributed to softening at high temperature.

Han, Y. D.; Jing, H. Y.; Nai, S. M. L.; Xu, L. Y.; Tan, C. M.; Wei, J.

2010-02-01

19

Piezoelectric properties of KCuNbO modified (Na{sub 0.5}K{sub 0.5})NbO lead-free piezoceramics  

Microsoft Academic Search

Dense KCuNbO modified (Na{sub 0.5}K{sub 0.5})NbO (NKN:KCN) ceramics were synthesized by using conventional oxide mixing process. The maximum mechanical quality factor Q{sub m} of NKN:KCN ceramics reaches up to 1150, the piezoelectric constant d and the planar electromechanical coefficient k{sub p} still maintain relatively high levels, which are about 100 pC\\/N and 40%, respectively. Middle frequency (455 kHz) lead-free resonators

Chen Qiang; Chen Lin; Li Qishou; Yue Xi; Xiao Dingquan; Zhu Jianguo; Shi Xiaoluo; Liu Zhiqian

2007-01-01

20

Piezoelectric Properties of Lead-Free (Na,Bi)TiO3--BaTiO3 (001) Epitaxial Thin Films around the Morphotropic Phase Boundary  

NASA Astrophysics Data System (ADS)

The piezoelectric properties and the crystallographic nature of (1-x)(Na,Bi)TiO3--xBaTiO3 (NBT--BT) thin films around the morphotropic phase boundary (MPB) composition (x=0.05{--}0.10) were studied. NBT--BT thin films were grown epitaxially on Pt(100)/MgO(100) substrates by RF magnetron sputtering and exhibited highly (001)-oriented single-phase perovskite with a tetragonal structure. A maximum piezoelectric coefficient e31 of -14.4 C/m2 was obtained at the x = 0.07 composition of the tetragonal side near MPB (x = 0.06). These results indicate that NBT--BT thin films around the MPB are a promising lead-free replacement for Pb(Zr,Ti)O3 (PZT) based applications.

Harigai, Takakiyo; Tanaka, Yoshiaki; Adachi, Hideaki; Fujii, Eiji

2010-11-01

21

Microstructural origin for the piezoelectricity evolution in (K0.5Na0.5)NbO3-based lead-free ceramics  

NASA Astrophysics Data System (ADS)

Chemically modified (K0.5Na0.5)NbO3 compositions with finely tuned polymorphic phase boundaries (PPBs) have shown excellent piezoelectric properties. The evolution of the domain morphology and crystal structure under applied electric fields of a model material, 0.948(K0.5Na0.5)NbO3-0.052LiSbO3, was directly visualized using in situ transmission electron microscopy. The in situ observations correlate extremely well with measurements of the electromechanical response on bulk samples. It is found that the origin of the excellent piezoelectric performance in this lead-free composition is due to a tilted monoclinic phase that emerges from the PPB when poling fields greater than 14 kV/cm are applied.

Guo, Hanzheng; Zhang, Shujun; Beckman, Scott P.; Tan, Xiaoli

2013-10-01

22

Manufacture and Cytotoxicity of a Lead-free Piezoelectric Ceramic as a Bone Substitute--Consolidation of Porous Lithium Sodium Potassium Niobate by Cold Isostatic Pressing  

PubMed Central

Aim The piezoelectric properties and cytotoxicity of a porous lead-free piezoelectric ceramic for use as a direct bone substitute were investigated. Methodology Cold isostatic pressing (CIP) was applied to fabricate porous lithium sodium potassium niobate (Li0.06Na0.5K0.44) NbO3 specimens using a pore-forming method. The morphologies of the CIP-processed specimens were characterized and compared to those of specimens made by from conventional pressing procedures. The effects of the ceramic on the attachment and proliferation of osteoblasts isolated from the cranium of 1-day-old Sprague-Dawley rats were examined by a scanning electron microscopy (SEM) and methylthiazol tetrazolium (MTT) assay. Results The results showed that CIP enhanced piezoelectricity and biological performance of the niobate specimen, and also promoted an extracellular matrix-like topography of it. In vitro studies showed that the CIP-enhanced material had positive effects on the attachment and proliferation of osteoblasts. Conclusion Niobate ceramic generated by CIP shows a promise for being a piezoelectric composite bone substitute.

Wang, Qi; Yang, Jun; Zhang, Wu; Khoie, Roxanne; Li, Yi-ming; Zhu, Jian-guo; Chen, Zhi-qing

2009-01-01

23

Influence of sintering temperature on piezoelectric properties of (K 0.4425 Na 0.52 Li 0.0375 )(Nb 0.8925 Sb 0.07 Ta 0.0375 )O 3 lead-free piezoelectric ceramics  

Microsoft Academic Search

Microstructure characteristics, phase transition, and electrical properties of (K0.4425Na0.52Li0.0375) (Nb0.8925Sb0.07Ta0.0375)O3 (KNLNST) lead-free piezoelectric ceramics prepared by normal sintering were investigated with an emphasis on the influence\\u000a of sintering temperature. The microstructure and piezoelectric, ferroelectric, and dielectric properties were investigated,\\u000a with a special emphasis on the influence of sintering temperature from 1,100 to 1,140C. Orthorhombic phases mainly exist\\u000a in the ceramics

Xuming Pang; Jinhao Qiu; Kongjun Zhu; Bin Shao

24

Piezoelectric piggy-back microactuator for hard disk drive  

Microsoft Academic Search

A new piezoelectric piggy-back microactuator for high density hard disk drives was designed and fabricated to achieve more accurate positioning of the magnetic head and increasing servo bandwidth. The microactuator is made of stiff piezoelectric ceramic material to actuate the slider on which the head-element is formed. It is designed to amplify the actuating displacement. The basic mechanical performance of

Yoshikazu Soeno; Sliinji Ichikawa; Takamitsu Tsuna; Yoshikazu Sato; Isamu Sato

1999-01-01

25

First-principles study on the electronic and optical properties of Na0.5Bi0.5TiO3 lead-free piezoelectric crystal  

NASA Astrophysics Data System (ADS)

First-principles calculation is used to study the structural, electronic, and optical properties of Na0.5Bi0.5TiO3 (NBT) lead-free piezoelectric crystal. The band structure calculation reveals that NBT has a direct band gap of 2.1 eV. The calculated imaginary part of dielectric function indicates interband transition mainly from O 2p valence bands to Ti 3d and Bi 6p conduction bands in the low-energy region. The calculated absorption spectrum is in agreement with the available experimental data. Based on the fit of the result of optical abruption spectrum, the optical band gap is estimated to be 3.03 eV. Other optical constants, such as refractive index, extinction coefficient, energy-loss spectrum, and reflectivity are discussed in details. Those found show that NBT has the potential applications in optoelectrics.

Zeng, Min; Or, Siu Wing; Chan, Helen Lai Wa

2010-02-01

26

Microscale 1-3-type lead-free piezoelectric/ferrite composites fabricated by a modified dice-and-fill method  

NASA Astrophysics Data System (ADS)

This paper introduces a facile method to fabricate magnetoelectric (ME) composites with microscale lead-free piezoceramic pillars embedded in a ferrite matrix without high-temperature co-sintering. The microscale piezoceramic pillars with a sectional width of about 150 m were obtained from lead-free piezoceramic discs by a dicing method. The spacing between the pillars was backfilled with cobalt ferrite (CFO) nanoparticles, and then a liquid epoxy was infiltrated into the backfilled spacing to bond the filled particles and the pillars. The ME property of the resultant 1-3-type piezoelectric/ferrite composites was verified and found to be significantly dependent on the filling density of the CFO powder, which could be adjusted by repeating the filling step. A maximum ME voltage response of up to 302 V Oe-1 was obtained in a 700 m high composite with pillars of 150 m width and 200 m spacing. The present method provides a potential way to fabricate finescale multiferroic composites for microdevice applications.

Xu, Ying; Li, Jing-Feng; Ma, Jing; Nan, Ce-Wen

2012-08-01

27

Properties of Miniature Cantilever-Type Ultrasonic Motor Using Lead-Free Array-Type Multilayer Piezoelectric Ceramics of (Sr,Ca)2NaNb5O15 under High Input Power  

NASA Astrophysics Data System (ADS)

The properties of miniature cantilever-type ultrasonic motors using lead-free array-type multilayer piezoelectric ceramics of (Sr,Ca)2NaNb5O15 (SCNN) developed using the design rule were investigated under high input power by comparison with the high-power properties of SCNN ceramics. The frequency dependence of the revolution speed reflected the nonlinear behavior of SCNN ceramics with the hard-spring effect and showed a mirror-reversed image relative to that of the motor of Pb(Zr,Ti)O3 (PZT) ceramics. The output power increased linearly with increasing input power up to 110 mW without heat generation, and the driving properties were almost the same as the expectations under low input power. The output power density characteristics of the motors were high in comparison with those of the commercialized motors of PZT ceramics. It appeared that the motors have a high potential as an environmental friendly piezoelectric device with excellent properties, reflecting the high-power properties of SCNN ceramics.

Doshida, Yutaka; Shimizu, Hiroyuki; Mizuno, Youich; Tamura, Hideki

2012-07-01

28

Improved Process for Hydrothermal Lead-Free Piezoelectric Powders and Performances of Sintered (K0.48Na0.52)NbO3 Ceramics  

NASA Astrophysics Data System (ADS)

In this study, we report some improvements in a hydrothermal method for lead-free piezoelectric powders and the performance of the sintered (K0.48Na0.52)NbO3 ceramics. To increase the obtained powder weight per source solution volume, the hydrothermal reaction conditions were modified. This improvement is important for mass production; however, it resulted in a larger particle size dispersion. Therefore, we examined to introduced the ball milling process that is useful for dense (K0.48Na0.52)NbO3 ceramics. When a large amount of powder was obtained, it took a long time to eliminate the residual alkaline ions in the hydrothermal powders by a washing process. Therefore, a neutralization was conducted in the powder washing process. Using this powder, a solid solution of (K,Na)NbO3 ceramics was synthesized. The relative density was successfully increased. Concerning the electrical properties, the relative permittivity was improved, and the piezoelectric constant d33 was also increased from 114 to 130 pC/N.

Maeda, Takafumi; Hemsel, Tobias; Morita, Takeshi

2011-07-01

29

Large Piezoelectric Constant and High Curie Temperature of Lead-Free Piezoelectric Ceramic Ternary System Based on Bismuth Sodium Titanate-Bismuth Potassium Titanate-Barium Titanate near the Morphotropic Phase Boundary  

Microsoft Academic Search

A lead-free piezoelectric ceramic ternary system based on bismuth sodium titanate, (Bi1\\/2Na1\\/2)TiO3 (BNT) - bismuth potassium titanate (Bi1\\/2K1\\/2)TiO3 (BKT) - barium titanate BaTiO3 (BT) near the morphotropic phase boundary (MPB) between the tetragonal and rhombohedral phases has been investigated. In the case of a(Bi1\\/2Na1\\/2)TiO3-bBaTiO3-c(Bi1\\/2K1\\/2)TiO3 [BNBK(100a\\/100b\\/100c)] solid solution ceramics, the highest piezoelectric constant d33=191 pC\\/N, Curie temperature, Tc=301C, electromechanical coupling factor,

Hajime Nagata; Masaki Yoshida; Yoichi Makiuchi; Tadashi Takenaka

2003-01-01

30

Enhanced piezoelectricity and nature of electric-field induced structural phase transformation in textured lead-free piezoelectric Na0.5Bi0.5TiO3-BaTiO3 ceramics  

NASA Astrophysics Data System (ADS)

This letter provides a comparative description of the properties of textured and randomly oriented poly-crystalline lead-free piezoelectric 0.93(Na0.5Bi0.5TiO3)-0.07BaTiO3 (NBT-BT) ceramics. A high longitudinal piezoelectric constant of (d33) ~ 322 pC/N was obtained in (001)PC textured NBT-7BT ceramics, which is almost ~2 times the d33 coefficient reported for randomly oriented ceramics of the same composition. In situ neutron diffraction experiments revealed that characteristically different structural responses are induced in textured and randomly oriented NBT-BT ceramics upon application of electric fields (E), which are likely related to the varying coherence lengths of polar nanoregions and internal stresses induced by domain switching.

Maurya, Deepam; Pramanick, Abhijit; An, Ke; Priya, Shashank

2012-04-01

31

Properties of non-stoichiometric 0.935(K0.5+xNa0.5+x)NbO3-0.065LiSbO3 lead-free piezoelectric ceramics  

NASA Astrophysics Data System (ADS)

0.935(K0.5+xNa0.5+x)NbO3-0.065LiSbO3 lead-free piezoelectric ceramics were prepared by normal sintering, and their piezoelectric and dielectric properties were investigated by varying the compensating amount x of alkaline elements (Na and K) addition. It was found that the crystal structure changed from tetragonal to orthorhombic with increasing x from -0.010 to 0.010. An MPB was tailored by optimizing the alkaline elements contents. Enhanced electrical and electromechanical responses of d33=253 pC/N, kp=0.47, kt=0.45 and tan?=0.027 were obtained in the ceramics with x=0.005. These excellent piezoelectric and electromechanical properties indicate that this system may be an attractive lead-free material for a wide range of electro-mechanical transducer applications.

Du, Juan; Zang, Guo-Zhong; Xiu-Jie, Yi; Wei, Yan-Yan; Wang, Yue-Fang

2012-02-01

32

Electrical Properties and Depolarization Temperature of (Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3 Lead-free Piezoelectric Ceramics  

NASA Astrophysics Data System (ADS)

The piezoelectric properties of a solid solution of the binary system, x(Bi1/2Na1/2)TiO3-(1-x)(Bi1/2K1/2)TiO3 [BNKT100x; x=0.50--0.98] were investigated, focusing on depolarization temperature, Td. Fine piezoelectric properties in lead-free piezoelectric ceramics were obtained near the morphotropic phase boundary (MPB) composition between the rhombohedral and tetragonal structures, and the highest electromechanical coupling factor, k33, and piezoelectric constant, d33, were 0.56 for BNKT84 and 157 pC/N for BNKT80, respectively. However, the Td of BNKT80 was low (174 C). The Td of the MPB composition was low, and the Td near the MPB composition was sharply decreased. It is thought that BNKT70 is a candidate composition for lead-free actuator applications owing to its relatively large piezoelectric constant, d33 (126 pC/N), dynamic d33 (214 pm/V), and high depolarization temperature, Td (206 C). In this study, we determined depolarization temperature, Td, from the temperature dependence of dielectric and piezoelectric properties.

Yoshii, Kazushige; Hiruma, Yuji; Nagata, Hajime; Takenaka, Tadashi

2006-05-01

33

Mechanical shock modeling and testing of lead-free solder joint in hard disk drive head assembly  

Microsoft Academic Search

Solder joint reliability in hard disk drive head assemblies is of great concern due to the increasing demand and popularity of portable electronic products such as mobile hard disk and laptop computers. The mechanical shock resulting from mishandling during transportation or customer usage may seriously affect the solder joint reliability and lead to malfunction of the electronic product eventually. However,

Chen Hongtao; Wang Chunqing; Li Mingyua

2005-01-01

34

Incipient piezoelectrics and electrostriction behavior in Sn-doped Bi1/2(Na0.82K0.18)1/2TiO3 lead-free ceramics  

NASA Astrophysics Data System (ADS)

Dielectric, ferroelectric, piezoelectric, and strain properties of lead-free Sn-doped Bi1/2(Na0.82K0.18)1/2TiO3 (BNKT) were investigated. A crossover from a nonergodic relaxor to an ergodic relaxor state at room temperature, accompanied by a giant electric-field-induced strain, was observed at 5 at. % Sn doping. Switching dynamics monitored during a bipolar poling cycle manifested that the observed giant strain originates from incipient piezoelectricity. When Sn doping level reached 8 at. %, BNKT exhibited an electrostrictive behavior with a highly temperature-insensitive electrostrictive coefficient of Q11 = 0.023 m4 C-2.

Han, Hyoung-Su; Jo, Wook; Kang, Jin-Kyu; Ahn, Chang-Won; Won Kim, Ill; Ahn, Kyoung-Kwan; Lee, Jae-Shin

2013-04-01

35

Lead-free piezoelectric ceramics of (Bi1\\/2Na1\\/2)TiO3-BaTiO3-BiFeO3 system  

Microsoft Academic Search

Bismuth sodium titanate, (Bi1\\/2Na1\\/2)TiO3 (BNT)-based solid solution, a(Bi1\\/2Nal\\/2)TiO3-bBaTiO3-cBiFeO3, [BNBTF(100a\\/100b\\/100c)], was studied for its dielectric, ferroelectric and piezoelectric properties, as a new group of lead-free piezoelectric ceramics. Curie temperatures, Tc. of the BNBTF ceramics shift to the higher temperature with an increasing amount of modified Bi ion, and temperature dependence of the resonance frequencies, fr is smaller with increasing amount of

Hajime Nagata; Nobuhiro Koizumi; Nobuhisa Kuroda; Isao Igarashi; Tadashi Takenaka

1999-01-01

36

Morphotropic phase boundary and electric properties in (1-x)Bi0.5Na0.5TiO3-xBiCoO3 lead-free piezoelectric ceramics  

NASA Astrophysics Data System (ADS)

Lead-free (1-x)Bi0.5Na0.5TiO3-xBiCoO3 (x = 0, 0.015, 0.025, 0.03, 0.035, 0.04, and 0.06) piezoelectric ceramics have been synthesized and their structure and electric properties have been investigated systemically. The rhombohedral-tetragonal morphotropic phase boundary (MPB) locates near x = 0.025-0.035. For the ceramics with x = 0.025, the saturated polarization (Ps), remnant polarization (Pr), coercive field (Ec), strain(S), piezoelectric constant (d33), and thickness electromechanical coupling factor (kt) are 40.6 ?C/cm2, 35.4 ?C/cm2, 5.25 kV/mm, 0.11%, 107pC/N, and 0.45, respectively. The low temperature humps of relative dielectric constant, which is indicative of TR-T, are becoming inconspicuous gradually with the increasing x and almost disappear at x = 0.04. The depolarization temperature Td decreases first and then increases with the increasing x. Our results may be helpful for further work on Bi0.5Na0.5TiO3-based lead-free piezoelectric ceramics.

Guo, Fei-Fei; Yang, Bin; Zhang, Shan-Tao; Liu, Xiao; Zheng, Li-Mei; Wang, Zhu; Wu, Feng-Min; Wang, Da-Li; Cao, Wen-Wu

2012-06-01

37

Piezoelectric Properties of Lead-Free Na0.5K0.5NbO3 Ceramics Co-Doped with NiO and CuO  

Microsoft Academic Search

Lead-free Na0.5K0.5NbO3 + 0.5 mol% NiO+y mol% CuO (y = 0?3) piezoelectric ceramics have been prepared by conventional solid state reaction technique. The crystal structure and microstructure were analyzed using X-ray diffraction and scanning electron microscopy, respectively. The results indicated that the co-doping of NiO and CuO was very effective in densification of ceramics. The KNN ceramics co-doped with 0.5mol%

Weon-Pil Tai; Young-Hyeok Kim; Yun-Po Ok; Han-Na Ji; Sang-Kyu Kang; Jae-Shin Lee

2010-01-01

38

Temperature stability of ([Na{sub 0.5}K{sub 0.5}NbO{sub 3}]{sub 0.93}-[LiTaO{sub 3}]{sub 0.07}) lead-free piezoelectric ceramics  

SciTech Connect

A polymorphic phase transition (PPT) is often engineered into lead-free materials to generate high piezoelectric activity at room temperature, limiting their temperature stability. We report [Na{sub 0.5}K{sub 0.5}NbO{sub 3}]{sub 0.93}-[LiTaO{sub 3}]{sub 0.07} tetragonal ceramics with favorable properties over a broad temperature range due to a high Curie temperature at 447 deg. C and PPT at -15 deg. C involving a transition to a monoclinic rather than low temperature orthorhombic phase. Piezoelectric k{sub 31} and d{sub 31} coefficients varied from 0.19 to 0.14 and -53 to -33 pC/N, respectively, over the range of -15 to 300 deg. C. Strain-electric field loops provided strains of {approx}0.2% and a high-field d{sub 33} of 205 pm/V.

Skidmore, Thomas A.; Comyn, Tim P.; Milne, Steven J. [Institute for Materials Research, University of Leeds, Leeds LS2 9JT (United Kingdom)

2009-06-01

39

Formation of Morphotropic Phase Boundary in (Na0.5K0.5)NbO3--BaZrO3--(Bi0.5Li0.5)TiO3 Lead-Free Piezoelectric Ceramics  

NASA Astrophysics Data System (ADS)

For the development of lead-free piezoelectric ceramics, which have a tetragonal--rhombohedral morphotropic phase boundary (MPB), 0.90(Na0.5K0.5)NbO3--xBaZrO3--(0.10 - x)(Bi0.5Li0.5)TiO3 ceramics have been synthesized by the conventional solid state reaction method. A phase diagram was summarized from the X-ray diffraction pattern and the dielectric measurements. It is found that 0.90(Na0.5K0.5)NbO3--xBaZrO3--(0.10 - x)(Bi0.5Li0.5)TiO3 ceramics have an MPB between x = 0.07 and 0.08. In the vicinity of the MPB, it was observed that the dielectric and piezoelectric properties were enhanced.

Zushi, Junta; Ariizumi, Takuma; Kojima, Seiji; Wang, Ruiping; Bando, Hiroshi

2013-07-01

40

FAST TRACK COMMUNICATION: Polymorphic phase transition and enhanced piezoelectric properties of LiTaO3-modified (Na0.52K0.48) (Nb0.93Sb0.07)O3 lead-free ceramics  

NASA Astrophysics Data System (ADS)

Lead-free (Na0.52K0.48-x)(Nb0.93-xSb0.07)O3-xLiTaO3 (NKNS7-xLT) solid solution piezoelectric ceramics were investigated in terms of their phase transition behaviour and various electrical properties. The polymorphic phase transition of NKNS7 compositions with an orthorhombic structure was shifted downwards with the addition of a small amount of LT; however, the tetragonal ferroelectric to cubic paraelectric phase transition was moved slightly upwards. The polymorphic phase boundary between the orthorhombic and the tetragonal phases was thus formed near room temperature among the compositions with 0.03 <= x <= 0.0375 where enhanced piezoelectric and electromechanical properties were achieved. The compositions close to the tetragonal side exhibit better piezoelectric properties and temperature stability. The optimum electrical properties of d33 = 362 pC N-1, kp = 53%, \\varepsilon _{33}^T =2165 , Qm = 37 and Tc = 271 C were obtained in the composition with x = 0.0375. The results indicate that the materials studied could be an excellent candidate for replacing the widely used lead-based piezoelectric ceramics.

Fu, Jian; Zuo, Ruzhong; Wang, Xiaohui; Li, Longtu

2009-01-01

41

Microstructure and electrical properties of La-modified K0.5Na0.5NbO3 lead-free piezoelectric ceramics  

Microsoft Academic Search

Lead-free ceramics (K0.5Na0.5)1-3xLaxNbO3 (0 <= x <= 0.0175) have been fabricated by a conventional sintering technique. The results of XRD show that the ceramics possess a perovskite structure with orthorhombic symmetry. Moreover, doping inhibits the grain growth, decreases the ferroelectric-paraelectric phase transition temperature and induces a diffuse phase transition. At low doping levels (x <= 0.0075), the observed remanent polarization

Daojiang Gao; K. W. Kwok; Dunmin Lin; H. L. W. Chan

2009-01-01

42

PHASE TRANSITION, DIELECTRIC AND PIEZOELECTRIC PROPERTIES OF NaNbO3-Ba0.85Ca0.15(Ti0.9Zr0.1)O3 LEAD-FREE CERAMICS  

NASA Astrophysics Data System (ADS)

A new lead-free solid solution of (1-x)NaNbO3-xBa0.85Ca0.15(Ti0.9Zr0.1)O3 was prepared by a traditional sintering method and its phase transition, dielectric and piezoelectric properties were studied. Ba0.85Ca0.15(Ti0.9Zr0.1)O3 diffuses into NaNbO3 lattices to form a new solid solution with perovskite structure. The addition of Ba0.85Ca0.15(Ti0.9Zr0.1)O3(x?0.025) transforms NaNbO3 from antiferroelectric to ferroelectric. The diffusive ferroelectric-paraelectric phase transition is induced in the ceramics with high concentration of Ba0.85Ca0.15(Ti0.9Zr0.1)O3. The ceramics with x = 0.05-0.125 possess large Pr values of 18.6-25.5 ?C/cm2. A morphotropic phase boundary between tetragonal and orthorhombic phases is formed at 0.05 < x < 0.15, leading to a significant enhancement of piezoelectric properties. The ceramic with x = 0.125 situated near the morphotropic phase boundary exhibits the optimum piezoelectric properties: d33 = 151 pC/N and kp = 31.6%.

Lei, Yuqing; Wu, Hong; Lin, Dunmin; Zheng, Qiaoji; Wu, Xiaochun; Fan, Ximing

2012-09-01

43

Investigation of a new lead-free Bi0.5(Na0.40K0.10)TiO3-(Ba0.7Sr0.3)TiO3 piezoelectric ceramic.  

PubMed

Lead-free piezoelectric compositions of the (1-x)Bi0.5(Na0.40K0.10)TiO3-x(Ba0.7Sr0.3)TiO3 system (when x = 0, 0.05, 0.10, 0.15, and 0.20) were fabricated using a solid-state mixed oxide method and sintered between 1,050C and 1,175C for 2 h. The effect of (Ba0.7Sr0.3)TiO3 [BST] content on phase, microstructure, and electrical properties was investigated. The optimum sintering temperature was 1,125C at which all compositions had densities of at least 98% of their theoretical values. X-ray diffraction patterns that showed tetragonality were increased with the increasing BST. Scanning electron micrographs showed a slight reduction of grain size when BST was added. The addition of BST was also found to improve the dielectric and piezoelectric properties of the BNKT ceramic. A large room-temperature dielectric constant, ?r (1,609), and piezoelectric coefficient, d33 (214 pC/N), were obtained at an optimal composition of x = 0.10. PMID:22221833

Jaita, Pharatree; Watcharapasorn, Anucha; Jiansirisomboon, Sukanda

2012-01-05

44

Polymorphic phase boundaries and enhanced piezoelectric response in extended composition range in the lead free ferroelectric BaTi1-xZrxO3  

NASA Astrophysics Data System (ADS)

Neutron powder diffraction study of Ba(Ti1-xZrx)O3 at close composition intervals has revealed coexistence of ferroelectric phases: orthorhombic (Amm2) + tetragonal (P4mm) for 0.02 <= x <=0.05 and rhombohedral (R3m) + orthorhombic (Amm2) for 0.07 <= x < 0.09. These compositions exhibit relatively enhanced piezoelectric properties as compared to their single phase counterparts outside this composition region, confirming the polymorphic phase boundary nature of the phase coexistence regions.

Kalyani, Ajay Kumar; Senyshyn, Anatoliy; Ranjan, Rajeev

2013-07-01

45

Dielectric behavior and microstructure of (Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-BaTiO3 lead-free piezoelectric ceramics  

NASA Astrophysics Data System (ADS)

(0.95-x)(Bi1/2Na1/2)TiO3-x(Bi1/2K1/2)TiO3-0.05BaTiO3 lead-free piezoelectric ceramics (abbreviated as BNT-BKT-BT100x with x varying from 0 to 20 mol %) are prepared by a solid-state reaction process. Variation of the dielectric properties and microstructure of BNT-BKT-BT100x ceramics with BKT content is studied. The results indicate that the relative permittivity ?r and loss tangent tan ? vary with the BKT amount. Scanning electron microscope observation also indicates that BKT in high amount affects the microstructure. X-ray diffraction analysis shows that the incorporated BKT diffuses into the BNT-BT lattice to form a solid solution during sintering.

Wang, X. X.; Choy, S. H.; Tang, X. G.; Chan, H. L. W.

2005-05-01

46

Effects of Li content on the phase structure and electrical properties of lead-free (Ag0.85-xLixNa0.1K0.05)NbO3 piezoelectric ceramics  

NASA Astrophysics Data System (ADS)

Lead-free ceramics (Ag0.85-xLixNa0.1K0.05)NbO3 (ALNKN-x, x = 0-0.16) doped with 0.5 mol. % CuO were prepared by solid state reaction method under air atmosphere. The effects of Li content on the phase structure and electrical properties of the ALNKN-x ceramics were investigated. A morphotropic phase boundary (MPB) between orthorhombic and rhombohedral phases is found at x ~ 0.08-0.14. Both the ferroelectric-ferroelectric phase transition temperature (TFE) and Curie temperature (TC) shift toward higher temperatures with increasing x. Only the phase transition peak near the TC is observed when x >= 0.12. The ferroelectric phase of the ALNKN-x ceramics becomes more stable with increasing x. Furthermore, the ceramics with x = 0.12 exhibit relatively good electrical properties along with a high Curie temperature (d33 = 44 pC/N, kp = 17.7%, Pr = 14.5 C/cm2, Ec = 37.2 kV/cm, and Tc = 335 C). The results provide helpful guidance to develop new lead-free piezoelectric materials with good temperature stability.

Wu, Lang; Liu, Naiming; Zhou, Fei; Teng, Yuancheng; Li, Yuxiang

2012-03-01

47

Reliability Evaluation of Piezoelectric Micro-Actuators With Application in Hard Disk Drives  

Microsoft Academic Search

Piezoelectric micro-actuators have been extensively studied and used in hard disk drive head positioning systems. In these cases, piezoelectric micro-actuators\\/sensors experience high frequency cyclic loading during their operations. The fatigue failure and the lifespan of such micro-actuators become a concern of researchers and engineers. However, the probability and statistics based reliability theory has not been well developed for piezoelectric micro

Zhimin He; Han Tong Loh; Eng Hong Ong

2008-01-01

48

Fabrication of piezoelectric ceramic micro-actuator and its reliability for hard disk drives  

Microsoft Academic Search

A new U-type micro-actuator for precisely positioning a magnetic head in high-density hard disk drives was proposed and developed. The micro-actuator is composed of a U-type stainless steel substrate and two piezoelectric ceramic elements. Using a high-d31 piezoelectric coefficient PMN-PZT ceramic plate and adopting reactive ion etching process fabricate the piezoelectric elements. Reliability against temperature was investigated to ensure the

Yang Jing; Jianbin Luo; Wenyan Yang; Guoxian Ju

2004-01-01

49

Origin of high piezoelectric response in A-site disordered morphotropic phase boundary composition of lead-free piezoelectric 0.93(Na0.5Bi0.5)TiO3-0.07BaTiO3  

NASA Astrophysics Data System (ADS)

Perovskite piezoelectric compositions near the morphotropic phase boundary (MPB) are known to exhibit high piezoelectric response. In lead-based ABO3 compound with B-site disorder, the origin of this enhancement has been associated with the presence of an intermediate monoclinic/orthorhombic state that bridges the adjacent ferroelectric rhombohedral and tetragonal phases. However, the origin of high piezoelectric response in lead-free ABO3 compounds with A-site disorder has not been conclusively established. We describe a microscopic model derived from comparative analyses of high resolution transmission electron microscopy and neutron diffraction that explains the origin of high piezoelectric response in lead-free MPB compositions of 0.93(Na0.5Bi0.5)TiO3-0.07BaTiO3. Direct observation of nanotwins with monoclinic symmetry confirmed the presence of an intermediate bridging phase that facilitates a pathway for polarization reorientation. Monoclinic distortions of an average rhombohedral phase are attributed to localized displacements of atoms along the non-polar directions.

Maurya, Deepam; Murayama, M.; Pramanick, A.; Reynolds, W. T.; An, Ke; Priya, Shashank

2013-03-01

50

Growth and characterization of lead-free piezoelectric BaZr0.2Ti0.8O3Ba0.7Ca0.3TiO3 thin films on Si substrates  

NASA Astrophysics Data System (ADS)

Lead-free piezoelectric BaZr0.2Ti0.8O3Ba0.7Ca0.3TiO3 (BCZT) thin films were grown on La0.7Sr0.3MnO3-buffered Si (0 0 1) by off-axis RF magnetron sputtering at temperatures ranging from 550 to 810 C. In this article, we present the detailed investigation on structure, leakage current behaviors and electromechanical properties of BCZT thin films. The crystallographic texture and grain size of the as-grown thin films are strongly dependent on the growth temperature, which consequently affects the leakage behaviors and local electromechanical properties. The crystallographic orientation becomes better and the grain size increases when increased the substrate temperature. The dominant leakage mechanism is found to be space-charge-limited conduction at low electric field, while a Fowler-Nordheim tunneling is confirmed in high electric field region for the films deposited at 710 C and 810 C. The increasing growth temperature also leads to remarkable improvement in the local electromechanical properties of the films. The BCZT film deposited at an optimal temperature of 810 C exhibits a considerably high effective piezoelectric coefficient d33,f of 94 4 pm/V, which is comparable to that of a typical lead zirconate titanate thin film.

Luo, B. C.; Wang, D. Y.; Duan, M. M.; Li, S.

2013-04-01

51

Electromechanical and ferroelectric properties of (Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-BaTiO3 lead-free piezoelectric ceramics  

NASA Astrophysics Data System (ADS)

Lead-free piezoelectric ceramics (0.95-x)(Bi1/2Na1/2)TiO3-x(Bi1/2K1/2)TiO3-0.05BaTiO3 (abbreviated as BNT-BKT-BT100x, with x ranged from 0 to 20 mol %) have been studied. Effects of amount of BKT on the electrical properties and crystal structure were examined. BNT-BKT-BT5 ceramics give good performances with piezoelectric constant d33=148 pC/N, electromechanical coupling factor kp=34 %, kt=49.2 %, free permittivity ?33T/?0=700, and dissipation factor tan?=2 % at 1 kHz. Accordingly, the sample shows larger remanent polarization and lower coercive field than 0.95BNT-0.05BT ceramics. X-ray diffraction analysis shows that incorporated BKT diffuses into the BNT-BT lattice to form a solid solution during sintering, but changes the crystal structure from rhombohedral to tetragonal symmetry at higher BKT amounts.

Wang, X. X.; Tang, X. G.; Chan, H. L. W.

2004-07-01

52

Diffuse phase transition and electrical properties of lead-free piezoelectric (LixNa1-x)NbO3 (0.04 <= x <= 0.20) ceramics near morphotropic phase boundary  

NASA Astrophysics Data System (ADS)

Temperature-dependent dielectric permittivity of lead-free (LixNa1-x)NbO3 for nominal x = 0.04-0.20, prepared by solid state reaction followed by sintering, was studied to resolve often debated issue pertaining to exactness of morphotropic phase boundary (MPB) location besides structural aspects and phase stability in the system near MPB. Interestingly, a diffuse phase transition has been observed in the dielectric permittivity peak arising from the disorder induced in A-site and structural frustration in the perovskite cell due to Li substitution. A partial phase diagram has been proposed based on temperature-dependent dielectric permittivity studies. The room temperature piezoelectric and ferroelectric properties were investigated and the ceramics with x = 0.12 showed relatively good electrical properties (d33 = 28 pC/N, kp = 13.8%, Qm = 440, Pr = 12.5 ?C/cm2, Ec = 43.2 kV/cm, and Tm = 340 C). These parameter values make this material suitable for piezoelectric resonator and filter applications. Moreover, a high dielectric permittivity (?'r = 2703) with broad diffuse peak near transition temperature, and low dielectric loss (<4%) over a wide temperature range (50-250 C) found in this material may also have a potential application in high-temperature multilayer capacitors in automotive and aerospace related industries.

Mitra, S.; Kulkarni, A. R.; Prakash, Om

2013-08-01

53

Phase transitional behavior, microstructure, and electrical properties in Ta-modified [(K0.458Na0.542)0.96Li0.04] NbO3 lead-free piezoelectric ceramics  

NASA Astrophysics Data System (ADS)

Lead-free [(K0.458Na0.542)0.96Li0.04] (Nb1-xTax)O3 ceramics were prepared by ordinary sintering technique. The effects of Ta content on the phase transitional behavior, Raman spectrum, microstructure, and dielectric, piezoelectric, and ferroelectric properties of the ceramics were investigated. X-ray diffraction results indicate that the phase structure undergoes a transition from orthorhombic to tetragonal phase with the increase in x. The small and large peaks observed in the Raman spectra can all be attributed to the internal modes of the NbO6 octahedron, and both ?5 and ?1 modes slightly shift to lower frequency numbers by increasing x. Ta substitution for Nb leads to the disappearance of the abnormal grain growth behavior, inhibits the grain growth, and improves the density of the ceramics. Increasing x leads to the different variations of dielectric constants before and after poling and makes the ceramics more relaxorlike. The proper substitution of Ta shifts the polymorphic phase transition (at To-T) to near room temperature, and a coexistence of orthorhombic and tetragonal phases is formed, which leads to significant enhancements of the electrical properties. For the ceramics with x=0.15, the electrical properties become optimum, which are as follows: piezoelectric coefficient d33=298 pC/N, electromechanical coupling coefficient kp=0.52, dielectric constant ?r=1195, dielectric loss tan ?=0.016, To-T=35 C, Curie temperature TC=366 C, remanent polarization Pr=28.68 ?C/cm2, and coercive field Ec=7.14 kV/cm. These properties are much higher than those of previously reported (K,Na,Li)(Nb,Ta)O3 systems with K:Na=1:1.

Chang, Yunfei; Yang, Zu-Pei; Ma, Difei; Liu, Zonghuai; Wang, Zenglin

2008-07-01

54

Raman- and Brillouin-scattering studies on lead-free piezoelectric Bi0.5(Na0.78K0.22)0.5- x TiO3 ceramics with A-site vacancies  

NASA Astrophysics Data System (ADS)

The Raman and Brillouin spectra of lead-free piezoelectric Bi0.5(Na0.78K0.22)0.5- x TiO3 ceramics with A-site vacancies were investigated for x = 0 0.05. The Raman spectra measured at room temperature showed seven broad bands over the range of 50-1000 cm-1, reflecting strong anharmonicity, inherent A-site disorder and the resulting breakdown of the Raman selection rule. The splitting of the A1 mode near 270 cm-1 indicated that the tetragonal symmetry was maintained over the whole x range, consistent with the X-ray diffraction results. The Brillouin spectra exhibited distributed longitudinal and transverse acoustic modes, in addition to central peaks. The distributed acoustic modes were attributed to the scattering events at all scattering angles from 0 to 180 due to multiple reflections and refractions at the grain boundaries. The relaxation time obtained from fitting the broad central peak by using a Debye function exhibited a slowing-down behavior in the paraelectric phase. The formation of the central peak was attributed to the existence of nano-sized polar regions due to the anharmonic vibrations and the hopping motions of the A-site cations.

Kim, Tae Hyun; Kojima, Seiji; Ahn, Chang Won; Kim, Ill Won; Ko, Jae-Hyeon

2013-04-01

55

Lead-free acoustic emission sensors  

SciTech Connect

Acoustic emission (AE) sensors have been fabricated using both soft- and hard-type lead-free (Na{sub 0.5}K{sub 0.5})NbO{sub 3}-based ceramics. The acoustic and electromechanical properties of the ceramics have been determined using the resonance technique. The lead-free AE sensors were calibrated using a laser source and compared to a commercial sensor. A lead zirconate titanate (PZT) 5H ceramics AE sensor has also been fabricated and calibrated for comparison. It was found that the sensitivity of lead-free AE sensors is comparable to that of the lead-based PZT sensor. To evaluate the sensors for potential application, they have been used in the detection of AE in an impact test. The lead-free sensors can reproduce AE signals accurately without giving artifacts and have potential use in commercial AE systems.

Lam, K. H.; Lin, D. M.; Chan, H. L. W. [Department of Applied Physics, Hong Kong Polytechnic University, Hunghom, Hong Kong, China and Materials Research Centre, Hong Kong Polytechnic University, Hunghom, Hong Kong (China)

2007-11-15

56

Complete set of material constants of 0.95(Na0.5Bi0.5)TiO3-0.05BaTiO3 lead-free piezoelectric single crystal and the delineation of extrinsic contributions  

NASA Astrophysics Data System (ADS)

Lead-free piezoelectric single crystal 0.95(Na0.5Bi0.5)TiO3 (NBT)-0.05BaTiO3 was grown by top-seeded solution growth method, which has rhombohedral symmetry with composition near morphotropic phase boundary. Full set of dielectric, piezoelectric, and elastic constants for [001]c poled domain-engineered single crystal was determined. Excellent electromechanical properties and low dielectric loss (d33 = 360 pC/N, d31 = -113 pC/N, d15 = 162 pC/N, k33 = 0.720, kt = 0.540, and tan ? = 1.1%) make it a good candidate to replace lead-based piezoelectric materials. The depolarization temperature (Td = 135 C) is the highest among all NBT-based materials and its electromechanical coupling properties are very stable below Td. Extrinsic contributions to piezoelectric properties were investigated by Rayleigh analysis.

Zheng, Limei; Yi, Xiujie; Zhang, Shantao; Jiang, Wenhua; Yang, Bin; Zhang, Rui; Cao, Wenwu

2013-09-01

57

Dielectric and piezoelectric properties of Y{sub 2}O{sub 3} doped (Bi{sub 0.5}Na{sub 0.5}){sub 0.94}Ba{sub 0.06}TiO{sub 3} lead-free piezoelectric ceramics  

SciTech Connect

Y{sub 2}O{sub 3} doped lead-free piezoelectric ceramics (Bi{sub 0.5}Na{sub 0.5}){sub 0.94}Ba{sub 0.06}TiO{sub 3} (0-0.7 wt%) were synthesized by the conventional solid state reaction method, and the effect of Y{sub 2}O{sub 3} addition on the structure and electrical properties was investigated. X-ray diffraction shows that Y{sub 2}O{sub 3} diffuses into the lattice of (Bi{sub 0.5}Na{sub 0.5}){sub 0.94}Ba{sub 0.06}TiO{sub 3} to form a solid solution with a pure perovskite structure. The temperature dependence of dielectric constant of Y{sub 2}O{sub 3} doped samples under various frequencies indicates obvious relaxor characteristics different from typical relaxor ferroelectric and the mechanism of the relaxor behavior was discussed. The optimum piezoelectric properties of piezoelectric constant d{sub 33} = 137 pC/N and the electromechanical coupling factor k{sub p} = 0.30 are obtained at 0.5% and 0.1% Y{sub 2}O{sub 3} addition, respectively.

Zhou Changrong [Department of Information Material Science and Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China)], E-mail: zcr750320@yahoo.com.cn; Liu Xinyu [Department of Information Material Science and Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Li Weizhou [School of Resources and Environments, Guangxi University, Nanning, Guangxi 530004 (China); Yuan Changlai [Department of Information Material Science and Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China)

2009-04-02

58

Detection and suppression for mechanical resonance in hard disk drives with built-in piezoelectric sensors  

NASA Astrophysics Data System (ADS)

Many components in hard disk drives (HDDs), when in operation, are subjected to vibration due to out of balance of rotating components, inertial impacts under servo driving and dynamic interactions between components. These vibrations have been found to have significant effect upon the servo performance of drive systems. In order to improve the servo performance by reducing the effect of mechanical resonance in HDDs, this paper seeks to detect and suppress mechanical resonance of the head actuator using smart sensors and multi-sensing control techniques. In this regard, sensitive and miniature piezoelectric elements from the polymer-based piezoelectric materials PVDF (polyvinylindin fluoride) or the ceramic-based piezoelectric materials PZT 9lead zircornate titanate) are built in the head actuator for sensing the mechanical vibration. In the experiment, the multi-sensing signals by the piezoelectric sensors and the laser Doppler vibrometer (LDV) are transferred into a voice coil motor (VCM) through a feedback controller so as to actively suppress structural resonance. Numerical simulation and experimental results indicate that the piezoelectric sensors provide an effective way in monitoring the HDD actuator resonance, and the active vibration control strategy is capable of suppressing main mechanical resonance in the head actuator effectively.

Gao, Peng; Lou, Yaolong; Okada, Kanzo

2002-07-01

59

Active Noise Control Using Piezoelectric Actuators in Hard Disk Drives  

Microsoft Academic Search

With the increasing use of electromechanical microsystems, such as hard disk drives, CD-ROM drives, and DVD drives in the consumer electronics industry, there is a growing demand for quieter products. The noise emitted from these devices may originate from the vibration of mechanical components in operation, such as bearings, gears, and actuators. The vibration is then transmitted to other parts

Feng Gao; Ying Yan; Fook Fah Yap

2003-01-01

60

Sintering and piezoelectric properties of lead-free (K0.38Na0.58Li0.04)(Nb0.86Ta0.10Sb0.04)O3 ceramics doped with Fe2O3  

Microsoft Academic Search

Lead-free (K0.38Na0.58Li0.04)(Nb0.86Ta0.10Sb0.04)O3 (KNLNTS) + x mol% Fe2O3 (x = 0 ~ 1) ceramics were prepared by conventional solid state reaction technique. The effect of Fe2O3 doping on the phase structure, microstructure and electrical properties of KNLNTS ceramics were studied. The addition of Fe2O3 was found to be effective in enhancing densification of KNLNTS ceramics. When x = 0.3, the piezoelectric

Yun-Po Ok; Han-Na Ji; Ki-Soo Kim; Weon-Pil Tai; Jeong-Hyeon Seol; In-Ki Hong; Jae-Shin Lee

2011-01-01

61

Enhanced ferroelectric and piezoelectric properties in doped lead-free (Bi0.5Na0.5)0.94Ba0.06TiO3 thin films  

Microsoft Academic Search

Doping effects with respect to the electrical properties of morphotropic phase boundary (Bi0.5Na0.5)0.94Ba0.06TiO3 thin films epitaxially grown on CaRuO3 electroded (LaAlO3)0.3(Sr2AlTaO6)0.35 (001) substrates were investigated. Substantial enhancement of ferroelectricity and piezoelectricity has been achieved in La+Ce codoped films with a remanent polarization Pr of 29.5 muC\\/cm2 and a remanent piezoelectric coefficient d33,f of 31 pm\\/V, whereas Mn doping seems more

D. Y. Wang; N. Y. Chan; S. Li; S. H. Choy; H. Y. Tian; H. L. W. Chan

2010-01-01

62

Enhanced ferroelectric and piezoelectric properties in doped lead-free (Bi0.5Na0.5)0.94Ba0.06TiO3 thin films  

Microsoft Academic Search

Doping effects with respect to the electrical properties of morphotropic phase boundary (Bi0.5Na0.5)0.94Ba0.06TiO3 thin films epitaxially grown on CaRuO3 electroded (LaAlO3)0.3(Sr2AlTaO6)0.35 (001) substrates were investigated. Substantial enhancement of ferroelectricity and piezoelectricity has been achieved in La+Ce codoped films with a remanent polarization Pr of 29.5 ?C\\/cm2 and a remanent piezoelectric coefficient d33,f of 31 pm\\/V, whereas Mn doping seems more

D. Y. Wang; N. Y. Chan; S. Li; S. H. Choy; H. Y. Tian; H. L. W Chan

2010-01-01

63

Piezoelectric and dielectric aging of Bi0.5(Na0.82K0.18)0.5TiO3 lead-free ferroelectric thick films  

NASA Astrophysics Data System (ADS)

Ferroelectric Bi0.5(Na0.82K0.18)0.5TiO3 (NKBT) thick films have been prepared using screen printing on Pt electroded alumina substrates. The room-temperature dielectric constant of resulting 60 ?m thick NKBT film reaches as high as 823 at 1 kHz and the depolarization temperature, Td, locates at 130 C. The effect of amplitude and frequency of the applied ac field and the aging temperature as well as the Bi excess on the dielectric and piezoelectric aging characteristics are systemically studied. The results show that the dielectric and piezoelectric aging are associated with the reorientation of defect dipoles which stabilized the non-180 domain walls. By this reorientation the domain wall motions are clamped by a time dependent force resulting in the observed decrease in the dielectric and piezoelectric properties during the aging procedural. Moreover, the aging in NKBT thick films exhibits strong frequency dependence, which is caused by that the reorientation and alignment of the defect dipoles with the local polar domains provide a pinning field to the micropolar region, where the regions with larger micropolar volume will experience stronger pinning potential. The NKBT thick films added with 0.5 mol % Bi2O3 exhibit relative lower aging rate of the dielectric constant and piezoelectric coefficient, resulting from the compensation of the Bi3+ vacancies by the addition of small amount of excess Bi2O3.

Zhang, Haibo; Jiang, Shenglin; Xiao, Jianzhong; Kajiyoshi, Koji

2010-06-01

64

A piezoelectric quad-morph actuated suspension for hard disk drives  

NASA Astrophysics Data System (ADS)

This paper presents a new milli-actuator using a piezoelectric quad-morph for fine head positioning in hard disk drives (HDDs). The newly proposed piezoelectric quad-morph is configured to produce a diagonal actuation, driving a parallel mechanism embodied into a suspension base plate into a lateral stroke. Finite element modeling shows the actuated suspension achieves a high sway frequency of 13 kHz and an adequate stroke. A parametric study shows that extending the lengths of the quad-morph and the parallel beams can improve both the sway frequency and the lateral stroke. The actuated suspension can also be reinforced with ribs for enhancing shock resistance and dynamic performance, yet without compromising lateral stroke generation. A prototype of the new design is fabricated and manually assembled using a bulk piezoelectric plate and a photo-chemically machined 0.1 mm thick stainless steel load beam. The driving principle of the quad-morph is tested and proven a viable and economical method to accomplish fine head positioning.

Lau, Gih Keong; Du, Hejun

2006-09-01

65

Dielectric, ferroelectric, and piezoelectric properties of Nb-substituted Bi1/2(Na0.82K0.18)1/2TiO3 lead-free ceramics  

NASA Astrophysics Data System (ADS)

The effects of niobium substitution on the crystal structure and on the ferroelectric and piezoelectric properties of Bi1/2(Na0.82K0.18)1/2(Ti)O3 (BNKT) ceramics have been investigated. X-ray diffraction analyses revealed that Nb-substitution induced a phase transition from the coexistence of rhombohedral-tetragonal symmetry to pseudocubic symmetry. Accordingly, the electric-fieldinduced polarization and strain hysteresis loops indicated that Nb substitution significantly disrupted the ferroelectric order of BNKT ceramics, leading to degradations in the remnant polarization, coercive field, and piezoelectric coefficient d 33. However, the destabilization of the ferroelectric order was accompanied by a significant enhancement in the electric-field-induced strain (EFIS), which peaked at x = 0.03 with a value of 0.47%. The abnormal enhancement in the EFIS could be attributed to a phase transition from a non-polar to a polar phase under an applied electric field.

Pham, Ky-Nam; Lee, Han Bok; Han, Hyoung-Su; Kang, Jin Kyu; Lee, Jae-Shin; Ullah, Aman; Ahn, Chang-Won; Kim, Ill Won

2012-01-01

66

Enhanced ferroelectric and piezoelectric properties in doped lead-free (Bi0.5Na0.5)0.94Ba0.06TiO3 thin films  

NASA Astrophysics Data System (ADS)

Doping effects with respect to the electrical properties of morphotropic phase boundary (Bi0.5Na0.5)0.94Ba0.06TiO3 thin films epitaxially grown on CaRuO3 electroded (LaAlO3)0.3(Sr2AlTaO6)0.35 (001) substrates were investigated. Substantial enhancement of ferroelectricity and piezoelectricity has been achieved in La+Ce codoped films with a remanent polarization Pr of 29.5 ?C/cm2 and a remanent piezoelectric coefficient d33,f of 31 pm/V, whereas Mn doping seems more favorite to reduce the leakage current by two order of magnitude. Both doped films exhibited diodelike I-V characteristics, which are correlated with resistance switching effect.

Wang, D. Y.; Chan, N. Y.; Li, S.; Choy, S. H.; Tian, H. Y.; Chan, H. L. W.

2010-11-01

67

Design and fabrication of a piezoelectric instrumented suspension for hard disk drives  

NASA Astrophysics Data System (ADS)

As data densities in computer hard disk drives increase, airflow-induced vibration of the disk drive suspension becomes a major barrier to positioning the read-write head with sufficient precision. One component in reducing these vibrations is a dedicated sensor system for detecting vibration on the sensor arm directly, which enables high-frequency sampling and modal selectivity. In this paper, an efficient method for identifying optimal position and shape of piezoelectric strain gages on a flexible structure is presented, and applied to the steel suspension of a hard disk drive. Zinc oxide deposition processes are adapted to steel substrates, and used to fabricate miniature zinc oxide strain gages at the optimal strain gage location. Substrates with sensors installed were assembled into full disk drive suspensions and tested in a commercial disk drive.

Kon, Stanley; Oldham, Kenn; Ruzicka, Ryan; Horowitz, Roberto

2006-04-01

68

Orientation-dependent piezoelectric properties in lead-free epitaxial 0.5BaZr0.2Ti0.8O3-0.5Ba0.7Ca0.3TiO3 thin films  

NASA Astrophysics Data System (ADS)

Orientation-engineered 0.5BaZr0.2Ti0.8O3-0.5Ba0.7Ca0.3TiO3 (BZT-BCT) thin films were deposited on La0.7Sr0.3MnO3-coated SrTiO3 single-crystalline (001), (110), and (111) substrates by off-axis radio-frequency magnetron sputtering. X-ray diffraction confirmed a highly epitaxial growth of all the as-deposited films. It is believed the strong orientation dependence of ferroelectric and piezoelectric properties on the films is attributed to the relative alignment of crystallites and spontaneous polarization vector. The optimal ferroelectric response lies in the [001] direction, whereas a comparatively large effective piezoelectric coefficient d33,eff of 100.1 +/- 5 pm/V was attained in [111] BZT-BCT thin film, suggesting its potential application for high-performance lead-free piezoelectric devices.

Luo, B. C.; Wang, D. Y.; Duan, M. M.; Li, S.

2013-09-01

69

Dielectric and piezoelectric properties in the lead-free system Na0.5K0.5NbO3-BiScO3-LiTaO3.  

PubMed

Phase relations, dielectric and piezoelectric properties are reported for the ternary system 98%[(1 - x) (Na(0.5)K(0.5)NbO(3))-x(LiTaO(3))]-2%[BiScO(3)] for compositions x ? 10 mol% LiTaO(3). The phase content at room-temperature changed from mixed phase, monoclinic + tetragonal, for unmodified 98%(Na(0.5)K(0.5)NbO(3))-2%(BiScO(3)), to tetragonal phase for compositions >2 mol% LiTaO(3). Curie peaks at 360 to 370C were observed for all compositions, but peaks became diffuse at x ? 3 mol%, and two dielectric peaks, at 370 and 470C, were observed for 5 mol% LiTaO(3). Phase segregation, and finite size affects associated with the core-shell structure, account for the occurrence of two dielectric peaks in 5 mol% LiTaO(3), and diffuse dielectric behavior. The value of d(33) piezoelectric charge coefficient increased from ~160 pC/N for 0 mol% LiTaO(3) to 205 to 214 pC/N for 1 to 2 mol% LiTaO3 solid solutions, before falling sharply at 3 mol% LiTaO(3). TEM-EDX analysis revealed core-shell grain structures with segregation of Bi, Sc, and Ta in the outer ~100-nm shell of the 5 mol% LT sample. PMID:21937312

Zhu, Fangyuan; Ward, Michael B; Comyn, Tim P; Bell, Andrew J; Milne, Steven J

2011-09-01

70

Dielectric behavior and microstructure of (Bi{sub 1/2}Na{sub 1/2})TiO{sub 3}-(Bi{sub 1/2}K{sub 1/2})TiO{sub 3}-BaTiO{sub 3} lead-free piezoelectric ceramics  

SciTech Connect

(0.95-x)(Bi{sub 1/2}Na{sub 1/2})TiO{sub 3}-x(Bi{sub 1/2}K{sub 1/2})TiO{sub 3}-0.05BaTiO{sub 3} lead-free piezoelectric ceramics (abbreviated as BNT-BKT-BT100x with x varying from 0 to 20 mol %) are prepared by a solid-state reaction process. Variation of the dielectric properties and microstructure of BNT-BKT-BT100x ceramics with BKT content is studied. The results indicate that the relative permittivity {epsilon}{sub r} and loss tangent tan {delta} vary with the BKT amount. Scanning electron microscope observation also indicates that BKT in high amount affects the microstructure. X-ray diffraction analysis shows that the incorporated BKT diffuses into the BNT-BT lattice to form a solid solution during sintering.

Wang, X.X.; Choy, S.H.; Tang, X.G.; Chan, H.L.W. [Department of Applied Physics and Materials Research Center, Hong Kong Polytechnic University, Hunghom Kowloon, Hong Kong (China)

2005-05-15

71

Enhanced ferroelectric and piezoelectric response in Mn-doped Bi0.5Na0.5TiO3BaTiO3 lead-free film by pulsed laser deposition  

NASA Astrophysics Data System (ADS)

Mn-doped Bi0.5Na0.5TiO3BaTiO3 thin film with the composition around the morphotropic phase boundary was grown on Pt-electrodized Si substrate by pulsed laser deposition. Highly (1 0 0)-oriented film with pure perovskite structure was obtained through carefully controlling the growth conditions. Well-defined ferroelectric PE loop was obtained with the average remnant polarization Pr and coercive field Ec of 11.3 ?C/cm2 and 6.5 kV/mm, respectively. Polycrystalline structures and multidomain states were revealed by piezoresponse force microscopy and large local strain response was obtained with the normalized strain Smax/Emax up to 92 pm/V. The excellent global electrical properties make it quite promising in environmental-friendly ferroelectric and piezoelectric devices.

Jin, Chengchao; Wang, Feifei; Leung, Chung Ming; Yao, Qirong; Tang, Yanxue; Wang, Tao; Shi, Wangzhou

2013-10-01

72

Phase diagram and structure-property relationships in the lead-free piezoelectric system: Na0.5K0.5NbO3-LiTaO3.  

PubMed

A phase-diagram for the Na(0.5)K(0.5)NbO(3)-LiTaO(3) solid solution series (NKN-LT) is presented for compositions ? 10 mol% LT, based on the combined results of temperaturevariable X-ray powder diffraction and dielectric measurements. In addition to the reported orthorhombic and tetragonal polymorphs of NKN-LT, a monoclinic phase is revealed. Changes to electrical properties as a function of LT substitution are correlated to phase content. Increasing the LT content from 5 to 7 mol% LT led to improved temperature stability of piezoelectric properties because of the avoidance of the monoclinic-tetragonal polymorphic phase transition during thermal cycling (at >25C). For 7 mol% LT samples: d(33) = 200 pC/N; T(c) = 440C; ?(r) = 550 and tan ? = 0.02 (at 20C). Modification of this composition by solid solution with BiScO(3) led to a decrease in d(33) values. Transmission electron microscopy of a sample of 0.95[0.93 NKN-0.07LT]-0.05BiScO(3) indicated a core-shell grain structure which led to temperature-stable dielectric properties. PMID:21937313

Skidmore, Thomas A; Comyn, Timothy P; Bell, Andrew J; Zhu, Fangyuan; Milne, Steven J

2011-09-01

73

Assessing lead-free intellectual property  

Microsoft Academic Search

This paper presents the analysis of information collected from numerous patent searches on lead-free alloys. The significance of claim structure and content is discussed in view of the growing number of lead-free patents. Patent analysis software was developed to effectively compare over 350 lead-free alloy patents. A case study was conducted to assess Sn-Ag-Cu and special purpose lead-free candidate alloy

Paul Casey; Michael Pecht

2004-01-01

74

Lead-free electric matches.  

SciTech Connect

Electric matches are used in pyrotechnics to initiate devices electrically rather than by burning fuses. Fuses have the disadvantage of burning with a long delay before igniting a pyrotechnic device, while electric matches can instantaneously fire a device at a user's command. In addition, electric matches can be fired remotely at a safe distance. Unfortunately, most current commercial electric match compositions contain lead as thiocyanate, nitroresorcinate or tetroxide, which when burned, produces lead-containing smoke. This lead pollutant presents environmental exposure problems to cast, crew, and audience. The reason that these lead containing compounds are used as electric match compositions is that these mixtures have the required thermal stability, yet are simultaneously able to be initiated reliably by a very small thermal stimulus. A possible alternative to lead-containing compounds is nanoscale thermite materials (metastable intermolecular composites or MIC). These superthermite materials can be formulated to be extremely spark sensitive with tunable reaction rate and yield high temperature products. We have formulated and manufactured lead-free electric matches based on nanoscale Al/MoO{sub 3} mixtures. We have determined that these matches fire reliably and to consistently ignite a sample of black powder. Initial safety, ageing and performance results are presented in this paper.

Son, S. F. (Steven F.); Hiskey, M. A. (Michael A.); Naud, D. (Darren); Busse, J. R. (James R.); Asay, B. W. (Blaine W.)

2002-01-01

75

Magnetoelectric effect in lead-free BNKLBT ceramic/terfenol-D continue fiber composite laminates  

SciTech Connect

A magnetostrictive-piezoelectric laminated composite has been developed by sandwiching a lead-free BNKLBT ceramic plate polarized in the thickness direction between two terfenol-D continuous fiber composite plates. This lead-free magnetoelectric (ME) laminated composite has a large ME voltage sensitivity of 2.5 V/Oe at the resonance frequency of 130.9 kHz under a low magnetic bias field (H{sub Bias}) of 0.6 kOe. This work shows the potential of BNKLBT lead-free ceramics in ME sensing application.

Lo, C. Y.; Choy, S. H.; Or, S. W.; Chan, H. L. W. [Department of Applied Physics and Materials Research Centre, Hong Kong Polytechnic University, Hunghom (Hong Kong)

2010-05-15

76

Raman Spectroscopy Research of Perovskites Lead Free Ferroelectrics  

NASA Astrophysics Data System (ADS)

Recently, lead-free ferroelectrics have been much of interests as an effective alternative to PZT ceramics for the environmental reasons. Notable progress has been made in chemically modified (K0.5Na0.5)NbO3 (KNN) and (Na0.5Bi0.5)TiO3 (NBT)-based lead-free piezoelectric ceramics, which have high piezoelectricity comparable to PZT ceramics. There are many phases and transitions in lead-free ferroelectrics, for instance, ferrolectric, antiferroelectric which are much to be learned from Raman spectroscopy. Some transitions in lead-free ferroelectrics are not sharp but diffuse, or have coexisting phases. Here, there is an introduction to ferroelectricity(FE) and anti-ferroelectricity(AFE). FE is a spontaneous electric polarization of a material that can be reversed by the application of an external electric field or changing temperature. AFE is that materials consist of an ordered array of electric dipoles, but with adjacent dipoles oriented in opposite directions. This can be contrasted with FE, in which the dipoles all point in the same direction. Various spectroscopic techniques have been employed to explore lead-free ferroelectrics, including infrared reflectivity, neutron and x-ray scattering, solid NMR, and Raman scattering, etc. FE type distortions are characterized by unstable or soft phonons, whose frequency decreases on approach transition temperature. Raman is effect for exploring soft mode of FE. For example, for BaTiO3, with temperature change, the body centered Ti atom displaced becoming acentric. Relatively, we can see that when Ti atom moves up while O atoms move down. As a result, dipole moment forms below phase transition. Electron cloud of Ti-O bond changes, with respect to vibration of molecule exhibiting Raman effect. In Raman spectroscopy, a change in molecular polarization potential - or amount of deformation of electron cloud - with respect to vibrational coordinate is required for molecule to exhibit Raman effect. Raman intensity reflects polarizability change and Raman shift stands for proportional to vibrational level involved. Thus from Raman, we can learn much about FE and AFE phase transformations. Raman spectroscopy is effect for researching phase transition in perovskites ferroelectrics.

Luo, L.; Ge, W.; Li, J.; Viehland, D.; Farley, C.; Bodnar, R. J.

2009-12-01

77

New lead-free solder alloy  

Microsoft Academic Search

As the electronics industry is moving towards lead-free manufacturing processes, a new lead-free solder alloy based on Sn9Zn1Bi2CuIn is described. The quaternary alloy with indium additions exhibits melting, wetting, and mechanical properties superior to those in binary, ternary, and quaternary alloys. Indium as a penternary addition decreases the melting point of this alloy to 181C which it is a lower

Mustafa Kamal; M. S. Meikhail; Abu Bakr El-Bediwi; El-Said Gouda

2005-01-01

78

Studies on lead-free multiferroic magnetoelectric composites  

NASA Astrophysics Data System (ADS)

Lead-free multiferroic magnetoelectric composites consisting of ferrimagnetic Ni0.93Co0.02Mn0.05Fe1.95O4 (NMF) and ferroelectric Na0.5Bi0.5TiO3 (NBT) phases were synthesized by the solid-state sintering method. The presence of constituent phases in composites was confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A systematic study of dc conductivity as a function of temperature (RT -450 C) revealed that the conduction is due to small polarons. The effect of constituent phase variation on the dielectric constant and piezoelectric strength (d33) was examined. The composites exhibited typical magnetic hysteresis (M-H) loops at room temperature. Furthermore, magnetoelectric (ME) output was evaluated as a function of applied magnetic field, which is a product property of the constituent phases. The compound 50% NMF-50%NBT is a new lead-free magnetoelectric composite with 155 ?V/cm ME output, which may have potential applications.

Babu, S. Narendra; Srinivas, K.; Bhimasankaram, T.

2009-11-01

79

Rotary Multilayer Split Morph---A Piezoelectric Microactuator for Dual-Stage Actuation Systems in High Track Density Hard Disk Drives  

Microsoft Academic Search

A novel annular rotary piezoelectric microactuator has been proposed for a dual-stage actuation system for future high track density hard disk drives. The microactuator is designed to be mounted on a flexure tongue and drives a slider directly to perform high-frequency track following. The configuration and operation of the microactuator are described. The controllable stroke and the resonance frequency of

Zhihong Wang; Weiguang Zhu; Ooi Kiang Tan; Xi Yao

2001-01-01

80

Roadmap of Lead-free Soldering  

Microsoft Academic Search

In this presentation is profiled in short form roadmap of Lead-free soldering process, which has a general character and sums the most important parameters and factors that concern achievements of good solder joint quality. This course is involved in the 5th semester of the Bachelor study program as well in extended form in Master Study program at Brno University of

Ivan Szendiuch

2007-01-01

81

Interface failure in lead free solder joints  

Microsoft Academic Search

The phenomenon of interface failure in lead free solder joints was explored using solder joint array tensile testing. The effects of pad metallization, solder alloy, reflow conditions, and post reflow thermal aging were quantified. The joint strength ranged from 5 to 115MPa. The joint ductility dropped to zero in some cases. The interface microstructure and failure mode were characterized for

Robert Darveaux; Corey Reichman; Nokibul Islam

2006-01-01

82

THE PROLIFERATION OF LEAD-FREE ALLOYS  

Microsoft Academic Search

The advent of the EU's RoHS law has encouraged a significant amount of research to find an alloy, for electronic assembly, that will satisfy RoHS's lead-free requirement and have optimum process ability and field reliability. The resulting research, much of it lead by iNEMI, resulted in the near eutectic tin-silver-copper alloy SAC387 (Sn95.5Ag3.8Cu 0.7) as an initial favorite to fill

Eric Bastow; Timothy Jensen

2009-01-01

83

Electrochemical migration of lead free solder joints  

Microsoft Academic Search

Electrochemical migration (ECM) tests on lead bearing and lead free solder joints on Cu lamination on FR-4 board were conducted\\u000a by applying constant voltage. This paper first studied the ECM of the soldered joints under distilled water after removing\\u000a the fluxes. In addition, conditions under high temperature and high humidity were also set up to investigate the changes of\\u000a the

D. Q. Yu; W. Jillek; E. Schmitt

2006-01-01

84

Lead free tin based solder composition  

US Patent & Trademark Office Database

Lead-free solder alloys based on a Sn--Ag--Mg system are disclosed. The alloy compositions have a melting temperature close to 183.degree. C. and a similar surface tension to that of Sn--Pb solder, and can thus be a readily substituted for conventional Sn--Pb solders. P may be added to the alloy compositions to reduce its tendency of oxidation.

2004-11-30

85

Reduction of the piezoelectric performance in lead-free (1-x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 piezoceramics under uniaxial compressive stress  

NASA Astrophysics Data System (ADS)

The effect of a uniaxial compressive stress on the properties of BZT-BCT samples across the morphotropic phase boundary (MPB) is investigated using direct piezoelectric coefficient measurements. In contrast to many lead zirconate titanate compositions, the piezoelectric coefficient decreases monotonically with increasing stress and does not show an initial increase or plateau. Electrically softer rhombohedral and MPB compositions are found to be more susceptible to a decrease in piezoelectric coefficient under an increasing pre-stress than tetragonal compositions. Depoling due to ferroelastic domain switching alone, as observed by x-ray diffraction, does not explain this reduction, but instead a decreasing domain wall density is proposed to be responsible for reduced piezoelectric coefficients under increasing compressive stress. The relaxation of the piezoelectric response after complete unloading supports this proposed mechanism.

Ehmke, Matthias C.; Daniels, John; Glaum, Julia; Hoffman, Mark; Blendell, John E.; Bowman, Keith J.

2012-12-01

86

First-Principles Calculation of Lead-Free Perovskite SnTiO3  

NASA Astrophysics Data System (ADS)

The phonon spectra, band structure and density of states of cubic perovskite SnTiO3 were investigated using first-principles density functional theory (DFT) computation. The potential energy curves of cations displacement and the formation energy of Sn substitution to B-site were calculated to estimate the structure stability. The results indicate that perovskite SnTiO3 is a promising ferroelectric end member for lead-free piezoelectric materials and applications.

Ye, Hongjun; Zhang, Ruizhi; Wang, Dawei; Cui, Yu; Wei, Jie; Wang, Chunlei; Xu, Zhuo; Qu, Shaobo; Wei, Xiaoyong

2013-09-01

87

Fabrication of Lead-Free Ferroelectric Microstructures by Electron-Beam-Induced Patterning Process  

Microsoft Academic Search

300 nm to 50 ?m-sized circular dots of Bi4Ti3O12 (BIT) and BaTiO3 (BT), lead-free ferroelectric materials, micropatterns were fabricated by electron-beam-induced micropatterning process using scanning electron microscope (SEM)-based electron beam lithography system. Obtained micro dots were characterized using optical microscope and atomic force microscope. The piezoelectric property of the BIT and BT micro dots were examined by piezoresponse scanning force

Tadashi Fujii; Sugure Hirabayashi; Masatoshi Adachi

2009-01-01

88

Modeling and control of a dual stage actuator hard disk drive with piezoelectric secondary actuator  

Microsoft Academic Search

High capacity of new magnetic material can be exploited only with a fine servo-positioning of the hard disk heads. This can be achieved by means of dual stage actuation, where the secondary actuator can be realized with different technologies. In this paper, the need for a secondary actuator is proven by explicitly including the nonlinear friction on the voice coil

Roberto Oboe; Alessandro Beghi; Bruno Murari

1999-01-01

89

Lead-free ceramics for pyroelectric applications  

NASA Astrophysics Data System (ADS)

The use of lead-free materials has recently become a very important issue in environmental protection of the earth. Two groups of lead-free ceramics, (K0.5,Na0.5)NbO3 based (KNN) and Bi1-y(NaxK1-x)yTiO3 based (BNKT), were studied for their thermal, dielectric, and pyroelectric properties as candidates for pyroelectric sensor applications. The BNKT-based ceramic, [Bi0.5(Na0.94K0.05Li0.016)0.5]0.95Ba0.05TiO3 (BNKLBT), shows excellent pyroelectric properties when compared with KNN-based ceramic and lead zirconate titanate. Its properties were measured as follows: pyroelectric coefficient p=360 ?C/m2 K, pyroelectric figure of merit of current, voltage, and detectivity Fi=221 pm/V, Fv=0.030 m2/C, and Fd=14.8 ?Pa-1/2. With these outstanding pyroelectric properties, the BNKLBT ceramic can be a promising material for pyroelectric sensor applications. The BNKLBT ceramic with different thicknesses (i.e., 0.3, 0.5, and 0.7 mm) have been used as the sensing element for fabricating infrared detectors. The current responsivity of the sensors was evaluated as functions of frequency.

Lau, S. T.; Cheng, C. H.; Choy, S. H.; Lin, D. M.; Kwok, K. W.; Chan, H. L. W.

2008-05-01

90

Development of the Lead Free Soldering Process for Portable Applications  

Microsoft Academic Search

In the frame of European Union founded IMECAT-project the lead free soldering process for portable electronic devices has been developed. For the evaluation suppose a special PCB testboard has been designed. The lead free components which are selected to this testboard are commonly used in portable applications. The smallest components are 0201-type lead free resistors which are assemblied in groups

Jarmo Mttnen; Pori Greta Maakannas

91

Properties of Cerium Containing Lead Free Solder  

NASA Astrophysics Data System (ADS)

With increasing concerns of the intrinsic toxicity of lead (Pb) in electronics, a series of tin (Sn) based alloys involving silver (Ag) and copper (Cu) have been proposed as replacements for Pb-Sn solder and widely accepted by industry. However, they have a higher melting point and often exhibit poorer damage tolerance than Pb-Sn alloys. Recently, a new class of alloys with trace amount of rare-earth (RE) elements has been discovered and investigated. In previous work from Prof. Chawla's group, it has been shown that cerium (Ce)-based Pb-free solder are less prone to oxidation and Sn whiskering, and exhibit desirable attributes of microstructural refinement and enhanced ductility relative to lanthanum (La)-based Sn-3.9Ag-0.7Cu (SAC) alloy. Although the formation of RESn3 was believed to be directly responsible for the enhanced ductility in RE-containing SAC solder by allowing microscopic voids to nucleate throughout the solder volume, this cavitation-based mechanism needs to be validated experimentally and numerically. Additionally, since the previous study has exhibited the realistic feasibility of Ce-based SAC lead-free solder alloy as a replacement to conventional SAC alloys, in this study, the proposed objective focuses on the in in-depth understanding of mechanism of enhanced ductility in Ce-based SAC alloy and possible issues associated with integration of this new class of solder into electronic industry, including: (a) study of long-term thermal and mechanical stability on industrial metallization, (b) examine the role of solder volume and wetting behavior of the new solder, relative to Sn-3.9Ag-0.7Cu alloys, (c) conduct experiments of new solder alloys in the form of mechanical shock and electromigration. The research of this new class alloys will be conducted in industrially relevant conditions, and the results would serve as the first step toward integration of these new, next generation solders into the industry.

Xie, Huxiao

92

Rotary Multilayer Split MorphA Piezoelectric Microactuator for Dual-Stage Actuation Systems in High Track Density Hard Disk Drives  

NASA Astrophysics Data System (ADS)

A novel annular rotary piezoelectric microactuator has been proposed for a dual-stage actuation system for future high track density hard disk drives. The microactuator is designed to be mounted on a flexure tongue and drives a slider directly to perform high-frequency track following. The configuration and operation of the microactuator are described. The controllable stroke and the resonance frequency of the slider/actuator assembly have been evaluated and optimized by finite-element analysis. The results reveal that the designed actuator/slider assembly should be a promising addition to the dual-stage actuation system.

Wang, Zhihong; Zhu, Weiguang; Tan, Ooi Kiang; Yao, Xi

2001-09-01

93

Lead free BNT ceramics as driving element in traveling wave type ultrasonic motor  

NASA Astrophysics Data System (ADS)

Ultrasonic motor (USM) as a new type of driving motor has many good features compared with conventional electromagnetic motor. However, due the content of Pb in the driving element piezoelectric ceramics, Pb(Zrx,Ti1-x)O3 (PZT), the application of USM will be restricted from the viewpoint of environmental requirement. In this paper lead free piezoceramics, Mn doped 0.94(Bi0.5Na0.5)TiO3 -0.06BaTiO3(BNT-BT), was used as driving element in ultrasonic motor in replacing PZT. Though the piezoelectric property of BNT-BT ceramic is inferior to that of PZT, the USM with BNT-BT driving element shows promising result and potential to replace PZT ceramic in application of ultrasonic motor.

Yu, Zuoba; Chan, Ka Cheung; Guo, Jifeng; Dai, J. Y.; Wang, Bo; Jiang, X. P.; Kwok, K. W.

2007-10-01

94

Available thermal budget in lead-free reflow process  

Microsoft Academic Search

The electronics industry will have to implement lead-free soldering in the near future. Lead-free technology implementation phases are divided into lead-free processes and leadfree product. The prime issue is the component availability and component heat tolerance with the higher soldering temperatures. There is concern about the stability and heat resistance of a range of plastic encapsulated devices, capacitors, filters, connectors

Aulis Tuominen; Pekka Nummenpaa; Timo Liukkonen

2004-01-01

95

Reliability and Leachate Testing of Lead-Free Solder Joints  

Microsoft Academic Search

A test program was started in 2000 at Boeing for the evaluation of the reliability of lead -free solder joints. One lead-free solder was tested for reflow operations (tin\\/3.8%silver\\/0.7%copper) and one solder was tested for wave soldering operations (tin\\/0.7%copper). Three lead-free circuit board finishes were also tested: immersion silver; electrolytic gold on top of nickel; and an OSP (organic solderability

Thomas A. Woodrow

96

Liquid Tin Corrosion and Lead Free Wave Soldering  

Microsoft Academic Search

Corrosion of solder pots and solder pot components in wave soldering equipment has been reduced with the introduction of corrosion resistant coatings and improved lead free solder alloys. The latest trends in protecting wave solder machine components from liquid metal corrosion by lead free solder alloys will be presented in order to provide guidelines for evaluating existing equipment as well

Jim Morris; Matthew J. O'Keefe; Martin Perez

97

NanoComposite Lead-Free Interconnect and Reliability  

Microsoft Academic Search

Lead free solder bumping requirements have challenged researchers to develop new technologies to achieve fine pitch interconnects. ITRS has predicts that by 2017 the industry will require 70 micron pitch area array lead free interconnects for flip chips. This paper describes bumping, assembly and reliability evaluation of a new nano composite 20 micron pitch interconnect technology. Nanoparticles are the most

Ravi Doraiswami; Rao Tummala

2005-01-01

98

Infant mortality failures of lead free solder joints  

Microsoft Academic Search

Two goals of the work - verification of suitability of mechanical tests of solder joints reliability and infant mortality (early failures) of lead-free joints are selected. The results of reliability tests of lead - free solder joints of SMT resistors showed a tendency to increase of infant mortality failure rate comparing to SnPb eutectic joints. These new results are presented.

M. Szwech; W. Niedzwiedz; Z. Drozd

2009-01-01

99

Determination of tensile properties of lead-free solder joints using nanoindentation  

Microsoft Academic Search

In this work, determination of tensile properties using depth-sensing technique has been demonstrated. An empirical model has been used to extract tensile properties of bulk pure Sn and lead free solder joints using nanoindentation technique. New scheme is proposed based on the non-linear curve fitting analysis of indentation load-displacement data. Elastic modulus, yield strength, perfect plastic hardness and strain hardening

B. S. S. Chandra Rao; K. Y. Zeng; V. Kripesh

2010-01-01

100

Nanoindentation on SnAgCu lead-free solder and analysis  

Microsoft Academic Search

To improve the measurement accuracy of hardness and modulus results of lead-free SnAgCu from nanoindentation experiments, evaluation of the creep effect on measured result and was reported. For SnAgCu solder in this study, it was found that penetration continues with a very long time and the penetration depth could increase extra 1000 nm when the load was held constant. Thus

Luhua Xu; J. H. L. Pang

2005-01-01

101

Nanoindentation on SnAgCu lead-free solder joints and analysis  

Microsoft Academic Search

The lead-free SnAgCu (SAC) solder joint on copper pad with organic solderability preservative (Cu-OSP) and electroless nickel\\u000a and immersion gold (ENIG) subjected to thermal testing leads to intermetallic growth. It causes corresponding reliability\\u000a concerns at the interface. Nanoindentation characterization on SnAgCu solder alloy, intermetallic compounds (IMCs), and the\\u000a substrates subjected to thermal aging is reported. The modulus and hardness of

Luhua Xu; John H. L. Pang

2006-01-01

102

Development of lead-free solders for hybrid microcircuits  

SciTech Connect

Extensive work has been conducted by industry to develop lead-free solders for electronics applications. The driving force behind this effort is pressure to ban or tax the use of lead-bearing solders. There has been further interest to reduce the use of hazardous chemical cleaners. Lead-free soldering and low-residue, ``no clean`` assembly processing are being considered as solutions to these environmental issues. Most of the work has been directed toward commercial and military printed wiring board (PWB) technology, although similar problems confront the hybrid microcircuit (HMC) industry, where the development of lead-free HMC solders is generally lagging. Sandia National Laboratories is responsible for designing a variety of critical, high reliability hybrid components for radars. Sandia has consequently initiated a project, as part of its Environmentally Conscious Manufacturing program, to develop low-residue, lead-free soldering for HMCs. This paper discusses the progress of that work.

Hosking, F.M.; Vianco, P.T.; Frear, D.R.; Robinson, D.G.

1996-01-01

103

Lead-Free Experiment in a Space Environment.  

National Technical Information Service (NTIS)

This Technical Memorandum addresses the Lead-Free Technology Experiment in Space Environment that flew as part of the seventh Materials International Space Station Experiment outside the International Space Station for approximately 18 months. Its intent ...

J. F. Blanche S. M. Strickland

2012-01-01

104

Development of Sn-Zn-Cu lead free solder  

Microsoft Academic Search

Sn-Zn based lead free solder is one type of promising candidate to replace Sn-Pb eutectic solder due to its low cost and melt temperature which near to Sn-Pb eutectic solder. The Sn-Zn-Cu lead free solder was developed by alloying Sn with Zn and Cu in this paper. The effect of Zn and Cu content on the wettability of solder to

Yang Min; Liu Xiuzhong; Liu Xinghong; Dai Jiahui

2010-01-01

105

Failure analysis techniques for lead-free solder joints  

Microsoft Academic Search

Purpose This paper aims to describe and document the application of commonly utilized solder joint failure analysis techniques to lead-free solder joints. Design\\/methodology\\/approach Traditional failure analysis techniques, including visual inspection, X-ray radiography, mechanical strength testing, dye and pry, metallography, microscopy and photomicrography, are reviewed. These techniques are demonstrated as applied to lead-free and tin lead solder joints. Common

Todd Castello; Dan Rooney; Dongkai Shangguan

2006-01-01

106

Lead-Free Soldering - Where The World Is Going  

Microsoft Academic Search

Lead-free soldering for electronic industry is a segment of glob al trend toward lead-free environment. Although initiated in U.S. in early 1990's, it advanced much more rapidly in Japan and Europe. This differentiation in Pb -free progress triggered great concerns of users of Pb -containing solders about maintaining busi ness opportunity, therefore further expedites the advancement of Pb -free soldering

Ning-Cheng Lee

107

High drop test reliability: lead-free solders  

Microsoft Academic Search

Recently, preventing environmental pollution, lead-free (Pb-free) solders are about to replace tin-lead (Sn-Pb) eutectic solders. Sn-Ag-Cu alloys are leading candidates for lead free solders. Sn-Ag-Cu-P was developed last year, but Sn-Ag-Cu-P alloys were not satisfactory to meet severe customer requirements like thermal aging process followed by drop tests. To improve drop test performance after the thermal aging process, a combination

M. Amagai; Yoshitaka Toyoda; Tsukasa Ohnishi; Satom Akita

2004-01-01

108

Fatigue Life Assessment for Lead-Free Solder Joints  

Microsoft Academic Search

\\u000a The authors will indicate the basic reliability problems associated with use of lead-free solder joints. They investigated\\u000a the thermal fatigue reliability of lead-free solder joints, and focused their attention on the formation of the intermetallic\\u000a compound and its effect on the initiation and propagation of the fatigue cracks. An isothermal fatigue test method was used\\u000a to improve the efficiency of

Masaki Shiratori; Qiang Yu

109

Lead-free solder assembly: impact and opportunity  

Microsoft Academic Search

Tlicrc Ius been major interest in Lead-free soldcring within the electronics assembly industry for the last scvcral years. and tlds will continue with the agrccmcnt on the languagc and implementation dates of the WEEWROHS lcgisliltiou in the EU. This paper will focus on several topics critical lo the implementation of lead-free soldering. Thesc topics include tlie impact of Tin-silver-copper as

E. Bradley

2003-01-01

110

Novel Testing Instrument for Lead-Free Solder Characterization  

Microsoft Academic Search

The European Union Restriction of Hazardous Sub- stances Directive of 2006 has revolutionized the use of materials for electronic packaging: tin-lead solder has had to be replaced with lead-free solder. While years of experience and data acquired in the field are available for tin-lead solder, the same cannot be said for lead-free solder. The lack of data on these new

D. Di Maio; O. Thomas; M. Dusek; C. Hunt

2011-01-01

111

LEAD-FREE REWORK PROCESS FOR CHIP SCALE PACKAGES  

Microsoft Academic Search

Legislation against the use of lead in electronics has been the driving force behind the use of lead-free solders, surface finishes, and component lead finishes. The major concern in using lead-free solders in the assembly and rework Chip Scale Packages (CSPs) is the relatively high temperatures that the components and the boards experience. Fine-pitch CSPs have very low standoff heights

Arun Gowda; K. Srihari

112

Lead-free nanogenerator made from single ZnSnO3 microbelt.  

PubMed

We demonstrated a single-microbelt nanogenerator first made using a ZnSnO(3) microbelt that generated an output power of ?3 nW under a compressive and releasing strain of 0.8-1%. The ZnSnO(3) nanobelts/microbelts were synthesized using a vapor transfer process at 1173 K. The X-ray diffraction pattern shows that the microbelts belong to ZnSnO(3) with rhombohedral structure. An individual ZnSnO(3) microbelt was bonded at its ends on a flexible polystyrene substrate as a nanogenerator, which gives an output voltage and current of 100 mV and 30 nA, respectively, corresponding to an energy conversion efficiency of 4.2-6.6% (based on 0.8-1% strain). Our results show that ZnSnO(3) microbelts are one of the highly promising materials for lead-free piezoelectric energy harvesting. PMID:22482511

Wu, Jyh Ming; Xu, Chen; Zhang, Yan; Wang, Zhong Lin

2012-04-11

113

Structural And Electrical Analysis Of Lead Free BZT-xBCT Ceramics  

NASA Astrophysics Data System (ADS)

A comparative study of structural and electric properties of a recently discovered lead free electroceramic, Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 or BZT-xBCT, was conducted in the entire range from x = 0 to x = 1. This novel ceramic composite is being seen as a genuine understudy for commercially one of the most widely used piezoelectric ceramic, PZT, which is facing worldwide criticism due to its lead toxicity. The new system can be very extensively used like PZT in transduction applications as sensor, actuator and ultrasonic devices apart from numerous other utilities. The XRD, SEM and Ferroelectric studies establish the structural transition and different phases as function of Zr /Ti and Ba /Ca ratios.

Bhardwaj, Chandan; Kumar, Ashvani; Kaur, Davinder

2010-12-01

114

Structural And Electrical Analysis Of Lead Free BZT-xBCT Ceramics  

SciTech Connect

A comparative study of structural and electric properties of a recently discovered lead free electroceramic, Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}-x(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} or BZT-xBCT, was conducted in the entire range from x = 0 to x = 1. This novel ceramic composite is being seen as a genuine understudy for commercially one of the most widely used piezoelectric ceramic, PZT, which is facing worldwide criticism due to its lead toxicity. The new system can be very extensively used like PZT in transduction applications as sensor, actuator and ultrasonic devices apart from numerous other utilities. The XRD, SEM and Ferroelectric studies establish the structural transition and different phases as function of Zr /Ti and Ba /Ca ratios.

Bhardwaj, Chandan; Kumar, Ashvani; Kaur, Davinder [Functional Nanomaterials Research Lab, Department of Physics and Centre of Nanotechnology, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

2010-12-01

115

Wettability analysis of tin-based, lead free solders  

SciTech Connect

The overall program is comprised of two efforts. The first effort studies the wettability of tin-based, lead free solders on two commonly used substrate materials: copper and gold-nickel plated Kovar{trademark}. The evaluation is being conducted by the meniscometer/wetting balance technique which uses the contact angle as the primary metric to quantify wettability. Information about the rate of wetting is also obtainable with this test. The second part of the program is comprised of an assessment of the solderability of actual circuit board assemblies (surface mount and through-hole). This report will describe data from the wettability analysis of lead free solders on copper.

Vianco, P T; Hosking, F M; Rejent, J A

1992-01-01

116

Development of lead-free single-element ultrahigh frequency (170-320MHz) ultrasonic transducers.  

PubMed

This paper presents the design, fabrication and characterization of single-element ultrahigh frequency (UHF) ultrasonic transducers in which the center frequency ranged from 170 to 320MHz. The center frequency of >300MHz is the highest value of lead-free ceramic ultrasonic transducers ever reported. With concern in the environmental pollution of lead-based materials, the transducer elements presented in this work were lead-free K0.5Na0.5NbO3/Bi0.5Na0.5TiO3 (KNN/BNT) composite thick films. All transducers were evaluated in a pulse-echo arrangement. The measured -6dB bandwidth of the transducers ranged from 35% to 64%. With the optimized piezoelectric properties of the composite film, the insertion loss of the UHF transducers was measured and determined to range from -50 to -60dB. In addition to the pulse-echo measurement, a 6?m tungsten wire phantom was also imaged with a 205MHz transducer to demonstrate the imaging capability. The measured -6dB axial and lateral resolutions were found to be 12?m and 50?m, respectively. The transducer performance presented in this work is shown to be better or comparable to previously reported results even though the frequency is much higher. PMID:23485349

Lam, Kwok Ho; Ji, Hong Fen; Zheng, Fan; Ren, Wei; Zhou, Qifa; Shung, K Kirk

2013-02-08

117

High Energy, Lead-Free Ignition Formulation for Thermate.  

National Technical Information Service (NTIS)

An efficient ignition formulation for thermate was developed during the XM89 Enhanced Incendiary Grenade program to use as an alternative to the standard lead oxide-containing formulation used in the AN-Ml4 thermate grenade. This lead-free formulation has...

G. V. Tracy E. Song

2002-01-01

118

Minimizing flux spatter during lead-free reflow assembly  

Microsoft Academic Search

Purpose The leaching of lead from electronic components in landfills to ground water is harmful to health and to the environment. Increasing concern over the use of lead in electronics manufacturing has led to legislation to restrict its use as a joining material. Consequently, significant recent research efforts have been geared to identification of suitable lead-free solder pastes. Typically,

Deepak Manjunath; Satyanarayan Iyer; Shawn Eckel; Purushothaman Damodaran; Krishnaswami Srihari

2006-01-01

119

Reliability of the aging lead free solder joint  

Microsoft Academic Search

Solder materials demonstrate evolving microstructure and mechanical behavior that changes significantly with environmental exposures such as isothermal aging and thermal cycling. These aging effects are greatly exacerbated at higher temperatures typical of thermal cycling qualification tests for harsh environment electronic packaging. In the current study, mechanical measurements of thermal aging effects and material behavior evolution of lead free solders have

Hongtao Ma; Jeffrey C. Suhling; Pradeep Lall; Michael J. Bozack

2006-01-01

120

Creep rupture of lead-free Sn3.5Ag-Cu solders  

Microsoft Academic Search

Creep-rupture properties of lead-free Sn-3.5Ag-based alloys with varying amount of Cu were investigated using rolled and heat-treated\\u000a dog-bone-shaped specimens. Nominal compositions of added copper were 0 wt.%, 0.5 wt.%, 0.75 wt.%, 1.0 wt.%, and 1.5 wt.%.\\u000a During creep tests, the matrix hardness dropped significantly, and the minimum strain rates (\\u000a $$\\\\dot \\\\varepsilon _{min} $$\\u000a ) were lowest for the 0.75Cu

D. K. Joo; Jin Yu; S. W. Shin

2003-01-01

121

Effect of lead content on the structure and piezoelectric properties of hard type lead titanatezirconate ceramics  

Microsoft Academic Search

In the present investigation we studied the effect of lead content on a hard type ceramics starting from lack to excess PbO. Specimens of Pbx(Mn0.017Sb0.033Zr0.48Ti0.47)O3 with 0.96?x?1.06 were prepared by conventional oxide mixing technique and sintered at temperatures between 1280 and 1350C. In samples with lower Pb concentration the pyrochlore phase appeared, while in those with higher Pb an excess

C. Miclea; C. Tanasoiu; L. Amarande; A. Gheorghiu; I. Spanulescu; C. Plavitu; C. T. Miclea; M. C. Cioangher; L. Trupina; A. Iuga

2007-01-01

122

Creep Analysis of a Lead-free Surface Mount Device  

Microsoft Academic Search

In this paper finite element analysis (FEA) is used to understand the effect of a non-uniform temperature distribution on the creep and fatigue behaviour of lead-free solder joints in an electronic assembly comprising of a chip resistor mounted on printed circuit board (PCB). Solder joints in surface mount devices (SMDs) operate over a temperature range as extreme as -55degC to

Pradeep Hegde; David Whalley; V. V. Silberschmidt

2007-01-01

123

An Approach for Impression Creep of Lead Free Microelectronic Solders  

Microsoft Academic Search

Currently, the microelectronics industry is transitioning from lead-containing to lead-free solders in response to legislation in the EU and Japan. Before an alternative alloy can be designated as a replacement for current Pb-Sn extensive testing must be accomplished. One major characteristic of the alloy that must be considered is creep. Traditionally, creep testing requires numerous samples and a long tin,

Onofrio A. Anastasio

2002-01-01

124

Development of fluxes for lead-free solders containing zinc  

Microsoft Academic Search

New lead-free solders based on the Sn-Zn eutectic (92 wt. pct Sn - 8 wt. pct Zn) are promising candidates to replace near-eutectic tin-lead solders because these solders are less expensive than alternatives such as Sn-Ag eutectic base solders and the melting point of the tin-zinc eutectic (198 C) is much closer to melting point of commonly used tin-lead eutectic

S. Vaynman; M. E. Fine

1999-01-01

125

Analysis of intermetallic compounds in lead-free solders  

Microsoft Academic Search

Intermetallic compounds (IMCs) are essential part of lead-free solders microstructure. In 96.5Sn3Ag0.5Cu (SAC305) solder is dominant element tin (Sn). But despite this Sn dominancy only 3% weight contain of silver (Ag) has influence on final structure of solid solder joint. Fundamental impact on strength properties of solder joint has also interaction between the solder and printed circuit board (PCB) pad.

A. Pietrikova; J. Durisin; J. Urbancik; J. Bansky

2009-01-01

126

Finite element analysis of lead-free drop test boards  

Microsoft Academic Search

Lead-free CSP assemblies were drop tested according to the JEDEC standard (JESD-B111) and the finite element analysis of the test assembly was carried out to simulate the strain and stress distributions generated in the assemblies. The vibration of the board during the test was measured with strain gauges and the results were compared to the FE model predictions. The eigenfrequency

Pekka Marjamki; Toni Mattila; Jorma Kivilahti

2005-01-01

127

Lead-free wave soldering development for pcb assembly  

Microsoft Academic Search

The scope of work entailed determining the performance of Sn0.7Cu and Sn3.8Ag0.7Cu lead-free alloys for wave soldering applications in combination with lead-he components, board fmishes, different flux types and operating atmospheres using a production scale wave soldering machine. The vertical solder filling of througb holes using passive components such as connecton was excellent for PCBs with NiAu, Ag and OSP

Vasudivan Sunappan; Peter Collier

2003-01-01

128

Failure of lead-free solder joint under thermal cycling  

Microsoft Academic Search

Microelectronic devices are often subjected to environmental and power cycling thermal loads. Thermal cycling and the shear forces lead to many failures in microelectronic devices. The most common failure is an open in one or more of the input\\/output (I\\/O). The open is the result of a cracked or damaged interconnects, whether it is a lead-free solder joint. Thermal cycling

Yung-Wen Wang; Mei-Ling Wu

2011-01-01

129

Constitutive models of creep for lead-free solders  

Microsoft Academic Search

The constitutive modeling of creep has been extensively studied due to the important of the creep failure mode in solder joints.\\u000a However, there are very few studies that considered room temperature aging contributions in their creep modeling studies.\\u000a This study investigated constitutive modeling of creep of solders by taking into account the possible contribution room temperature\\u000a aging. Lead-free solder (Sn4.0Ag0.5Cu)

Hongtao Ma

2009-01-01

130

NEW MEXICO TECH LEAD-FREE SOLDER RESEARCH  

Microsoft Academic Search

In recent years a growing concern for lead-free solder has propelled industry to re-evaluate surface mount technology (SMT) production. This is based on the European Union's reduction of hazardous substances (RoHS) directive for a cleaner environment. Military and Aerospace industries, though they have been given exemption from this directive, are very dependent upon commercial industry that must be RoHS compliant.

Stephen Bracht; Aghavni Ball; Lisa Salerno

131

Electrical property evaluation of manganese-fluorine codoping of lead zirconate titanate thin films: Compatibility between hard material and piezoelectric activity  

Microsoft Academic Search

For some microelectromechanical system (MEMS) applications, the conditions of operation, high temperature, high stress, etc., can be very severe. Under these conditions the piezoelectric performance of polar material can decrease due to a partial (or a total) depoling induced by external excitations. So, it is important to have a piezoelectric active material that presents a good stability versus external parameters

M. Detalle; D. Rmiens; L. Lebrun; D. Guyomar

2006-01-01

132

Piezoelectric properties of Li- and Ta-modified (K{sub 0.5}Na{sub 0.5})NbO{sub 3} ceramics  

SciTech Connect

Lead-free, potassium sodium niobate piezoelectric ceramics substituted with lithium (K{sub 0.5-x/2},Na{sub 0.5-x/2},Li{sub x})NbO{sub 3} or lithium and tantalum (K{sub 0.5-x/2},Na{sub 0.5-x/2},Li{sub x})(Nb{sub 1-y},Ta{sub y})O{sub 3} have been synthesized by traditional solid state sintering. The compositions chosen are among those recently reported to show high piezoelectric properties [Y. Saito, H. Takao, T. Tani, T. Nonoyama, K. Takatori, T. Homma, T. Nagaya, and M. Nakamura, Nature (London) 42, 84 (2004); Y. Guo, K. Kakimoto, and H. Ohsato, Appl. Phys. Lett. 85, 4121 (2004); Mater. Lett. 59, 241 (2005)]. We show that high densities and piezoelectric properties can be obtained for all compositions by pressureless sintering in air, without cold isostatic pressing, and without any sintering aid or special powder treatment. Resonance and converse piezoelectric (strain-field) measurements show a thickness coupling coefficient k{sub t} of 53% and converse piezoelectric coefficient d{sub 33} around 200 pm/V for the Li-substituted ceramics, and a k{sub t} of 52% and d{sub 33} over 300 pm/V for the Li- and Ta-modified samples. The unipolar strain-field hysteresis is small and comparable to that measured under similar conditions in hard Pb(Zr,Ti)O{sub 3}. A peak of piezoelectric properties can be noted close to the morphotropic phase boundary. These ceramics look very promising as possible, practicable, lead-free replacements for lead zirconate titanate.

Hollenstein, Evelyn; Davis, Matthew; Damjanovic, Dragan; Setter, Nava [Ceramics Laboratory, Ecole Polytechnique Federale de Lausanne-EPFL, Lausanne (Switzerland)

2005-10-31

133

Piezoelectric Polymers.  

National Technical Information Service (NTIS)

The purpose of this review is to detail the current theoretical understanding of the origin of piezoelectric and ferroelectric phenomena in polymers; to present the state-of-the-art in piezoelectric polymers and emerging material systems that exhibit prom...

J. S. Harrison Z. Ounaies

2001-01-01

134

Lead-free piezoelectric ceramics based on (0.97 - x)K0.48Na0.52NbO3-0.03Bi0.5(Na0.7K0.2Li0.1)0.5ZrO3-xB0.5Na0.5TiO3 ternary system  

NASA Astrophysics Data System (ADS)

In this work, the ternary system of potassium-sodium niobate has been designed to enhance the piezoelectric properties without sacrificing the Curie temperature greatly, and (0.97 - x)K0.48Na0.52NbO3-0.03Bi0.5(Na0.7K0.2Li0.1)0.5ZrO3-xB0.5Na0.5TiO3 ceramics have been prepared by the conventional solid-state method. The effect of B0.5Na0.5TiO3 content on the microstructure and electrical properties of the ceramics is studied. The phase diagram shows a phase boundary of the rhombohedral-tetragonal (R-T) phase coexistence in the composition range of 0.5% < x < 1.5%, and then an enhanced dielectric, ferroelectric, and piezoelectric behavior is obtained at such a phase boundary zone. The ceramic with x = 0.01 has an optimum electrical behavior of d33 ~ 285 pC/N, kp ~ 0.40, ?r ~ 1235, tan ? ~ 0.031, Pr ~ 14.9 ?C/cm2, and Ec ~ 15.2 kV/cm, together with a high Curie temperature of ~347 C. The large d33 in such a ternary system is due to a composition-induced R-T phase transition and a higher ?rPr, and the thermal stability performance is strongly dependent on the phase structure. As a result, the design of the ternary system is an effective way to enhance the piezoelectric properties of potassium-sodium niobate materials.

Cheng, Xiaojing; Wu, Jiagang; Wang, Xiaopeng; Zhang, Binyu; Zhu, Jianguo; Xiao, Dingquan; Wang, Xiangjian; Lou, Xiaojie; Liang, Wenfeng

2013-09-01

135

Lead-Free Low-Melting and Semiconductive Vanadate Glass Applicable to Low-Temperature Sealing  

NASA Astrophysics Data System (ADS)

We optimized the fundamental composition and additives in a semiconducting V2O5--P2O5--TeO2 glass system to develop lead-free low-melting glass suitable for low-temperature sealing below 400 C. Glass with a composition of 55.7V2O5--19.8P2O5--23.5TeO2 (mol %) has a low glass transformation temperature (Tg < 300 C) as well as hard crystallization, and it is desired as a low-temperature sealing material. The effects of adding BaO, Sb2O3, MnO2, or Fe2O3 to the fundamental composition of 55.7V2O5--19.8P2O5--23.5TeO2 (mol %) on the thermal properties and water-vapor resistance were then characterized. Adding 11.7 mol % Fe2O3 improved the water-vapor resistance drastically and decreased the thermal expansion coefficient without increasing Tg. Sealing at 360 C with our lead-free Fe2O3-added vanadate glass enabled practical airtight packaging on an electronic device.

Naito, Takashi; Aoyagi, Takuya; Sawai, Yuichi; Tachizono, Shinichi; Yoshimura, Kei; Hashiba, Yuji; Yoshimoto, Mamoru

2011-08-01

136

Nanoindentation on SnAgCu lead-free solder joints and analysis  

NASA Astrophysics Data System (ADS)

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 Youngs 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 Youngs 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.

Xu, Luhua; Pang, John H. L.

2006-12-01

137

Can Whiskers Grow on Bulk Lead-Free Solder?  

NASA Astrophysics Data System (ADS)

Many possible mechanisms for whisker growth exist, each possible in various scenarios investigated in the literature. This contribution addresses the importance of residual mechanical stress in a solder alloy for providing some of the energy necessary to drive possible whisker growth. We investigate the indentations made on bulk lead-free solder (Sn3.5Ag) to introduce various levels of residual energy associated with localized residual stresses. We confirm that localized residual stresses, in the absence of a thin-film geometry, significant oxide thickness, and interdiffusional stresses from intermetallic Cu-Sn compounds, do not result in the formation of whiskers in bulk Sn3.5Ag. Thus, the combination of stresses associated with thin films (either thermal misfit, plating, or chemical) and the oxidation of Sn at the surface is likely required for continuous whisker growth.

Nychka, John A.; Li, Yan; Yang, Fuqian; Chen, Rong

2008-01-01

138

Failure analysis of lead-free solder joints for flip chip on board  

Microsoft Academic Search

With the great environmental concern, lead-free solders gradually replace lead-based solders in electronic packages. However, the relatively short history of lead-free solders makes their reliability database inadequate. In other words, there is an urgent need to establish the reliability information of lead-free solders. In this study, a failure analysis is conducted to investigate the reliability of lead free solders. The

Fu-Ming Tzu; Long-Sun Chao; Jung-Hua Chou

2007-01-01

139

Modeling Material Properties of Lead-Free Solder Alloys  

NASA Astrophysics Data System (ADS)

A full set of physical and thermophysical properties for lead-free solder (LFS) alloys have been calculated, including liquidus/solidus temperatures, fraction solid, density, coefficient of thermal expansion, thermal conductivity, Youngs modulus, viscosity, and liquid surface tension, all as a function of composition and temperature (extending into the liquid state). The results have been extensively validated against data available in the literature. A detailed comparison of the properties of two LFS alloys Sn-20In-2.8Ag and Sn-5.5Zn-4.5In-3.5Bi with Sn-37Pb has been made to show the utility and need for calculations that cover a wide range of properties, including the need to consider the effect of nonequilibrium cooling. The modeling of many of these properties follows well-established procedures previously used in JMatPro software for a range of structural alloys. This paper describes an additional procedure for the calculation of the liquid surface tension for multicomponent systems, based on the Butler equation. Future software developments are reviewed, including the addition of mechanical properties, but the present calculations can already make a useful contribution to the selection of appropriate new LFS alloys.

Guo, Zhanli; Saunders, Nigel; Miodownik, Peter; Schill, Jean-Philippe

2008-01-01

140

Piezoelectric moduli of piezoelectric ceramics  

SciTech Connect

The effective piezoelectric moduli of polycrystalline piezoelectric ceramics are calculated using a straightforward averaging method (a Voigt average) and a more rigorous effective-medium theory recently developed for piezocomposites. The effects of polarization orientation within each crystallographic domain and the shape of the domain on the effective piezoelectric moduli are presented. The effective-medium theory, which includes full coupling of the elastic and dielectric interactions, gives results in reasonable agreement with experimental ones.

Nan, C.W.; Clarke, D.R. [Univ. of California, Santa Barbara, CA (United States). Coll. of Engineering

1996-10-01

141

Study of Lead Free Ferroelectric Films for New Solar Cells  

NASA Astrophysics Data System (ADS)

We report on the deposition by a sol-gel process of Ba0.8Sr0.2TiO3 and Ba0.9Sr0.1TiO3 films on platinum coated silicon substrates. X-Ray diffraction patterns show that the films are (111) preferentially oriented. The surface morphology is smooth, without cracks and the grain size is about 50 nm as determined by AFM and SEM. The dielectric constant measured from 102 to 106 Hz decreases slightly and is around 400 at 104 Hz. The losses are constant in a first approximation for a 1.5 ?m thick BST(80/20) film with a value of 0.03 at 10 kHz. The existence of an hysteresis cycle attests that the films, whatever their thickness, are in a ferroelectric state. Pyroelectric coefficients have been determined and the best figure of merit obtained on BST(90/10) at 293 K and 10 kHz is of 149 ?C/m3/K. The best dielectric and pyroelectric properties (tg? = 0.006 at 1 MHz, tunability = 30%, ? = 340 ?C/m2/K) were obtained on the 400 nm BST(90/10) film. Work is in progress to characterize the piezoelectric and photovoltaic properties of our BST films.

Fasquelle, D.; Mascot, M.; Carru, J. C.; Hikam, M.; Iriani, Y.; Soegijono, B.

2009-09-01

142

Study of Lead Free Ferroelectric Films for New Solar Cells  

SciTech Connect

We report on the deposition by a sol-gel process of Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} and Ba{sub 0.9}Sr{sub 0.1}TiO{sub 3} films on platinum coated silicon substrates. X-Ray diffraction patterns show that the films are (111) preferentially oriented. The surface morphology is smooth, without cracks and the grain size is about 50 nm as determined by AFM and SEM. The dielectric constant measured from 10{sup 2} to 10{sup 6} Hz decreases slightly and is around 400 at 10{sup 4} Hz. The losses are constant in a first approximation for a 1.5 {mu}m thick BST(80/20) film with a value of 0.03 at 10 kHz. The existence of an hysteresis cycle attests that the films, whatever their thickness, are in a ferroelectric state. Pyroelectric coefficients have been determined and the best figure of merit obtained on BST(90/10) at 293 K and 10 kHz is of 149 {mu}C/m{sup 3}/K. The best dielectric and pyroelectric properties (tg{delta} = 0.006 at 1 MHz, tunability = 30%, {gamma} = 340 {mu}C/m{sup 2}/K) were obtained on the 400 nm BST(90/10) film. Work is in progress to characterize the piezoelectric and photovoltaic properties of our BST films.

Fasquelle, D.; Mascot, M.; Carru, J. C. [LEMCEL, Universite du Littoral Cote d'Opale, 50 rue F. Buisson, BP717-62228-Calais-France (France); Hikam, M.; Iriani, Y.; Soegijono, B. [Department of Physics, Faculty of Mathematics and Sciences, University of Indonesia, Depok 16424 Indonesia (Indonesia)

2009-09-14

143

Piezoelectricity Demo  

NSDL National Science Digital Library

This lesson plan from the Oregon Museum of Science and Industry explores the history of piezoelectricity, with hands-on examples of how itâs used, models of why it happens, and how it is applied in nanotechnology. Pressing on the piezoelectric buzzer in the background causes a current to flow and the neon bulb in the foreground to glow.

2012-03-13

144

Synthesis of lead-free (K, Na)(Nb, Ta)O3 nanopowders using a sol-gel process.  

PubMed

Lead-free (K0.5Na0.5)(Nb0.7Ta0.3)O3 piezoelectric material was successfully synthesized via a sol-gel process. Crystalline (K0.5Na0.5)(Nb0.7Ta0.3)O3 nanopowders were obtained after heat treatment at 700 degrees C. The particle size was estimated to be 87nm +/- 23 nm. The transmission electron microscopy images showed that individual nanoparticles were single crystalline and had a pseudo-cubic structure with a lattice parameter of -3.96 angstroms. Both X-ray diffraction and scanning electron microscopy studies consistently showed that the crystallization of the (K0.5Na0.5)(Nb0.7Ta0.3)O3 occurred slightly above 500 degrees C. The samples have an appropriate stoichiometry as found via energy dispersive X-ray spectroscopy. The demonstration of the synthesis of (K0.5Na0.5)(Nb0.7Ta0.3)O3 via a sol-gel process as presented in this paper can provide an important foundation for the development of a synthetic route towards (K0.5Na0.5)(Nb0.7Ta0.3)O3 doped with various other elements for high performance piezoelectric devices. PMID:22849167

Rajesh, Dodla; Kim, Seungwook; Jeong, Jinhoo; Nahm, Sahn; Kim, Woong

2012-04-01

145

Microstructure, Phase Transition, and Electrical Properties of K x Na1- x NbO3 Lead-Free Piezoceramics  

NASA Astrophysics Data System (ADS)

The microstructure, phase transition, and electrical properties of lead-free K x Na1- x NbO3 ( x = 0.46 to 0.51, abbreviated as KNN) piezoceramics prepared by a conventional solid-state reaction method were investigated with an emphasis on the influence of the K/Na ratio. Scanning electron microscopy (SEM) images showed that the grain growth was slightly improved by increasing x. However, all ceramic samples possessed high densifications with fine grains from several hundred nanometers to several micrometers. X-ray diffraction (XRD) results showed that a discontinuous change of lattice parameters appeared between x = 0.49 and 0.50, which suggested a typical morphotropic phase boundary (MPB) separating two different orthorhombic phases O I and O II. The sample with composition x = 0.49 had the peak values of the piezoelectric constant d 33 of 146 pC/N and the planar electromechanical coupling coefficient k p of 43%. These results indicated that improving the piezoelectric properties in KNN ceramics could be achieved by optimizing the K/Na ratio.

Li, Y. M.; Shen, Z. Y.; Jiang, L.; Liao, R. H.; Wang, Z. M.; Hong, Y.

2012-03-01

146

Preparation and characterization of novel piezoelectric and pyroelectric polymer electrets  

Microsoft Academic Search

The preparation and characterization of novel piezoelectric and pyroelectric electrets is discussed with respect to their electret properties. Charged heterogeneous electrets, like closed-cell microporous polypropylene (pp) foams and `soft-hard' fluoropolymer hybrids are shown to yield large quasi-static and dynamic piezoelectric responses, indistinguishable from true piezoelectricity. Piezoelectric coefficients comparable to that of ceramic counterparts have been achieved. For the investigation of

R. Schwodiauer; G. S. Neugschwandtner; K. Schrattbauer; M. Lindner; M. Vieytes; S. Bauer-Gogonea; S. Bauer

2000-01-01

147

Novel lead-free Sn-Cu-xBi nanosolders by chemical reduction method.  

PubMed

With environmental concerns on the toxicity of lead, investigations on lead-free solders become crucial. Studies on lowering process temperature of lead-free solders are required, because the melting points of lead-free solders are higher than original SnPb solders. Melting points of binary solders could be decreased by addition another materials. In this study, Sn-Cu-xBi lead-free nanoparticles were synthesized with precisely controlled size and composition by chemical precipitation method. Effects of different precursor concentration and surfactant addition were discussed. The influence of different amounts of Bi in the SnCu-based nano-particles was also probed. PMID:19441388

Huang, Po-Chun; Duh, Jenq-Gong

2009-02-01

148

Piezoelectric Film.  

ERIC Educational Resources Information Center

|Presents activities that utilize piezoelectric film to familiarize students with fundamental principles of electricity. Describes classroom projects involving chemical sensors, microbalances, microphones, switches, infrared sensors, and power generation. (MDH)|

Garrison, Steve

1992-01-01

149

Thermomigration: An experimental damage mechanics study on nanoelectronic lead free solder alloys  

NASA Astrophysics Data System (ADS)

This dissertation focuses on experimental study of thermomigration in lead-free solder alloys. Thermomigration in microelectronic solder joints was not a concern until significant miniaturization of electronics devices required to run high current densities with smaller solder joint sizes. High current density induces electromigration and Joule heating at the same time. The imbalance of Joule heating generated at top and bottom of solder joint causes a temperature gradient which is large enough to induce thermomigration damage. In the literature, most studies report electromigration induced damage without considering the influence of thermomigration, thus the effect of electromigration and thermomigration can not be individually identified. This dissertation studies the experimental damage mechanics of thermomigration without electromigration by studying formation and destruction of intermetallic compound, and vacancy migration due to diffusion driving forces. Microstructural degradation and hardness testing were used to quantify thermomigration induced damage. After studying material science and physics behind the thermomigration process, using test vehicles, the combined effects of electromigration and thermomigration were studied experimentally. The studies were repeated at a subzero temperatures to see the effect of low temperature on thermomigration and electromigration, and reliability of nanoelectronic solder joints. A new time to failure equation is proposed to show a threshold temperature below which diffusion slows down significantly. By ensuring the solder operating temperature is well kept below the threshold value by proper thermal management, the solder joint life can be extended.

Abdul Hamid, Mohd Foad

150

Electrical properties of lead-free 0.98(Na0.5K0.5Lix)NbO3-0.02Ba(Zr0.52Ti0.48)O3 ceramics  

NASA Astrophysics Data System (ADS)

Lead-free 0.98(Na0.5K0.5Lix)NbO3-0.02Ba(Zr0.52Ti0.48)O3 piezoelectric ceramics were investigated. The experimental results show that Li content strongly affects the orthorhombic-tetragonal morphotropic phase boundary (MPB) which results in different piezoelectric properties. The phase transition composition shows a range from 0.05 to 0.1. The sample with a composition of x = 0.1 showed the maximum values of piezoelectric coefficient ( d 33= 201 ?C/N), electromechanical coupling coefficient ( k p= 39%), and remnant polarization ( P r= 21 ?C/cm2).

Lee, Seung-Hwan; Kim, Hyun-Ju; Lee, Sung-Gap; Koh, Jung-Hyuk; Baek, Sang-Don; Lee, Young-Hie

2012-02-01

151

Simulation of uniaxial tensile properties for lead-free solders with modified Anand model  

Microsoft Academic Search

The uniaxial tensile inelastic deformation behavior for three types of lead-free solders, Sn3Ag0.5Cu, Sn3.5Ag and Sn0.7Cu, were simulated by a unified viscoplastic constitutive model, the Anand model. To obtain the material parameters for the Anand model, a series of constant true strain rate and temperature tests were conducted on three types of lead-free solders at various strain rates from 110?4s?1

Ning Bai; Xu Chen; Hong Gao

2009-01-01

152

Preparation of ultra-fine copper powder and its lead-free conductive thick film  

Microsoft Academic Search

In this paper, non-agglomerated monodispersed ultra-fine copper metallic powders have been synthesized with chemical reduction method. Fine lead-free glass powders were also prepared by solid synthesis process. Thick film paste prepared by above-mentioned copper metallic powders and lead-free glass powders was applied as conductive paste of MLCC. Mixture of glass and zinc oxide give the thick film a high adhesion

Songping Wu

2007-01-01

153

Investigation of the stress-strain curves of lead-free solder alloy  

Microsoft Academic Search

In this paper, a new methodology to extract the elasto-plastic properties of lead-free solder materials from an instrumented sharp indentation loading curve has been proposed using dimensional analysis and finite element computation. The nano indenter XP technology is used to test samples of lead-free eutectic SnAgCu solder alloys to obtain a load-displacement curve, which can be used to calculate its

Niu Xiaoyan; Ma Yong; Li Zhigang; Shu Xuefeng; Yang Guitong

2008-01-01

154

Reduction of lead free solder aging effects using doped SAC alloys  

Microsoft Academic Search

The microstructure, mechanical response, and failure behavior of lead free solder joints in electronic assemblies are constantly evolving when exposed to isothermal aging and\\/or thermal cycling environments. In our prior work on aging effects, we have demonstrated that large degradations occur in the material properties (stiffness and strength) and creep behavior of Sn-Ag-Cu (SAC) lead free solders during aging. These

Zijie Cai; Yifei Zhang; Jeffrey C. Suhling; Pradeep Lall; R. Wayne Johnson; Michael J. Bozack

2010-01-01

155

Wettability of electroless Ni in the under bump metallurgy with lead free solder  

Microsoft Academic Search

This study investigates the wettability of several lead-free solders, including Sn, Sn?Ag, and Sn?Bi, on electroless Ni (EN)\\u000a with various phosphorus content. The role of phosphorus on solder wettability is studied. Microstructure evolution in the\\u000a lead-free solder\\/EN joint is investigated with the aid of electron probe microanalyzer (EPMA) to relate metallurgical reactions\\u000a between the solder and the EN. The SN

Bi-Lian Young; Jenq-Gong Duh; Bi-Shiou Chiou

2001-01-01

156

The effect of lead free soldering on formation of black pad failure  

Microsoft Academic Search

By this time usable solder alloys for lead-free soldering had already been developed. NEMI (National Electronics Manufacturing Initiative) recommends Sn\\/3.9Ag\\/0.6Cu (0.2%) solder alloy for reflow soldering instead of leaded solder alloys, due to its excellent mechanical properties and other good parameters. The next step is the choosing of suitable pad finish for lead-free soldering. In the age of fine pitch

Oliver Krammer

2005-01-01

157

Rate-dependent properties of Sn-Ag-Cu based lead free solder joints  

Microsoft Academic Search

The increasing demand for portable electronics has led to the shrinking in size of electronic components and solder joint dimensions. The industry also made a transition towards the adoption of lead-free solder alloys, commonly based around the Sn-Ag-Cu alloys. As knowledge of the processes and operational reliability of these lead-free solder joints (used especially in advanced packages) is limited, it

Yong'An Su; Long Bin Tan; V. B. C. Tan; Tong Yan Tee

2009-01-01

158

Lead-free chip scale packages: assembly and drop test reliability  

Microsoft Academic Search

Three underfill options compatible with lead-free assembly have been evaluated: capillary underfill, fluxing underfill, and corner bond underfill. Chip scale packages (CSPs) with eutectic Sn\\/Pb solder were used for control samples. Without underfill, lead-free and Sn\\/Pb eutectic drop test results were comparable. Capillary flow underfills, dispensed and cured after reflow, are commonly used in CSP assembly with eutectic Sn\\/Pb solder.

Yueli Liu; Guoyun Tian; Shyam Gale; R. Wayne Johnson; Lawrence Crane

2006-01-01

159

Effects of PCB design variations on bend and ATC performance of lead-free solder joints  

Microsoft Academic Search

Sn-Ag-Cu (SAC) solder alloys, such as Sn-3.0Ag-0.5 Cu (SAC305) are the popular choices of lead-free solders replacing SnPb solders. However, SAC solders are more brittle in nature due to high stiffness and excessive intermetallic compounds growth at the solder joint to pad interface. This leads to higher risks in solder joints failures. Memory module type lead-free BGA packages are constantly

Hongtao Ma; Kuo-Chuan Liu; Tae-Kyu Lee; Dong Hyun Kim

2010-01-01

160

Reliability of lead free solders joints and manufacturability during the SMT process  

Microsoft Academic Search

In systematic investigations the failure behaviour of lead free solder joints for different solder alloys as well as substrate metallization was analyzed. The emphasis of the investigations was the optimization of the processing parameters for the printing of different lead-free no-clean solder pastes in the standard pitches from 1.27 mm to 0.4 mm. Furthermore, evidence was provided of the aging-determined

T. Herzog

2004-01-01

161

Reliability assessment of flip-chip assemblies with lead-free solder joints  

Microsoft Academic Search

Due to environmental awareness, and the health hazards involved in using lead in solders, large efforts to develop lead-free soldering have been made in recent years. Sn-Ag alloys are expected to be one of the best candidate lead-free solders. Furthermore, from a reliability viewpoint, there has been interest in improved thermal fatigue resistance of solder interconnects. In this study, two

A. Schubert; R. Dudek; H. Walter; E. Jung; A. Gollhardt; B. Michel; H. Reichl

2002-01-01

162

Reliability study of surface mount printed circuit board assemblies with lead-free solder joints  

Microsoft Academic Search

Purpose The purpose of this paper is to evaluate the lead-free solder joint reliability of a variety of surface mount components assembled onto printed circuit boards (PCBs) under a number of different tests. Design\\/methodology\\/approach Lead-free solder with a composition of Sn96.5-Ag3.0-Cu0.5 was used in a surface mount reflow process. Different types of surface mount dummy components with a

Jeffery C. C. Lo; B. F. Jia; Z. Liu; J. Zhu; S. W. Ricky Lee

2008-01-01

163

The Influence of Elevated Temperature Aging on Reliability of Lead Free Solder Joints  

Microsoft Academic Search

The microstructure, mechanical response, and failure behavior of lead free solder joints in electronic assemblies are constantly evolving when exposed to isothermal aging and\\/or thermal cycling environments. In our prior work on aging effects (Ma, et al., ECTC 2006), we demonstrated that the observed material behavior variations of SAC405 and SAC305 lead free solders during room temperature aging (25 degC)

Hongtao Ma; J. C. Suhling; Yifei Zhang; P. Lall; M. J. Bozack

2007-01-01

164

HDPUG's Design for Lead-Free Solder Joint Reliability of High-Density Packages  

Microsoft Academic Search

The lead-free solder-joint reliability of the high-density packages, 256-pin PBGA (plastic ball grid array), 388-pin PBGA, and 1657-pin CCGA (ceramic column grid array), on PCB (printed circuit board) subjected to temperature cycling is investigated. Emphasis is placed on the determination of the creep responses (e.g., stress, strain, and strain energy density) of the lead-free solder joints of these packages. The

John Lau; Walter Dauksher; Joe Smetana; Dongkai Shangguan; Irv Menis; Dave Love; Bob Sullivan

165

Generation of Tin(II) Oxide Crystals on Lead-Free Solder Joints in Deionized Water  

NASA Astrophysics Data System (ADS)

The effect of the anode and cathode on the electrochemical corrosion behavior of lead-free Sn-Ag-Cu and Sn-Ag-Cu-Bi solder joints in deionized water was investigated. Corrosion studies indicate that SnO crystals were generated on the surfaces of all lead-free solder joints. The constituents of the lead-free solder alloys, such as Ag, Cu, and Bi, did not affect the corrosion reaction significantly. In contrast to lead-free solders, PbO x was formed on the surface of the traditional 63Sn-37Pb solder joint in deionized water. A cathode, such as Au or Cu, was necessary for the electrochemical corrosion reaction of solders to occur. The corrosion reaction rate decreased with reduction of the cathode area. The formation mechanism of SnO crystals was essentially a galvanic cell reaction. The anodic reaction of Sn in the lead-free solder joints occurred through solvation by water molecules to form hydrated cations. In the cathodic reaction, oxygen dissolved in the deionized water captures electrons and is deoxidized to hydroxyl at the Au or Cu cathode. By diffusion, the anodic reaction product Sn2+ and the cathodic reaction product OH- meet to form Sn(OH)2, some of which can dehydrate to form more stable SnO xH2O crystals on the surface of the solder joints. In addition, thermodynamic analysis confirms that the Sn corrosion reaction could occur spontaneously.

Chang, Hong; Chen, Hongtao; Li, Mingyu; Wang, Ling; Fu, Yonggao

2009-10-01

166

Resolution of the ferroelectric domains structure in (K,Na)NbO3-based lead-free ceramics by confocal Raman microscopy  

NASA Astrophysics Data System (ADS)

We highlight some practical aspects in the study of ferroelectric domains in lead-free modified (K,Na)NbO3 piezoceramics through Confocal Raman Microscopy (CRM). In addition, CRM allows the determination of the nature of domain walls and correlation between the structure and piezoelectric properties. The typical configuration of the ferroelectric domain is analyzed in polycrystalline grains of small sizes not exceeding 6 ?m, where tetragonal and orthorhombic domains are coexisting. The accumulated stress produced by the phase coexistence softens the octahedron force constant and reduces the polarization. So, the polarization decrease is associated to the apparition of the orthorhombic phase (O). Finally, we believe that the general strategy and design principles described in this study will open new avenues in developing novel strategies of domains characterization that allow improving the piezoresponse.

Rubio-Marcos, F.; Del Campo, A.; Fernndez, J. F.

2013-05-01

167

Synthesis of piezoelectric materials by ultrasonic assisted hydrothermal method  

NASA Astrophysics Data System (ADS)

Hydrothermal method enables to synthesize high quality piezoelectric materials. To shorten the reaction time and to get higher quality materials, we propose an ultrasonic irradiation to the solution during the hydrothermal method. We named it ultrasonic assisted hydrothermal method (UAHTM). We have synthesized lead-free piezoelectric material and PZT thin film and the effect of UAHTM have been confirmed. In this study, we tried to improve UAHTM. First, to generate powerful and stable ultrasonic irradiation at high temperature on UAHTM, we developed a new transducer using LiNbO3 single crystal. Second, to prevent contamination to the materials, A Teflon cover on the tip of transducer was attached.

Isobe, Gaku; Ageba, Ryo; Maeda, Takafumi; Bornmann, Peter; Hemsel, Tobias; Morita, Takeshi

2012-05-01

168

Mechanical properties of SnPb and lead-free solders at high rates of strain  

NASA Astrophysics Data System (ADS)

The mechanical properties of 63% Sn-37% Pb and lead-free solders have been measured at high strain rates (500-3000 s-1) using a split Hopkinson pressure bar. The solders were produced by quenching in water from the melt, to give the phase structure associated with rapid cooling. Measurements were made at -40 C, room temperature and +60 C. The Sn-Pb solder was strongly strain rate and temperature dependent, whereas the lead-free solders showed only a weak dependence on these parameters. All of the materials behaved elasto-plastically until a plateau stress of circa 200 MPa. An unexpected, and possibly important, feature of the lead-free solders was the division of the specimens into two groups with different strengths at low temperatures.

Siviour, C. R.; Walley, S. M.; Proud, W. G.; Field, J. E.

2005-11-01

169

Compositional dependence of phase structure and electrical properties in (K0.42Na0.58)NbO3-LiSbO3 lead-free ceramics  

NASA Astrophysics Data System (ADS)

(1-x)(K0.42Na0.58)NbO3-xLiSbO3 [(1-x)KNN-xLS] lead-free piezoelectric ceramics were prepared by the conventional mixed oxide method. The compositional dependence of the phase structure and the electrical properties of the ceramics were studied. A morphotropic phase boundary (MPB) between the orthorhombic and tetragonal phases was identified in the composition range of 0.04piezoelectric properties. The ceramics with 5 mol. % LS exhibit enhanced electrical properties (d33~270 pC/N, kp~47.2%, Tc~364 C , To-t=35 C, ?r~1412, tan ?~2.8%, and Pr~25.7 ?C/cm2 Ec~11.1 kV/cm) and possess low dielectric loss (<2%) at 10 and 100 kHz at high temperature (250-400 C). The low dielectric loss at high temperature is very important for high-temperature application of the ceramics. The related mechanism of the enhanced electrical properties of the ceramics was also discussed. These results show that (1-x)KNN-xLS (x=0.05) ceramic is a promising lead-free piezoelectric material.

Wu, Jiagang; Xiao, Dingquan; Wang, Yuanyu; Zhu, Jianguo; Yu, Ping; Jiang, Yihang

2007-12-01

170

Intermediate strain rate dependant mechanical properties for lead-free solders  

Microsoft Academic Search

Lead-free solders have strain rate dependent mechanical properties. In this work we report the elastic modulus and yield strength of several lead-free solder alloys at different strain rates. They are SnAgCu (with Ag 1 to 4% and Cu at 0.5%, namely SAC105, SAC205, SAC305 and SAC405), SAC-X (X=In, Ni and Bi), SnCu, SnCu-X and SnAg alloys. The intermediate strain rate

Luhua Xu; Kok Ee Tan; J. H. L. Pang

2010-01-01

171

Isothermal cyclic bend fatigue test method for lead free solder joints  

Microsoft Academic Search

Isothermal three-point and four-point cyclic bend fatigue test method have been developed for Sn-Ag-Cu solder joints. Reported bend tests from the literature were conducted at room temperature (25degC) and there is lack of data for lead-free solder joints. In this study, VQFN assembly with Sn-Ag-Cu lead-free solder was tested under three-point and four-point cyclic bending load at room temperature (25degC)

John H. L. Pang; Fa-Xing Che

2006-01-01

172

Piezoelectric Effect  

NSDL National Science Digital Library

In this activity, by the Concord Consortium's Molecular Literacy project, students explore the piezoelectric effect, which is the conversion between electricity and mechanical motion. The model used in this activity shows this conversion and users can manipulate the model to change the voltage and observe changes to a crystal. The activity itself is a java-based interactive resource built upon the free, open source Molecular Workbench software. In these activities, students are allowed to explore at their own pace in a digital environment full of demonstrations, illustrations, and models they can manipulate. In addition to the activity, visitors will find an overview of the activity and central and key concepts.

2008-10-23

173

Mechanical Characterization of Lead-Free Sn-Ag-Cu Solder Joints by High-Temperature Nanoindentation  

NASA Astrophysics Data System (ADS)

The reliability of Pb-free solder joints is controlled by their microstructural constituents. Therefore, knowledge of the solder microconstituents' mechanical properties as a function of temperature is required. Sn-Ag-Cu lead-free solder alloy contains three phases: a Sn-rich phase, and the intermetallic compounds (IMCs) Cu6Sn5 and Ag3Sn. Typically, the Sn-rich phase is surrounded by a eutectic mixture of ?-Sn, Cu6Sn5, and Ag3Sn. In this paper, we report on the Young's modulus and hardness of the Cu6Sn5 and Cu3Sn IMCs, the ?-Sn phase, and the eutectic compound, as measured by nanoindentation at elevated temperatures. For both the ?-Sn phase and the eutectic compound, the hardness and Young's modulus exhibited strong temperature dependence. In the case of the intermetallics, this temperature dependence is observed for Cu6Sn5, but the mechanical properties of Cu3Sn are more stable up to 200C.

Lotfian, S.; Molina-Aldareguia, J. M.; Yazzie, K. E.; Llorca, J.; Chawla, N.

2013-06-01

174

Reliability testing and data analysis of an 1657CCGA (ceramic column grid array) package with lead-free solder paste on lead-free PCBs (printed circuit boards)  

Microsoft Academic Search

In this study, the thermal cycling test of the 1657CCGA package with 95.5wt%Sn3.9wt%Ag0.6wt%Cu and 63wt%Sn37wt%Pb solder pastes on lead-free PCBs with HASL (hot-air solder leveling) CuSn, NiAu (electroless Ni and immersion Au, ENIG), and Entek OSP (organic solderability preservative) surface finishes are performed. The test stopped at 7500 cycles (0 to 100C, 40-minute cycle). The test data is best fitted

John Lau; W. Dauksher; Ed Ott; Dongkai Shangguan; Joe Smetana; Rob Horsley; Todd Castello; Dave Love; I. Menis; Bob Sullivan

2004-01-01

175

Lead-free solder materials for sustainable development of green electronics in China  

Microsoft Academic Search

Building recycle society is the key to ensure the sustainable development of China. The green electronics, including the advanced electronic packaging technology, play a most important role to promote the development of recycle society. In this paper, the development and trend of the green electronic industry, technology and laws in China and other countries are reviewed. New lead-free solder alloys

Jusheng Ma; Guohai Chen

2005-01-01

176

Effects of aging on the stress-strain and creep behaviors of lead free solders  

Microsoft Academic Search

Solder materials demonstrate evolving micro structure and mechanical behavior that changes significantly with environmental exposures such as isothermal aging and thermal cycling. These aging effects are greatly exacerbated at higher temperatures typical of thermal cycling qualification tests for harsh environment electronic packaging. In the current study, mechanical measurements of thermal aging effects and material behavior evolution of lead free solders

Hongtao Ma; Jeffrey C. Suhling; Pradeep Lall; Michael J. Bozack

2006-01-01

177

Effects of Physical Aging on the Stress-Strain and Creep Behaviors of Lead Free Solders  

Microsoft Academic Search

Solder materials demonstrate evolving properties that change significantly with environmental exposures such as isothermal aging and thermal cycling. Such physical aging effects are exacerbated at higher temperatures typical of thermal cycling qualification tests for harsh environment electronic packaging. In this work, measurements of thermal aging induced material behavior evolution have been performed for tin-lead and lead free solders. Extreme care

Hongtao Ma; J. C. Suhling; P. Lall; M. J. Bozack

2006-01-01

178

Development and characterization of AuCu seal ring for lead free packaging of MEMS devices  

Microsoft Academic Search

Seal rings are developed for packaging of circular openings of sensors and the fluidic flow based Micro Electro Mechanical Systems. Lead free technique based on isothermal solidification is used in this course of study. Thick film Au and high purity Cu substrates have been used during the development practice. Indium is used as the interlayer metal. Interconnections of high thermal

R. P. Sharma; P. K. Khanna; D. Kumar

2010-01-01

179

How to Identify Lead-Free Certification Marks for Drinking Water System & Plumbing Materials - Presentation  

EPA Science Inventory

In 2011, Congress passed the ?Reduction of Lead in Drinking Water Act,? which effectively reduces the lead content allowed in material used for potable water plumbing. The Act, which will go into effect on January 4, 2014, changes the definition of ?lead-free? by reducing allowed...

180

A study of nanoparticles in SnAg based lead free solders  

Microsoft Academic Search

Co, Ni, Pt, Al, P, Cu, Zn, Ge, Ag, In, Sb or Au inclusions in SnAg based lead free solders were evaluated to study if these nanoparticles can reduce the growth of intermetallic compounds after four time reflow processes and thermal aging. Also, these nanoparticles were studied if they can reduce the frequency of occurrence of intermetallic compound fractures in

Masazumi Amagai

2008-01-01

181

Assembly challenges of high density large fine pitch lead-free flip chip package  

Microsoft Academic Search

Assembly challenges for a high density, high performance integrated circuit package have been studied with respect to leadfree solder, fine pitch, large die on an organic substrate. The stresses induced by the large die size, higher reflow temperature due to lead-free solder and the low solder standoff due to fine-pitch configuration has shown to affect the quality of the assembly

Ser Choong Chong; Yeow Meng Tan; Tai Chong Chai; Samuel Lim; Wai Yin Hnin; Chek Kweng Cheng

2006-01-01

182

Coarsening processes in the lead-free solder alloy AgCu: theoretical and experimental investigations  

Microsoft Academic Search

Experimental investigations show that the microstructure of solders changes over time. In order to estimate the reliability and the lifetime of microelectronic solder materials it is important to predict the rate of microstructural change. Starting with an experimentally based overview on nucleation, spinodal decomposition as well as subsequent phase growth as observed in (lead-free) microelectronic solder connections this paper concentrates

W. H. Muller; T. Bohme

2005-01-01

183

Identification of Mechanical Properties of Intermetallic Compounds on Lead Free Solder  

Microsoft Academic Search

In this paper, we present methods for obtaining mechanical properties of silicon substrates and two intermetallic compounds (IMC) formed at the interfaces between lead-free solders and the copper and between leadfree solders and nickel substrates. To determine the mechanical properties of the silicon substrate, 255 um (100) and 306 um (110) thick silicon wafers were adopted. With proper sensor locations

Iting Tsai; Li Jung Tai; S. F. Yen; T. H. Chuang; R. Lo; T. Ku; Enboa Wu

2005-01-01

184

Development of a lead free chip scale package for wireless applications  

Microsoft Academic Search

Chip scale packages have seen a growth of over two times in the last two years and are expected to have more demands in the booming telecommunications market. This rapid growth of chip scale packages combined with green packaging solutions has made the implementation of lead free solders for chip scale package applications inevitable. But the effect of various lead

Vaidyanathan Kripesh; Poi-Siong Teo; C. T. Tai; Gautham Vishwanadam; Yew Cheong Mui

2001-01-01

185

Study on thermal simulation technology for SMA in lead-free reflow soldering  

Microsoft Academic Search

The thermal mathematical model under intensive convection in lead-free reflow soldering process is constructed for surface mounted assemblies, and the heat conduction governing equation, initial condition and boundary condition are made. A thermal mathematical model of SMA is transformed into solid model which can be analyzed by the thermal analysis software FLOTHERM. Then by defining the reasonable boundary condition and

Wu Zhaohua; Zhou Dejian

2008-01-01

186

Rate dependence of bending fatigue failure characteristics of lead-free solder joint  

Microsoft Academic Search

This study concerns the failure mechanism of a lead-free SAC305 solder joint under the isothermal bending fatigue condition. For this, series of bending fatigue tests are carried out with the variations of bending displacement and frequency, and FEM analysis is conducted to examine the relationship between mechanical behavior of a solder joint and fatigue life cycle. The results of this

Woong Ho Bang; Liang-Shan Chen; Choong-Un Kim; Tae-Kyu Lee; Kuo-Chuan Liu

2009-01-01

187

The impact of thermal cycling regime on the shear strength of lead-free solder joints  

Microsoft Academic Search

Purpose The purpose of this work is to undertake a comparison of accelerated test regimes for assessing the reliability of solder joints, in particular those made using lead-free solders. Design\\/methodology\\/approach Identical samples of 1206, 0805 and 0603 resistors were subjected to six different cycling regimes to investigate the effect of thermal excursions, ramp rates and temperature dwells. Findings

Milos Dusek; Martin Wickham; Christopher Hunt

2005-01-01

188

Impact reliability estimation of lead free solder joint with IMC layer  

Microsoft Academic Search

To secure the reliability of lead free solder is a critical issue for a chip-scale packaging process. While lots of researches on the solder reliability have been conducted by applying numerical simulation techniques, researches on IMC (intermetallic compound) are not intensively condoned due to its thin thickness, geometric irregularity and so on. However, the IMC layer which is generated during

Jong-Min Kim; Seung-Wan Woo; Yoon-Suk Chang; Young-Jin Kim; Jae-Boong Choi; Kum-Young Ji

2009-01-01

189

Effect of microstructure design on reliability of FBGA lead-free solder joints  

Microsoft Academic Search

In this paper, the fine pitch ball grid array (FBGA) assembly with lead free solder was tested under thermal cycling condition. Finite element modeling and simulation was conducted. The microstructure designs of via in pad of substrate and through hole (via) in PCB under the solder joint were simulated. The solder mask definition (SMD) and non-solder mask definition (NSMD) on

F. X. Che; J. E. Luan

2009-01-01

190

Effect of Ni Plating Thickness on Fatigue Failure of Lead-free Solder Joints  

Microsoft Academic Search

The purpose of this paper is to study the effect of plating thickness on fatigue failure of lead-free solder joints after thermal aging. Cyclic three-point bending tests were carried out and investigate the relationships between intermetallic compound (IMC) layer development and the fatigue life of solder joints. After the fatigue tests, cross- sections of solder joint were observed by scanning

M. Omiya; Takeshi Miyazaki; Hirotsugu Inoue; K. Kishimoto; M. Amagai

2006-01-01

191

Quality and reliability assurance by implementation of lead-free technology in electronic industry  

Microsoft Academic Search

For industrial implementation of lead-free materials are necessary important changes in process parameters (temperature, tolerances), auxiliary materials (fluxes, pastes) and manufacturing equipment. One of the most important problems of these changes is the warranty of good quality and reliability of electrical joints realized in new, environment-friendly technology. Especially for small electronic enterprises, it will be difficult to prove that the

Drozd Zdzislaw; Szwech Marcin; Bronowski Jaroslaw

2003-01-01

192

Lead-free ferroelectric BaTiO 3 doped-(Na 0.5 Bi 0.5 )TiO 3 thin films processed by pulsed laser deposition technique  

NASA Astrophysics Data System (ADS)

MPB lead free BNT-BT 0.08 thin films were deposited on Pt/Si substrate, in optimized pulsed laser deposition conditions. Structural and morphological characteristics have been correlated with deposition process and target morphology. The BNT-BT 0.08 thin film exhibits a well-defined ferroelectric hysteresis loop at room temperature. The leakage current density in BNT-BT 0.08 thin film is relatively low. Local piezoelectric and ferroelectric responses in BNT-BT 0.08 thin films, were identified.

Dragoi, Cristina; Cernea, Marin; Trupina, Lucian

2011-09-01

193

Lead-free In2O3-doped (Bi0.5Na0.5)0.93Ba0.07TiO3 ceramics synthesized by direct reaction sintering  

NASA Astrophysics Data System (ADS)

Lead-free (Bi0.5Na0.5)0.93Ba0.07TiO3-x wt %In2O3 ceramics synthesized by direct reaction sintering have been studied. X-ray diffraction reveals that all (Bi0.5Na0.5)0.93Ba0.07TiO3-x wt %In2O3 ceramics are of a perovskite structure with coexistence of rhombohedral and tetragonal phases. It is found that the direct reaction sintering promotes growing of ceramic grains while doping of In2O3 contributes to inhibit and homogenize the grain growth, as shown by scanning electron microscopy. The ceramics show excellent piezoelectric and dielectric properties with thickness electromechanical coupling factor kt=0.503, piezoelectric constant d33=205 pC/N, dielectric constant ?33T/V0=1046, and loss tangent tan ?=0.036.

Zhou, Tao-Sheng; Huang, Rong-Xia; Shang, Xun-Zhong; Peng, Fei; Guo, Jian-Yong; Chai, Li-Ying; Gu, Hao-Shuang; He, Yun-Bin

2007-04-01

194

Absolute and relative fatigue life prediction methodology for virtual qualification and design enhancement of lead-free BGA  

Microsoft Academic Search

The semiconductor industry is driving toward lead-free solder due to environmental concern and legislation requirement. The industry has also concluded that SnAgCu solder alloy so far is the best lead-free alternative to SnPb solder. Therefore, most existing and new packages have to be tested and qualified using lead-free solder. One of the critical concerns is board level solder joint reliability

Hun Shen Ng; Tong Yan Tee; Kim Yong Goh; Jing-en Luan; Tommi Reinikainen; Esa Hussa; Arni Kujala

2005-01-01

195

FP5-CSG-IMECAT : Highlights of a EC funded Project on Lead-Free Materials and Assembly Development Technologie  

Microsoft Academic Search

The EC has financially supported a pan-European collaboration on the development of lead-free interconnection materials and use of these materials for electronic assembly in a wide variety of industrial applications. The project started in April 2002 and is now close to the end. For the lead-free interconnection materials the focus was on lead-free solders, as well as on adhesives. The

Bart Vandevelde; Jan Vanfleteren; Bjorn Vandecasteele; Mario Gonzalez; Petar Ratchev; Inge Schildermans; Geert Willems; Joachim Wiese; Hans-Werner Hagedorn; Dion Manessis; M. Mango; Jarmo Mttnen; Daniel Vanderstraeten; Eddy Blansaer; Frank Kriebel

196

Lead free heterogeneous multilayers with giant magneto electric coupling for microelectronics/microelectromechanical systems applications  

NASA Astrophysics Data System (ADS)

Lead free magneto electrics with a strong sub resonant (broad frequency range) magneto electric coupling coefficient (MECC) is the goal of the day which can revolutionise the microelectronics and microelectromechanical systems (MEMS) industry. We report giant resonant MECC in lead free nanograined Barium Titanate-CoFe (Alloy)-Barium Titanate [BTO-CoFe-BTO] sandwiched thin films. The resonant MECC values obtained here are the highest values recorded in thin films/multilayers. Sub-resonant MECC values are quite comparable to the highest MECC reported in 2-2 layered structures. MECC got enhanced by two orders at a low frequency resonance. The results show the potential of these thin films for transducer, magnetic field assisted energy harvesters, switching devices, and storage applications. Some possible device integration techniques are also discussed.

Nair, Swapna S.; Pookat, Geetha; Saravanan, Venkata; Anantharaman, M. R.

2013-08-01

197

An integrated microfluidic chip with 40 MHz lead-free transducer for fluid analysis  

SciTech Connect

The design, fabrication, and evaluation of a high-frequency transducer made from lead-free piezoceramic for the application of microfluidic analysis is described. Barium strontium zirconate titanate [(Ba{sub 0.95}Sr{sub 0.05})(Zr{sub 0.05}Ti{sub 0.95})O{sub 3}, abbreviated as BSZT] ceramic has been chosen to be the active element of the transducer. The center frequency and bandwidth of this high-frequency ultrasound transducer have been measured to be 43 MHz and 56.1%, respectively. The transducer was integrated into a microfluidic channel and used to measure the sound velocity and attenuation of the liquid flowing in the channel. Results suggest that lead-free high-frequency transducers could be used for in situ analysis of property of the fluid flowing through the microfluidic system.

Lee, S. T. F.; Lam, K. H.; Lei, L.; Zhang, X. M.; Chan, H. L. W. [Department of Applied Physics and Materials Research Centre, The Hong Kong Polytechnic University, Kowloon (Hong Kong)

2011-02-15

198

Giant electrocaloric effect in lead-free thin film of strontium bismuth tantalite  

NASA Astrophysics Data System (ADS)

Giant electrocaloric effect was observed in lead-free material for the first time. A demonstration of large electrocaloric effect in 200 nm sol-gel thin film SrBi2Ta2O9 is described here. The ferroelectric hysteresis loops and the film permittivity were measured. The extracted data characterized the electrocaloric temperature change, up to 4.93K in 12V (i.e., 0.41 K V-1) near the Curie point. It is concluded that the giant electrocaloric effect exists in lead-free materials, and a large family of layered perovskite oxides may exhibit analogical property. The absence of lead allows eco-friendly application and enhances compatibility with integrated circuit process in future applications.

Chen, Hao; Ren, Tian-Ling; Wu, Xiao-Ming; Yang, Yi; Liu, Li-Tian

2009-05-01

199

Large strain response in acceptor- and donor-doped Bi 0.5 Na 0.5 TiO 3 -based lead-free ceramics  

Microsoft Academic Search

Effects of Fe and La addition on the dielectric, ferroelectric, and piezoelectric properties of Bi0.5Na0.5TiO3Bi0.5Li0.5TiO3BaTiO3Mn ceramics were investigated. Similar to the doping effect in lead-based piezoelectric materials, here the Fe-doped ceramic\\u000a created a hard effect with an improved mechanical quality factor (Q\\u000a m)~160, coercive field (E\\u000a c)~2.9kV\\/mm, decreased dielectric constant $$ \\\\left( {\\\\varepsilon_{33}^{T} \\/\\\\varepsilon_{0} } \\\\right)\\\\sim 80 3, $$ and

Tao Wang; Feifei Wang; Chung Ming Leung; Siu Wing; Yanxue Tang; Xinman Chen; Xiaomei Qin; Wangzhou Shi

2011-01-01

200

Modified Anand constitutive model for lead-free solder Sn3.5Ag  

Microsoft Academic Search

An improved Anand constitutive model is proposed to describe the inelastic deformation of lead free solder Sn-3.5Ag used in solder joints of microelectronic packaging. The new model accurately predicted the overall trend of steady-state stress-strain behavior of the solder for the temperature range from 233 K to 398 K and the strain rate range from 0.005 s-1 to 0.1 s-1h0,

Xu Chen; Gang Chen; Masao Sakane

2004-01-01

201

Lifetime Modeling based on an Advanced Test Chip Configuration for Lead-free Solder Joints  

Microsoft Academic Search

This paper presents the results of thermo-mechanical lifetime tests. A novel test vehicle was employed to characterize solder joint reliability of miniaturized lead-free tin-silver-copper solder bumps. The test vehicle consists of a stiff ceramic chip (AI2O3) with four corner solder joints assembled on a FR-4 PWB. The distance between the solder joint centers is variable (d= 800\\/1600\\/2400\\/3200 mum). This allows

Bjrn Bhme; Mike Rllig; Steffen Wiese; Klaus-Jrgen Wolter

2006-01-01

202

Numerical Analysis on Stress and Strain in QFP Lead-Free Solder with Temperature Impact  

Microsoft Academic Search

To study the relation between the QFP lead-free solder stress and strain accumulation under the condition of the impact of temperature (-55C~125C), Visco-plastic finite element model based upon Anand constitutive equations is established to numerically analyze the interfacial stress of solder formed by three different kinds of solders to the same substrate FR-4. The results shows that the interface stress

Li Zhi; Zhao Mei-rong; You Min; Lu Wei-bin; Wang Yun-Tao

2009-01-01

203

Size and microstructure effects on the stress-strain behaviour of lead-free solder joints  

Microsoft Academic Search

The properties of lead-free solders such as Sn3.8Ag0.7Cu are less understood than traditional Sn-Pb solders, as well as the factors affecting these material properties. Therefore, the present paper focuses on determination of stress-strain properties for both small-scale solder joints and for bulk solder for three different strain rates. The paper also analyses the obtained experimental results, and compares material properties

Pradeep Hegde; David C. Whalley; Vadim V. Silberschmidt

2009-01-01

204

Printed circuit boards for lead-free soldering: materials and failure mechanisms  

Microsoft Academic Search

Purpose This paper aims to evaluate the influence of previous exposure to moisture on delamination and formation of CAF (conductive anodic filament) in printed circuit boards used for lead-free soldering. Design\\/methodology\\/approach The moisture absorption and desorption characteristics of printed circuit boards were evaluated according to the IPC\\/JEDEC J-STD-020C standard for handling of moisture sensitive components. The CAF test

Per Johander; Per-Erik Tegehall; Abelrahim Ahmed Osman; Gran Wetter; Dag Andersson

2007-01-01

205

A study of lead-free BGA backward compatibility through solderability testing at component level  

Microsoft Academic Search

A study was conducted to assess the backward compatibility of two different lead-free BGA components using Jedec Solderability testing method (JESD22-B102D). The test was conducted at component level. The two components tested were 2929mm Thermally Enhanced PBGA (TePBGA-II) and 3535mm Tape BGA (TBGA) with SAC387 and Sn3.5Ag solder balls. Four units from each of the two component types were used

Eu Poh Leng; Wong Tzu Ling; Nowshad Amin; Ibrahim Ahmad

2008-01-01

206

Reflow ageing influences and wettability effects of immersion tin final finishes with lead-free solder  

Microsoft Academic Search

Purpose The purpose of this paper is to investigate the oxidation behaviour of an immersion tin final finish after multiple reflow ageing under air and nitrogen atmospheres and to study their influence on the wetting behaviour with lead-free solder. To design a model that describes the degradation of wetting behaviour after reflow-cycling of the immersion tin final finish. Design\\/methodology\\/approach

Thomas Hetschel; Klaus-Jrgen Wolter; Fritz Phillipp

2009-01-01

207

Rework Process Window and Microstructural Analysis for Lead-Free Mirrored Bga Design Points  

Microsoft Academic Search

Hot gas rework of BGAs with a mirrored BGA design configuration using SnAgCu based lead-free alloys is more challenging as compared to conventional SnPb techniques. Rework of BGAs using a conventional SnPb alloy system has historically required that mirrored BGA solder joints remain below the eutectic melt temperature of 183?C to avoid secondary (or partial) reflow of these mirrored solder

Matthew Kelly; Mitchell Ferrill; Polina Snugovsky; Rupen Trivedi; Gaby Dinca; Chris Achong; Zohreh Bagheri

208

Results of comparative reliability tests on lead-free solder alloys  

Microsoft Academic Search

The use of lead-free solder brings up concerns regarding the reliability of the new alloys to be used. In a European project (LEADFREE) SnAg, SnAgCu, SnAgCuSb, SnZn and SnPbAg have been tested in order to evaluate comparative data of the growth of cracks in solder joints. Reliability tests performed in other projects use accelerated tests proposed for tin-lead solders and

Giinter Grossmann; Giovanni Nicoletti; Ursin Solr

2002-01-01

209

Thermal and Mechanical Reliability Tests of Lead - free soldered SMT Joints  

Microsoft Academic Search

One of the main goals in development of electronics manufacturing technology, after implementation of EU Directive RoHS, is the reliability improvement of electronic interconnection systems. Investigations of lead-free technology for small producers of electronic equipment (SME's) were made in Warsaw University of Technology (WUT) in frame of GreenRoSE Project financed by EC. Achieved results of accelerated thermal and mechanical cycling

Z. Drozd; M. Szwech; R. Kisiel

2007-01-01

210

Shear Failure Analysis of Sub50 ?m Flip Chip Lead-free Solder Bumps  

Microsoft Academic Search

Sn-0.7Cu, Sn-3.5Ag, Sn-4Ag-0.5Cu lead-free solder bumps were produced by stencil printing of solder pastes on wafers having electroless Ni-P immersion Au (ENIG) under bump metallization (UBM). The diameter of the solder bumps was 4547 ?m. Shear tests were carried out to evaluate the bonding quality of the solder bumps after multiple reflows and thermal aging at 150C. The fracture surface,

Mingliang Huang

2007-01-01

211

Modeling of interfacial intermetallic compounds in the application of very fine lead-free solder interconnections  

Microsoft Academic Search

Intermetallic compounds (IMCs) are formed between lead-free solders and base metals during soldering processes. The morphology\\u000a as well as the amount of the IMCs, in particular the interfacial IMCs, are important to mechanical performance of the solder\\u000a joints in their service environment. This is especially the case in state-of-art ultrafine-pitch wafer-level packaging, in\\u000a which solder joints could become as small

Zhiheng Huang; Paul P. Conway; Rongshan Qin

2009-01-01

212

THERMOMECHANICAL ANALYSIS OF A CHIP SCALE PACKAGE (CSP) USING LEAD FREE AND LEAD CONTAINING SOLDER MATERIALS  

Microsoft Academic Search

This work is intended to provide a quantitative estimation of the accumulated inelastic strain of two different lead free solder alloys, namely, Sn3.5Ag and Sn3.8Ag0.5Cu. The eutectic Sn37Pb solder is also considered to establish a baseline. Thermomechanical stress and strain analysis was conducted on a Chip Scale Package (CSP). The solder joint fatigue was modeled for two typical temperature cycling

M. GONZALEZ; B. VANDEVELDE; E. BEYNE

213

Lead-free wafer level-chip scale package: assembly and reliability  

Microsoft Academic Search

This paper discusses the reliability testing results of a lead-free version of the micro SMD, National Semiconductor's Wafer Level-Chip Scale Package (WL-CSP). The micro SMD, a true wafer scale package has proven to be highly adaptable in the conventional assembly process, requiring no special considerations during the surface mount assembly operation. The current micro SMD utilizes standard Sn\\/Pb solder bumps

V. Patwardhan; N. Kelkar; L. Nguyen

2002-01-01

214

Wetting behaviour of lead free solder on electroplated Ni and Ni-W alloy barrier film  

Microsoft Academic Search

In this work, electrodeposited Ni-W alloys were studied as barrier films between Cu substrate and lead free Sn3.8Ag0.7Cu (SAC387) solder. Wetting angle and spreading rate of SAC387 on Ni-W alloys with different tungsten contents were investigated and compared with that on Ni film deposited from Watt's bath. Ni-W alloy films of about 1.5 to 2.5 mum were deposited from ammonia-citrate

C. S. Chew; A. S. M. A. Haseeb; M. R. Johan

2009-01-01

215

Nanoindentation for measuring individual phase mechanical properties of lead free solder alloy  

Microsoft Academic Search

The elimination of lead from electronics due to its detrimental effects to environment and health is pushing component manufacturers\\u000a to consider lead free solder alloys as the substitute. Application of such alloys requires a better understanding of their\\u000a mechanical behavior at small volume size and at elevated temperatures. Such information is still lacking for both solder joints\\u000a and bulk materials.

Yong Sun; Jin Liang; Zhi-Hui Xu; Guofeng Wang; Xiaodong Li

2008-01-01

216

Wetting behaviour of lead free solder on electroplated Ni and Ni-W alloy barrier film  

Microsoft Academic Search

In this work, electrodeposited of Ni-W alloys were studied as barrier films between Cu substrate and lead free Sn3.8Ag0.7Cu (SAC387) solder. Wetting angle and spreading rate of SAC387 on Ni-W alloys with different tungsten contents were investigated and compared with that on Ni film deposited from Watt's bath. Ni-W alloy films of about 1.5 to 2.5 m were deposited from

C. S. Chew; A. S. M. A. Haseeb; M. R. Johan

2010-01-01

217

A Study of Lead-Free BGA Backward Compatibility Through Solderability Testing at Component Level  

Microsoft Academic Search

A study was conducted to assess the backward compatibility of three different lead-free BGA components using Jedec Solderability testing method (JESD22-B102D). The test was conducted at component level. The three components tested were 29??29 mm Thermally Enhanced PBGA (TePBGA-II) and 35??35mm Tape BGA (TBGA) with SAC387 and Sn3.5Ag solder balls, as well as 33??33 mm Flip Chip HiCTE BGA with

Eu Poh Leng; Wong Tzu Ling; N. Amin; I. Ahmad

2008-01-01

218

Development of SnZn lead-free solders bearing alloying elements  

Microsoft Academic Search

SnZn solder alloys have been considered as one of the more attractive lead-free solders since it can easily replace SnPb\\u000a eutectic alloy without increasing the soldering temperature. However, there are still some problems to be resolved, such as\\u000a the argument about the poor oxidation resistance and embrittlement behavior. In order to overcome these drawbacks, and further\\u000a enhance the properties of

Liang ZhangSong-bai; Song-bai Xue; Li-li Gao; Zhong Sheng; Huan Ye; Zheng-xiang Xiao; Guang Zeng; Yan Chen; Sheng-lin Yu

2010-01-01

219

Regulations and market trends in lead-free and halogen-free electronics  

Microsoft Academic Search

Purpose This paper seeks to investigate the electronics industry's reaction to environmental regulations specifically in terms of lead-free solders and halogen-free flame-retardants (FRs). Design\\/methodology\\/approach This work achieves its objective by discussing the various international environmental regulations pertaining to electronics manufacturing and relating the industry reactions to those regulations. It also provides the market trends related to lead- and

Lei Nie; Michael Pecht; Richard Ciocci

2007-01-01

220

Comparison of Printed Circuit Board Property Variations in Response to Simulated Lead-Free Soldering  

Microsoft Academic Search

Use of lead-free solders such as Sn\\/Ag\\/Cu results in exposure of printed circuit boards to higher temperatures during assembly compared with eutectic tin-lead solder. If the thermo-mechanical and electrical properties of the laminate materials get affected by exposure to this higher temperature, that may impact the performance and reliability of the circuit board. Variations, if any, in laminate material properties

Bhanu Sood; Ravikumar Sanapala; Diganta Das; Michael Pecht; C. Y. Huang; M. Y. Tsai

2010-01-01

221

Low temperature electromigration and thermomigration in lead-free solder joints  

Microsoft Academic Search

High current density and high temperature gradient are major reliability concern for next generation nanoelectronic packaging and power electronics. High current density experiments on lead free solder joints coated with NiAu and non-coated Cu pads were conducted at ?20, ?30, ?40 and ?50C ambient temperatures. The time to failure (TTF) shows that solder joints with NiAu coated Cu pads last

Cemal Basaran; Mohd F. Abdulhamid

2009-01-01

222

A novel mechanical shock test method to evaluate lead-free BGA solder joint reliability  

Microsoft Academic Search

Portable electronic products such as cell phones are often subjected to drop tests to simulate consumer usage and to ensure required field reliability is met. Product-level drop tests can cause solder joint failures in both lead-free and tin-lead BGA packages due to the combination of highly localized strain created by high strain-rate mechanical shock. In order to understand this phenomenon

Dave Reiff; Edwin Bradley

2005-01-01

223

Low temperature electromigration and thermomigration in lead-free solder joints  

Microsoft Academic Search

High current density and high temperature gradient are major reliability concern for next generation high density power electronics. High current density experiments on lead free solder joints coated with NiAu and non-coated Cu pads were conducted at -20C, -30C, -40C and -50C ambient temperatures. The time to failure (TTF) shows that solder joints with NiAu coated Cu pads last longer.

Mohd Foad Abdul Hamid; Cemal Basaran

2008-01-01

224

Effect of Nickel Pad Metallization Thickness on Fatigue Failure of BGA Lead-Free Solder Joints  

Microsoft Academic Search

The purpose of this paper is to present our work on the effect of nickel (Ni) pad metallization thickness on fatigue failure of lead-free solder joints after thermal aging. Cyclic three-point bending tests were carried out to investigate the relationship between intermetallic compound (IMC) layer development and the fatigue life of solder joints. After the fatigue tests, cross-sections of solder

Masaki Omiya; Takeshi Miyazaki; Kikuo Kishimoto; Masazumi Amagai

2008-01-01

225

Knowledge-based reliability qualification and an acceleration model for lead-free solder joint  

Microsoft Academic Search

Lead free solder joints in surface mount packages like ball grid array (BGA) have a great impact on the reliability of final products. In this study, the approach to knowledge-based qualification for solder joint reliability is fully described. An acceleration failure model has been derived for Sn3.0Ag0.5Cu based solder joint interconnect with dual inline memory module (DIMM) applications and to

Yuchul Hwang; Hwan-Ki Jeon; Young-Gyun Ryu; Juseong Kang

2011-01-01

226

Failure analysis of lead-free solder joints for high-density packages  

Microsoft Academic Search

Failure analyses of the lead-free and SnPb solder joints of high-density packages such as the plastic ball grid array and the ceramic column grid array soldered on SnCu hot-air solder levelling electroless nickel-immersion gold or NiAu, and organic solderability preservative Entek printed circuit boards are presented. Emphasis is placed on determining the failure locations, failure modes, and intermetallic compound composition

John Lau; Dongkai Shangguan; Todd Castello; Rob Horsley; Joe Smetana; Nick Hoo; Walter Dauksher; Dave Love; Irv Menis; Bob Sullivan

2004-01-01

227

Experimental investigation on the failure of lead-free solder joints under drop impact  

Microsoft Academic Search

Purpose The purpose of this paper is to investigate the mechanism of ball grid array (BGA) lead-free solder joint failure under board-level drop impact. Design\\/methodology\\/approach A round shaped test board was used. First, drop tests at three different heights were carried out. Then, dye stain testing and metallurgical analysis were performed in order to study the failure mechanism

Fang Liu; Guang Meng; Mei Zhao

2010-01-01

228

Reliability testing and data analysis of lead-free solder joints for high-density packages  

Microsoft Academic Search

Temperature cycling tests, and statistical analysis of the results, for various high-density packages on printed-circuit boards with Sn-Cu hot-air solder levelling, electroless nickel-immersion gold, and organic solder preservative finishes are investigated in this study. Emphasis is placed on the determination of the life distribution and reliability of the lead-free solder joints of these high-density package assemblies while they are subjected

John Lau; Nick Hoo; Rob Horsley; Joe Smetana; Dongkai Shangguan; Walter Dauksher; Dave Love; Irv Menis; Bob Sullivan

2004-01-01

229

Modeling and reliability analysis of lead-free solder joints of bottom leaded plastic (BLP) package  

Microsoft Academic Search

The electronic packaging and assembly technology is developing to high-density, fine-pitch and micromation. At the same time, an ever increasing need has developed for a lead-free solder joint interconnection due to the restrictions on the use of lead, and the upward spiraling market demand of green products. As a result the reliability of solder joint has attracted a great deal

Chen Xiangyang; Zhou Dejian

2006-01-01

230

Smog chamber reactivities of emissions from leaded and lead-free fuels  

Microsoft Academic Search

Work was undertaken to determine photochemical specific reactivities of emissions from automobiles using leaded-premium- and regular-grade fuels and prototype lead-free fuels of comparable octane quality. Emissions were photoirradiated in a 100-ft³ environmental (smog) chamber constructed of aluminum and Pyrex glass at three sets of initial hydrocarbon (HC) and oxides of nitrogen (NO\\/sub x\\/) concentrations. Reactivity was measured and expressed in

G. P. Jr. Sturm; B. Dimitriades

1973-01-01

231

Improving the performance of lead-free solder reinforced with multi-walled carbon nanotubes  

Microsoft Academic Search

In this study, varying weight fractions of multi-walled carbon nanotubes were successfully incorporated into 95.8Sn3.5Ag0.7Cu solder, to synthesize novel lead-free composite solders. The composite solders were synthesized via the powder metallurgy route of: blending, compaction, sintering and extrusion. The extruded materials were then characterized for their physical, thermal and mechanical properties. With the addition of increasing weight percentage of carbon

S. M. L. Nai; J. Wei; M. Gupta

2006-01-01

232

Influence of 0.03 wt.% Carbon Black Addition on the Performance of Sn-3.5Ag Lead-Free Solder  

NASA Astrophysics Data System (ADS)

In an effort to improve the performance of lead-free solder, Sn-3.5 wt.%Ag (Sn-3.5Ag) solder alloy with 0.03 wt.% carbon black was prepared under high pressure (5.5 GPa) and high temperature (1200C). We have investigated the microstructure, melting behavior, and mechanical properties of the alloy using x-ray diffraction, differential scanning calorimetry (DSC), Vickers hardness testing, tensile testing, and scanning electron microscopy (SEM). The melting point was found to be unchanged, while the hardness and the tensile strength increased with the addition of carbon black. SEM images showed that the average thickness of the intermetallic compound (IMC) layer decreased with the addition of carbon black, indicating improvement in solder joint reliability.

Van Son, Phung; Fujitsuka, Akira; Ohshima, Ken-Ichi

2012-07-01

233

Piezoelectric drive circuit  

DOEpatents

A piezoelectric motor drive circuit is provided which utilizes the piezoelectric elements as oscillators and a Meacham half-bridge approach to develop feedback from the motor ground circuit to produce a signal to drive amplifiers to power the motor. The circuit automatically compensates for shifts in harmonic frequency of the piezoelectric elements due to pressure and temperature changes. 7 figs.

Treu, C.A. Jr.

1999-08-31

234

Engineered piezoelectricity in graphene.  

PubMed

We discover that piezoelectric effects can be engineered into nonpiezoelectric graphene through the selective surface adsorption of atoms. Our calculations show that doping a single sheet of graphene with atoms on one side results in the generation of piezoelectricity by breaking inversion symmetry. Despite their 2D nature, piezoelectric magnitudes are found to be comparable to those in 3D piezoelectric materials. Our results elucidate a designer piezoelectric phenomenon, unique to the nanoscale, that has potential to bring dynamical control to nanoscale electromechanical devices. PMID:22196055

Ong, Mitchell T; Reed, Evan J

2012-01-06

235

Morphotropic phase boundary and electrical properties in (1-x)Bi0.5Na0.5TiO3-xBi(Zn0.5Ti0.5)O3 lead-free piezoceramics  

NASA Astrophysics Data System (ADS)

(1-x)Bi0.5Na0.5TiO3-xBi(Zn0.5Ti0.5)O3 [(1-x)BNT-xBZT, x=0, 0.025, 0.0375, 0.050, and 0.075] lead-free piezoceramics were prepared and their structures and electrical properties were investigated. It is found that BZT can increase the Curie temperature of BNT. A morphotropic phase boundary (MPB) separating rhombohedral and tetragonal phases exists near x=0.0375. As the result, the MPB composition shows improved electrical properties; the saturated polarization, remnant polarization, and coercive field are 42.0 ?C/cm2, 36.5 ?C/cm2, and 3.5 kV/mm, respectively, while the piezoelectric coefficient, planar electromechanical coupling factor, and unipolar strain are 92 pC/N, 0.22, and 0.08%, respectively. The structures and electrical properties are discussed by comparing with that of other BNT-based piezoceramics. Our results do not only supplement for BNT-based lead-free piezoceramics, but also may provide a way to develop new lead-free piezoceramics with high Curie temperature.

Zhang, Shan-Tao; Yan, Feng; Yang, Bin

2010-06-01

236

Effect of Rapid Solidification on Structure and Properties of Some Lead-Free Solder Alloys  

Microsoft Academic Search

Four of the binary lead-free solder alloys of compositions Sn-0.5Cu, Sn-3.5Ag, Sn-5Sb and Sn-9Zn, were rapidly solidified by melt-spinning technique as a technique for producing new alloy compositions. The results show that rapid solidification causes formation of some intermetallic compounds such as Ag3Sn and Cu6Sn5 in the two alloys Sn-3.5Ag and Sn-0.5Cu, which cannot be formed at the equilibrium phase

Mustafa Kamal; El-Said Gouda

2006-01-01

237

Accelerated thermal fatigue of lead-free solder joints as a function of reflow cooling rate  

Microsoft Academic Search

Leadless chip resistor (LCR) assemblies were manufactured using both traditional tin-lead (Sn37Pb) and lead-free (Sn3.8Ag0.7Cu)\\u000a solders. The leadfree test vehicles were assembled using three different cooling rates: 1.6C\\/sec, 3.8C\\/sec, and 6.8C\\/sec.\\u000a They were then exposed to accelerated thermalcycling (ATC) tests between 0C and 100C with a 1014C\\/min ramp rate and a\\u000a 5-min dwell time. The test results indicated that these

Y. Qi; A. R. Zbrzezny; M. Agia; R. Lam; H. R. Ghorbani; P. Snugovsky; D. D. Perovic; J. K. Spelt

2004-01-01

238

Investigation on properties of Ga to Sn9Zn lead-free solder  

Microsoft Academic Search

The influences of different Ga content on the properties of Sn9Zn lead-free solder were investigated. The results indicate\\u000a that Ga plays an important role not only in the structure and melting behavior, but also in the solderability and mechanical\\u000a property. Sn9Zn0.5Ga shows finer and more uniform microstructure than Sn9Zn. With the addition of low-melting-point Ga,\\u000a TL (liquidus temperature) and TS

Wenxue Chen; Songbai Xue; Hui Wang; Jianxin Wang; Zongjie Han

2010-01-01

239

Creep Deformation of Lead-Free Sn3.5Ag-Bi Solders  

Microsoft Academic Search

Creep rupture properties of lead-free Sn-3.5Ag-based alloys with varying amounts of Bi were investigated using dog-bone-shaped rolled and heat-treated bulk specimens. Nominal compositions of Bi additions were 0, 2.5, 4.8, 7.5, and 10 wt%, respectively. The minimum strain rates (\\\\dot{\\\\varepsilon}min) were lowest for the 2.5Bi specimens. The stress exponents (n) of \\\\dot{\\\\varepsilon}min were usually around 4 0.6, with the exception

Seung Woo Shin; Jin Yu

2003-01-01

240

Evaluation of Bulk Mechanical Properties of Selected Lead-Free Solders in Tension and in Shear  

NASA Astrophysics Data System (ADS)

Lead-free solders are fast emerging as better alternatives to Sn-Pb solders. The reliability of a soldered joint to withstand imposed stresses in an assembly is decided by its mechanical properties. The present work is about the investigation of tensile and shear properties of four binary eutectic alloys Sn-3.5Ag, Sn-58Bi, Sn-0.7Cu, Sn-9Zn and a ternary alloy Sn-57Bi-1.3Zn in comparison with conventional Sn-38Pb alloy. It is observed that the lead-free solders have better mechanical properties than the latter. SEM studies of tensile and shear fracture show ductile dimples circular in tension and parabolic in shear modes supporting the mechanical behavior of the alloys investigated. Eutectic alloys Sn-Ag, Sn-Zn, and Sn-Cu form potential substitutes for Sn-Pb for electronic interconnects exposed to high temperatures, while Sn-Bi and Sn-Bi-Zn are attractive alternatives in addressing the need of lower processing temperatures in printed circuit boards and other applications.

Devaki Rani, S.; Murthy, G. S.

2013-03-01

241

Study on Dynamic Failure Model of Lead-Free Solders Using Shpb Techniques  

NASA Astrophysics Data System (ADS)

The dynamic compressive properties of 96.3Sn3Ag0.7Cu and 99.3Sn0.7Cu solders were studied by means of a split Hopkinson pressure bar at strain rates ranging from 500 to 2000 s-1. Tests were conducted at room temperature and under uniaxial compressive conditions. Eutectic SnPb solders were used as the reference. From the data of tests, it was found that yield strength and flow stress increased remarkably with the increase of strain rate. On logarithmic scales, the yield strength increased linearly with strain rate. These lead-free solders revealed certain visco-plastic behavior and strain rate sensitivity, which predicted using Johnson-Cook material model. Related parameters in the model were determined from the experiment. Compared with the typical Pb-containing solder Sn63Pb37, these lead-free solders showed some fine properties and could substitute some Pb-containing solder alloys in microelectronic components packaging and interconnects.

Niu, Xiaoyan; Yuan, Guozheng; Li, Zhigang; Shu, Xuefeng

242

Assessment of circuit board surface finishes for electronic assembly with lead-free solders  

SciTech Connect

The suitability of various metallic printed wiring board surface finishes was assessed for new technology applications that incorporate assembly with Lead-free solders. The manufacture of a lead-free product necessitates elimination of lead (Pb) from the solder, the circuit board as well as the component lead termination. It is critical however for the selected interconnect Pb-free solder and the corresponding printed wiring board (PWB) and component lead finishes to be mutually compatible. Baseline compatibility of select Pb-free solders with Pb containing PWB surface finish and components was assessed. This was followed by examining the compatibility of the commercially available CASTIN{trademark} (SnAgCuSb) Pb-free solder with a series of PWB metallic finishes: Ni/Au, Ni/Pd, and Pd/Cu. The compatibility was assessed with respect to assembly performance, solder joint integrity and long term attachment reliability. Solder joint integrity and mechanical behavior of representative 50 mil pitch 20I/O SOICs was determined before and after thermal stress. Mechanical pull test studies demonstrated that the strength of SnAgCuSb solder interconnections is notably greater than that of SnPb interconnections.

Ray, U.; Artaki, I.; Finley, D.W.; Wenger, G.M. [Bell Labs., Princeton, NJ (United States). Lucent Technologies; Pan, T.; Blair, H.D.; Nicholson, J.M. [Ford Motor Co., Dearborn, MI (United States); Vianco, P.T. [Sandia National Labs., Albuquerque, NM (United States)

1996-10-01

243

Evaluation of Diffusion Barrier Between Lead-Free Solder Systems and Thermoelectric Materials  

NASA Astrophysics Data System (ADS)

The intermetallic compound SnTe rapidly formed at interfaces between p-type bismuth telluride (Bi0.5Sb1.5Te3) thermoelectric materials and lead-free solders. The intermetallic compound influences the mechanical properties of the joints and the reliability of the thermoelectric modules. Various lead-free solder alloys, Sn-3.5Ag, Sn-3Ag-0.5Cu, Sn-0.7Cu, and Sn-2.5Ag-2Ni, were used to investigate the interfacial reactions. The results thus obtained show that Ag and Cu preferentially diffused into the Te-rich phase in Bi0.5Sb1.5Te3, so layers of Ag-Te and Cu-Te compounds could not form an effective diffusion barrier. Electroless nickel-phosphorus was plated at the interfaces to serve as a diffusion barrier, and the (Cu,Ni)6Sn5 compound formed instead of SnTe. Furthermore, the intermetallic compound NiTe formed between nickel- phosphorus and Bi0.5Sb1.5Te3 and also served as a diffusion barrier. A plot of thickness as a function of annealing time yielded the growth kinetics of the intermetallic compounds in the thermoelectric material systems. The activation energy for the growth of the NiTe intermetallic compound is 111 kJ/mol.

Lin, T. Y.; Liao, C. N.; Wu, Albert T.

2012-01-01

244

Evaluation of Bulk Mechanical Properties of Selected Lead-Free Solders in Tension and in Shear  

NASA Astrophysics Data System (ADS)

Lead-free solders are fast emerging as better alternatives to Sn-Pb solders. The reliability of a soldered joint to withstand imposed stresses in an assembly is decided by its mechanical properties. The present work is about the investigation of tensile and shear properties of four binary eutectic alloys Sn-3.5Ag, Sn-58Bi, Sn-0.7Cu, Sn-9Zn and a ternary alloy Sn-57Bi-1.3Zn in comparison with conventional Sn-38Pb alloy. It is observed that the lead-free solders have better mechanical properties than the latter. SEM studies of tensile and shear fracture show ductile dimples circular in tension and parabolic in shear modes supporting the mechanical behavior of the alloys investigated. Eutectic alloys Sn-Ag, Sn-Zn, and Sn-Cu form potential substitutes for Sn-Pb for electronic interconnects exposed to high temperatures, while Sn-Bi and Sn-Bi-Zn are attractive alternatives in addressing the need of lower processing temperatures in printed circuit boards and other applications.

Devaki Rani, S.; Murthy, G. S.

2013-08-01

245

The Effects of High Temperature Storage on Lead Free Solder Joint Material Strength Using Pull Test Method  

Microsoft Academic Search

The purpose of this study is to discuss on the effect of high temperature storage (HTS) on lead free solder joint material for ball grid array application using pull test method. Three samples of different lead free solder joint material were choosed in this experiment that are Sn3.8Ag0.7Cu (SAC387), Sn2.3Ag0.08Ni 0.01Co (SANC), and Sn3.5Ag. Then the lead free solder joint

MuhammadNajib Harif; I. Ahmad; A. Zaharim

2006-01-01

246

iNEMI LEAD-FREE MICRO-BGA, CBGA, MICTOR CONNECTOR AND THROUGH-HOLE PDIP REWORK EVALUATIONS  

Microsoft Academic Search

A team of iNEMI (InterNational Electronics Manufacturing Initiative) companies collaborated to develop Tin-lead and Lead-free rework processes for double-sided printed circuit boards in three thicknesses (0.062\\

Quyen Chu; Nabel Ghalib; Bryant Bulao; Charlie Han; Greg Smith

247

Lead-free low-melting point sealing glass in SnOCaOP 2O 5 system  

Microsoft Academic Search

Development of lead-free low-melting point sealing glass with properties such as low coefficient of thermal expansion (CTE), low glass transition temperature (Tg), low softening temperature (Tf), low cost, high electrical resistance and high chemical stability, has been under strong market demands. Research on the development of lead-free low-melting point sealing glass in SnOCaOP2O5 (SCP) system was carried out. A large

Jianhe Hong; Desen Zhao; Jinfei Gao; Mingzhong He; Haifeng Li; Gang He

2010-01-01

248

Rate-dependent properties of Sn-Ag-Cu based lead-free solder joints for WLCSP  

Microsoft Academic Search

The increasing demand for portable electronics has led to the shrinking in size of electronic components and solder joint dimensions. The industry also made a transition towards the adoption of lead-free solder alloys, commonly based around the SnAgCu alloys. As knowledge of the processes and operational reliability of these lead-free solder joints (used especially in advanced packages) is limited, it

Y. A. Su; L. B. Tan; T. Y. Tee; V. B. C. Tan

2010-01-01

249

Microstructure and Mechanical Properties Investigation of Lead-free Solder Sn99.3Cu0.7  

Microsoft Academic Search

In the late years, environment concerns have attracted more and more attention in many countries, because of pollution from the lead-based solders and its compounds. Many countries are about to ban using of lead-based solders in microelectronic packaging; the lead-free solders will replace the tin-lead (Sn-Pb) eutectic solders. Due to higher melting temperature of most candidate lead-free solders, however, mechanical

Fulong Zhu; Honghai Zhang; Rongfeng Guan; Sheng Liu

2005-01-01

250

A reliability comparison of lead free and Eutectic solder for stencil printing based flip-chip applications  

Microsoft Academic Search

Three lead free solders (Sn3.5Ag, Sn0.7Cu and Sn3.8Ag0.7Cu) were evaluated for flip-chip applications using the eutectic solder Sn37Pb bumping process as the baseline. Reliability of the lead free solder bump produced by the stencil printing method is investigated based on (1) ball shear test after multiple reflow to simulate the solder bump quality during the assembly process; (2) high temperature

Esther W. C. Yau; Jing-Feng Gong; Benny F. W. Hong; Philip C. H. Chan

2003-01-01

251

Liquid-state interfacial reaction of Sn10Sb5Cu high temperature lead-free solder and Cu substrate  

Microsoft Academic Search

Sn-Sb alloys are potential solders for replacement of high-Pb solders because of their high melting temperature in lead-free solders. However, Cu substrate is extremely dissolved by the Sn-Sb binary alloy during the high temperature soldering process, which will cause serious reliability problem of the solder joint. Based on this critical issue, we designed a new high temperature lead-free Sn-10Sn-5Cu ternary

Qiulian Zeng; Jianjun Guo; Xiaolong Gu; Xinbing Zhao

2008-01-01

252

Computational parametric study on the strain hardening effect of lead-free solder joints in board level mechanical drop tests  

Microsoft Academic Search

Many lead-free solder alloys have been proposed as alternatives to the conventional eutectic Sn-37wt%Pb (SnPb). This replacement induces the drop\\/impact reliability issues of portable products. Under the drop\\/impact loading, the main failure mode is interfacial brittle failure between lead-free solder joints and intermetallic compound (IMC) layer. The identification of failure mechanism in the solder joint under drop test becomes a

Tong Jiang; Xu Zhengjian; S. W. Ricky Lee; Fubin Song; Jeffery C. C. Lo; Chaoran Yang

2011-01-01

253

Conceptual design for 12 V lead-free accumulators for automobile and stationary applications  

Microsoft Academic Search

Conceptual design for 12V lead-free accumulators is presented using basic research results on lithium insertion materials. Among possible materials, Li[Li1\\/3Ti5\\/3]O4 is selected for a negative-electrode material, and Li[Ni1\\/2Mn3\\/2]O4, LiMn2O4, LiCo1\\/3Ni1\\/3Mn1\\/3O2, and LiFePO4 are specifically considered as positive-electrode materials. Combination of these materials with Li[Li1\\/3Ti5\\/3]O4 gives a 2, 2.5 or 3V lithium-ion battery. Series connection of such a lithium-ion battery makes

Kingo Ariyoshi; Tsutomu Ohzuku

2007-01-01

254

[Leaching behavior of heavy metal elements in lead-free solders].  

PubMed

Leaching behavior of heavy metal elements from Sn-3.5 Ag-0.5 Cu, Sn-3.5 Ag, Sn-0.5 Cu lead-free solders and their joints were investigated in typical acid, alkaline and saline corrosion solutions. It is found that for solder alloys, significant leaching of Sn was observed in NaCl saline solution, about two orders of magnitude higher than that in acid and alkaline solution. However, in the case of solder joints, more leaching of Sn was observed in acid solution from Sn-3.5 Ag/Cu and Sn-0.5 Cu/Cu joints, and in NaOH alkaline solution for Sn-3.5 Ag - 0.5 Cu joint. PMID:18839597

Zhao, Jie; Meng, Xian-ming; Chen, Chen; Zang, Hua-xun; Ma, Hai-Tao

2008-08-01

255

Electromigration induced failure on lead-free micro bumps in three-dimensional integrated circuits packaging  

NASA Astrophysics Data System (ADS)

We report electromigration induced failure on lead-free micro bumps in three-dimensional integrated circuits samples with chip on chip configuration. Compared to flip chip solder joints, micro bumps of chip-on-chip samples exhibit better electromigration resistance and are able to withstand a higher current density. No exhibited electromigration-induced failure was observed when current density was below 2 104 A/cm2. A threshold current density to trigger electromigration in chip-on-chip samples was found to be 3.43 104 A/cm2. When current density was higher than 7.5 104 A/cm2 at an ambient temperature of 150 C, no void propagation through whole bump opening was found; instead, electromigration induced voids were observed at the cathode side of Al trace.

Ouyang, Fan-Yi; Hsu, Hao; Su, Yu-Ping; Chang, Tao-Chih

2012-07-01

256

Retarding Electromigration in Lead-Free Solder Joints by Alloying and Composite Approaches  

NASA Astrophysics Data System (ADS)

The voids induced by electromigration (EM) can trigger serious failure across the entire cathode interface of solder joints. In this study, alloying and composite approaches showed great potential for inhibiting EM in lead-free solder joints. Microsized Ni, Co, and Sb particles were added to the solder matrix. Cu and Sn particles were added to the melting solder to form in situ Cu6Sn5, which formed a barrier layer in the underbump metallization of flip-chip solder joints. The polarity effect induced by EM was observed to be significantly inhibited in the alloyed and composite solder joints. This indicates that the Sn-Ni, Sn-Co, Sn-Sb, and Cu6Sn5 intermetallic compounds may act as barriers to obstruct the movement of the dominant diffusion species along phase boundaries, which in turn improves the resistance to EM. However, Sb particles could induce crack formation and propagation that might lead to joint fracture.

Zhao, Ran; Ma, Limin; Zuo, Yong; Liu, Sihan; Guo, Fu

2013-02-01

257

Effect of surface oxide on the melting behavior of lead-free solder nanowires and nanorods  

NASA Astrophysics Data System (ADS)

Lead-free nanosolders have shown promise in nanowire and nanoelectronics assembly. Among various important parameters, melting is the most fundamental property affecting the assembly process. Here we report that the melting behavior of tin and tin/silver nanowires and nanorods can be significantly affected by the surface oxide of nanosolders. By controlling the nanosolder reflow atmosphere using a flux, the surface oxide of the nanowires/nanorods can be effectively removed and complete nanosolder melting can be achieved. The complete melting of the nanosolders leads to the formation of nanoscale to microscale spherical solder balls, followed by Ostwald ripening phenomenon. The contact angle of the microscale solder balls formed on Si substrate was measured by direct electron microscopic imaging. These results provide new insights into micro- and nanoscale phase transition and liquid droplet coalescence from nanowires/nanorods to spheroids, and are relevant to nanoscale assembly and smaller ball grid array formation.

Gao, Fan; Rajathurai, Karunaharan; Cui, Qingzhou; Zhou, Guangwen; NkengforAcha, Irene; Gu, Zhiyong

2012-07-01

258

Piezoelectric Ultrasonic Motors  

Microsoft Academic Search

Piezoelectric ultrasonic motors are a new type of actuator. They are characterized by high torque at low rotational speed, simple mechanical design and good controllability. They also provide a high holding torque even if no power is applied. Compared to electromagnetic actuators the torque per volume ratio of piezoelectric ultrasonic motors can be higher by an order of magnitude. Recently

Jorg Wallaschek

1995-01-01

259

IPP: Piezoelectric Energy Harvesters  

NASA Video Gallery

Piezoelectric devices can convert mechanical energy -- like ambient vibrations -- into electrical energy that can power small devices.A group of NASA engineers is developing a way to amplify the forces being put into piezoelectric devices so we can harvest more energy from them.

Robert Allen

2010-12-15

260

Piezoelectric hydraulic pump performance  

Microsoft Academic Search

A piezohydraulic pump making use of the step and repeat capability of piezoelectric actuators has been developed for actuation of aircraft control surfaces. The piezohydraulic pump utilizes a piezoelectric stack actuator to drive a piston in a cylinder. The cylinder is fitted with two check valves. On the compression stroke, oil is forced out of the cylinder. On the intake

Lisa D. Mauck; William S. Oates; Christopher S. Lynch

2001-01-01

261

Investigation of electromigration behavior in lead-free flip chip solder bumps  

NASA Astrophysics Data System (ADS)

Packaging technology has also evolved over time in an effort to keep pace with the demanding requirements. Wirebond and flip chip packaging technologies have become extremely versatile and ubiquitous in catering to myriad applications due to their inherent potential. This research is restricted strictly to flip chip technology. This technology incorporates a process in which the bare chip is turned upside down, i.e., active face down, and is bonded through the I/O to the substrate, hence called flip chip. A solder interconnect that provides electrical connection between the chip and substrate is bumped on a processed silicon wafer prior to dicing for die-attach. The assembly is then reflow-soldered followed by the underfill process to provide the required encapsulation. The demand for smaller and lighter products has increased the number of I/Os without increasing the package sizes, thereby drastically reducing the size of the flip chip solder bumps and their pitch. Reliability assessment and verification of these devices has gained tremendous importance due to their shrinking size. To add to the complexity, changing material sets that are results of recently enacted lead-free solder legislations have raised some compatibility issues that are already being researched. In addition to materials and process related flip chip challenges such as solder-flux compatibility, Coefficient of Thermal Expansion (CTE) mismatch, underfill-flux compatibility and thermal management, flip chip packages are vulnerable to a comparatively newer challenge, namely electromigration observed in solder bumps. It is interesting to note that electromigration has come to the forefront of challenges only recently. It has been exacerbated by the reduction in bump cross-section due to the seemingly continuous shrinking in package size over time. The focus of this research was to understand the overall electromigration behavior in lead-free (SnAg) flip chip solder bumps. The objectives of the research were to comprehend the physics of failure mechanism in electromigration for lead-free solder bumps assembled in a flip chip ceramic package having thick copper under bump metallization and to estimate the unknown critical material parameters from Black's equation that describe failure due to electromigration. In addition, the intent was to verify the 'use condition reliability' by extrapolation from experimental conditions. The methodology adopted for this research was comprised of accelerated electromigration tests on SnAg flip chip solder bumps assembled on ceramic substrate with a thick copper under bump metallization. The experimental approach was comprised of elaborate measurement of the temperature of each sample by separate metallization resistance exhibiting positive resistance characteristics to overcome the variation in Joule heating. After conducting the constant current experiments and analyzing the failed samples, it was found that the primary electromigration failure mode observed was the dissolution of the thick copper under bump metallization in the solder, leading to a change in resistance. The lifetime data obtained from different experiments was solved simultaneously using a multiple regression approach to yield the unknown Black's equation parameters of current density exponent and activation energy. In addition to the implementation of a systematic failure analysis and data analysis procedure, it was also deduced that thermomigration due to the temperature gradient across the chip does impact the overall electromigration behavior. This research and the obtained results were significant in bridging the gap for an overall understanding of this critical failure mode observed in flip chip solder bumps. The measurement of each individual sample temperature instead of an average temperature enabled an accurate analysis for predicting the 'use condition reliability' of a comparable product. The obtained results and the conclusions can be used as potential inputs in future designs and newer generations of flip chip devices that might undergo

Kalkundri, Kaustubh Jayant

262

Polarity effect of electromigration on mechanical properties of lead-free solder joints  

NASA Astrophysics Data System (ADS)

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 (15x10 3A/cm2) and different stressing time (3144 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.

Ren, Fei

263

SHPB tests for mechanical behavior of lead-free solder alloys  

NASA Astrophysics Data System (ADS)

Dynamic behavior of solder joints in microelectronic packages is key issue for drop/impact reliability design of mobile electronic products. The dynamic mechanical behavior of 63Sn37Pb, 96.5Sn3.5Ag and 96.5Sn3.0Ag0.5Cu at high strain rates have been investigated by using the split Hopkinson pressure/tension bar testing technique (SHPB). Stress-strain relations of the three solders were obtained at strain rates of 600s-1, 1200s-1 and 2200s-1, respectively. The experimental results show that the lead-free solders are strongly strain rate dependent. 96.5Sn3.5Ag is the most sensitive to strain rate, while 63Sn37Pb is the least. 96.5Sn3.0Ag0.5Cu has the greatest yield stress and tensile strength. Relations of the yield stress and the tensile strength of the solders with strain rate were fitted.

Qin, Fei; An, Tong; Chen, Na

2008-11-01

264

Dielectric properties of lead-free BZT-KNN perovskite ceramics for energy storage.  

PubMed

Lead-free (1-x)Ba(Zr?.??Ti?.??)O?-x(K?.?Na?.?)NbO? ; x=0-0.05) (BZT-KNN) perovskite ceramics, a materials with potential applications for energy storage, are investigated. The samples are prepared by a solid-state reaction method. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) are used to study the microstructure of the samples. Their dielectric properties and impedance spectra are reported as functions of temperature and frequency. The addition of 1?mol?% (K?.?Na?.?)NbO? to Ba(Zr?.??Ti?.??)O? improves the dielectric constant and enhances its diffuseness in a wide temperature range. The small amount of (K?.?Na?.?)NbO? is found to markedly affect the microstructure of the Ba(Zr?.??Ti?.??)O? ceramic (grain size and other characteristics) without changing the phase or crystal symmetry. In addition, we report that fine substructures in the grains, so-called sheet structures, are responsible for the dielectric properties (both diffuseness and dielectric constant) of (1-x)Ba(Zr?.??Ti?.??)O?-x(K?.?Na?.?)NbO? (x=0-0.03; especially x=0.01) ceramics. PMID:21994154

Gui, Dong-Yun; Liu, Han-Xing; Hao, Hua; Sun, Yue; Cao, Ming-He; Yu, Zhi-Yong

2011-10-17

265

Piezoelectricity of biopolymers.  

PubMed

The piezoelectricity of semicrystalline biopolymers was first discovered for wood and bone in the 1950's. Piezoelectric properties have since been investigated for a number of biological substances, including polysaccharides, proteins and deoxyribonucleates. The shear piezoelectric constants -d14 = d25 were determined for their oriented structures with a uniaxial symmetry Dinfinity. From studies of synthetic polypeptides and optically active polymers, it was concluded that the origin of piezoelectricity lies in the internal rotation of dipoles such as CONH. Values of d14 = -10 pC/N were determined for highly elongated films of poly-L-lactic acid, optically active and biodegradable. The implantation of this polymer induced the growth of bone, possibly because ionic current caused by piezoelectric polarization stimulated the activity of bone cells. Submicron-thick polyurea films were prepared by evaporating diisocyanate and diamine monomers in vacuum. After poling, the films exhibited pyro- and piezoelectric effects. The tensile piezoelectric constant d31 = 10 pC/N persisting up to 200 degrees C was also observed for aliphatic polyurea films. PMID:8857351

Fukada, E

266

Flexible and transparent nanogenerators based on a composite of lead-free ZnSnO3 triangular-belts.  

PubMed

A flexible and transparent lead-free triangular-belt ZnSnO(3) nanogenerator is demonstrated. When a mechanical deformation of ?0.1% is applied to the triangular-belt ZnSnO(3) nanogenerator, the output voltage and current reached 5.3 V and 0.13 ?A, respectively, which indicated a maximum output power density of ?11 ?Wcm(-3). This is the highest output power that has been demonstrated by lead-free ZnSnO(3) triangular-belts. PMID:22941870

Wu, Jyh Ming; Xu, Chen; Zhang, Yan; Yang, Ya; Zhou, Yusheng; Wang, Zhong Lin

2012-09-03

267

Pulsed laser deposition of lead-free (Na0.5Bi0.5)1?xBaxTiO3 ferroelectric thin films with enhanced dielectric properties  

NASA Astrophysics Data System (ADS)

Ferroelectric lead-free (Na0.5Bi0.5)1?xBaxTiO3 thin films obtained by pulsed laser deposition have been structurally and electrically investigated for compositions, x = 0 and x = 0.06, in and out of the morphotropic phase boundary (MPB). Sodium bismuth titanate Na0.5Bi0.5TiO3 (NBT), pure or in solid solution with other materials (like BaTiO3), is considered to be the best candidate material for lead-free ferroelectric and piezoelectric applications such as actuators and nonvolatile memory devices. Bulk solid solutions with BaTiO3 (BT), (1?x)NBT-xBT (NBT-x%BT) have been investigated widely, also due to a morphotropic phase boundary (MPB) with enhanced dielectric and ferroelectric properties between a rhombohedral and a tetragonal ferroelectric phase, at x = 0.06. Nonetheless, to transpose bulk properties to NBT-BT thin films is a major achievement. XRD technique has been used for structural characterizations of NBT-BT films. Dielectric spectroscopy measurements were performed at room temperature in the frequency range 100 Hz-1 MHz. The best films show pure perovskite phase and good crystalline structure, as a function of specific deposition conditions. Unusual characteristics, especially dielectric constant values higher than those for bulk, have been found for films with specific crystallographic orientations.

Andrei, A.; Scarisoreanu, N. D.; Birjega, R.; Dinescu, M.; Stanciu, G.; Craciun, F.; Galassi, C.

2013-08-01

268

Atomisti modeling of the microstructure and transport properties of lead-free solder alloys  

NASA Astrophysics Data System (ADS)

Damage mechanics models of lead-free solder joints in nanoelectronics continue to improve, and in doing so begin to utilize quantitative values describing processes at the atomic level, governing phenomena like electromigration and thermomigration. In particular, knowledge of the transport properties of specific microstructures helps continuum level models fully describe these larger-scale damage phenomena via multi-scale analysis. For example, diffusivities for different types of grain boundaries (fast diffusion paths for solvent and solute atoms, and vacancies), and a description of the boundary structure as a function of temperature, are critical in modeling solder microstructure evolution and, consequently, joint behavior under extreme temperature and electric current. Moreover, for damage that develops at larger length scales, surface energies and diffusivities play important roles in characterizing void stability and morphology. Unfortunately, experiments that investigate these kind of damage phenomena in the atomistic realm are often inconsistent or unable to directly quantify important parameters. One case is the particular transport and structural properties of grain boundaries in Sn (the main component in lead-free solder alloys) and their behavior in the presence of Ag and Cu impurities. This information is crucial in determining accurate diffusivity values for the common SnAgCu (SAC) type solder. Although an average grain boundary diffusivity has been reported for polycrystalline Sn in several works, the value for grain boundary width is estimated and specific diffusivities for boundaries known to occur in Sn have not been reported, to say nothing of solute effects on Sn diffusivity and grain boundary structure. Similarly, transport properties of Sn surfaces remain relatively uninvestigated as well. These gaps and inconsistencies in atomistic data must be remedied for micro- and macro-scale modeling to improve. As a complement to experimental work and possessing the ability to fill in the gaps, molecular simulation serves to reinforce experimental predictions and provide insight into the atomistic processes that govern studied phenomena. In the present body of work, we employ molecular statics and dynamics simulations in the characterization and computation of betaSn surface energies and surface diffusivities, the determination of diffusivities and structural properties of specific betaSn grain boundaries, and the investigation of Cu and Ag solute effects on betaSn grain boundaries. In our study of betaSn surfaces, energies for low number Miller index surfaces are computed and the (100) plane is found to have the lowest un-relaxed energy. We then find that two simple hopping mechanisms dominate adatom diffusion transitions on this surface. For each, we determine hopping rates of the adatom and compute its tracer diffusivity. Our work on grain boundaries investigates the self-diffusion properties and structure of several betaSn symmetric tilt grain boundaries using molecular dynamics simulations. We find that larger diffusive widths are exhibited by higher excess potential energy grain boundaries. Diffusivities in the directions parallel to the interface plane are also computed and activation energies are found with the Arrhenius relation. These are shown to agree well with experimental data. Finally, we examine the effect that solute atoms of Ag and Cu have on the microstructure of betaSn. Excess energies of the (101) symmetric tilt betaSn grain boundary are computed as a function of solute concentration at the interface, and we show that Ag lowers the energy at a greater rate than Cu. We also quantify segregation enthalpies and critical solute concentrations (where the excess energy of the boundary is reduced to zero). The effect of solute type on shear stress is also examined, and we show that solute has a strong effect on the stabilization of higher energy grain boundaries under shear stress. We then look at the self-diffusivity of Sn in the (101) symmetric tilt betaSn grain boundary and show that adding b

Sellers, Michael S.

269

Switching characteristics of (Bi1/2Na1/2)TiO3-BaTiO3-(Bi1/2K1/2)TiO3 lead-free ferroelectric ceramics  

NASA Astrophysics Data System (ADS)

The polarization switching characteristics of lead-free a(Bi1/2Na1/2)TiO3-bBaTiO3-c(Bi1/2K1/2)TiO3 (abbreviated as BNBK 100a/100b/100c) ferroelectric ceramics are investigated. This is achieved through examining their polarization and strain hystereses inside and outside the morphotropic phase boundary (MPB). The total induced electrostrain (?33,total) and apparent piezoelectric charge coefficient (d33) first increase dramatically and then decrease gradually as the BNBK composition moves from the tetragonal phase to the MPB and then to the rhombohedral phase. The measured polarization hystereses indicate that the BNBK compositions situated near the rhombohedral side of the MPB typically possess higher coercive field (Ec) and remanent polarization (Pr), while the compositions situated near the tetragonal side of the MPB possess higher apparent permittivity. Adverse effects on the ferroelectric properties are observed when BNBK is doped with donor dopants such as La and Nb. On the contrary, intricate hysteresis behaviors are observed when acceptor dopant Mn is introduced into BNBK. Under an alternating electric field of +/-5.0 MVm-1, BNBK 85.4/2.6/12, a composition well within the MPB, exhibits an ?33,total of ~0.14%, an apparent d33 of 295 pCN-1, an Ec of 2.5 MVm-1 and a Pr of 22.5 ?Ccm-2. These notable ferroelectric property values suggest a candidate material for lead-free actuator applications. The present study provides a systematic set of hysteresis measurements which can be used to characterize the switching behaviors of BNBK-based lead-free ferroelectrics.

Shieh, J.; Wu, K. C.; Chen, C. S.

2007-04-01

270

Microstructure Characterization Of Lead-Free Solders Depending On Alloy Composition  

NASA Astrophysics Data System (ADS)

Fatigue and crack nucleation in solder joints is basically associated with changes in the microstructure. Therefore the microstructure evolution of SnAgCu solder joints during solidification and subsequent application is an important subject for reliability investigations and physics of failure analysis. The scope of this study is a systematic overview of the as-cast microstructures in small sized lead-free SnAgCu solder spheres after solidification. A total of 32 alloy compositions have been investigated with varying Ag content from 0 to 5 wt.% and varying Cu content from 0 to 1.2 wt.%. The solder spheres had a diameter of approx. 270 ?m and were all manufactured under the similar conditions. Subsequent cross-sectioning was carried out in order to analyze the microstructure by optical and electron microscopy as well as Electron Backscatter Diffraction and Energy Dispersive X-ray Spectroscopy. The results allow a comprehensive overview of the dependence of the as-cast microstructure on the solder composition. It is shown that strong changes in microstructure can be caused by small changes in solder composition. In addition, a solidification phenomenon known as cyclic twinning has been found in the samples. Three different microstructures related to that phenomenon will be presented and detailed characterizations of these structures are given in this study. These microstructures differ in their appearance by solidification morphology, phase distribution as well as grain structure and can be described as follows: 1. large dentritic areas of different grain orientations which are characterized by approx. 60 twin boundaries; 2. areas of small ?-Sn cells with approx. 60 twin relation and larger intermetallic precipitates; 3. large grains consisting of a ?-Sn matrix with very fine intermetallic precipitates and high angle grain boundaries between adjacent grains.

Panchenko, Iuliana; Mueller, Maik; Wolter, Klaus-Juergen

2010-11-01

271

Piezoelectric Volumetric Array.  

National Technical Information Service (NTIS)

A three-dimensional array of acoustic sensors. The array can be used for both the transmission and reception of acoustic signals. The array comprises electroplated piezoelectric polymer layers that are laminated with a non- conductive epoxy to form indivi...

K. C. Benjamin

2002-01-01

272

Micro Piezoelectric Ultrasonic Motors.  

National Technical Information Service (NTIS)

This paper reviews recent developments of micro ultrasonic rotary motors using piezoelectric resonant vibrations. Following the historical background, four ultrasonic motors recently developed at Penn State University are introduced: windmill, PZT tube, m...

K. Uchino S. Cagatay B. Koc S. Dong P. Bouchilloux

2003-01-01

273

Parametric study on flip chip package with lead-free solder joints by using the probabilistic designing approach  

Microsoft Academic Search

The low cost tinlead solders have been widely used in electronic industries for many years, but it is also well known to be one of the major factors for environmental pollution risk. Today, several kinds of lead-free soldered alloy have been developed as a choice for replacement of the high lead solders. However, because of the shortage of the facilitated

D. G. Yang; J. S. Liang; Q. Y. Li; L. J. Ernst; G. Q. Zhang

2004-01-01

274

A study of nanoparticles in SnAg-based lead free solders for intermetallic compounds and drop test performance  

Microsoft Academic Search

Co, Ni, Pt, Al, P, Cu, Zn, Ge, Ag, In, Sb or Au including in Sn-Ag based lead free solders were evaluated to study if these nanoparticles can reduce the growth of intermetallic compounds after 4 time reflow processes and thermal aging. Also, these nanoparticles were studied if they can reduce the frequency of occurrence of intermetallic compound fractures in

M. Amagai

2006-01-01

275

On the Incorporation of Fine Pitch Lead Free CSPs in High Reliability SnPb Based Microelectronics Assemblies  

Microsoft Academic Search

Thethermalcyclingperformanceofleadfreesoldered ball grid arrays (BGAs) and chip size packages (CSPs) soldered with eutectic SnPb solder paste, so-called backward compatible assemblies, tends to drop with increasing Pb concentration in the joints. This is a particular concern for fine pitch CSPs where con- centrations are invariably rather large. Flip chip assembly life is almost always improved by underfilling, although lead free sol-

D. Blass; M. Meilunas; P. Borgesen

2011-01-01

276

Assembly and solder joint reliability of plastic ball grid array with lead-free versus lead-tin interconnect  

Microsoft Academic Search

Many governments, particularly in Japan and Europe, have proposed laws reducing or eliminating the use of lead (Pb) and other toxic substances in products in an effort to decrease landfill pollution and ground water contamination. Thus, there exists a need for lead-free components in order to comply with government standards and to meet market demands for green products. As the

K.-M. Levis; A. Mawer

2000-01-01

277

Intermetallics Characterization of Lead-Free Solder Joints under Isothermal Aging  

NASA Astrophysics Data System (ADS)

Solder interconnect reliability is influenced by environmentally imposed loads, solder material properties, and the intermetallics formed within the solder and the metal surfaces to which the solder is bonded. Several lead-free metallurgies are being used for component terminal plating, board pad plating, and solder materials. These metallurgies react together and form intermetallic compounds (IMCs) that affect the metallurgical bond strength and the reliability of solder joint connections. This study evaluates the composition and extent of intermetallic growth in solder joints of ball grid array components for several printed circuit board pad finishes and solder materials. Intermetallic growth during solid state aging at 100C and 125C up to 1000 h for two solder alloys, Sn-3.5Ag and Sn-3.0Ag-0.5Cu, was investigated. For Sn-3.5Ag solder, the electroless nickel immersion gold (ENIG) pad finish was found to result in the lowest IMC thickness compared to immersion tin (ImSn), immersion silver (ImAg), and organic solderability preservative (OSP). Due to the brittle nature of the IMC, a lower IMC thickness is generally preferred for optimal solder joint reliability. A lower IMC thickness may make ENIG a desirable finish for long-life applications. Activation energies of IMC growth in solid-state aging were found to be 0.54 0.1 eV for ENIG, 0.91 0.12 eV for ImSn, and 1.03 0.1 eV for ImAg. Cu3Sn and Cu6Sn5 IMCs were found between the solder and the copper pad on boards with the ImSn and ImAg pad finishes. Ternary (Cu,Ni)6Sn5 intermetallics were found for the ENIG pad finish on the board side. On the component side, a ternary IMC layer composed of Ni-Cu-Sn was found. Along with intermetallics, microvoids were observed at the interface between the copper pad and solder, which presents some concern if devices are subject to shock and vibration loading.

Choubey, Anupam; Yu, Hao; Osterman, Michael; Pecht, Michael; Yun, Fu; Yonghong, Li; Ming, Xu

2008-08-01

278

Micromachined piezoelectric acoustic transducers  

NASA Astrophysics Data System (ADS)

The feasibilities and functionalities of three different types of diaphragm-based piezoelectric MEMS acoustic transducers (produced by combining micromachining procedures with piezoelectric ZnO thin-film processing) have been successfully demonstrated for audio and ultrasound applications. They are based on a dome-shaped diaphragm, parylene-supported diaphragm and parylene-held cantilever-like diaphragm, and have been fabricated compatibly with an IC fabrication processing that allows a cost-effective mass production of the transducer elements. Dome-shaped-diaphragm piezoelectric acoustic transducers have successfully been fabricated on a 1.5 ?m thick silicon nitride diaphragm (2,000 ?m in radius, with a circular clamped boundary on a silicon substrate) with electrodes and piezoelectric ZnO film. Due to the 3- dimensional nature of a dome diaphragm, the dome- diaphragm transducer has a stress-releasing capability and generates the high frequency sound effectively. The transducer's sound output (measured with B&K 4135 microphone 2 mm away from the transducer) is 70-113 dB SPL in 10-200 kHz ranges. We have successfully fabricated piezoelectric acoustic transducers built on 1.5 ?m thick parylene diaphragms (both flat 5,000*5,000 ?m 2 square diaphragm and dome-shaped 2,000 ?m-radius diaphragm with circular clamped boundary on a silicon substrate) with electrodes and piezoelectric ZnO film. Parylene-held cantilever-like diaphragm acoustic transducers have been fabricated and demonstrated to release the residual stress (and also to make the diaphragm mechanically flexible) much like a cantilever, and yet is itself a diaphragm with its four edges clamped. We have successfully fabricated and tested various piezoelectric acoustic transducers built on a silicon nitride layer (either in cantilever form and/or freely-suspended island form) with electrodes and piezoelectric ZnO film. Finite element modeling (FEM) is used to simulate the responses of the three different types of the micromachined acoustic transducers based on a piezoelectric active component. Full three-dimensional elements are used to model the piezoelectric acoustic transducers because such devices are not only anisotropic, but also couple electric and elastic fields, and satisfy the boundary conditions of the two fields independently. The finite element analysis accounts for the interaction (coupling) between electric and structural fields.

Han, Cheol-Hyun

279

Enhanced piezoelectric and ferroelectric properties in Mn-doped Na0.5Bi0.5TiO3-BaTiO3 single crystals  

NASA Astrophysics Data System (ADS)

High piezoelectric and ferroelectric properties have been found in Mn-doped Na0.5Bi0.5TiO3-BaTiO3 single crystals, which were grown by a top-seeded solution method. The electrical resistivity, dielectric constant, and ferroelectric and piezoelectric properties were all found to be notably enhanced by Mn. The piezoelectric constant d33 and electromechanical coupling coefficients kt and k31 were found to be as high as 483 pC/N, 0.56, and 0.40, respectively. These values are much higher than those previously reported for Pb-free piezoelectric crystals, demonstrating the real potential for alternative lead-free systems for sensor and piezoelectric applications.

Zhang, Qinhui; Zhang, Yaoyao; Wang, Feifei; Wang, Yaojin; Lin, Di; Zhao, Xiangyong; Luo, Haosu; Ge, Wenwei; Viehland, D.

2009-09-01

280

Piezoelectric Ceramics and Their Applications  

ERIC Educational Resources Information Center

|Describes the piezoelectric effect in ceramics and presents a quantitative representation of this effect. Explains the processes involved in the manufacture of piezoelectric ceramics, the materials used, and the situations in which they are applied. (GS)|

Flinn, I.

1975-01-01

281

CMOS-Compatible Piezoelectric Microphone.  

National Technical Information Service (NTIS)

Piezoelectric Microphone: advantageous over condenser microphone except sensitivity; Major Sensitivity-Limiting Factor in Piezoelectric Microphone: residual stress in the diaphragm; Modeled and demonstrated stress releasing effect of corrugations; Fabrica...

E. S. Kim

1999-01-01

282

Fracture mechanics of piezoelectric materials  

Microsoft Academic Search

This paper presents an analysis of crack problems in homogeneous piezoelectrics or on the interfaces between two dissimilar\\u000a piezoelectric materials based on the continuity of normal electric displacement and electric potential across the crack faces.\\u000a The explicit analytic solutions are obtained for a single crack in an infinite piezoelectric or on the interface of piezoelectric\\u000a bimaterials. For homogeneous materials it

T. C. Wang; X. L. Han

1999-01-01

283

New Piezoelectric Polymers  

NASA Astrophysics Data System (ADS)

Four kinds of piezoelectric polymers are introduced. Submicron thin films of polyurea are prepared by vapor deposition polymerization. Poled films of aromatic polyurea exhibit the piezoelectric constant d31=20 pC/N, which is almost independent of temperature in the range of 100 to 200C. Aliphatic polyureas show a ferroelectric hysteresis with a coercive field of about 100 MV/m. Single crystalline films of a copolymer of vinylidene fluoride and trifluoroethylene were prepared by annealing elongated films at a paraelectric temperature range avoiding the side surface contacts. No lamella structures were present and the crystallinity was near 100%. The large electromechanical coupling factors k33=0.3 and k31=0.1 were observed. A large electrostrictive constant R=2.610-17 m2/V2 was observed for polyurethane. With a dc bias field of 15 MV/m, a piezoelectric constant of d33=600 pC/N was obtained, which was larger than that of PZT. A shear piezoelectric constant d14=-10 pC/N was obtained for oriented films of poly-L-lactic acid, which were optically active and biodegradable. After poling, this polymer showed the tensile piezoelectricity and pyroelectricity.

Fukada, Eiichi

1998-05-01

284

High temperature piezoelectric drill  

NASA Astrophysics Data System (ADS)

The current NASA Decadal mission planning effort has identified Venus as a significant scientific target for a surface in-situ sampling/analyzing mission. The Venus environment represents several extremes including high temperature (460C), high pressure (~9 MPa), and potentially corrosive (condensed sulfuric acid droplets that adhere to surfaces during entry) environments. This technology challenge requires new rock sampling tools for these extreme conditions. Piezoelectric materials can potentially operate over a wide temperature range. Single crystals, like LiNbO3, have a Curie temperature that is higher than 1000C and the piezoelectric ceramics Bismuth Titanate higher than 600C. A study of the feasibility of producing piezoelectric drills that can operate in the temperature range up to 500C was conducted. The study includes the high temperature properties investigations of engineering materials and piezoelectric ceramics with different formulas and doping. The drilling performances of a prototype Ultrasonic/Sonic Drill/Corer (USDC) using high temperate piezoelectric ceramics and single crystal were tested at temperature up to 500C. The detailed results of our study and a discussion of the future work on performance improvements are presented in this paper.

Bao, Xiaoqi; Scott, James; Boudreau, Kate; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Shrout, Tom; Zhang, Shujun

2009-03-01

285

Roles of service parameters on the mechanical behavior of lead-free solder joints  

NASA Astrophysics Data System (ADS)

Lead-based solders have been extensively used as interconnects in various electronic applications due to their low cost and suitable material properties. However, in view of environmental and health concerns, the electronics industry is forced to develop lead-free alternative solders. Eutectic Sn-3.5Ag based solders are being considered as suitable substitutes due to their non-toxicity, tolerable melting temperatures, and comparable mechanical as well as electrical properties. Smaller electronic packaging and emerging new technologies impose several constraints on the solder interconnect that require better inherent properties in the solder to resist failure during operation. Hence, it is important to develop a clear understanding of the deformation behavior of eutectic Sn-Ag solder joints. Mechanical characterization was performed to investigate the behavior of eutectic Sn-Ag solder joints. Peak shear stress and flow stress decreased with increasing testing temperature and with decreasing simple shear-strain rate. The effect of simple shear-strain rate on the peak shear stress was found to be more significant at temperature regimes less than 125C. The deformation structure of specimens deformed at higher temperatures was dominated by grain boundary deformation, while at lower temperatures it was dominated by shear banding. Stress relaxation studies on eutectic Sn-Ag solder joints were carried out to provide a better understanding of various parameters contributing to thermomechanical damage accumulation. Monotonic stress relaxation tests at various pre-strain conditions and testing temperatures can provide information relevant to the effects of ramp rates during heating and cooling excursions experienced during thermomechanical fatigue. Peak shear stress and residual shear stress, resulting from stress relaxation period, decreased with increasing testing temperature for a given pre-strain condition. A faster ramp rate was found to cause higher resultant residual stress as compared to slower ramp rates. In order to understand the roles of service related parameters, such as pre-strain and pre-strain rate imposed prior to the repeated strain cycling, cyclic strain amplitude and cyclic strain rate, and testing temperature, cyclic shear straining with associated stress relaxation was carried out on pre-strained eutectic Sn-Ag solder joints. These parameters may play significant roles during actual thermomechanical fatigue cycles of the solder joints in electronic devices. Cyclic straining may be able to provide more stress relaxation in specimens deformed to higher pre-strain/cyclic-strain at a higher pre-strain rate/cyclic-strain rate under low testing temperature. In specimens deformed at higher temperatures, residual stress build-up is less significant and as a consequence cyclic straining has no significant influence on the stress relaxation behavior. At high temperature, processes such as crack healing (or recovery) can take place, whereas microstructural damage may accumulate easier at lower temperatures.

Rhee, Hongjoo

286

Multiscale Modeling of Mechanical Shock Behavior of Environmentally-Benign Lead-Free Solders in Electronic Packaging  

NASA Astrophysics Data System (ADS)

With the increasing focus on developing environmentally benign electronic packages, lead-free solder alloys have received a great deal of attention. Mishandling of packages, during manufacture, assembly, or by the user may cause failure of solder joint. A fundamental understanding of the behavior of lead-free solders under mechanical shock conditions is lacking. Reliable experimental and numerical analyses of lead-free solder joints in the intermediate strain rate regime need to be investigated. This dissertation mainly focuses on exploring the mechanical shock behavior of lead-free tin-rich solder alloys via multiscale modeling and numerical simulations. First, the macroscopic stress/strain behaviors of three bulk lead-free tin-rich solders were tested over a range of strain rates from 0.001/s to 30/s. Finite element analysis was conducted to determine appropriate specimen geometry that could reach a homogeneous stress/strain field and a relatively high strain rate. A novel self-consistent true stress correction method is developed to compensate the inaccuracy caused by the triaxial stress state at the post-necking stage. Then the material property of micron-scale intermetallic was examined by microcompression test. The accuracy of this measure is systematically validated by finite element analysis, and empirical adjustments are provided. Moreover, the interfacial property of the solder/intermetallic interface is investigated, and a continuum traction-separation law of this interface is developed from an atomistic-based cohesive element method. The macroscopic stress/strain relation and microstructural properties are combined together to form a multiscale material behavior via a stochastic approach for both solder and intermetallic. As a result, solder is modeled by porous plasticity with random voids, and intermetallic is characterized as brittle material with random vulnerable region. Thereafter, the porous plasticity fracture of the solders and the brittle fracture of the intermetallics are coupled together in one finite element model. Finally, this study yields a multiscale model to understand and predict the mechanical shock behavior of lead-free tin-rich solder joints. Different fracture patterns are observed for various strain rates and/or intermetallic thicknesses. The predictions have a good agreement with the theory and experiments.

Fei, Huiyang

287

Solidification Condition Effects on Microstructures and Creep Resistance of Sn3.8Ag0.7Cu Lead-Free Solder  

Microsoft Academic Search

Metallurgical, mechanical, and environmental factors all affect service reliability of lead-free solder joints and are under\\u000a extensive study for preparation of the transition from Sn-Pb eutectic soldering to lead-free soldering in the electronic industry.\\u000a However, there is a general lack of understanding about the effects of solidification conditions on the microstructures and\\u000a mechanical behavior of lead-free solder alloys, particularly on

J. Liang; N. Dariavach; D. Shangguan

2007-01-01

288

Piezoelectric nonlinearity and frequency dispersion of the direct piezoelectric response of BiFeO3 ceramics  

NASA Astrophysics Data System (ADS)

We report on the frequency and stress dependence of the direct piezoelectric d33 coefficient in BiFeO3 ceramics. The measurements reveal considerable piezoelectric nonlinearity, i.e., dependence of d33 on the amplitude of the dynamic stress. The nonlinear response suggests a large irreversible contribution of non-180 domain walls to the piezoelectric response of the ferrite, which, at present measurement conditions, reached a maximum of 38% of the total measured d33. In agreement with this interpretation, both types of non-180 domain walls, characteristic for the rhombohedral BiFeO3, i.e., 71 and 109, were identified in the poled ceramics using transmission electron microscopy. In support to the link between nonlinearity and non-180 domain-wall contribution, we found a correlation between nonlinearity and processes leading to depinning of domain walls from defects, such as quenching from above the Curie temperature and high-temperature sintering. In addition, the nonlinear piezoelectric response of BiFeO3 showed a frequency dependence that is qualitatively different from that measured in other nonlinear ferroelectric ceramics, such as ``soft'' (donor-doped) Pb(Zr,Ti)O3 (PZT), i.e., in the case of the BiFeO3 large nonlinearities were observed only at low field frequencies (<0.1 Hz) possible origins of this dispersion are discussed. Finally, we show that, once released from pinning centers, the domain walls can contribute extensively to the electromechanical response of BiFeO3; in fact, the extrinsic domain-wall contribution is relatively as large as in Pb-based ferroelectric ceramics with morphotropic phase boundary (MPB) composition, such as PZT. This finding might be important in the search of new lead-free MPB compositions based on BiFeO3 as it suggests that such compositions might also exhibit large extrinsic domain-wall contribution to the piezoelectric response.

Rojac, Tadej; Bencan, Andreja; Drazic, Goran; Kosec, Marija; Damjanovic, Dragan

2012-09-01

289

Piezoelectric wave motor  

DOEpatents

A piezoelectric motor having a stator in which piezoelectric elements are contained in slots formed in the stator transverse to the desired wave motion. When an electric field is imposed on the elements, deformation of the elements imposes a force perpendicular to the sides of the slot, deforming the stator. Appropriate frequency and phase-shifting of the electric field will produce a wave in the stator and motion in a rotor. In a preferred aspect, the piezoelectric elements are configured so that deformation of the elements in the direction of an imposed electric field, generally referred to as the d.sub.33 direction, is utilized to produce wave motion in the stator. In a further aspect, the elements are compressed into the slots so as to minimize tensile stresses on the elements in use.

Yerganian, Simon Scott (Lee' s Summit, MO)

2003-02-11

290

Piezoelectric wave motor  

DOEpatents

A piezoelectric motor having a stator in which piezoelectric elements are contained in slots formed in the stator transverse to the desired wave motion. When an electric field is imposed on the elements, deformation of the elements imposes a force perpendicular to the sides of the slot, deforming the stator. Appropriate frequency and phase shifting of the electric field will produce a wave in the stator and motion in a rotor. In a preferred aspect, the piezoelectric elements are configured so that deformation of the elements in direction of an imposed electric field, generally referred to as the d.sub.33 direction, is utilized to produce wave motion in the stator. In a further aspect, the elements are compressed into the slots so as to minimize tensile stresses on the elements in use.

Yerganian, Simon Scott (Lee' s Summit, MO)

2001-07-17

291

Study on erosion resistance characteristics of Fe-MWCNT composite plating with respect to lead-free solder  

NASA Astrophysics Data System (ADS)

Sn-3mass%Ag-0.5mass%Cu lead-free solder causes strong erosion of Fe plating, which is used in hand soldering. In order to improve the durability of the soldering iron tip, we tried Fe-MWCNT (Multi-walled Carbon Nanotube) composite plating on the tip. Microstructures and the erosion resistance of the Fe-MWCNT composite plating under heating were examined. On the basis of the SEM/EDS analysis, it was confirmed that there were MWCNTs in the Fe-MWCNT composite plating. Even when heated to 673 K, MWCNTs were found to be present in the plating film under a stable condition. It was shown that the performance of erosion resistance for lead-free solders under high temperature (673 K) is improved due to the MWCNT addition to the Fe plating.

Watanabe, J.; Sekimori, N.; Hatsuzawa, K.; Uetani, T.; Shohji, I.

2012-08-01

292

Lead-free piezoceramics with giant strain in the system Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-BaTiO{sub 3}-K{sub 0.5}Na{sub 0.5}NbO{sub 3}. I. Structure and room temperature properties  

SciTech Connect

Lead-free piezoelectric ceramics (1-x-y)Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-xBaTiO{sub 3}-yK{sub 0.5}Na{sub 0.5}NbO{sub 3} (0.05{<=}x{<=}0.07 and 0.01{<=}y{<=}0.03), have been synthesized by a conventional solid state sintering method. The room temperature ferroelectric and piezoelectric properties of these ceramics were studied. Based on the measured properties, the ceramics were categorized into two groups: group I compositions having dominant ferroelectric order and group II compositions displaying mixed ferroelectric and antiferroelectric properties at room temperature. A composition from group II near the boundary between these two groups exhibited a strain as large as {approx}0.45% at an electric field of 8 kV/mm. Polarization in this composition was not stable in that the piezoelectric coefficient d{sub 33} at zero electric field was only about 30 pm/V. The converse piezoelectric response becomes weaker when the composition deviated from the boundary between the groups toward either the ferroelectric or antiferroelectric compositions. These results were rationalized based on a field induced antiferroelectric-ferroelectric phase transition.

Zhang, S.-T.; Kounga, Alain Brice; Aulbach, Emil; Granzow, Torsten; Jo, Wook; Kleebe, Hans-Joachim; Roedel, Juergen [Institute of Materials Science, Technische Universitaet Darmstadt, Petersenstr. 23, 64287 Darmstadt (Germany)

2008-02-01

293

Lead-free (K, Na)NbO 3 ferroelectric thin films: Preparation, structure and electrical properties  

Microsoft Academic Search

Lead-free ferroelectric (K, Na)NbO3 (KNN) thin films were prepared on Pt\\/Ti\\/SiO2\\/Si substrate by a solgel method. Sodium acetate, potassium acetate and niobium pentaethoxide were used as starting metalorganic compounds in KNN precursor solutions. The thermal decomposition of KNN gel was studied by thermal analysis method. Thin films of KNN with a perovskite structure were obtained by pyrolysis at 400C and

Xin Yan; Wei Ren; Xiaoqing Wu; Peng Shi; Xi Yao

2010-01-01

294

Development of lead-free metal fuel tank. Hot-dip aluminum coated steel sheet evaluations for fuel tank applications  

Microsoft Academic Search

To prevent dissolved lead from draining into soil and underground water from the disposal of end of life vehicles (ELV) shredder residue, a lead-free vehicle development program has been initiated. As an alternative material to the present hot-dip lead-tin coated steel sheet (terne sheet), which has been in use for a long time, a hot-dip aluminum coated steel sheet was

S. Choji; T. Sakauchi

1999-01-01

295

On the Mutual Effect of Viscoplasticity and Interfacial Damage Progression in Interfacial Fracture of Lead-Free Solder Joints  

Microsoft Academic Search

The main goal of this paper is to shed light on the effect of strain rate and viscoplastic deformation of bulk solder on the\\u000a interfacial failure of lead-free solder joints. For this purpose, interfacial damage evolution and modeI fracture behavior\\u000a of the joint were evaluated experimentally by performing stable fracture tests at different strain rates employing an optimized\\u000a tapered double

Milad Maleki; Joel Cugnoni; John Botsis

2011-01-01

296

Failure mode analysis of lead-free solder joints under differential reflow profiles by high speed impact testing  

Microsoft Academic Search

The aim of this research is to investigate the mechanical behavior of lead-free solder for high speed impact. A high speed impact test was set up to measure the solder joint reliability. Differential impact speed and room temperature aging effect has been studied with Ni\\/Au substrate. Furthermore, two different solder alloys (96.5Sn-3Ag-0.5Cu, 98.5Sn-1Ag-0.5C) and three different reflow profiles are considered.

C. Y. Lin; Y. R. Chen; G. S. Shen; D. S. Liu; C. Y. Kuo; C. L. Hsu

2008-01-01

297

The properties of Sn9Zn lead-free solder alloys doped with trace rare earth elements  

Microsoft Academic Search

The Sn-Zn alloys have been considered as lead-free solders. It is well known that their poor properties of wetting and oxidation\\u000a resistance are the main problems to prevent them from becoming commercially viable solders. In this paper, trace rare earth\\u000a (RE) elements of mainly Ce and La have been used as alloying elements into the Sn-9Zn alloy. The results indicated

C. M. L. Wu; D. Q. Yu; C. M. T. Law; L. Wang

2002-01-01

298

Reliability issues on the high speed DRAM flip-chip package using gold stud bump, lead free solder, and underfill  

Microsoft Academic Search

In this study, flip-chip packaging method was using gold stud bump on chip side and SnAgCu, lead free solder pad on organic substrate. Also capillary underfill enhanced the mechanical properties of gold-solder bump joint. This method was set up to the mass production of the high speed DRAM (Dynamic Random Access Memory) flip-chip package. This kind of gold stud flip-chip

Woong Sun Lee; Myoung Geun Park; Il Whan Cho; Sung Chul Kim; Ki Young Kim; Qwan Ho Chung; Kwang Yoo Byun

2008-01-01

299

CREEP FRACTURE BEHAVIOUR OF JOINTS SOLDERED BY A NANOCOMPOSITE SOLDER, LEAD-FREE AND CONVENTIONAL TIN-LEAD SOLDERS  

Microsoft Academic Search

Creep resistance and thermal fatigue performance of soldered connections\\/joints are essential reliability concerns for microelectronic, optoelectronic and photonic packaging systems. In this study, creep fracture behaviour of lap shear joints soldered by a tin-lead based composite solder reinforced by nano-sized metallic particles and a lead-free Sn-Ag-Bi alloy solder was characterized at different homologous temperatures, with a comparison to a traditional

X. P. Zhang; Y. W. Shi; S. Shrestha; L. Dorn

300

A Novel Mechanism of Embrittlement Affecting the Impact Reliability of Tin-Based Lead-Free Solder Joints  

Microsoft Academic Search

This work addresses a new mode of brittle failure that occurs in the bulk of tin-based lead-free solder joints, unlike the\\u000a typical brittle failures that occur in the interfacial intermetallics. Brittle failures in the joint bulk result from the\\u000a low-temperature ductile-to-brittle transition in the fracture behavior of ?-tin. The bulk embrittlement of these joints is\\u000a discussed by referring to the

Konstantina Lambrinou; Wout Maurissen; Paresh Limaye; Bart Vandevelde; Bert Verlinden; Ingrid De Wolf

2009-01-01

301

Investigation of mechanical shock testing of lead-free SAC solder joints in fine pitch BGA package  

Microsoft Academic Search

The lead-free SnAgCu (SAC 305\\/405) solder that replaced the tinlead eutectic solder tends to be more brittle in nature due to high stiffness and excessive solder interfacial reactions. This leads to higher occurrences of solder joints failure during surface mount assembly and handling operations as a result of PCB bending, shock impact and drop. In this work, mechanical tests simulating

Y. T. Chin; P. K. Lam; H. K. Yow; T. Y. Tou

2008-01-01

302

The effects of surface finish on the reliability of lead free and tin lead chip scale package solder joints  

Microsoft Academic Search

Purpose The effects of thermal fatigue and printed circuit board (PCB) surface finish on the pull strength, failure modes and reliability of chip scale package (CSP) solder joints were investigated. Design\\/methodology\\/approach Mechanical pull test, metallographic examination and electrical measurement were used. Tin lead (Sn-Pb) and lead free (Sn-Ag-Cu) alloys were used with Au\\/Ni and organic solderability preservative (OSP)

Meng-Kuang Huang; Chiapyng Lee; Pei-Lin Wu; Shyh-Rong Tzan

2005-01-01

303

Effect of process-induced voids on isothermal fatigue resistance of CSP lead-free solder joints  

Microsoft Academic Search

With the progressive miniaturization of electronic devices, process-induced voids in lead-free solder joints affect the assessment of thermal fatigue resistance. Voids appear randomly in a solder joint, making quantitative evaluation of fatigue life difficult. This study examined the effect of process-induced voids on the thermal fatigue resistance of CSP solder joints. CSP specimens were subjected to isothermal mechanical fatigue tests;

Qiang Yu; Tadahiro Shibutani; Do-Seop Kim; Yusuke Kobayashi; Jidong Yang; Masaki Shiratori

2008-01-01

304

Failure study of Sn-Ag-Cu lead-free solder joint by digital image speckle analysis (DISA)  

Microsoft Academic Search

Failure analysis of lead-free solder joints for PBGA assemblies subjected to thermal cycling aging is reported. A micro-digital image speckle correlation system (Micro-DISC) was employed for micro-deformation and strain analysis. The Sn-3.8Ag-0.7Cu (SAC) soldered assembly was subject to a temperature ramp from room temperature of 25 degC to 125 degC. The growth of interfacial IMC compounds and the interfacial voids\\/crack

Luhua Xu; J. H. L. Pang; Faxing Che

2005-01-01

305

BOARD LEVEL DROP TESTS COMPARING LEAD-FREE AND EUTECTIC SOLDER INTERCONNECTS ON A BGA PACKAGE FOR MOBILE ICT APPLICATIONS  

Microsoft Academic Search

There is considerable reported evidence that a large percentage of failures which afflict portable electronic products are due to impact or shock during use. Failures of the external housing, internal electronic components, package-to-board interconnects, and liquid crystal display panels may occur as the result of accidental drops. Moreover, the introduction of lead-free solder to the electronics industry will bring additional

Greg M. Heaslip; Jeff M. Punch; Bryan A. Rodgers; Claire Ryan

306

Experimental and numerical analysis of BGA lead-free solder joint reliability under board-level drop impact  

Microsoft Academic Search

Board-level solder joint reliability is very critical for handheld electronic products during drop impact. In this study, board-level drop test and finite element method (FEM) are adopted to investigate failure modes and failure mechanisms of lead-free solder joint under drop impact. In order to make all ball grid array (BGA) packages on the same test board subject to the uniform

Fang Liu; Guang Meng; Mei Zhao; Jun feng Zhao

2009-01-01

307

Optical and piezoelectric biosensors  

SciTech Connect

One of the most significant applications of analytical chemistry involves its use in the determination of biologically important analytes. In recent years, considerable research in analytical biochemistry has centered on the development of small, portable, and (in some cases) disposable monitoring devices that are collectively referred to as biosensors. Biosensors are based on a number of different operating principles, including amperometric and potentiometric electrochemistry, fiber optics, and piezoelectricity or microacoustics. In this second of a two-part FOCUS, optical and piezoelectric sensors are discussed.

Borman, S.

1987-10-01

308

Induced piezoelectricity in isotropic biomaterial.  

PubMed Central

Isotropic material can be made to exhibit piezoelectric effects by the application of a constant electric field. For insulators, the piezoelectric strain constant is proportional to the applied electric field and for semiconductors, an additional out-of-phase component of piezoelectricity is proportional to the electric current density in the sample. The two induced coefficients are proportional to the strain-dependent dielectric constant (depsilon/dS + epsilon) and resistivity (drho/dS - rho), respectively. The latter is more important at frequencies such that rhoepsilonomega less than 1, often the case in biopolymers.Signals from induced piezoelectricity in nature may be larger than those from true piezoelectricity.

Zimmerman, R L

1976-01-01

309

Induced piezoelectricity in isotropic biomaterial.  

PubMed

Isotropic material can be made to exhibit piezoelectric effects by the application of a constant electric field. For insulators, the piezoelectric strain constant is proportional to the applied electric field and for semiconductors, an additional out-of-phase component of piezoelectricity is proportional to the electric current density in the sample. The two induced coefficients are proportional to the strain-dependent dielectric constant (depsilon/dS + epsilon) and resistivity (drho/dS - rho), respectively. The latter is more important at frequencies such that rhoepsilonomega less than 1, often the case in biopolymers. Signals from induced piezoelectricity in nature may be larger than those from true piezoelectricity. PMID:990389

Zimmerman, R L

1976-12-01

310

Design of optimized piezoelectric HDD-sliders  

NASA Astrophysics Data System (ADS)

As storage data density in hard-disk drives (HDDs) increases for constant or miniaturizing sizes, precision positioning of HDD heads becomes a more relevant issue to ensure enormous amounts of data to be properly written and read. Since the traditional single-stage voice coil motor (VCM) cannot satisfy the positioning requirement of high-density tracks per inch (TPI) HDDs, dual-stage servo systems have been proposed to overcome this matter, by using VCMs to coarsely move the HDD head while piezoelectric actuators provides fine and fast positioning. Thus, the aim of this work is to apply topology optimization method (TOM) to design novel piezoelectric HDD heads, by finding optimal placement of base-plate and piezoelectric material to high precision positioning HDD heads. Topology optimization method is a structural optimization technique that combines the finite element method (FEM) with optimization algorithms. The laminated finite element employs the MITC (mixed interpolation of tensorial components) formulation to provide accurate and reliable results. The topology optimization uses a rational approximation of material properties to vary the material properties between 'void' and 'filled' portions. The design problem consists in generating optimal structures that provide maximal displacements, appropriate structural stiffness and resonance phenomena avoidance. The requirements are achieved by applying formulations to maximize displacements, minimize structural compliance and maximize resonance frequencies. This paper presents the implementation of the algorithms and show results to confirm the feasibility of this approach.

Nakasone, Paulo H.; Yoo, Jeonghoon; Silva, Emilio C. N.

2010-03-01

311

Wear Behavior of the Lead-Free Tin Bronze Matrix Composite Reinforced by Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Copper-coated carbon nanotubes were prepared by the electroless plating route. The structure and component of copper/carbon tubes were characterized using a transmission electron microscope and energy dispersive spectrometer. The results show that the surface of the carbon tubes was covered by the copper particles. Copper/carbon tubes were used as the substitute of part of tin and all of lead in the tin bronze matrix, and the tribological properties of carbon nanotube-reinforced Cu-4 wt pct Sn-6 wt pct Zn composites were studied. The effects of the carbon nanotube volume fraction and sliding distance in unlubricated ball-on-disc wear test were investigated. The 3 vol pct carbon nanotube-reinforced Cu-4 wt pct Sn-6 wt pct Zn composite shows the Vickers hardness of 126.9, which is approximately 1.6 times higher than that of Cu-6 wt pct Sn-6 wt pct Zn-3 wt pct Pb tin bronze. The wear rate and average friction coefficients of 3 vol pct carbon nanotube-reinforced Cu-4 wt pct Sn-6 wt pct Zn composite were lower than those of the Cu-6 wt pct Sn-6 wt pct Zn-3 wt pct Pb tin bronze, respectively.

Zeng, Jun; Fan, Huiqing; Wang, Yangli; Zhang, Siquan

2011-12-01

312

Piezoelectric quartz crystal biosensors  

Microsoft Academic Search

Biosensing methods utilize the intrinsic selectivity of a biorecognition process to create relatively simple, low cost, analytical alternatives for a variety of research investigations. Here, biosensor applications of the piezoelectric quartz crystal (PQC) are reviewed. The discussion is divided into sections focusing on the development of PQC based analytical techniques, applications in solution phase sensing pertaining to PQC biosensors, and

Renee L. Bunde; Eric J. Jarvi; Jeffrey J. Rosentreter

1998-01-01

313

Piezoelectric direct drive servovalve  

NASA Astrophysics Data System (ADS)

A single-stage servovalve using direct piezoelectric actuator drive is described. The single-stage servovalve design offers higher bandwidth than conventional two-stage valves. It takes advantage of the high energy density in piezoelectric materials while addressing the need for internal amplification of stroke. When used alone, the valve can regulate pressure, and when used in combination with a hydraulic output device it forms part of an effective servohydraulic actuator. Development of a direct drive prototype valve is described. Discussion includes design issues related to low stroke smart material actuators such as piezoelectrics. Component and subsystem testing and results are reviewed. Electronic drive and control of the piezoelectric and overall device along with performance in the control of fluid flow is discussed. The value of the new servovalve is shown in the combination of the valve with a hydraulic output device. Data are supplied for this servohydraulic actuator. The new actuator shows promise for a motion simulator application and more generally for motion control at higher bandwidth than is possible with currently available servohydraulics.

Lindler, Jason E.; Anderson, Eric H.

2002-07-01

314

Piezoelectric deicing device  

Microsoft Academic Search

A fast voltage pulse is applied to a transducer which comprises a composite of multiple layers of alternately polarized piezoelectric material. These layers are bonded together and positioned over the curved leading edge of an aircraft wing structure. Each layer is relatively thin and metallized on both sides. The strain produced in the transducer causes the composite to push forward

R. C. Finke; B. A. Banks

1985-01-01

315

Piezoelectric ultrasonic motors: overview  

Microsoft Academic Search

This paper reviews recent developments of ultrasonic motors using piezoelectric resonant vibrations. Following the historical background, ultrasonic motors using standing and traveling waves are introduced. Driving principles and motor characteristics are explained in comparison with conventional electromagnetic motors. After a brief discussion on speed and thrust calculation, finally, reliability issues of ultrasonic motors are described.

Kenji Uchino

1998-01-01

316

Compact piezoelectric ultrasonic motors  

Microsoft Academic Search

This paper reviews recent developments of compact ultrasonic motors using piezoelectric resonant vibrations. Following the historical background, ultrasonic motors using the standing and traveling waves are introduced. Driving principles and motor characteristics are explained in comparison with the conventional electromagnetic motors.

Kenji Uchino; Burhanettin Koc

1999-01-01

317

Investigation of the Effect of PCB Base Materials and Pad Surface Finish on the Thermal Fatigue Life of Lead-free Solder Joints of PBGA and Passive Resistors  

Microsoft Academic Search

Legislation that mandates the banning of lead in electronics due to environmental and health concerns has been actively pursued in many countries during the past fifteen years. Although a large number of research studies have been performed and are currently under way in the lead-free solder area, especially on the reliability of lead-free solder joints, abundant data exists predominantly on

Fubin Song; S. W. R. Lee; M. Osterman; M. Pecht

2006-01-01

318

Effects of K/Na ratio on the phase structure and electrical properties of (K{sub x}Na{sub 0.96-x}Li{sub 0.04})(Nb{sub 0.91}Ta{sub 0.05}Sb{sub 0.04})O{sub 3} lead-free ceramics  

SciTech Connect

(K{sub x}Na{sub 0.96-x}Li{sub 0.04})(Nb{sub 0.91}Ta{sub 0.05}Sb{sub 0.04})O{sub 3} (x=0.32-0.56) lead-free piezoelectric ceramics were prepared by conventional sintering. The effects of K/Na ratio on the phase structure and electrical properties of the ceramics were studied. These results indicate that the phase structure undergoes a transition from orthorhombic to tetragonal phase with increase of x. The ceramics with x=0.38 exhibit enhanced electrical properties (d{sub 33}{approx}306 pC/N; k{sub p}{approx}48%; k{sub t}{approx}49%; T{sub c}{approx}337 deg. C; {epsilon}{sub r}{approx}1327; tan {delta}{approx}2.5%; P{sub r}{approx}34.9 {mu}C/cm{sup 2}; E{sub c}{approx}11.3 kV/cm). Enhanced electrical properties of the ceramics should be attributed to the polymorphic phase transition near room temperature. These results show that the ceramic with x=0.38 is a promising lead-free piezoelectric material.

Wu Jiagang; Xiao Dingquan; Wang Yuanyu; Zhu Jianguo; Wu Lang; Jiang Yihang [Department of Materials Science, Sichuan University, Chengdu 610064 (China); Department of Materials Science, Sichuan University, Chengdu 610064 (China) and College of Materials Science and Metallurgy Engineering; Guizhou University, Guizhou 550003 (China); Department of Materials Science, Sichuan University, Chengdu 610064 (China)

2007-12-17

319

Method of Fabricating a Piezoelectric Composite Apparatus.  

National Technical Information Service (NTIS)

A method for fabricating a piezoelectric macro-fiber composite actuator comprises providing a piezoelectric material that has two sides and attaching one side upon an adhesive backing sheet. The method further comprises slicing the piezoelectric material ...

A. Jalink B. D. Little J. W. High P. H. Mirick R. Bryant R. F. Hellbaum R. L. Fox W. K. Wilkie

2003-01-01

320

SINTERING OF LEAD-FREE (K0.5Na0.5)NbO3 BASED SOLID SOLUTION  

Microsoft Academic Search

In this study lead-free solid solution (K0.5Na0.5)NbO3 was prepared, structure, dielectric parameters of ceramics were investigated. The doping of sintering aids did not affect the crystallographic structure of the ceramics significantly; all ceramic samples had a single-phase perovskite structure. Added elements CdO, ZnO, MnO2, V2O5 effectively decreased the sintering temperature of KNN by 5080C. All sintering aids influenced sinterability, microstructure

I. SMELTERE; M. DAMBEKALNE; M. LIVINSH; M. DUNCE; A. MISHNOV; V. ZAULS

2009-01-01

321

Effect of zinc additions on structure and properties of SnAg eutectic lead-free solder alloy  

Microsoft Academic Search

The effects of a third element, i.e., Zn in the range of 0.52.5 wt.%, on structure and properties of the binary SnAg eutectic\\u000a lead-free solder alloy were investigated. To identify the structure of the resulting alloys, X-ray diffraction analysis has\\u000a been carried out. Resistivity, contact angles, Vickers microhardness and Youngs modulus have been measured. The results showed\\u000a that all Zn

Mustafa Kamal; El Said Gouda

2008-01-01

322

Effects of Cu, Ag and Sb on the creep-rupture strength of lead-free solder alloys  

Microsoft Academic Search

The materials used in the present research are pure Sn metal and Sn-0.5% Cu, Sn-3.5%Ag, Sn-0.3%Sb, and Sn-3.5%Ag-0.5%Cu alloys.\\u000a Effects of Cu, Ag and Sb on the creep-rupture strength of lead-free solder alloys have been investigated. Creep tests are\\u000a performed at the stress and temperature range of 3 to 12 MPa and 378 to 403 K, respectively. A 3.5% addition

Noboru Wade; Kepeng Wu; Johji Kunii; Seiji Yamada; Kazuya Miyahara

2001-01-01

323

A Novel Mechanism of Embrittlement Affecting the Impact Reliability of Tin-Based Lead-Free Solder Joints  

NASA Astrophysics Data System (ADS)

This work addresses a new mode of brittle failure that occurs in the bulk of tin-based lead-free solder joints, unlike the typical brittle failures that occur in the interfacial intermetallics. Brittle failures in the joint bulk result from the low-temperature ductile-to-brittle transition in the fracture behavior of ?-tin. The bulk embrittlement of these joints is discussed by referring to the results of impact tests performed on both solder joints and bulk solder specimens. The mechanism of bulk embrittlement is largely explained based on the results of a fractography study performed on the bulk joint failures using scanning electron microscopy.

Lambrinou, Konstantina; Maurissen, Wout; Limaye, Paresh; Vandevelde, Bart; Verlinden, Bert; de Wolf, Ingrid

2009-09-01

324

Piezoelectric step-motion actuator  

SciTech Connect

A step-motion actuator using piezoelectric material to launch a flight mass which, in turn, actuates a drive pawl to progressively engage and drive a toothed wheel or rod to accomplish stepped motion. Thus, the piezoelectric material converts electrical energy into kinetic energy of the mass, and the drive pawl and toothed wheel or rod convert the kinetic energy of the mass into the desired rotary or linear stepped motion. A compression frame may be secured about the piezoelectric element and adapted to pre-compress the piezoelectric material so as to reduce tensile loads thereon. A return spring may be used to return the mass to its resting position against the compression frame or piezoelectric material following launch. Alternative embodiment are possible, including an alternative first embodiment wherein two masses are launched in substantially different directions, and an alternative second embodiment wherein the mass is eliminated in favor of the piezoelectric material launching itself.

Mentesana; Charles P. (Leawood, KS)

2006-10-10

325

Nonlinear dielectric response in piezoelectric materials for underwater transducers  

NASA Astrophysics Data System (ADS)

SONAR transducers based on single crystal lead magnesium niobate-lead titanate (PMNT) have demonstrated improvements over conventional lead zirconate titanate ceramics. Compositional modifications to PMNT have combined the high piezoelectric coefficient (d33 > 2000 pC/N) and electromechanical coupling factor (k33 > 0.90) with the low mechanical losses (QM > 1000) of ``hard'' piezoelectric ceramics. The dielectric losses of single crystal PMNT have not been investigated as extensively as the mechanical losses but may significantly affect the performance of a device when water loaded. In this work, nonlinearities in the dielectric permittivity and losses have been investigated as a function of applied electric field, measurement frequency, and temperature. It is shown that electromechanically ``hard'' single crystals offer greater stability of the dielectric properties while maintaining a high permittivity with respect to conventional lead zirconate titanate ceramics.

Sherlock, N. P.; Garten, L. M.; Zhang, S. J.; Shrout, T. R.; Meyer, R. J.

2012-12-01

326

Raman spectroscopy of piezoelectrics  

NASA Astrophysics Data System (ADS)

Raman spectroscopy represents an insightful characterization tool in electronics, which comprehensively suits the technological needs for locally and quantitatively assessing crystal structures, domain textures, crystallographic misalignments, and residual stresses in piezoelectric materials and related devices. Recent improvements in data processing and instrumental screening of large sampling areas have provided Raman spectroscopic evaluations with rejuvenating effectiveness and presently give spin to increasingly wider and more sophisticated experimental explorations. However, the physics underlying the Raman effect represents an issue of deep complexity and its applicative development to non-cubic crystallographic structures can yet be considered in its infancy. This review paper revisits some applicative aspects of the physics governing Raman emission from crystalline matter, exploring the possibility of disentangling the convoluted dependences of the Raman spectrum on crystal orientation and mechanical stress. Attention is paid to the technologically important class of piezoelectric materials, for which working algorithms are explicitly worked out in order to quantitatively extract both structural and mechanical information from polarized Raman spectra. Systematic characterizations of piezoelectric materials and devices are successively presented as applications of the developed equations. The Raman response of complex crystal structures, described here according to a unified formalism, is interpreted as a means for assessing both crystallographic textures and stress-related issues in the three-dimensional space (thus preserving their vectorial and tensorial nature, respectively). Statistical descriptions of domain textures based on orientation distribution functions are also developed in order to provide a link between intrinsic single-crystal data and data collected on polycrystalline (partly textured) structures. This paper aims at providing rigorous spectroscopic foundations to Raman approaches dealing with the analyses of functional behavior and structural reliability of piezoelectric devices.

Pezzotti, Giuseppe

2013-06-01

327

Piezoelectric deicing device  

NASA Astrophysics Data System (ADS)

A fast voltage pulse is applied to a transducer which comprises a composite of multiple layers of alternately polarized piezoelectric material. These layers are bonded together and positioned over the curved leading edge of an aircraft wing structure. Each layer is relatively thin and metallized on both sides. The strain produced in the transducer causes the composite to push forward resulting in detachment and breakup of ice on the leading edge of the aircraft wing.

Finke, R. C.; Banks, B. A.

1985-10-01

328

Multimaterial piezoelectric fibres.  

PubMed

Fibre materials span a broad range of applications ranging from simple textile yarns to complex modern fibre-optic communication systems. Throughout their history, a key premise has remained essentially unchanged: fibres are static devices, incapable of controllably changing their properties over a wide range of frequencies. A number of approaches to realizing time-dependent variations in fibres have emerged, including refractive index modulation, nonlinear optical mechanisms in silica glass fibres and electroactively modulated polymer fibres. These approaches have been limited primarily because of the inert nature of traditional glassy fibre materials. Here we report the composition of a phase internal to a composite fibre structure that is simultaneously crystalline and non-centrosymmetric. A ferroelectric polymer layer of 30 mum thickness is spatially confined and electrically contacted by internal viscous electrodes and encapsulated in an insulating polymer cladding hundreds of micrometres in diameter. The structure is thermally drawn in its entirety from a macroscopic preform, yielding tens of metres of piezoelectric fibre. The fibres show a piezoelectric response and acoustic transduction from kilohertz to megahertz frequencies. A single-fibre electrically driven device containing a high-quality-factor Fabry-Perot optical resonator and a piezoelectric transducer is fabricated and measured. PMID:20622864

Egusa, S; Wang, Z; Chocat, N; Ruff, Z M; Stolyarov, A M; Shemuly, D; Sorin, F; Rakich, P T; Joannopoulos, J D; Fink, Y

2010-07-11

329

Multimaterial piezoelectric fibres  

NASA Astrophysics Data System (ADS)

Fibre materials span a broad range of applications ranging from simple textile yarns to complex modern fibre-optic communication systems. Throughout their history, a key premise has remained essentially unchanged: fibres are static devices, incapable of controllably changing their properties over a wide range of frequencies. A number of approaches to realizing time-dependent variations in fibres have emerged, including refractive index modulation, nonlinear optical mechanisms in silica glass fibres and electroactively modulated polymer fibres. These approaches have been limited primarily because of the inert nature of traditional glassy fibre materials. Here we report the composition of a phase internal to a composite fibre structure that is simultaneously crystalline and non-centrosymmetric. A ferroelectric polymer layer of 30?m thickness is spatially confined and electrically contacted by internal viscous electrodes and encapsulated in an insulating polymer cladding hundreds of micrometres in diameter. The structure is thermally drawn in its entirety from a macroscopic preform, yielding tens of metres of piezoelectric fibre. The fibres show a piezoelectric response and acoustic transduction from kilohertz to megahertz frequencies. A single-fibre electrically driven device containing a high-quality-factor Fabry-Perot optical resonator and a piezoelectric transducer is fabricated and measured.

Egusa, S.; Wang, Z.; Chocat, N.; Ruff, Z. M.; Stolyarov, A. M.; Shemuly, D.; Sorin, F.; Rakich, P. T.; Joannopoulos, J. D.; Fink, Y.

2010-08-01

330

Dielectric and piezoelectric properties of 0.95(Na0.5K0.5)NbO3-0.05CaTiO3 ceramics with Ag2O contents  

NASA Astrophysics Data System (ADS)

Lead-Free ceramics 0.95(Na0.5K0.5)NbO3-0.05CaTiO3- x mol. % Ag2O have been fabricated as a function of the amount of Ag2O content. NKN-CT ceramics showed the highest piezoelectric properties and ferroelectric properties at the 0.5 mol. %Ag2O content. The NKN-CT-Ag2O0.5 mol. % ceramics show a good performance with piezoelectric constant d 33 = 221 ?C/N, k p = 0.38%, respectively. The corresponding Curie temperature and remnant polarization reached 370C and 22.5 C/cm2, respectively. These results appear that NKN-CTAg2O ceramics are promising candidate materials for lead-free piezoelectric application.

Lee, Seung-Hwan; Baek, Sang-Don; Kim, Hyun-Ju; Kim, Seung-Hyun; Lee, Sung-Gap; Kim, Dae-Young; Lee, Young-Hie; Nam, Sung-Pill; Lee, Ku-Tak

2012-12-01

331

Piezoelectric dispenser based on a piezoelectric-metal-cavity actuator  

NASA Astrophysics Data System (ADS)

A piezoelectric dispenser has been fabricated based on the idea of a piezoelectric-metal-cavity (PMC) actuator. The PMC actuator consists of a metal ring sandwiched between two identical piezoelectric unimorphs. The radial contraction of the piezoelectric ceramic is converted into a flextensional motion of the unimorph, causing a large flexural displacement in the center part of the actuator. With the PMC actuator as a fluid chamber, the large flexural actuation can be used to produce the displacement needed to eject fluid. By applying an appropriate voltage to the piezoelectric unimorphs, a drop-on-demand ejection of ink or water can be achieved. The efficiency of fluid ejection can be enhanced after installing a valve in the fluid chamber. With the simple PMC structure, the dispenser can be operated with a low driving voltage of 12-15 V.

Lam, K. H.; Sun, C. L.; Kwok, K. W.; Chan, H. L. W.

2009-07-01

332

Piezoelectric Vibration Energy Harvesting Device.  

National Technical Information Service (NTIS)

A piezoelectric vibration energy harvesting device which is made up of a first mass, a second, a first spring coupled to the first mass, and a second spring coupled to the second mass. A piezoelectric element is bonded between the first mass and the secon...

K. Andic K. K. Deng

2005-01-01

333

Optical piezoelectric transducer based nanoultrasonics  

Microsoft Academic Search

In this work, we review our recent development on nanoultrasonics based on an optical piezoelectric transducer. By embedding strain patterns in piezoelectric nano-layers and by manipulating optical field intensity in temporal and spatial domains, THz nanoacoustic waves with an acoustic wavelength on the order of or shorter than 10 nm can be generated with a nanometer-scaled lateral spot size, much

Chi-Kuang Sun; Kung-Hsuan Lin; Yu-Chieh Wen; Tzu-Ming Liu; Pai-Chi Li; Jen-Inn Chyi

2007-01-01

334

Design of piezoelectric motor systems  

NASA Astrophysics Data System (ADS)

Designing, building, and testing piezoelectric motor systems are fundamental to the successful development and application of these relatively new components in practical devices. This dissertation describes the design, development, building, and testing of several unique motor systems along with the equipment and techniques for doing so. Designing original piezoelectric motors requires a fresh look at the existing selection of successful and unsuccessful motor systems. An extensive literature survey of piezoelectric motor systems over the past thirty years is provided as the first section of this work. Examining the construction geometry, the vibration and piezoelectric material orientation, and the output motion of these designs, new ideas as either variations on old designs or completely new and untested designs can be created. These ideas can be refined with analysis to develop a set of prototypes, which may be tested to compare their performance to the current art of piezoelectric motors. The design and testing of two new motor systems are described in detail in this work. Other problems associated with piezoelectric motor systems, including the measurement and calculation of the properties of piezoelectric materials; the calculation of their vibration characteristics, and problems with the analysis of piezoelectric motors form the final sections of this document.

Friend, James Robert

1998-12-01

335

V-Stack piezoelectric actuator  

Microsoft Academic Search

Aeroelastic control of wings by means of a distributed, trailing-edge control surface is of interest with regards to maneuvers, gust alleviation, and flutter suppression. The use of high energy density, piezoelectric materials as motors provides an appealing solution to this problem. A comparative analysis of the state of the art actuators is currently being conducted. A new piezoelectric actuator design

Emil V. Ardelean; Robert L. Clark

2001-01-01

336

Morphotropic phase boundary and electrical properties of lead-free (1-x)BaTiO3-xBi(Li1/3Ti2/3)O3 ceramics  

NASA Astrophysics Data System (ADS)

Dense polycrystalline ceramics of lead-free perovskite solid solution (1-x)BaTiO3-xBi(Li1/3Ti2/3)O3 (0.05<=x<=0.20) have been synthesized via the conventional solid state reaction method. A morphotropic phase boundary separating the tetragonal and orthorhombic phases was observed between the compositions x=0.07 and 0.10. With increasing Bi(Li1/3Ti2/3)O3 content, the solid solution displays a stronger frequency dispersion in its dielectric behavior and a significant suppression in the sharp dielectric anomaly at the Curie point as well as the remanent polarization. However, the Curie point of the solid solution is almost independent of x in the composition range studied. These behaviors can be explained by the observed core-shell grain structure. The incorporation of Bi(Li1/3Ti2/3)O3 into BaTiO3 leads to the formation of nanodomains in the shell, which imparts the relaxor characteristics to the dielectric behavior. The core of the grain preserves the large lamellar domains as those in BaTiO3, contributing to the sharp transition at ~130 C. The best piezoelectric coefficient was obtained in the composition x=0.07 with d33=110 pC/N.

Ma, C.; Tan, X.

2010-06-01

337

Electrical Properties of Lead-Free Relaxor Ferroelectric Solid Solution Single Crystal (Na1/2Bi1/2)TiO3-BaTiO3 Grown by Bridgman Method  

NASA Astrophysics Data System (ADS)

Lead-free relaxor ferroelectric solid solution single crystals of (Na1/2Bi1/2)TiO3-BaTiO3 (NBT-BT) grown by the Bridgman method without the flux of Bi2O3 and Na2O have good optical quality and electrical properties. It was found that their transition from the rhombohedral phase to the tetragonal phase occurs at about 250 C, accompanied by isotropization. Moreover, the domain wall structure changes with heating, and dielectric dispersion gradually disappears at 250 C. Relative permittivity increases with further heating and shows a peak at Ta of 340 C with the appearance of brightness in a polarizing microscope, accompanied by a small frequency dispersion in \\tan?. Polarization-electric field (P-E) hysteresis loops reveal a narrow shape without saturation with increasing electric field due to random fields based on defects at A-sites in perovskite compounds. Strain (S) versus electric field curves under bipolar fields reveal a slightly piezoelectric behavior without polarization reversal. The value of d33 (Smax/Emax) was estimated to be about 250 pm/V at room temperature.

Yasuda, Naohiko; Hashimoto, Shinji; Ohwa, Hidehiro; Sakurada, Osamu; Fujita, Kazuhiko; Yamashita, Yohachi; Iwata, Makoto; Ishibashi, Yoshihiro

2009-09-01

338

Phase transitions, relaxor behavior, and large strain response in LiNbO3-modified Bi0.5(Na0.80K0.20)0.5TiO3 lead-free piezoceramics  

NASA Astrophysics Data System (ADS)

The effect of LiNbO3 (LN) addition on the ferroelectric behavior and piezoelectric properties of Bi0.5(Na0.80K0.20)0.5TiO3 (BNKT20) lead-free piezoceramics were systematically investigated. Results showed that the LN substitution into BNKT20 induced a transition from coexistence of ferroelectric tetragonal and rhombohedral phases to relaxor pseudocubic phases, which is accompanied by the significant disruption of ferroelectric order and with the shift of the ferroelectric-relaxor transition temperature TF-R down to room temperature. Accordingly, a large accompanying normalized strain of ~0.38% (corresponding to a large signal d33* of ~475 pm/V) were obtained in BNKT20 with 2.5 mol. %LN addition near the phase boundary. Temperature-dependent measurements of both polarization and strain from room temperature to 120 C suggested that the origin of the large strain is due to a reversible field-induced ergodic relaxor-to-ferroelectric phase transformation. Moreover, an attractive property for application as high-temperature dielectrics was obtained in this system modified with 8 mol. %LN with a high permittivity of 1760 +/- 15% from room temperature up to 500 C, spanning a range of about 450 C.

Hao, Jigong; Bai, Wangfeng; Li, Wei; Shen, Bo; Zhai, Jiwei

2013-07-01

339

Modeling stress strain curves for lead-free 95.5Sn3.8Ag0.7Cu solder  

Microsoft Academic Search

Mechanics of materials characterization of lead-free solder mechanical properties and stress strain curve properties are needed for applications in finite element analysis. In this study, tensile properties for lead-free 95.5Sn-3.8Ag-0.7Cu solder alloy were obtained from bulk tensile specimen tests. A modified Ramberg-Osgood model was developed to describe the temperature and strain rate dependent stress-strain curves for the solder alloys. The

John H. L. Pang; B. S. Xiong; F. X. Che

2004-01-01

340

A high-performance lead-free solder the effects of In on 99.3Sn\\/0.7Cu  

Microsoft Academic Search

With the established surface mount infrastructure and the temperature constraints of components and printed circuit boards, the melting temperatures of lead-free solder alloys need to be designed as close to 63Sn\\/37Pb as practical, and not to exceed 215C. However, metallurgically, the Sn-based lead-free solders cannot approach a melting point as low as 183C without incorporating a high content of low-melting

Jennie S. Hwang; Zhenfeng Guo; Holger Koenigsmann

2001-01-01

341

Creep rupture of lead-free Sn3.5Ag and Sn3.5Ag0.5Cu solders  

Microsoft Academic Search

The aim of this study is to investigate the creep rupture behavior of lead-free Sn-3.5Ag and Sn-3.5Ag-0.5Cu solders at three temperatures ranging from room temperature (RT) to 90 C, under a tensile stress range of s\\/E=10-4 to 10-3. The ultimate tensile strength (UTS) and creep resistance were found to be decreased with increasing temperature for each given lead-free solder. Both

Chih-Kuang Lin; De-You Chu

2005-01-01

342

Effects of thermomechanical cycling on lead and lead-free (SnPb and SnAgCu) surface mount solder joints  

Microsoft Academic Search

Accelerated reliability tests have been performed on leadless and leaded lead-free and lead containing SMT component assemblies. Results so far have shown that lead-free reflow soldering is a viable alternative for conventional lead based reflow soldering. The selected ternary eutectic solder alloy SnAg3.8Cu0.7 requires higher processing temperatures which could restrict the use of certain board and component types, but other

F. A. Stam; E. Davitt

2001-01-01

343

Predicting tensile properties of the bulk 96.5Sn-3.5Ag lead-free solder  

NASA Astrophysics Data System (ADS)

Equations are presented for predicting tensile properties as functions of temperature and strain rate for the bulk-eutectic 96.5Sn-3.5Ag lead-free solder. At 25C, we obtained 49.0 GPa for Youngs modulus based on acoustic measurements, which is higher than most of those measured by tensile tests that are subject to viscoelastic creep; 23.1 MPa and 26.3 MPa for yield stress and ultimate tensile strength (UTS) of specimens that are cast, annealed, and aged at a strain rate of 2.010-4 s-1; 48.7% for total elongation, which is larger than most of the reported values. The presence of initial defects in the specimens, such as porosity and void, might cause the reduction in measured total elongations.

Cheng, Yi-Wen; Siewert, Thomas A.

2003-06-01

344

Ultrasonic Linear Motor Using Multilayer Piezoelectric Actuators  

Microsoft Academic Search

In order to lower operating voltage and improve the lifetime of an ultrasonic linear motor, we have developed an ultrasonic oscillator with multilayer piezoelectric actuators. Multilayer piezoelectric actuators are operable at low voltage. However, the tensile strength of the multilayer piezoelectric actuator is small. Therefore, the multilayer piezoelectric actuators are build within an elastic body to lower the tensile stress

Tomoki Funakubo; Toshiharu Tsubata; Yoshihisa Taniguchi; Kazuhiro Kumei; Takanao Fujimura; Chikara Abe

1995-01-01

345

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

NASA Astrophysics Data System (ADS)

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 65C 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.

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

2011-09-01

346

Piezoelectric Volumetric Array  

NASA Astrophysics Data System (ADS)

A three-dimensional array of acoustic sensors. The array can be used for both the transmission and reception of acoustic signals. The array comprises electroplated piezoelectric polymer layers that are laminated with a non-conductive epoxy to form individual multi-layer array transducer elements. Circuit support layer layers are incorporated between the multi-layer array transducer elements. Because of the three-dimensional configuration of the array, logical transducers can be created from multiple transducer elements, and transmission and reception of acoustic signals in any direction can be realized.

Benjamin, Kim C.

2002-09-01

347

Shear piezoelectricity in bone at the nanoscale  

NASA Astrophysics Data System (ADS)

Recent demonstration of shear piezoelectricity in an isolated collagen fibril, which is the origin of piezoelectricity in bone, necessitates investigation of shear piezoelectric behavior in bone at the nanoscale. Using high resolution lateral piezoresponse force microcopy (PFM), shear piezoelectricity in a cortical bone sample was studied at the nanoscale. Subfibrillar structure of individual collagen fibrils with a periodicity of 60-70 nm were revealed in PFM map, indicating the direct contribution of collagen fibrils to the shear piezoelectricity of bone.

Minary-Jolandan, Majid; Yu, Min-Feng

2010-10-01

348

Fatigue failure kinetics and structural changes in lead-free interconnects due to mechanical and thermal cycling  

NASA Astrophysics Data System (ADS)

Environmental and human health concerns drove European parliament to mandate the Reduction of Hazardous Substances (RoHS) for electronics. This was enacted in July 2006 and has practically eliminated lead in solder interconnects. There is concern in the electronics packaging community because modern lead-free solder is rich in tin. Presently, near-eutectic tin-silver-copper solders are favored by industry. These solders are stiffer than the lead-tin near-eutectic alloys, have a higher melting temperature, fewer slip systems, and form intermetallic compounds (IMC) with Cu, Ni and Ag, each of which tend to have a negative effect on lifetime. In order to design more reliable interconnects, the experimental observation of cracking mechanisms is necessary for the correct application of existing theories. The goal of this research is to observe the failure modes resulting from mode II strain and to determine the damage mechanisms which describe fatigue failures in 95.5 Sn- 4.0 Ag - 0.5 Cu wt% (SAC405) lead-free solder interconnects. In this work the initiation sites and crack paths were characterized for SAC405 ball-grid array (BGA) interconnects with electroless-nickel immersion-gold (ENIG) pad-finish. The interconnects were arranged in a perimeter array and tested in fully assembled packages. Evaluation methods included monotonic and displacement controlled mechanical shear fatigue tests, and temperature cycling. The specimens were characterized using metallogaphy, including optical and electron microscopy as well as energy dispersive spectroscopy (EDS) and precise real-time electrical resistance structural health monitoring (SHM). In mechanical shear fatigue tests, strain was applied by the substrates, simulating dissimilar coefficients of thermal expansion (CTE) between the board and chip-carrier. This type of strain caused cracks to initiate in the soft Sn-rich solder and grow near the interface between the solder and intermetallic compounds (IMC). The growth near the interface was found to be caused by dislocation pile-ups at the IMC when the plastic zone ahead of the crack tip reached this interface. In temperature cycling testing, strains arose within the interconnect due to CTE mismatch between the solder and IMC. The substrates had matched CTE for all specimens in this research. Because of this, all the temperature cycling cracks were observed at interfaces, generally between the solder and IMC. Additionally, real-time electrical resistance may be a useful non-destructive evaluation (NDE) tool for the empirical observation of fatigue cracking in ball-grid arrays (BGA) during both mechanical and temperature cycling tests.

Fiedler, Brent Alan

349

Solidification Condition Effects on Microstructures and Creep Resistance of Sn-3.8Ag-0.7Cu Lead-Free Solder  

NASA Astrophysics Data System (ADS)

Metallurgical, mechanical, and environmental factors all affect service reliability of lead-free solder joints and are under extensive study for preparation of the transition from Sn-Pb eutectic soldering to lead-free soldering in the electronic industry. However, there is a general lack of understanding about the effects of solidification conditions on the microstructures and mechanical behavior of lead-free solder alloys, particularly on the long-term reliability. This study attempts to examine the creep resistance of the Sn-Ag-Cu eutectic alloy (Sn-3.8Ag-0.7Cu, SAC387) with a variety of solidification conditions with cooling rates ranging from 0.3 C/s to 17 C/s. Results indicate that solidification conditions have a major influence on the creep resistance of SAC387 alloy; up to two orders of magnitude change in the steady-state creep rates were observed at low stress levels. An understanding of the mechanical property change with microstructures, which are determined by the solidification conditions, should shed some light on the fundamental deformation and fracture mechanisms of lead-free solder alloys and can provide valuable information for long-term reliability assessment of lead-free solder interconnections.

Liang, J.; Dariavach, N.; Shangguan, D.

2007-07-01

350

New Pyroelectric Contributions to Piezoelectricity.  

National Technical Information Service (NTIS)

The authors show that the Voigt constitutive equations, the traditional algebraic proof of the equality of the direct and converse piezoelectric effects, and the usual neglect of the magnetic field are incorrect in pyroelectrics. A measurement of vector H...

D. F. Nelson M. Lax

1973-01-01

351

Conservation Laws in Linear Piezoelectricity.  

National Technical Information Service (NTIS)

We use Noether's theorem on variational principles invariant under a group of infinitesimal transformations to obtain a class of conservation laws for linear piezoelectric materials and linear elastic dielectrics.

J. S. Yang R. C. Batra

1995-01-01

352

Piezoelectricity: Venerable Effect, Modern Thrusts.  

National Technical Information Service (NTIS)

A synopsis of the piezoelectric effect is presented in the context of its history, traditional uses, and relation to crystal symmetry. Associated effects are briefly noted. Future prospects, particularly in the area of microelectromechanical systems/struc...

A. Ballato

1994-01-01

353

a Novel Piezoelectric Device  

NASA Astrophysics Data System (ADS)

This paper introduces a new based-on ultrasonic wave micro-fluid driving technique that is different from the present principle. The standing wave is generated by ultrasonic vibration in the device, and acoustic field is generated simultaneously. The particles in fluid medium of the device move towards the node of the standing waves caused by the effect of acoustic radiation pressure. A new device structure has been designed based on piezoelectric drive principle. The vibration modes and response has been obtained by FEA. The simulation results also indicate the feasibility of movements. Considering the influence of vibrator dimension, the dimension of the vibrator has been optimized. The experiment has been accomplished in the device with polystyrene spheres and achieves the enrichment of the particles.

Yuan, Song-Mei; Tang, Zhuang-Yun

354

Methodology for analyzing stress states during in-situ thermomechanical cycling in individual lead free solder joints using synchrotron radiation  

SciTech Connect

To examine how a lead-free solder joint deforms in a thermal cycling environment, both the elastic and plastic stress and strain behavior must be understood. Methods to identify evolution of the internal strain (stress) state during thermal cycling are described. A slice of a package containing a single row of solder joints was thermally cycled from 0 C to 100 C with a period of about 1 h with concurrent acquisition of transmission Laue patterns using synchrotron radiation. These results indicated that most joints are single crystals, with some being multicrystals with no more than a few Sn grain orientations. Laue patterns were analyzed to estimate local strains in different crystal directions at different temperatures during a thermal cycle. While the strains perpendicular to various crystal planes all vary in a similar way, the magnitude of strain varies. The specimens were subsequently given several hundred additional thermal cycles and measured again to assess changes in the crystal orientations. These results show that modest changes in crystal orientations occur during thermal cycling.

Zhou, Bite; Bieler, Thomas R.; Lee , Tae-Kyu; Liu, Kuo-Chuan; (MSU); (Cisco)

2010-07-22

355

Methodology for Analyzing Strain States During In Situ Thermomechanical Cycling in Individual Lead-Free Solder Joints Using Synchrotron Radiation  

NASA Astrophysics Data System (ADS)

To examine how a lead-free solder joint deforms in a thermal cycling environment, both the elastic and plastic stress and strain behavior must be understood. Methods to identify evolution of the internal strain (stress) state during thermal cycling are described. A slice of a package containing a single row of solder joints was thermally cycled from 0C to 100C with a period of about 1 h with concurrent acquisition of transmission Laue patterns using synchrotron radiation. These results indicated that most joints are single crystals, with some being multicrystals with no more than a few Sn grain orientations. Laue patterns were analyzed to estimate local strains in different crystal directions at different temperatures during a thermal cycle. While the strains perpendicular to various crystal planes all vary in a similar way, the magnitude of strain varies. The specimens were subsequently given several hundred additional thermal cycles and measured again to assess changes in the crystal orientations. These results show that modest changes in crystal orientations occur during thermal cycling.

Bieler, Thomas R.; Lee, Tae-Kyu; Liu, Kuo-Chuan

2009-12-01

356

Compatibility of lead-free solders with lead containing surface finishes as a reliability issue in electronic assemblies  

SciTech Connect

Enhanced performance goals and environmental restrictions have heightened the consideration for use of alternative solders as replacements for the traditional tin-lead (Sn-Pb) eutectic and near-eutectic alloys. However, the implementation of non-Pb bearing surface finishes may lag behind solder alloy development. A study was performed which examined the effect(s) of Pb contamination on the performance of Sn-Ag-Bi and Sn-Ag-Cu-Sb lead-free solders by the controlled addition of 63Sn-37Pb solder at levels of 0.5 {minus} 8.0 wt.%. Thermal analysis and ring-in-plug shear strength studies were conducted on bulk solder properties. Circuit board prototype studies centered on the performance of 20I/O SOIC gull wing joints. Both alloys exhibited declines in their melting temperatures with greater Sn-Pb additions. The ring-in-plug shear strength of the Sn-Ag-Cu-Sb solder increased slightly with Sn-Pb levels while the Sn-Ag-Bi alloy experienced a strength loss. The mechanical behavior of the SOIC (Small Outline Integrated Circuit) Sn-Ag-Bi solder joints reproduced the strength levels were insensitive to 10,106 thermal cycles. The Sn-Ag-Cu-Sb solder showed a slight decrease in the gull wing joint strengths that was sensitive to the Pb content of the surface finish.

Vianco, P.; Rejent, J. [Sandia National Labs., Albuquerque, NM (United States); Artaki, I.; Ray, U.; Finley, D.; Jackson, A. [AT and T Bell Labs., Princeton, NJ (United States)

1996-03-01

357

Relaxor nature in lead-free Sr5LaTi3Nb7O30 tetragonal tungsten bronze ceramics  

NASA Astrophysics Data System (ADS)

Lead-free tetragonal tungsten bronze Sr5LaTi3Nb7O30 ceramics were prepared and the correlation of the relaxor nature and crystal structure was studied using dielectric spectroscopy and powder X-ray diffraction. Three dielectric relaxations were observed below the deviation temperature TD ~ 330 K. Relaxation I and II followed the Vogel-Fulcher law with the freezing temperatures of 189 K and ~90 K. Low temperature relaxation III, which was first observed in filled tungsten bronze, followed well the Arrhenius law. Dielectric response becomes static below 50 K. Polarization-field (P-E) hysteresis loops were evaluated from 183 K to 298 K. Pr value of 0.41?C/cm2 was observed at 183 K. Deviation of lattice parameter c from the linear contraction and increasing of tetragonality (c/a ratio) were observed below TD, reflecting the structure change during the formation of polar nanoregions and the following freezing process. Opposite tendency was observed below 100 K for all the lattice parameters, corresponding to relaxation III. Generally, the main dielectric relaxation I and II were attributed to flipping and breathing of polar nanoregions along c axis, while the concerted rotations of the oxygen octahedra in the ab plane were suggested as the origin of relaxation III.

Li Zhu, Xiao; Li, Kun; Asif Rafiq, Muhammad; Qiang Liu, Xiao; Ming Chen, Xiang

2013-09-01

358

On the Mutual Effect of Viscoplasticity and Interfacial Damage Progression in Interfacial Fracture of Lead-Free Solder Joints  

NASA Astrophysics Data System (ADS)

The main goal of this paper is to shed light on the effect of strain rate and viscoplastic deformation of bulk solder on the interfacial failure of lead-free solder joints. For this purpose, interfacial damage evolution and mode I fracture behavior of the joint were evaluated experimentally by performing stable fracture tests at different strain rates employing an optimized tapered double cantilever beam (TDCB) design. The viscoplastic behavior of the solder was characterized in shear, and the constitutive parameters related to the Anand model were determined. A rate-independent cohesive zone damage model was identified to best simulate the interfacial damage progression in the TDCB tests by developing a three-dimensional (3D) finite-element (FE) model and considering the viscoplastic response of the bulk solder. The influence of strain rate on the load capability and failure mode of the joint was clarified by analyzing the experimental and simulation results. It was shown how, at the lower strain rates, the normal stress generated at the interface is limited by the significant creep relaxation developed in the bulk solder and thus is not sufficiently high to initiate interfacial damage, whereas at higher rates, a large amount of the external energy is dissipated into interfacial damage development.

Maleki, Milad; Cugnoni, Joel; Botsis, John

2011-10-01

359

Hybrid input-output approach to metal production and its application to the introduction of lead-free solders.  

PubMed

The production process of metals such as copper, lead, and zinc is characterized by mutual interconnections and interdependence, as well as by the occurrence of a large number of byproducts, which include precious or rare metals, such as gold, silver, bismuth, and indium. On the basis of the framework of waste input-output (WIO), we present a hybrid 10 model that takes full account of the mutual interdependence among the metal production processes and the interdependence between them and all the other production sectors of the economy as well. The combination of a comprehensive representation of the whole national economy and the introduction of process knowledge of metal production allows for a detailed analysis of different materials-use scenarios under the consideration of full supply chain effects. For illustration, a hypothetical case study of the introduction of lead-free solder involving the production of silver as a byproduct of copper and lead smelting processes was developed and implemented using Japanese data. To meet the increased demand for the recovery and recycling of silver resources from end-of-life products, the final destination of metal silver in terms of products and user categories was estimated, and the target components with the highest silver concentration were identified. PMID:18546732

Nakamura, Shinichiro; Murakami, Shinsuke; Nakajima, Kenichi; Nagasaka, Tetsuya

2008-05-15

360

(Na, Bi)TiO3 based lead-free ferroelectric thin films on Si substrate for pyroelectric infrared sensors  

NASA Astrophysics Data System (ADS)

In this study, we report ferroelectric and pyroelectric properties of (Na0.5Bi0.5)TiO3-BaTiO3 (NBT-BT) thin films on Si substrates using chemical solution deposition for the first time. The NBT-BT thin films deposited on Pt/Ti/SiO2/Si substrates have exhibited a typical hysteresis loop with remnant polarization of 5 ?C/cm2 and coercive field of 80 kV/cm. Furthermore NBT-BT films showed pyroelectricity with pyroelectric coefficient of 0.610?8 C/cm2K. Monolithic-integration of Si electronics and lead-free ferroelectric NBT thin films has been archived using SiN passivation layer. It was previously believed that LSI processes could not incorporate any sodium-containing material which would cause characteristic degradation, such as threshold voltage shift. In this work, no threshold voltage shift in MOS characteristics was observed using this SiN layer. The SiN layer not only blocked diffusion from NBT chemistry, but also from crystallized NBT films during NBT formation process.

Akai, D.; Yoshita, R.; Ishida, M.

2013-04-01

361

Crystal Plasticity Finite-Element Analysis of Deformation Behavior in Multiple-Grained Lead-Free Solder Joints  

NASA Astrophysics Data System (ADS)

The elastic and plastic anisotropy of the tin phase in a Pb-free tin-based solder joint has a very important effect on the reliability of solder joints. The crystal plasticity finite-element (CPFE) method takes into account the effect of anisotropy, and it can be used to solve crystal mechanical deformation problems under complicated external and internal boundary conditions imposed by inter- and intragrain micromechanical interactions. In this study, experimental lap-shear test results from the literature are used to calibrate the CPFE model. The spatial neighbor orientation relationships of the crystals were assessed by studying four different sets of orientations using a very simple model to establish a basis for further development of the model. Average shear strain and Schmid factor analyses were applied to study the activity of slip systems. Further optimization of model parameters using comparisons with experiments will be needed to identify more suitable rules for stress evolution among the 10 slip systems in Sn. By suppression of some of the slip systems the CPFE model is able to simulate heterogeneous deformation phenomena that are similar to those observed in experiments. This work establishes a basis for an incremental model development strategy based upon experiments, modeling, and comparative analysis to establish model parameters that could predict the slip processes that lead to damage evolution in lead-free solder joints.

Darbandi, P.; Bieler, T. R.; Pourboghrat, F.; Lee, Tae-kyu

2013-02-01

362

Thermomechanical Fatigue Performance of Lead-Free Chip Scale Package Assemblies with Fast Cure and Reworkable Capillary Flow Underfills  

NASA Astrophysics Data System (ADS)

In this paper, we present the results of temperature cycling test for full and partial capillary flow underfilled lead-free chip scale packages (CSPs), the tests were carried out on the basis of JEDEC standard. Two kinds of representative fast cure and reworkable underfill materials are used in this study, and CSPs without underfills were also tested for comparison. The test results show that the two underfill materials reduce the thermomechanical fatigue performance of CSP assemblies. The underfill with high Tg and storage modulus yielded better performance; indeed, the coefficient of thermal expansion (CTE) is also very critical to the thermomechanical fatigue performance, but its effects is not so obvious in this study owing to the similar CTEs of the underfills used. In addition, the negative effect of a partial underfill pattern is smaller than that of a full underfill pattern. Failure analysis shows that the dominant failure mode observed is solder cracking near the package and/or printed circuit board pads.

Shi, Hongbin; Tian, Cuihua; Ueda, Toshitsugu

2012-05-01

363

Microstructure and in situ observation of undercooling for nucleation of b-Sn relevant to lead-free solder alloys  

SciTech Connect

Difficult nucleation of b-Sn during solidification of tin and tin-based lead-free solder alloys can result in high degrees of undercooling of the liquid prior to solidification. The undercooling can produce solder joints with large grains, anisotropic behavior, and undesirable mechanical properties. This paper describes our examination of the amount of undercooling of tin on both graphite (non-wetting) and copper (wetting) surfaces using in situ x-ray diffraction. The microstructure was further characterized by optical microscopy, scanning electron microscopy, and electron backscattering diffraction imaging microscopy. Undercoolings as high as 61C were observed for Sn solidified on graphite, while lower undercoolings, up to 30C, were observed for Sn solidified on copper. The microstructure of the high purity Sn sample solidified on graphite showed very few grains in the cross-section, while the commercially pure Sn sample solidified with only one grain and was twinned. Tin solidified on copper contained significant amounts of copper in the tin, intermetallic phase formation at the interface, and a eutectic microstructure.

Elmer, J. W. [Lawrence Livermore National Laboratory (LLNL); Specht, Eliot D [ORNL; Kumar, Mukul [Lawrence Livermore National Laboratory (LLNL)

2010-01-01

364

Microstructure and In Situ Observations of Undercooling for Nucleation of [beta]-Sn Relevant to Lead-Free Solder Alloys  

SciTech Connect

Difficult nucleation of {beta}-Sn during solidification of tin and tin-based lead-free solder alloys can result in high degrees of undercooling of the liquid prior to solidification. The undercooling can produce solder joints with large grains, anisotropic behavior, and undesirable mechanical properties. This paper describes our examination of the amount of undercooling of tin on both graphite (non-wetting) and copper (wetting) surfaces using in situ x-ray diffraction. The microstructure was further characterized by optical microscopy, scanning electron microscopy, and electron backscattering diffraction imaging microscopy. Undercoolings as high as 61 C were observed for Sn solidified on graphite, while lower undercoolings, up to 30 C, were observed for Sn solidified on copper. The microstructure of the high purity Sn sample solidified on graphite showed very few grains in the cross-section, while the commercially pure Sn sample solidified with only one grain and was twinned. Tin solidified on copper contained significant amounts of copper in the tin, intermetallic phase formation at the interface, and a eutectic microstructure.

Elmer, John W.; Specht, Eliot D.; Kumar, Mukul (ORNL); (LLNL)

2010-03-16

365

Structural Origins of Silk Piezoelectricity  

PubMed Central

Uniaxially oriented, piezoelectric silk films were prepared by a two-step method that involved: (1) air drying aqueous, regenerated silk fibroin solutions into films, and (2) drawing the silk films to a desired draw ratio. The utility of two different drawing techniques, zone drawing and water immersion drawing were investigated for processing the silk for piezoelectric studies. Silk films zone drawn to a ratio of ?= 2.7 displayed relatively high dynamic shear piezoelectric coefficients of d14 = ?1.5 pC/N, corresponding to over two orders of magnitude increase in d14 due to film drawing. A strong correlation was observed between the increase in the silk II, ?-sheet content with increasing draw ratio measured by FTIR spectroscopy (C?? e2.5 ?), the concomitant increasing degree of orientation of ?-sheet crystals detected via WAXD (FWHM = 0.22 for ?= 2.7), and the improvement in silk piezoelectricity (d14? e2.4 ?). Water immersion drawing led to a predominantly silk I structure with a low degree of orientation (FWHM = 75) and a much weaker piezoelectric response compared to zone drawing. Similarly, increasing the ?-sheet crystallinity without inducing crystal alignment, e.g. by methanol treatment, did not result in a significant enhancement of silk piezoelectricity. Overall, a combination of a high degree of silk II, ?-sheet crystallinity and crystalline orientation are prerequisites for a strong piezoelectric effect in silk. Further understanding of the structural origins of silk piezoelectricity will provide important options for future biotechnological and biomedical applications of this protein.

Yucel, Tuna; Cebe, Peggy

2012-01-01

366

Structural Origins of Silk Piezoelectricity.  

PubMed

Uniaxially oriented, piezoelectric silk films were prepared by a two-step method that involved: (1) air drying aqueous, regenerated silk fibroin solutions into films, and (2) drawing the silk films to a desired draw ratio. The utility of two different drawing techniques, zone drawing and water immersion drawing were investigated for processing the silk for piezoelectric studies. Silk films zone drawn to a ratio of ?= 2.7 displayed relatively high dynamic shear piezoelectric coefficients of d(14) = -1.5 pC/N, corresponding to over two orders of magnitude increase in d(14) due to film drawing. A strong correlation was observed between the increase in the silk II, ?-sheet content with increasing draw ratio measured by FTIR spectroscopy (C(?)? e(2.5) (?)), the concomitant increasing degree of orientation of ?-sheet crystals detected via WAXD (FWHM = 0.22 for ?= 2.7), and the improvement in silk piezoelectricity (d(14)? e(2.4) (?)). Water immersion drawing led to a predominantly silk I structure with a low degree of orientation (FWHM = 75) and a much weaker piezoelectric response compared to zone drawing. Similarly, increasing the ?-sheet crystallinity without inducing crystal alignment, e.g. by methanol treatment, did not result in a significant enhancement of silk piezoelectricity. Overall, a combination of a high degree of silk II, ?-sheet crystallinity and crystalline orientation are prerequisites for a strong piezoelectric effect in silk. Further understanding of the structural origins of silk piezoelectricity will provide important options for future biotechnological and biomedical applications of this protein. PMID:23335872

Yucel, Tuna; Cebe, Peggy; Kaplan, David L

2011-01-13

367

Are lead-free hunting rifle bullets as effective at killing wildlife as conventional lead bullets? A comparison based on wound size and morphology.  

PubMed

Fragmentation of the lead core of conventional wildlife hunting rifle bullets causes contamination of the target with lead. The community of scavenger species which feed on carcasses or viscera discarded by hunters are regularly exposed to these lead fragments and may die by acute or chronic lead intoxication, as demonstrated for numerous species such as white-tailed eagles (Haliaeetus albicilla) where it is among the most important sources of mortality. Not only does hunting with conventional ammunition deposit lead in considerable quantities in the environment, it also significantly delays or threatens the recovery of endangered raptor populations. Although lead-free bullets might be considered a suitable alternative that addresses the source of these problems, serious reservations have been expressed as to their ability to quickly and effectively kill a hunted animal. To assess the suitability of lead-free projectiles for hunting practice, the wounding potential of conventional bullets was compared with lead-free bullets under real life hunting conditions. Wound dimensions were regarded as good markers of the projectiles' killing potential. Wound channels in 34 killed wild ungulates were evaluated using computed tomography and post-mortem macroscopical examination. Wound diameters caused by conventional bullets did not differ significantly to those created by lead-free bullets. Similarly, the size of the maximum cross-sectional area of the wound was similar for both bullet types. Injury patterns suggested that all animals died by exsanguination. This study demonstrates that lead-free bullets are equal to conventional hunting bullets in terms of killing effectiveness and thus equally meet the welfare requirements of killing wildlife as painlessly as possible. The widespread introduction and use of lead-free bullets should be encouraged as it prevents environmental contamination with a seriously toxic pollutant and contributes to the conservation of a wide variety of threatened or endangered raptors and other members of the guild of scavengers. PMID:23186634

Trinogga, Anna; Fritsch, Guido; Hofer, Heribert; Krone, Oliver

2012-11-25

368

Large Transverse Piezoelectricity in Strained (Na,Bi)TiO3--BaTiO3 Epitaxial Thin Films on MgO(110)  

NASA Astrophysics Data System (ADS)

Large transverse piezoelectricity has been demonstrated in lead-free epitaxial (Na,Bi)TiO3--BaTiO3 (NBT--BT) thin films grown on MgO(110) substrates. Through the internal strain caused by the difference in thermal expansion between NBT--BT and MgO, the crystal structure of the films was distorted to orthorhombic lattice, which does not form in bulk NBT--BT. The films showed a planar anisotropic nature where the effective transverse piezoelectricity along the orthorhombic b-axis was much larger than that along the orthorhombic a-axis. For the NBT--BT film with 9% BaTiO3, transverse piezoelectric coefficient d31* along the orthorhombic b-axis reached as high as -221 pC/N.

Adachi, Hideaki; Tanaka, Yoshiaki; Harigai, Takakiyo; Ueda, Michihito; Fujii, Eiji

2011-05-01

369

Measurement of acceleration factor for lead-free solder (SnAg3.8Cu0.7) in thermal cycling test of BGA components and calibration of lead-free solder joint model for life prediction by finite element analyses  

Microsoft Academic Search

Lead-free solder is taken into use in the electronics industry and there is a lack of data which shows how much thermal cycling tests accelerate the failure mechanisms compared to the real use conditions for the lead-free alloy. In this paper, a methodology on how to estimate the acceleration factor (AF) is described. The AF-experiments give an indication that the

K. Andeersson; O. Salmela; A. Perttula; J. Sarkka; M. Tammenmaa

2005-01-01

370

Piezoelectric Film Load Cell Robot Collision Detector.  

National Technical Information Service (NTIS)

A piezoelectric load cell which can be utilized for detecting collisions and obstruction of a robot arm end effector includes a force sensing element of metallized polyvinylidene fluoride (PVDF) film. The piezoelectric film sensing element and a resilient...

J. R. Lembke

1988-01-01

371

Dynamic Analysis of Piezoelectric Strained Elements.  

National Technical Information Service (NTIS)

This report is addressed to the dynamic analysis of piezoelectric structural elements under a static mechanical bias. In the first part of the report, the current literature pertaining to the dynamic applications of piezoelectric crystals is reviewed; att...

M. C. Dokmeci

1992-01-01

372

How to extract continuum materials properties for (lead-free) solders from tensile tests and nanoindentation experiments  

Microsoft Academic Search

Fabrication of modern microelectronic components requires miscellaneous solder materials for joining. In order to guarantee\\u000a the quality of the manufacturing process and the reliability of the resulting solder joint it is necessary to know the material\\u000a properties of the joining parts and of the solder materials. In particular Youngs modulus, yield stress, and the hardness\\u000a are of great interest. Moreover,

W. H. Mller; H. Worrack; J. Sterthaus; J. Villain; J. Wilden; A. Juritza

2009-01-01

373

Flexural Analysis of Piezoelectric Coupled Structures  

Microsoft Academic Search

\\u000a The analysis of a coupled piezoelectric structure has recently been keenly researched because piezoelectric materials are\\u000a more extensively used either as actuators or sensors. The challenge of developing a basic mechanics model for the piezoelectric\\u000a coupled structure has been met by many researchers. (1987) developed a uniform strain model for a beam with surface bonded and embedded piezoelectric actuator patches

Q. Wang; S. T. Quek

374

Piezoelectrically-driven Thermoacoustic Refrigerator  

NASA Astrophysics Data System (ADS)

Thermoacoustic refrigeration is an emerging refrigeration technology which does not require any moving parts or harmful refrigerants in its operation. This technology uses acoustic waves to pump heat across a temperature gradient. The vast majority of thermoacoustic refrigerators to date have used electromagnetic loudspeakers to generate the acoustic input. In this thesis, the design, construction, operation, and modeling of a piezoelectrically-driven thermoacoustic refrigerator are detailed. This refrigerator demonstrates the effectiveness of piezoelectric actuation in moving 0.3 W of heat across an 18 degree C temperature difference with an input power of 7.6 W. The performance characteristics of this class of thermoacoustic-piezoelectric refrigerators are modeled by using DeltaEC software and the predictions are experimentally validated. The obtained results confirm the validity of the developed model. Furthermore, the potential of piezoelectric actuation as effective means for driving thermoacoustic refrigerators is demonstrated as compared to the conventional electromagnetic loudspeakers which are heavy and require high actuation energy. The developed theoretical and experimental tools can serve as invaluable means for the design and testing of other piezoelectrically-driven thermoacoustic refrigerator configurations.

Chinn, Daniel George

375

On the factors affecting the dissolution of copper in molten lead-free solders and development of a method to assess the soldering parameters  

Microsoft Academic Search

Purpose The purpose of this paper is to investigate the various factors that influence the dissolution of copper in molten solder, paying particular attention to important parameters: temperature, solder composition and flow rate. Design\\/methodology\\/approach To determine the dissolution rate of copper in lead-free solders, a simple and automated technique is developed. This methodology provides repeatable measurements that allow

D. Di Maio; C. P. Hunt

2009-01-01

376

Nanostructured lead-free ferroelectric Na0.5Bi0.5TiO3-BaTiO3 whiskers: synthesis mechanism and structure.  

PubMed

Nanostructured lead-free ferroelectric Na(0.5)Bi(0.5)TiO(3)-BaTiO(3) (NBTBT) whiskers with a high aspect ratio were synthesized topochemically using Na(2)Ti(6)O(13) (NTO) as a host structure for the first time. High energy X-ray diffraction coupled with an atomic pair distribution function (PDF) and Raman scattering analyses were used to confirm the average structure of the lead-free NBTBT whiskers, which was found to be rhombohedral, i.e. a ferroelectric enabling type. High resolution transmission electron microscopic (HRTEM) analysis revealed local monoclinic-type structural distortions, indicating a modulated structure at the nanoscale in the morphotropic phase boundary (MPB) composition of the lead-free NBTBT whiskers. The structural rearrangement during the synthesis of the lead-free NBTBT whiskers was found to occur via translation of the edge shared octahedra of NTO into a corner sharing coordination. High temperature morphological changes that depict the disintegration of the isolated whiskers into their individual grains due to the higher grain boundary energy have been found to occur in close analogy with Rayleigh-type instability. PMID:22430816

Maurya, Deepam; Petkov, Valeri; Kumar, Ashok; Priya, Shashank

2012-03-19

377

Effect of intermetallic and Kirkendall voids growth on board level drop reliability for SnAgCu lead-free BGA solder joint  

Microsoft Academic Search

Lead free solder joints used in surface mount packages like ball grid array (BGA) have a great impact on the reliability of the end product. In accelerated thermal cycling (ATC) tests, cyclic excursions of temperatures cause concurrent degradation of the solder joint resulting in intermetallic compound (IMC) growth and thermal fatigue damage. The effect of thermal cycling aging on board

Luhua Xu; John H. L. Pang

2006-01-01

378

Recent developments of polar piezoelectric polymers  

Microsoft Academic Search

Following the extensive studies on the piezoelectric, pyroelectric and ferroelectric properties of polyvinylidene fluoride and its copolymers, a vast number of polymers were investigated for these properties. Piezoelectric thin films of polyurea were prepared by vapor deposition polymerization in vacuum and stable up to 200 degC. Piezoelectric odd nylon was characterized by the field induced rotation of amide dipoles in

Eiichi Fukada

2006-01-01

379

Lead-free In{sub 2}O{sub 3}-doped (Bi{sub 0.5}Na{sub 0.5}){sub 0.93}Ba{sub 0.07}TiO{sub 3} ceramics synthesized by direct reaction sintering  

SciTech Connect

Lead-free (Bi{sub 0.5}Na{sub 0.5}){sub 0.93}Ba{sub 0.07}TiO{sub 3}-x wt %In{sub 2}O{sub 3} ceramics synthesized by direct reaction sintering have been studied. X-ray diffraction reveals that all (Bi{sub 0.5}Na{sub 0.5}){sub 0.93}Ba{sub 0.07}TiO{sub 3}-x wt %In{sub 2}O{sub 3} ceramics are of a perovskite structure with coexistence of rhombohedral and tetragonal phases. It is found that the direct reaction sintering promotes growing of ceramic grains while doping of In{sub 2}O{sub 3} contributes to inhibit and homogenize the grain growth, as shown by scanning electron microscopy. The ceramics show excellent piezoelectric and dielectric properties with thickness electromechanical coupling factor k{sub t}=0.503, piezoelectric constant d{sub 33}=205 pC/N, dielectric constant {epsilon}{sub 33}{sup T}/{epsilon}{sub 0}=1046, and loss tangent tan {delta}=0.036.

Zhou Taosheng; Huang Rongxia; Shang Xunzhong; Peng Fei; Guo Jianyong; Chai Liying; Gu Haoshuang; He Yunbin [School of Materials Sciences and Engineering, Hubei University, Wuhan 430062 (China) and Key Laboratory of Ferroelectric and Piezoelectric Materials and Devices of Hubei Province, Hubei University, Wuhan 430062 (China); Department of Physics, Tulane University, New Orleans, Louisiana 70118 (United States)

2007-04-30

380

Bending strength of piezoelectric ceramics and single crystals for multifunctional load-bearing applications.  

PubMed

The topic of multifunctional material systems using active or smart materials has recently gained attention in the research community. Multifunctional piezoelectric systems present the ability to combine multiple functions into a single active piezoelectric element, namely, combining sensing, actuation, or energy conversion ability with load-bearing capacity. Quantification of the bending strength of various piezoelectric materials is, therefore, critical in the development of load-bearing piezoelectric systems. Three-point bend tests are carried out on a variety of piezoelectric ceramics including soft monolithic piezoceramics (PZT-5A and PZT-5H), hard monolithic ceramics (PZT-4 and PZT-8), single-crystal piezoelectrics (PMN-PT and PMN-PZT), and commercially packaged composite devices (which contain active PZT-5A layers). A common 3-point bend test procedure is used throughout the experimental tests. The bending strengths of these materials are found using Euler-Bernoulli beam theory to be 44.9 MPa for PMN-PZT, 60.6 MPa for PMN-PT, 114.8 MPa for PZT- 5H, 123.2 MPa for PZT-4, 127.5 MPa for PZT-8, 140.4 MPa for PZT-5A, and 186.6 MPa for the commercial composite. The high strength of the commercial configuration is a result of the composite structure that allows for shear stresses on the surfaces of the piezoelectric layers, whereas the low strength of the single-crystal materials is due to their unique crystal structure, which allows for rapid propagation of cracks initiating at flaw sites. The experimental bending strength results reported, which are linear estimates without nonlinear ferroelastic considerations, are intended for use in the design of multifunctional piezoelectric systems in which the active device is subjected to bending loads. PMID:22711404

Anton, Steven R; Erturk, Alper; Inman, Daniel

2012-06-01

381

Colloidal processing of PMN-PT thick films for piezoelectric sensor applications  

NASA Astrophysics Data System (ADS)

65%Pb(Mg1/3Nb2/3)O3-35%PbTiO3 (65PMN-35PT, or PMN-PT) is a highly piezoelectric ceramic with superior piezoelectric coefficients over the more popular Pb(Zr0.5Ti0.5)O 3 (PZT). Because of its complex chemistry and high volatility of lead above 1000C, the perovskite phase of PMN-PT is hard to process and has prevented PMN-PT from various piezoelectric applications, especially in the new area of piezoelectric micro-electro-mechanical systems (PMEMS) involving thick or thin piezoelectric films. In this thesis, a novel precursor suspension method is introduced that substantially lowers the sintering temperature of PMN-PT to 850C from a PMN precursor powder made by coating Mg(OH) 2 on Nb2O5 particles. The precursor suspension method entails suspending PMN powders in PT precursor and uses the reaction sintering capability of PMN with nano-sized PT in the temperature range of 800C1000C. Moreover, free-standing PMN-PT thick films were obtained by tape casting the PMN-PT powder. This new geometry of PMN-PT shows giant electric-field enhanced piezoelectric responses comparable with those of single crystals. As an example of application, the PMN-PT thick film is bonded to a thinner layer of copper by electroplating and made into piezoelectric cantilever sensors. In conclusion, the colloidal suspension processing method produces free-standing PMN-PT thick films with ultrahigh piezoelectric properties.

Luo, Hongyu

382

Piezoresistive and piezoelectric MEMS strain sensors for vibration detection  

NASA Astrophysics Data System (ADS)

Both piezoresistive and piezoelectric materials are commonly used to detect strain caused by structural vibrations in macro-scale structures. With the increasing complexity and miniaturization of modern mechanical systems such as hard disk drive suspensions, it is imperative to explore the performance of these strain sensors when their dimensions must shrink along with those of the host structures. The miniaturized strain sensors must remain as small as possible so as to minimum their effect on structure dynamics, yet still have acceptable sensing resolution. The performances of two types of novel micro-scale strain gage for installation on stainless steel parts are compared in this paper. Micro-fabrication processes have been developed to build polycrystalline silicon piezoresistive strain sensors on a silicon substrate, which are later bonded to a steel substrate for testing. Piezoresistor geometries are optimized to effectively increase the gage factor of piezoresistive sensors while reducing sensor size. The advantage and disadvantage of these piezoresistors are compared to those of piezoelectric sensors. Experimental results reveal that the MEMS piezoelectric sensors are able to achieve a better resolution than piezoresistors, while piezoresistors can be built in much smaller areas. Both types of the MEMS strain sensors are capable of high sensitivity measurements, subject to differing constraints.

Kon, Stanley; Oldham, Kenn; Horowitz, Roberto

2007-05-01

383

Piezoelectric materials used in underwater acoustic transducers  

SciTech Connect

Piezoelectric materials have been used in underwater acoustic transducers for nearly a century. In this paper, we reviewed four different types of piezoelectric materials: piezoelectric ceramics, single crystals, composites, and polymers, which are widely used in underwater acoustic transducers nowadays. Piezoelectric ceramics are the most dominant material type and are used as a single-phase material or one of the end members in composites. Piezoelectric single crystals offer outstanding electromechanical response but are limited by their manufacturing cost. Piezoelectric polymers provide excellent acoustic impedance matching and transducer fabrication flexibility although their piezoelectric properties are not as good as ceramics and single crystals. Composites combined the merits of ceramics and polymers and are receiving increased attention. The typical structure and electromechanical properties of each type of materials are introduced and discussed with respect to underwater acoustic transducer applications. Their advantages and disadvantages are summarized. Some of the critical design considerations when developing underwater acoustic transducers with these materials are also touched upon.

Li, Huidong; Deng, Zhiqun; Carlson, Thomas J.

2012-07-07

384

EFFECT OF BiFeO3 DOPING ON FERROELECTRIC AND PIEZOELECTRIC PROPERTIES OF (Bi0.5Na0.5)TiO3 AND BaTiO3 CERAMICS  

Microsoft Academic Search

The effects of BiFeO3 (BF) doping on the phase transition temperatures especially of lead-free piezoelectric materials were studied. Up to 20 mole% of BFO was doped in (Bi0.5Na0.5)TiO3 (BNT) and BaTiO3 (BT) ceramics synthesized by solid state reactions. In BNT, ferroelectric transition temperature (TC) increased with doping but depolarization temperature (Td) was almost independent of BF contents. In BT, however,

K. H. RYU; T. K. SONG; M.-H. KIM; S. H. LEE; Y. S. SEONG; S. J. JEONG; J. S. SONG

2006-01-01

385

Effect of (Mn, F) and (Mg, F) co-doping on dielectric and piezoelectric properties of lead zirconate titanate ceramics  

NASA Astrophysics Data System (ADS)

The influence of (Mn, F) and (Mg, F) dopants on the piezoelectric properties of lead zirconate titanate (PZT) ceramic compositions close to the morphotropic phase boundary is investigated. PZT ceramics are prepared by a chemical route based on co-precipitation of oxalates and hydroxides. The acceptor is incorporated into the B site of the materials and the fluorine ion is introduced into anionic sites. The d33 coefficient, the mechanical quality factor Qm and other properties are measured. Scanning electron microscopy is used to determine the grain size of the materials. Electron spin resonance is used to determine the valency state of Mn in fluorinated PZT ceramics. In Mn doped PZT, the introduction of a fluorine ion makes the poling process easier and increases the piezoelectric coefficients whereas the fluorination of Mg doped PZT constantly leads to hard materials with a lower piezoelectric response. This study shows that (Mn, F) co-doping produces semihard materials with high piezoelectric coefficients.

Boucher, E.; Guyomar, D.; Lebrun, L.; Guiffard, B.; Grange, G.

2002-11-01

386

Triple-scale analysis and fabrication of new biocompatible MgSiO3 piezoelectric thin films  

NASA Astrophysics Data System (ADS)

Recently, the lead free piezoelectric material, which should be used for medical devices, such as health monitoring system (HMS) and drug delivery system (DDS), is strongly required. In this study, we discovered a newly designed MgSiO3 thin film, as a biocompatible piezoelectric actuator, by using the first-principles calculation and process crystallography simulation algorithm. At first, crystal structure was calculated by using the first-principles density functional theory. Secondly, the best substrate for MgSiO3 was searched by using the process crystallography simulation. Next, MgSiO3 thin film was generated in our laboratory by using the RF magnetron sputtering apparatus. Finally, crystallographic orientation was obtained by using X-ray diffractometer and the piezoelectric property of thin film was measured by the ferroelectric measurement system. As a result, lattice parameters of MgSiO3 with tetragonal structure were obtained as a=b=0.3449nm and c=0.3538nm, and its aspect ratio was 1.026. Au(111) was chosen as the best substrate, on which MgSiO3 thin film with minimum total energy could be grown. Then, MgSiO3(111) was generated on Au(111)/SrTiO3(110) by using the RF magnetron sputtering apparatus. The piezoelectric strain constant d33 of MgSiO3 thin film generated at 400C was measured as 219.8pm/V and it was higher than one of the existing piezoelectric material BaTiO3. Consequently, we succeeded the generation of a new biocompatible MgSiO3 piezoelectric thin film, which can be applied to medical devices in the future.

Hwang, Hwisim; Uetsuji, Yasutomo; Katayama, Tsutao; Nakamachi, Eiji

2010-03-01

387

Piezoelectricity, ferroelectricity, and crystal structure  

Microsoft Academic Search

By visualizing polar crystals as a network of permanent dipole moments, the piezo- and ferroelectric properties of dielectrics may be derived from the standpoint of molecular symmetry. This approach is used to clarify the relation between the sphalerite and wurtzite structures, the ferroelectric feedback effect in barium titanate, aspects of domain formation, and the interrelationship between ferro and piezoelectricity.

A. von Hippel

1952-01-01

388

Kinematic theory of piezoelectric hysteresis  

Microsoft Academic Search

A biasing voltage applied across a bonded piezoelectric plate causes a transverse deflection. For slowly varying voltages, the displacement shows a characteristic hysteresis. A kinematic model is proposed which relates nonlinearly the displacement and its rate to the applied voltage. The analysis is developed to account quantitatively for the measured quasistatic hysteresis and decay, and to predict resonant dynamical effects.

P. G. Harper

1981-01-01

389

V-Stack piezoelectric actuator  

NASA Astrophysics Data System (ADS)

Aeroelastic control of wings by means of a distributed, trailing-edge control surface is of interest with regards to maneuvers, gust alleviation, and flutter suppression. The use of high energy density, piezoelectric materials as motors provides an appealing solution to this problem. A comparative analysis of the state of the art actuators is currently being conducted. A new piezoelectric actuator design is presented. This actuator meets the requirements for trailing edge flap actuation in both stroke and force. It is compact, simple, sturdy, and leverages stroke geometrically with minimum force penalties while displaying linearity over a wide range of stroke. The V-Stack Piezoelectric Actuator, consists of a base, a lever, two piezoelectric stacks, and a pre-tensioning element. The work is performed alternately by the two stacks, placed on both sides of the lever. Pre-tensioning can be readily applied using a torque wrench, obviating the need for elastic elements and this is for the benefit of the stiffness of the actuator. The characteristics of the actuator are easily modified by changing the base or the stacks. A prototype was constructed and tested experimentally to validate the theoretical model.

Ardelean, Emil V.; Clark, Robert L.

2001-07-01

390

Piezoelectricity: history and new thrusts  

Microsoft Academic Search

Piezoelectricity was discovered by the brothers Curie in 1880. What started out as a scientific curiosity has grown to have very significant commercial importance. We sketch here some of the milestones of its history, a hit of its phenomenology, and conclude with some present applications and prospects for the future

A. Ballato

1996-01-01

391

Modeling NDT piezoelectric ultrasonic transmitters.  

PubMed

Ultrasonic NDT applications are frequently based on the spike excitation of piezoelectric transducers by means of efficient pulsers which usually include a power switching device (e.g. SCR or MOS-FET) and some rectifier components. In this paper we present an approximate frequency domain electro-acoustic model for pulsed piezoelectric ultrasonic transmitters which, by integrating partial models of the different stages (driving electronics, tuning/matching networks and broadband piezoelectric transducer), allows the computation of the emission transfer function and output force temporal waveform. An approximate frequency domain model is used for the evaluation of the electrical driving pulse from the spike generator. Tuning circuits, interconnecting cable and mechanical impedance matching layers are modeled by means of transmission lines and the classical quadripole approach. The KLM model is used for the piezoelectric transducer. In addition, a PSPICE scheme is used for an alternative simulation of the broadband driving spike, including the accurate evaluation of non-linear driving effects. Several examples illustrate the capabilities of the specifically developed software. PMID:15047298

San Emeterio, J L; Ramos, A; Sanz, P T; Ruz, A; Azbaid, A

2004-04-01

392

Large converse magnetoelectric effect in Na0.5Bi0.5TiO3-CoFe2O4 lead-free multiferroic composites  

NASA Astrophysics Data System (ADS)

Lead-free multiferroic composites of ferroelectric, Na0.5Bi0.5TiO3 (NBT) and ferrimagnetic, CoFe2O4 (CFO) were synthesized by the solid-state sintering method and a systematic study of structural, magnetic, and magnetoelectric properties was undertaken. X-ray diffraction and field emission scanning electron microscopy displayed the formation of single phase for parent phases and the presence of both phases in the composites. Magnetic properties were investigated using a vibrating sample magnetometer (VSM) and ferromagnetic resonance (FMR) measurements at room temperature. Strong magnetoelectric (ME) coupling was demonstrated by an electric field tunable FMR field shift. A large value of converse ME coefficient 109 Oe-cm kV-1 was observed for NBT/CFO 70/30 composite. Furthermore, these lead-free multiferroic composites exhibiting a large converse magnetoelectric effect at room temperature provide great opportunities for electrostatically tunable devices at microwave frequencies.

Narendra Babu, S.; Malkinski, Leszek

2012-04-01

393

Yearly measurements of blood lead in Swedish children since 1978: The declining trend continues in the petrol-lead-free period 19952007  

Microsoft Academic Search

BackgroundWe have measured blood lead concentrations (B-Pb) in Swedish children, yearly since 1978. As reported previously, a substantial decrease of B-Pb was found for the period 19781994 (2440 children measured), as an effect of gradual reduction of lead in petrol. In another report focusing on the petrol-lead-free period 19952001, we noted that B-Pb seemed to stabilize at an average level

Ulf Strmberg; Thomas Lundh; Staffan Skerfving

2008-01-01

394

Prediction of stress-strain relationship with an improved Anand constitutive Model For lead-free solder Sn3.5Ag  

Microsoft Academic Search

An improved Anand constitutive model is proposed to describe the inelastic deformation of lead-free solder Sn-3.5Ag used in solder joints of microelectronic packaging. The new model accurately predicted the overall trend of steady-state stress-strain behavior of the solder for the temperature range from 233 K to 398 K and the strain rate range from 0.005 s-1 to 0.1 s-1. h0,

Xu Chen; Gang Chen; Masao Sakane

2005-01-01

395

A lead-free, low-temperature sintering die-attach technique for high-performance and high-temperature packaging  

Microsoft Academic Search

For semiconductor devices to function in products, they need packaging to provide interconnection and protection. Die-attach materials, which join the devices to the rest of the system, play a vital role in ensuring the system performance and reliability. Today, lead-tin and lead-free solder alloys, and conductive epoxies are widely used for attaching the devices because they can be easily processed

Guo-Quan Lu; Jesus Noel Calata; Zhiye Zhang; John G. Bai

2004-01-01

396

Effects of Ramp-Time on the Thermal-Fatigue Life of SnAgCu Lead-Free Solder Joints  

Microsoft Academic Search

The effects of temperature-cycling ramp-time on the thermal-fatigue life of lead-free solder joints are investigated in this study. Emphasis is placed on the determination of creep responses and the creep strain energy density per cycle of a PBGA (plastic ball grid array) packages (SnAgCu) leadfree solder joints on a FR-4 printed circuit board (PCB) subjected to various ramp times (0.5,

John Lau; Walter Dauksher

2005-01-01

397

Study of structural changes and properties for SnZn9 lead-free solder alloy with addition of different alloying elements  

Microsoft Academic Search

The binary lead-free solder alloy SnZn9 was considered as a potential alternative to leadtin solder alloys, when compared with other solders. In this paper, the effects of the addition of Ag, Bi, Cu and Sb on structure, melting temperature, wettability and electrical resistivity for this rapidly solidified alloy have been investigated. The results showed that a new phase Ag5Zn8 appeared,

Mustafa Kamal; M. S. Meikhail; Abu Bakr El-bediwi; El-said Gouda

2005-01-01

398

On the relative contribution of temperature, moisture and vapor pressure to delamination in a plastic IC package during lead-free solder reflow  

Microsoft Academic Search

The elimination of lead in electronics assembly has presented challenges on the process. During the conventional eutectic tin-lead solder reflow process, the delamination of the interface between the leadframe pad and the encapsulant has been found to be a precursor to the popcorning of plastic IC packages. The melting point of lead-free solder is more than 30-40C higher than that

Hu Guojun; Andrew A. O. Tay

2005-01-01

399

A comparison on the emission of polycyclic aromatic hydrocarbons and their corresponding carcinogenic potencies from a vehicle engine using leaded and lead-free gasoline.  

PubMed Central

Our objective in this study was to assess the effect of using two kinds of lead-free gasoline [including 92-lead-free gasoline (92-LFG) and 95-lead-free gasoline (95-LFG), rated according to their octane levels] to replace the use of premium leaded gasoline (PLG) on the emissions of polycyclic aromatic hydrocarbons (PAHs) and their corresponding benzo[a]pyrene equivalent (BaP(eq)) amounts from the gasoline-powered engine. The results show that the three gasoline fuels originally contained similar total PAHs and total BaP(eq) contents; however, we found significant differences in the engine exhausts in both contents. The above results suggest that PAHs originally contained in the gasoline fuel did not affect the PAH emissions in the engine exhausts. The emission factors of both total PAHs and total BaP(eq) obtained from the three gasoline fuels shared the same trend: 95-LFG > PLG > 92-LFG. The above result suggests that when PLG was replaced by 95-LFG, the emissions would increase in both total PAHs and total BaP(eq), but when replaced by 92-LFG would lead to the decreased emissions of both contents. By taking emission factors and their corresponding annual gasoline consumption rates into account, we found that both total PAH and total BaP(eq) emissions increased from 1994 to 1999. However, the annual increasing rates in total BaP(eq) emissions were slightly higher than the corresponding increasing rates in total PAHs.

Mi, H H; Lee, W J; Tsai, P J; Chen, C B

2001-01-01

400

Analysis and Testing of Plates with Piezoelectric Sensors and Actuators.  

National Technical Information Service (NTIS)

Piezoelectric material inherently possesses coupling between electrostatics and structural dynamics. Utilizing linear piezoelectric theory results in an intrinsically coupled pair of piezoelectric constitutive equations. One equation describes the direct ...

J. S. Bevan

1998-01-01

401

Structure-Property Study of Piezoelectricity in Polyimides.  

National Technical Information Service (NTIS)

High performance piezoelectric polymers are of interest to NASA as they may be useful for a variety of sensor applications. Over the past few years research on piezoelectric polymers has led to the development of promising high temperature piezoelectric r...

C. Park J. Hinkley J. G. Smith J. S. Harrison Z. Ounaies

1999-01-01

402

Piezoelectric Composite Apparatus and a Method for Fabricating the Same.  

National Technical Information Service (NTIS)

A method for fabricating a piezoelectric fiber sheet comprises providing a plurality of wafers of piezoelectric material, bonding the wafers together with an adhesive material to form a stack of alternating layers of piezoelectric material and adhesive ma...

A. Jalink J. W. High R. F. Hellbaum R. G. Bryant R. L. Fox W. K. Wilkie

2005-01-01

403

Design and Implementation of a Piezoelectric Clutch Mechanism Using Piezoelectric Buzzers  

Microsoft Academic Search

This paper investigates design, fabrication and test of a piezoelectric clutch mechanism, which contains a driving member connected to a DC motor and a driven member connected to a mechanical load. Each member comprises a piezoelectric disk, a shaft, a plastic lid and others. The connection between radiation surfaces of the piezoelectric disks is controlled according to electrical drives of

Kuo-Tsai Chang

2007-01-01

404

High Performance V-stack Piezoelectric Actuator  

Microsoft Academic Search

A comparative analysis of the state-of-the-art actuators is conducted. A new piezoelectric actuator design is presented. It is compact, simple, sturdy, and leverages stroke geometrically with minimum force penalties. The V-stack Piezoelectric Actuator consists of a base, a lever, two piezoelectric stacks, and a pretensioning element. Work is performed alternately by the two stacks placed on each side of the

Emil V. Ardelean; Daniel G. Cole; Robert L. Clark

2004-01-01

405

Piezoelectrically actuated dome-shaped diaphragm micropump  

Microsoft Academic Search

This paper describes a piezoelectric micropump built on a dome-shaped diaphragm with one-way parylene valves. The micropump uses piezoelectric ZnO film (less than 10 ?m thick) to actuate a parylene dome diaphragm, which is fabricated with an innovative, IC-compatible process on a silicon substrate. Piezoelectric ZnO film is sputter-deposited on a parylene dome diaphragm with its C-axis oriented perpendicular to

Guo-Hua Feng; Eun Sok Kim

2005-01-01

406

Piezoelectric vibrator mounting system for a nebulizer  

US Patent & Trademark Office Database

System for mounting a piezoelectric vibrator comprises an annular projected vibrator support (27) integrally formed with an insulating support (21), a piezoelectric vibrator (1) located on the annular vibrator support (27) and an elastic annular holder (22) having an essentially L-shaped section for holding down the periphery of the piezoelectric vibrator (1) fitted to the insulating support (21), a plurality of connecting electrode members (23,24) being mounted on the vibrator support (27) and each of the connecting electrode members (23,24) being pressed against the corresponding electrodes (2B,2A') of the piezoelectric vibrator (1).

Takahashi; Minoru (Chiba, JP); Kotani; Tsutomu (Chiba, JP); Endo; Shinichi (Chiba, JP)

1991-06-04

407

Efficient power amplifiers for piezoelectric applications  

NASA Astrophysics Data System (ADS)

The principal obstacle to greater utilization of piezoelectric actuators in aerospace applications is the extreme inefficiency and heat rejection requirements of the driving electronics. The purpose of this investigation is to take a critical look at how amplifiers for piezoelectric systems are designed and to look for potential areas for improvement. A dimensional analysis of a piezoelectric actuator is performed that indicates that power consumption in an unloaded actuator is extremely low, placing the blame for the exorbitant power demands squarely on the driving electronics. Several strategies for power savings in piezoelectric driving electronics are presented including pulse width modulation, discrete charge control, and a hybrid charge-recovery strategy.

Main, John A.; Newton, David V.; Massengill, Lloyd; Garcia, Ephrahim

1996-12-01

408

Strong piezoelectricity in bioinspired peptide nanotubes.  

PubMed

We show anomalously strong shear piezoelectric activity in self-assembled diphenylalanine peptide nanotubes (PNTs), indicating electric polarization directed along the tube axis. Comparison with well-known piezoelectric LiNbO(3) and lateral signal calibration yields sufficiently high effective piezoelectric coefficient values of at least 60 pm/V (shear response for tubes of approximately 200 nm in diameter). PNTs demonstrate linear deformation without irreversible degradation in a broad range of driving voltages. The results open up a wide avenue for developing new generations of "green" piezoelectric materials and piezonanodevices based on bioactive tubular nanostructures potentially compatible with human tissue. PMID:20131852

Kholkin, Andrei; Amdursky, Nadav; Bdikin, Igor; Gazit, Ehud; Rosenman, Gil

2010-02-23

409

Parameter identification method for piezoelectric shunt damping  

NASA Astrophysics Data System (ADS)

Piezoelectric shunt damping is a method to reduce structural vibration by shunting a piezoelectric element with an electrical circuit. This paper proposes a method to identify the physical parameters that are required to design piezoelectric shunt damping systems. Employing self-sensing actuator methodology, the proposed method requires no additional sensor or actuator other than a simple bridge circuit. The parameters can be identified from a transfer function simply by linear least squares method. To demonstrate the validity of the proposed method, the shunt damping of the steel plate with the piezoelectric ceramic is performed based on the identified parameters.

Takagi, Kentaro; Nagase, Kenji; Oshima, Kazuhiko; Hayakawa, Yoshikazu; Luo, Zhi-Wei

2004-02-01

410

Piezoelectric transducers, state of research  

Microsoft Academic Search

Methods for preparing, treating and sintering powders to be used in the production of ceramic elements (coprecipitation, isostatic compression, sintering under shock loading) are reviewed. Faults inherent in a piezoelectric ceramic element are outlined. Perovskite type compounds, analogous to PbTiO3, which are strongly anisotropic and have a very low k31 coupling factor; lead compounds which are strongly anisotropic and give

L. Eyraud; P. Eyraud; F. Bauer

1984-01-01

411

A novel monolithic piezoelectric sensor  

Microsoft Academic Search

A novel monolithic piezoelectric sensor (MPS) is presented for the detection of physical, chemical and biochemical measurands. This new sensor overcomes specific deficiencies associated with the quartz crystal microbalance (QCM) while still employing a well-characterized, temperature-stable thickness-shear mode (TSM). The sensor is applicable to both gaseous and liquid phase measurements; however, the principal benefit of the MPS is in liquid

M. G. Schweyer; J. A. Hilton; J. E. Munson; J. C. Andle; J. M. Hammond; R. M. Lec

1997-01-01

412

Piezoelectric measurement of laser power  

DOEpatents

A method for measuring the energy of individual laser pulses or a series of laser pulses by reading the output of a piezoelectric (PZ) transducer which has received a known fraction of the total laser pulse beam. An apparatus is disclosed that reduces the incident energy on the PZ transducer by means of a beam splitter placed in the beam of the laser pulses. 4 figs.

Deason, V.A.; Johnson, J.A.; Telschow, K.L.

1989-11-20

413

Piezoelectric immunosensors -- Theory and applications  

SciTech Connect

A Mini Review of recent advances in piezoelectric immunobiosensors is presented. First a review of the theory and history of the technique is given, followed by a critical survey of the use of this method in various fields of analysis. A biosensor can be defined as a device incorporating biological material connected to or integrated within a transducer. The specificity and sensitivity is complemented by the transducer, which electronically measures and computes the signal.

O`Sullivan, C.K.; Vaughan, R.; Guilbault, G.G. [Univ. Coll. Cork (Ireland). Dept. of Chemistry

1999-09-01

414

Vibration energy harvesting using piezoelectric unimorph cantilevers with unequal piezoelectric and nonpiezoelectric lengths  

PubMed Central

We have examined a piezoelectric unimorph cantilever (PUC) with unequal piezoelectric and nonpiezoelectric lengths for vibration energy harvesting theoretically by extending the analysis of a PUC with equal piezoelectric and nonpiezoelectric lengths. The theoretical approach was validated by experiments. A case study showed that for a fixed vibration frequency, the maximum open-circuit induced voltage which was important for charge storage for later use occurred with a PUC that had a nonpiezoelectric-to-piezoelectric length ratio greater than unity, whereas the maximum power when the PUC was connected to a resistor for immediate power consumption occurred at a unity nonpiezoelectric-to-piezoelectric length ratio.

Gao, Xiaotong; Shih, Wei-Heng; Shih, Wan Y.

2010-01-01

415

Parameter fitting of constitutive model and FEM analysis of solder joint thermal cycle reliability for lead-free solder Sn3.5Ag  

Microsoft Academic Search

The experimental tests of tensile for lead-free solder Sn-3.5Ag were performed for the general work temperatures range from\\u000a 11 to 90 C and strain rate range from 510?5 to 210?2 s?1, and its stressstrain curves were compared to those of solder Sn-37Pb. The parameters in Anand model for solder Sn-3.5Ag\\u000a were fitted based on experimental data and nonlinear fitting method,

Ping Zhou; Bing-ting Hu; Jie-min Zhou; Ying Yang

2009-01-01

416

Lead-free 95.5Sn3.8Ag0.7Cu solder joint reliability analysis for micro-BGA assembly  

Microsoft Academic Search

A design-for-reliability methodology was applied to a micro-BGA assembly with lead-free, 95.5Sn-3.8Ag-0.7Cu solder joints. A rate dependent viscoplastic Anand model was curve fitted from a series of constant strain rate tensile test and creep test results. The material parameters for the viscoplastic Anand model for 95.5Sn-3.8Ag-0.7Cu solder was implemented in finite element analysis. Low cycle isothermal fatigue test was conducted

J. H. L. Pang; P. T. H. Low; B. S. Xiong

2004-01-01

417

Mechanical tensile fracture behaviors of solid-state-annealed eutectic SnPb and lead-free solder flip chip bumps  

Microsoft Academic Search

The mechanical tensile fracture behavior was examined for solid-state-annealed eutectic SnPb and lead-free solder flip chip bumps. Annealing temperatures were in the range of 125 to 170C for 500 hrs. Prior to the solid state annealing, the eutectic Sn-37Pb (SnPh) and Sn-0.7Cu (SnCu) solders showed fracture through the bulk solder. The brittle interfacial fracture occurred in 'Sn-3.5Ag (SnAg) solder. After

Jin-Wook Jang; Ananda De Silva; Jong-Kai Lin; Darrel Frear

2003-01-01

418

Preparation and Electrical Properties of Lead-Free Bi0.5(Na0.4K0.6)0.5TiO3 Thin Films  

Microsoft Academic Search

Lead-free Bi0.5(Na0.4K0.6)0.5TiO3 films have been synthesized by a chemical solution deposition method and deposited on p-Si(111) substrate by spin coating. Powder of the precursor solution heated at 650C was studied by infrared scattering spectroscopy. The structural characteristics and crystallization of the films were examined by X-ray diffraction. The surface morphology and quality were studied using atomic force microscopy. The films

Changhong Yang; Zhuo Wang; Guangpeng Ma; Shengli Gu; Yuguo Yang; Dongmei Yang; Jianru Han

2005-01-01

419

Solder Joint Reliability Assessment for Flip Chip Ball Grid Array Components with Various Designs in Lead-Free Solder Materials and Solder Mask Dimensions  

Microsoft Academic Search

This study investigates the reliability of flip chip ball grid array (FCBGA) components with three types of solder materials:\\u000a eutectic solder with a composition Sn63Pb37 and the lead-free solders SnAg3.0Cu0.5 and SnAg4.0Cu0.5. Two substrate-side solder\\u000a mask (S\\/M) opening sizes, 0.4mm and 0.525mm, were used. Both the monotonic and cyclic mechanical four-point bend tests are\\u000a conducted for the reliability assessment. It

Y. S. Chen; C. S. Wang; T. C. Wang; W. H. Chan; K. C. Chang; T. D. Yuan

2007-01-01

420

Effects of rare earth metal substituents on the high power piezoelectric properties in lead zirconate titanate-lead (antimony,manganese)O(3) ceramics  

NASA Astrophysics Data System (ADS)

Improved piezoelectric materials with higher vibrational velocities are needed to meet the demands of advanced high power electromechanical applications. In this thesis, the effects of the rare earth (RE) metal substituents on the vibrational velocity, the piezoelectric properties and polarization behavior of Pb(Zr,Ti)O3-Pb(Sb,Mn)O3 ceramics have been investigated. Under high drive levels, the mechanical quality factor and the vibrational velocity were both significantly improved by RE substitution. For a longitudinal vibrator, driven under the d31 mode, root mean square value (rms value) of vibration velocity as high as 0.9 m/s under an electric field of 10 kV/m (rms value) has been found for Yb-substituted specimens, which is 1.5 times higher than that of base Pb(Zr,Ti)O3-Pb(Sb,Mn)O 3 ceramics. For most of rare earth substituents investigated in this system, regardless of the species ionic radii, the piezoelectric properties were observed to have combinative "hard" and "soft" characteristics. "Hard" piezoelectrics have higher Qm values, but lower k31 values. On the other hand, "soft" piezoelectrics have lower Qm values, but higher k31 values. The increased mechanical quality factor Qm (typical of "hard" piezoelectrics) and increased electromechanical coupling coefficient k31 (typical of "soft" ones) were both achieved by RE substitution. With increasing rare earth substituent ionic size, there was no absolute proportional relationship between k31/Qm and dopant ionic size observed. Polarization-electric field (P-E) measurements revealed a significant relaxational polarization similar to a "soft" piezoelectric, in addition to an internal dipolar field similar to a "hard" piezoelectric. A possible explanation for the combinative "hardening" and "softening" effects is the coexistence of randomly quenched and mobile defects. The time dependences after poling of the mechanical quality factor Q m, electromechanical coupling coefficient k31 and dielectric constant K have been investigated for both "soft" and "hard" lead zirconate titanate (PZT) ceramics. A significant increase of Qm with time was observed for "hard" PZTs, however "soft" ones did not exhibit any changes during the same time period. The aging rate after poling was found to be related to the degree of "hard" characteristics. Polarization versus electric field (P-E) measurements of "hard" PZTs revealed the development of a shift of the response along the E axis with time. It is believed that an internal dipolar field develops with time, due to a reorientation of defect dipoles along the direction of spontaneous polarization through oxygen diffusion. (Abstract shortened by UMI.)

Gao, Yongkang

421

Rapid Prototyping of Novel Piezoelectric Composites  

Microsoft Academic Search

Piezoelectric ceramic-polymer composites have been conceptualized, prototyped, fabricated by rapid prototyping in order to surpass those fabricated with traditional processing methods in novelty as well as performance. Rapid prototyping offers unmatched design and fabrication flexibility in achieving structural complexity and hierarchy in developing piezoelectric composites. A detailed account of all salient aspects of Fused Deposition of Ceramics (FDC) and Fused

A. Safari; E. K. Akdogan

2006-01-01

422

Saint-Venant's Principle in Linear Piezoelectricity.  

National Technical Information Service (NTIS)

Toupin's version of Saint-Venant's principle in linear elasticity is generalized to the case of linear piezoelectricity. That is, it is shown that, for a straight prismatic bar made of a linear piezoelectric material and loaded by a self-equilibrated syst...

R. C. Batra Y. S. Yang

1995-01-01

423

Nucleic Acid Hybridization Detected by Piezoelectric Resonance  

Microsoft Academic Search

Ordinary AT-cut, quartz, piezoelectric crystals as commonly used in watches, radios, computers, etc., were used to detect the hybridization of complementary strands of synthetic RNA's. The method is based on the large absolute mass increase accompanying hybridization. Nucleic acid strands were covalently attached to the polymer-modified surface of a piezoelectric crystal. When these immobilized probe strands were melted and then

Newton C. Fawcett; Jeffrey A. Evans; Liang-Chy Chien; Naomi Flowers

1988-01-01

424

Polyimides: Piezoelectric properties and interfacial imidization  

Microsoft Academic Search

This work presents novel computational methodologies to bridge computational and experimental time scales and to incorporate chemical reactions into classical simulations. Specifically, the mechanisms underlying both the piezoelectric properties and interfacial imidization of polyimides are examined. The dielectric relaxation strength, Deltaepsilon, is directly proportional to the piezoelectric response in amorphous polymers. A simulation technique is presented which allows the calculation

Jennifer Ann Young

1999-01-01

425

Exact moduli of layered piezoelectric media  

Microsoft Academic Search

We derive exact results for overall moduli of multiphase piezoelectric layered media. Specific formulae are given for elastic, piezoelectric and dielectric constants together with thermal stress and pyroelectric coefficients in terms of phase moduli and volume fractions. The constituent layers and the composite aggregate are assumed to be orthorhombic of class 2 mm. The method of solution simply follows from

Tungyang Chen

1997-01-01

426

Using Piezoelectric Materials for Wearable Electronic Textile  

Microsoft Academic Search

An open issue for electronic textiles (e-textiles) used for wearable computing is the choice of materials. This paper describes the desirable characteristics of piezoelectric materials for wearable e-textiles, including shape sensing, sound detection, and sound emission. The paper then describes an initial prototype of a glove for user input that employs piezoelectrics to sense the movement of the hands to

Joshua Edmison; Mark T. Jones; Zahi Nakad; Thomas Martin

2002-01-01

427

Power Electronics Design Choice for Piezoelectric Microrobots  

Microsoft Academic Search

Piezoelectric actuators are advantageous for mi- crorobots due to their light weight, high bandwidth, high force production, low power consumption, and simplicity of integration. However, the main disadvantage of either stack or cantilever piezoelectric actuators are the high drive voltages required for adequate force and displacement. This especially limits the ability for such actuators to be used in autonomous microrobots

Erik Steltz; M. Seeman; Srinath Avadhanula; Ronald S. Fearing

2006-01-01

428

A microprocessor controlled piezoelectric power converter  

Microsoft Academic Search

Piezoelectric transformer (PT) for power conversion is receiving more and more attention because of its small thickness and high energy density. A major challenge of PT converter is the resonant characteristic of the PT that affects the performance of the whole converter. This paper presents a microprocessor controlled piezoelectric power converter system for cold cathode fluorescent lamp (CCFL) that can

S. W. Fung; M. H. Pong

2004-01-01

429

Fundamental Understanding of Piezoelectric Strain Sensors  

Microsoft Academic Search

This paper investigates the behavior of piezoelectric elements as strain sensors. Strain is measured in terms of the charge generated by the element as a result of the direct piezoelectric effect. Strain measurements from piezoceramic (PZT) and piezofilm (PVDF) sensors are compared with strains from a conventional foil strain gage and the advantages of each type of sensor are discussed,

Jayant Sirohi; Inderjit Chopra

2000-01-01

430

Properties of polarization echoes in piezoelectric powders  

Microsoft Academic Search

A theoretical description is given for nonlinear formation mechanisms and properties of the polarization echoes in piezoelectric powders, earlier experimentally investigated in both the radiofrequency (rf) and the microwave (mw) frequency domains. For rf echoes, a phenomenological model is elaborated for dynamics of dislocations in mechanically vibrating piezoelectric particles resonantly excited by short-duration pulses of rf electric field. The model

T. Ya Asadullin; Ya Ya Asadullin

1997-01-01

431

Giant piezoelectricity on Si for hyperactive MEMS.  

PubMed

Microelectromechanical systems (MEMS) incorporating active piezoelectric layers offer integrated actuation, sensing, and transduction. The broad implementation of such active MEMS has long been constrained by the inability to integrate materials with giant piezoelectric response, such as Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PMN-PT). We synthesized high-quality PMN-PT epitaxial thin films on vicinal (001) Si wafers with the use of an epitaxial (001) SrTiO(3) template layer with superior piezoelectric coefficients (e(31,f) = -27 3 coulombs per square meter) and figures of merit for piezoelectric energy-harvesting systems. We have incorporated these heterostructures into microcantilevers that are actuated with extremely low drive voltage due to thin-film piezoelectric properties that rival bulk PMN-PT single crystals. These epitaxial heterostructures exhibit very large electromechanical coupling for ultrasound medical imaging, microfluidic control, mechanical sensing, and energy harvesting. PMID:22096193

Baek, S H; Park, J; Kim, D M; Aksyuk, V A; Das, R R; Bu, S D; Felker, D A; Lettieri, J; Vaithyanathan, V; Bharadwaja, S S N; Bassiri-Gharb, N; Chen, Y B; Sun, H P; Folkman, C M; Jang, H W; Kreft, D J; Streiffer, S K; Ramesh, R; Pan, X Q; Trolier-McKinstry, S; Schlom, D G; Rzchowski, M S; Blick, R H; Eom, C B

2011-11-18

432

Anomalous phase transitions of lead-free piezoelectric xNa0.5Bi0.5TiO3-(1-x)BaTiO3 solid solutions with enhanced phase transition temperatures  

NASA Astrophysics Data System (ADS)

Temperature-dependent structural phase transitions and dielectric properties for a series of xNa0.5Bi0.5TiO3-(1-x)BaTiO3 (NBT-BT) samples where x ranges from 0.05 to 0.30 have been investigated. Non-ambient x-ray diffraction together with dielectric data as a function of temperature have demonstrated an enhancement in the ferroelectric to paraelectric phase transition temperature with the increase in NBT content, including inhibition of two well-known low-temperature polymorphic phase transitions of BaTiO3 . Anomalous dielectric response has been observed for samples with x?0.20 suggesting a crossover from a first-order to a second-order phase transition. The critical point lies between x=0.15 and x=0.20 . Deviation from the classical Curie-Weiss law has been seen for samples having x?0.10 . A modified Curie-Weiss law was employed to model the dielectric response in the paraelectric phase and the maximum value of the critical exponent ? was found to be 1.45 for x=0.30 . It is suggested that the dielectric properties are heavily influenced by the induced strain upon doping rather than chemical inhomogeneities and structural disorder, which are common occurrences in doped ferroelectrics.

Datta, K.; Thomas, P. A.; Roleder, K.

2010-12-01

433

Assessment of the effects of the Japanese shift to lead-free solders and its impact on material substitution and environmental emissions by a dynamic material flow analysis.  

PubMed

Lead-free electronics has been extensively studied, whereas their adoption by society and their impact on material substitution and environmental emissions are not well understood. Through a material flow analysis (MFA), this paper explores the life cycle flows for solder-containing metals in Japan, which leads the world in the shift to lead-free solders in electronics. The results indicate that the shift has been progressing rapidly for a decade, and that substitutes for lead in solders, which include silver and copper, are still in the early life cycle stages. The results also show, however, that such substitution slows down during the late life cycle stages owing to long electronic product lifespans. This deceleration of material substitution in the solder life cycle may not only preclude a reduction in lead emissions to air but also accelerate an increase in silver emissions to air and water. As an effective measure against ongoing lead emissions, our scenario analysis suggests an aggressive recycling program for printed circuit boards that utilizes an existing recycling scheme. PMID:22964401

Fuse, Masaaki; Tsunemi, Kiyotaka

2012-09-07

434

Effect of Heat Treatment Conditions on Properties of Lead-Free Bi{sub 2}GeO{sub 5} Ferroelectric Glass Ceramics  

SciTech Connect

Nowadays, lead-free ferroelectric materials have attracted much interest among materials scientists as a result of environmental concern. The bismuth germanate (Bi{sub 2}GeO{sub 5}) phase, one of the lead-free ferroelectric crystals, is of particular interest as its composition already contains good glass former (GeO{sub 2}) and can be prepared by an alternative glass ceramic route. In this work, the conventional melt-quenching method was used to produce the parent glass with composition of 60 mol% BiO{sub 1.5}:20 mol% GeO{sub 2}:20 mol% BO{sub 1.5}. The as-received glass pieces were subjected to the heat treatment schedule at various crystallization temperatures and dwell-times. The glass and glass ceramics samples were then investigated by XRD, Raman spectroscopy and their dielectric properties were also measured. The XRD and Raman spectroscopy showed that the crystallinity of the prepared glass ceramics depended very much on crystallization temperature and dwell-time. The larger dielectric constant and lower dielectric loss were obtained as crystallinity of the glass ceramics enhanced. The highest dielectric constant (epsilon{sub r}) was found at 77 with a low dielectric loss of about 0.005.

Kantha, P.; Pengpat, K.; Rujijanagul, G.; Tunkasiri, T.; Eitssayeam, S. [Department of Physics, Faculty of Science, Chiang Mai University, Chiang Mai 50202 (Thailand); Intatha, U. [School of Science, Mae Fha Luang University, Chiang Rai, 57100 (Thailand); Sirisoonthorn, S. [National Metal and Materials Technology Center, Klong Luang, Pathumthani 12120 (Thailand)

2009-07-23

435

Microstructural evolution of a lead-free solder alloy Sn-Bi-Ag-Cu prepared by mechanical alloying during thermal shock and aging  

NASA Astrophysics Data System (ADS)

In a previous study, a lead-free solder, Sn-6Bi-2Ag-0.5Cu, was developed by mechanical alloying. The alloy shows great potential as a lead-free solder system. In the present work, the microstructural evolution during thermal shock and aging was examined. In the as-soldered joints small bismuth (1 m to 2 m) and Ag3Sn (1 m) particles were finely dispersed in a nearly pure tin matrix with a small amount of ?-Cu6Sn5 phase in the bulk of solder. During thermal shock and aging microstructural evolution occurred with Cu-Sn intermetallic compound (IMC) layer growth at interface, bismuth phase coarsening and Ag3Sn phase coarsening. The microstructure of the solder appeared to be stable at high temperature. The shear strength of the present solder joint is higher than that of Sn-37Pb and Sn-3.5Ag solders. Shear failure occurred Cu-Sn IMC layer-solder interface and in the bulk of solder.

Huang, M. L.; Wu, C. M. L.; Lai, J. K. L.; Chan, Y. C.

2000-08-01

436

Orthotropic piezoelectric composite materials actuator and its preliminary application  

Microsoft Academic Search

In this paper, the laminated piezoelectric composite materials with orthotropic properties, the structures, performances of orthotropic piezoelectric actuation elements are studied. Orthotropic piezoelectric composite materials present remarkable differences in two primary directions perpendicular to each other. As actuation chips, the laminated orthotropic piezoelectric composite materials present opposite deformation tendencies in two primary directions, which conforms to the deformation law of

Ying Luo; Guoqi Zhao; Jianzu Gu; Zuting Liu

2002-01-01

437

Nonlinear piezoelectricity in wurtzite semiconductors  

NASA Astrophysics Data System (ADS)

We present first-principles calculations of piezoelectric coefficients of first and second order for AlN, GaN, InN, and ZnO, along with the composition dependence (bowing) of the linear terms. We show that eight second order coefficients are required and provide a simple description on how to incorporate second order effects in the calculation of the polarization and fields. We demonstrate that the second order effect leads to corrections of the order of 15% for quantum wells and up to 40% for epitaxial quantum dots.

Prodhomme, Pierre-Yves; Beya-Wakata, Annie; Bester, Gabriel

2013-09-01

438

Piezoelectric transducers, state of research  

NASA Astrophysics Data System (ADS)

Methods for preparing, treating and sintering powders to be used in the production of ceramic elements (coprecipitation, isostatic compression, sintering under shock loading) are reviewed. Faults inherent in a piezoelectric ceramic element are outlined. Perovskite type compounds, analogous to PbTiO3, which are strongly anisotropic and have a very low k31 coupling factor; lead compounds which are strongly anisotropic and give strongly attenuated ceramic elements; PVDF type polymers; electrostrictive materials; composite materials; and polar glass materials and electrets are described. Techniques for metallizing elements to improve the adhesive power of the electrodes and contacts; and adhesives and glues used for manufacturing transducers and composites are considered.

Eyraud, L.; Eyraud, P.; Bauer, F.

1984-06-01

439

Modeling and Control of a Dual Stage Actuator Hard Disk Drive  

Microsoft Academic Search

A data-based approach is presented for modeling and controller design of a dual-stage servo actuator in a hard disk drive. The servo actuator in this hard disk drive consists of a conventional voice coil motor and a piezo-electrically actuated suspension. A weighted Hankel matrix based realization algorithm that uses frequency domain data is applied to estimate a discrete-time model of

Uwe Boettcher; Raymond A. De Callafon; Frank E. Talke

2010-01-01

440

Data based modeling and control of a dual-stage actuator hard disk drive  

Microsoft Academic Search

A data-based approach is presented for modeling and controller design of a dual-stage servo actuator in a hard disk drive. The servo actuator in this hard disk drive consists of a conventional voice coil motor and a piezo-electrically actuated suspension. A weighted Hankel matrix based real- ization algorithm that uses frequency domain data is applied to estimate a discrete-time model

Uwe Boettcher; Raymond A. de Callafon; Frank E. Talke

2009-01-01

441

Effect of hardness of frictional materials on properties of ultrasonic motors  

Microsoft Academic Search

In this paper, PTFE composite, epoxy composite, phenolic composites, hard aluminum, cemented carbide as friction materials are respectively paired to ultrasonic motors, with the stator composed by phosphor bronze and piezoelectric ceramic. Mechanical properties and transient characteristics of ultrasonic motors are tested. The results show a monotonic increase in rotation speed, and a monotonic decrease in stalling torque with friction

Qing-jun Ding; Lin Yang; Chun-sheng Zhao

2008-01-01

442

Development of a ?-shaped actuated suspension for 100-kTPI hard disk drives  

Microsoft Academic Search

A suspension-based piezoelectric microactuator has been developed for dual-stage servo systems in hard disk drives. The suspension is designed to meet the requirements of high recording density, high shock resistance, high productivity, and a load\\/unload structure. This paper describes the structure of the actuator and its mechanical characteristics

Mikio Tokuyama; Toshihiko Shimizu; Hiromitsu Masuda; Shigeo Nakamura; Masao Hanya; Osamu Iriuchijima; Jun Soga

2001-01-01

443

Dual-stage track-following servo design for hard disk drives  

Microsoft Academic Search

Discrete time, 25 KTPI track-following servos were designed for magnetic hard disk drive dual stage actuators using the ?-synthesis methodology. The design methodology was tested on two microactuator models. The first is a model of a piezoelectrically actuated suspension, under development by Hutchinson Technology Incorporated. The second is a model of an electrostatically actuated MEMS microactuator, under development by the

Daniel Hernandez; Sung-Su Park; Roberto Horowitz; Andrew K. Packard

1999-01-01

444

Short seeking control with minimum jerk trajectories for dual actuator hard disk drive systems  

Microsoft Academic Search

This paper is concerned with short seeking control for hard disk drives with a dual actuation servo system consisting of a coarse actuator (voice coil motor, VCM) and a fine actuator (piezoelectric actuator, PZT). Short seeking refers to moving the recording head over a few tracks. The primary elements in short seeking control are the feedback controller, the feedforward controller

Jiagen Ding; Federico Marcassa; Masayoshi Tomizuka

2004-01-01

445

Steerable Adaptive Bullet (StAB) piezoelectric flight control system  

NASA Astrophysics Data System (ADS)

This paper outlines a new class of piezoelectric flight control actuators which are specifically intended for use in guided hard-launched munitions from under 5.56mm to 40mm in caliber. In March of 2011, US Pat. 7,898,153 was issued, describing this new class of actuators, how they are mounted, laminated, energized and used to control the flight of a wide variety of munitions. This paper is the technical conference paper companion to the Patent. A Low Net Passive Stiffness (LNPS) Post Buckled Precompressed (PBP) piezoelectric actuator element for a 0.40 caliber body, 0.50 caliber round was built and tested. Aerodynamic modeling of the flight control actuator showed that canard deflections of just +/-1 are more than sufficient to provide full flight control against 99% atmospherics to 2km of range while maintaining just 10cm of dispersion with lethal energy pressure levels upon terminal contact. Supersonic wind tunnel testing was conducted as well as a sweep of axial compression. The LNPS/PBP configuration exhibited an amplification factor of 3.8 while maintaining equivalent corner frequencies in excess of 100 Hz and deflection levels of +/-1. The paper concludes with a fabrication and assembly cost analysis on a mass production scale.

Barrett, Ron; Barnhart, Ryan; Bramlette, Richard

2012-03-01

446

Piezoelectric paint: characterization for further applications  

NASA Astrophysics Data System (ADS)

Piezoelectric paint is a very attractive piezoelectric composite in many fields, such as non-destructive testing, or structural health monitoring. However, there are still many obstacles which restrict the real application of it. One of the main problems is that piezoelectric paint lacks a standard fabrication procedure, thus characterization is needed before use. The work presented here explores the characterization of piezoelectric paint. It starts with fabrication of samples with certain piezoelectric powder weight percentages. The microstructures of the samples are investigated by a scanning electron microscope; the results indicate that the fabrication method can produce high quality samples. This is followed by measurements of Youngs modulus and sensitivity. The piezoelectric charge constant d31 is then deduced from the experimental data; the results agree well with a published result, which validates the effectiveness of the fabrication and characterization method. The characterized piezoelectric paint can expand its applications into different fields and therefore becomes a more promising and competitive smart material.

Yang, C.; Fritzen, C.-P.

2012-04-01

447

A continuum damage model for piezoelectric materials  

NASA Astrophysics Data System (ADS)

In this paper, a constitutive model is proposed for piezoelectric material solids containing distributed cracks. The model is formulated in a framework of continuum damage mechanics using second rank tensors as internal variables. The Helmhotlz free energy of piezoelectric materials with damage is then expressed as a polynomial including the transformed strains, the electric field vector and the tensorial damage variables by using the integrity bases restricted by the initial orthotropic symmetry of the material. By using the Talrejas tensor valued internal state damage variables as well as the Helmhotlz free energy of the piezoelectric material, the constitutive relations of piezoelectric materials with damage are derived. The model is applied to a special case of piezoelectric plate with transverse matrix cracks. With the Kirchhoff hypothesis of plate, the free vibration equations of the piezoelectric rectangular plate considering damage is established. By using Galerkin method, the equations are solved. Numerical results show the effect of the damage on the free vibration of the piezoelectric plate under the close-circuit condition, and the present results are compared with those of the three-dimensional theory.

Fu, Yiming; Wang, Xianqiao

2008-04-01

448

Optimum power and efficiency of piezoelectric vibration energy harvesters with sinusoidal and random vibrations  

NASA Astrophysics Data System (ADS)

Assuming a sinusoidal vibration as input, an inertial piezoelectric harvester designed for maximum efficiency of the electromechanical energy conversion does not always lead to maximum power generation. In this case, what can be gained by optimizing the efficiency of the device? Detailing an answer to this question is the backbone of this paper. It is shown that, while the maximum efficiency operating condition does not always lead to maximum power generation, it corresponds always to maximum power per square unit deflection of the piezoelectric harvester. This understanding allows better optimization of the generated power when the deflection of the device is limited by hard stops. This is illustrated by experimental measurements on vacuum-packaged MEMS harvesters based on AlN as piezoelectric material. The results obtained for a sinusoidal vibration are extended to random vibrations. In this case, we demonstrate that the optimum generated power is directly proportional to the efficiency of the harvester, thus answering the initial question. For both types of studied vibrations, simple closed-form formulas describing the generated power and efficiency in optimum operating conditions are elaborated. These formulas are based on parameters that are easily measured or modeled. Therefore, they are useful performance metrics for existing piezoelectric harvesters.

Renaud, M.; Elfrink, R.; Jambunathan, M.; de Nooijer, C.; Wang, Z.; Rovers, M.; Vullers, R.; van Schaijk, R.

2012-10-01

449

Influence of phase composition on electrostrains of doped (Bi0.5Na0.5)TiO3-BaTiO3-(Bi0.5K0.5)TiO3 lead-free ferroelectric ceramics  

NASA Astrophysics Data System (ADS)

The actuating properties such as the electrostrain and piezoelectric charge coefficient d33 of the lead-free 0.854(Bi0.5Na0.5)TiO3-0.026BaTiO3-0.12(Bi0.5K0.5)TiO3 (abbreviated as BNBK 85.4/2.6/12) ferroelectric ceramic upon manganese (Mn) or cobalt (Co) doping are investigated. These dopants are chosen to improve the sinterability and ferroelectric characteristics of BNBK 85.4/2.6/12. Intricate straining behaviors are observed upon Mn dopingan electrostrain of about 0.1% can be maintained when the Mn doping amount is in between 0.5 and 1.5 mol%. Once outside this doping range, the induced electrostrain is considerably smaller. In contrast, for the Co-doped BNBK 85.4/2.6/12 ceramics, the values of electrostrain and d33 stay relatively constant regardless of the Co doping level. By examining the evolution of crystalline phase composition with increasing doping concentration, the mole content of the rhombohedral phase is shown to be a critical factor in deciding the straining behaviors of the doped BNBK 85.4/2.6/12 ceramics. At each increasing step in Mn or Co doping level, there is a marked similarity in the evolution of the induced electrostrain and rhombohedral phase content.

Shieh, J.; Lin, Y. C.; Chen, C. S.

2010-09-01

450

The Coulombic traction on the surfaces of an interface crack in dielectric\\/piezoelectric or metal\\/piezoelectric bimaterials  

Microsoft Academic Search

This paper deals with the Coulombic traction usually neglected, but inherently acting, on the surfaces of an interface crack\\u000a in dielectric\\/piezoelectric or metal\\/piezoelectric bimaterials. The dielectric material phase is treated as a special kind\\u000a of piezoelectric material with a little piezoelectricity, whereas the metal phase is treated as another special kind of piezoelectric\\u000a material with an extremely large permittivity and

Q. Li; Y. H. Chen

2009-01-01

451

Effects of Zn, Ge doping on electrochemical migration, oxidation characteristics and corrosion behavior of lead-free Sn3.0Ag0.5Cu solder for electronic packaging  

Microsoft Academic Search

Due to lead-free pressure, Sn-Ag-Cu solder is regarded as the potential substitute. However, higher melting point and faintish soldering restrict its wide application. Metal or rare earth metal doping can improve its soldering. In this thesis, effects of Zn, Ge metal doping on electrochemical corrosion behavior of lead-free Sn-3.0Ag-0.5Cu (SAC) solder in 3.5wt.% NaCl solution were investigated by potentiodynamic polarization.

L. Hua; H. N. Hou; H. Q. Zhang; T. Wu; Y. H. Deng

2010-01-01

452

Modeling and analysis of 96.5Sn3.5Ag lead-free solder joints of wafer level chip scale package on buildup microvia printed circuit board  

Microsoft Academic Search

In this study, time-temperature-dependent nonlinear analyses of lead-free solder bumped wafer level chip scale package (WLCSP) on microvia buildup printed circuit board (PCB) assemblies subjected to thermal cycling conditions are presented. The lead-free solder considered is 96.5Sn-3.5Ag. The 62Sn-2Ag-36Pb solder is also considered to establish a baseline. These two solder alloys are assumed to obey the Garofalo-Arrhenius steady-state creep constitutive

John H. Lau; S.-W. R. Lee

2002-01-01

453

Highly piezoelectric Biocompatible and Soft Composite Fibers  

NASA Astrophysics Data System (ADS)

We report the fabrication of highly piezoelectric biocompatible soft fibers containing Barium Titanate (BT) ferroelectric ceramic particles dispersed in electrospun poly lactic acid (PLA). These fibers form mats that have two orders of magnitude larger piezoelectric constant per weight than single crystal barium titanate films. We demonstrate that the observed super-piezoelectricity results from the electrospinning induced polar alignment of the ferroelectric particles and the increased surface area compared to single crystal films. Due to the biocompatibility of PLA that encases the ferroelectric particles, these mats can be applied even in biological applications such as bio-sensors, artificial muscles and energy harvesting devices.

Jakli, Antal; Morvan, Jason; Buyuktanir, Ebru; West, John

2012-02-01

454

Highly piezoelectric biocompatible and soft composite fibers  

NASA Astrophysics Data System (ADS)

We report the fabrication of highly piezoelectric biocompatible soft fibers containing barium titanate ferroelectric ceramic particles dispersed in electrospun poly lactic acid (PLA). These fibers form mats that have two orders of magnitude larger piezoelectric constant per weight than single crystal barium titanate films. We propose that the observed apparent piezoelectricity results from the electrospinning induced polar alignment of the ferroelectric particles that pole the fibers similar to ferroelectret polymer foams that are poled by corona discharge. Due to the biocompatibility of PLA that encases the ferroelectric particles, these mats can be used in biological applications such as bio-sensors, artificial muscles, and energy harvesting devices.

Morvan, J.; Buyuktanir, E.; West, J. L.; Jkli, A.

2012-02-01

455

Improvement on the microstructure stability, mechanical and wetting properties of SnAgCu lead-free solder with the addition of rare earth elements  

Microsoft Academic Search

Ternary lead-free solder alloys SnAgCu were considered as the potential alternatives to leadtin alloys comparing with other solders. In this paper, microstructure and mechanical properties of Sn2.5Ag0.7Cu, Sn3.5Ag0.7Cu, Sn3.5Ag0.7Cu0.1RE, and Sn3.5Ag0.7Cu0.25RE alloys were researched. Coarse ?-Sn grains were formed in Sn2.5Ag0.7Cu and Sn3.5Ag0.7Cu alloys and bulky Ag3Sn intermetallics were found in Sn3.5Ag0.7Cu alloy. With the addition of trace rare earth

D. Q Yu; J Zhao; L Wang

2004-01-01

456

Interfacial Reactions of Sn, Sn-3.0Ag-0.5Cu, and Sn-9Zn Lead-Free Solders with Fe-42Ni Substrates  

NASA Astrophysics Data System (ADS)

Interfacial reactions between Sn, Sn-3.0 wt.%Ag-0.5 wt.%Cu (SAC), and Sn-9 wt.%Zn (SZ) lead-free solders and Fe-42 wt.%Ni (alloy 42) substrates at 240C, 255C, and 270C were investigated in this study. FeSn2, (Fe,Ni, Cu)Sn2, and (Ni,Fe)5Zn21 phases were formed, respectively, at the interface in the Sn/alloy 42, SAC/alloy 42, and SZ/alloy 42 couples. As the reaction time and temperature were increased, the layered intermetallic compound (IMC) assumed two distinct structures, i.e., a thicker layer and a pillar-shaped IMC, in all couples. The IMC thickness of these couples increased with the increase of reaction time and temperature. The IMC thickness was also proportional to the square root of the reaction time. The interfacial reaction mechanism of these couples was diffusion controlled.

Yen, Yee-Wen; Hsieh, Yu-Ping; Jao, Chien-Chung; Chiu, Chao-Wei; Li, Yi-Shan

2013-09-01

457

Microstructure and Sn Crystal Orientation Evolution in Sn-3.5Ag Lead-Free Solders in High-Temperature Packaging Applications  

NASA Astrophysics Data System (ADS)

Understanding the reliability of eutectic Sn-3.5Ag lead-free solders in high-temperature packaging applications is of significant interest in power electronics for the next-generation electric grid. Large-area (2.5 mm 2.5 mm) Sn-3.5Ag solder joints between silicon dies and direct bonded copper substrates were thermally cycled between 5C and 200C. Sn crystal orientation and microstructure evolution during thermal cycling were characterized by electron backscatter diffraction in the scanning electron microscope. Comparisons were made between the observed initial texture and microstructure and its evolution during thermal cycling. Gradual lattice rotation and grain boundary misorientation evolution observed due to thermal cycling suggested a continuous recrystallization mechanism. Recrystallization behavior was correlated with dislocation slip activities.

Zhou, Bite; Muralidharan, Govindarajan; Kurumadalli, Kanth; Parish, Chad M.; Leslie, Scott; Bieler, Thomas R.

2013-10-01

458

Preparation and Ferroelectric Properties of Lead-Free A0.5Bi0.5TiO3 (a = na or k) Thin Films  

NASA Astrophysics Data System (ADS)

Both ferroelectric Na0.5Bi0.5TiO3 (NBT) and K0.5Bi0.5TiO3 (KBT) are considered as the best known lead-free materials. In this experiment, we prepared NBT and KBT thin films on Pt/TiO2/SiO2/Si substrates by metalorganic solution deposition. The structural properties and surface morphologies were measured using X-ray diffraction and atomic force microscopy. The NBT and KBT films show higher leakage currents due to the oxygen vacancies in the films. The remanent polarization and coercive field of NBT (KBT) thin film are 9 (5.2) ?C/cm2 and 50 (25) kV/cm at an applied electric field of 150 kV/cm. The relative dielectric constants of NBT and KBT are 340 and 316 at 1 MHz, respectively.

Ding, Y. L.; Zhang, X. H.; Yang, C. H.; Zhang, X. Y.; Yang, H. L.

459

Magnetoelectric response in lead-free multiferroic NiFe2O4-Na0.5Bi0.5TiO3 composites  

NASA Astrophysics Data System (ADS)

Multiferroic composites that comprise NiFe2O4(NFO) and Na0.5Bi0.5TiO3(NBT) are synthesized using the sol-gel method. The results of XRD and scanning electron microscopy indicate the single-phase formation of NFO and NBT and the presence of two phases in the composites. The dielectric constant and dielectric loss are determined as functions of frequency over a wide range of frequencies from 40 Hz to 1 MHz. Room-temperature magnetization measurements show that these composites are soft magnetic. Further, the multiferroic character is confirmed by their magnetoelectric (ME) response at room temperature. The optimal ME response is 0.14% in a 67NFO-33NBT composite. The present study demonstrates that NFO-NBT could be effective as a lead-free multiferroic composite and provides an alternative for environmental-friendly ME devices.

Narendra Babu, S.; Hsu, Jen-Hwa; Chen, Y. S.; Lin, J. G.

2011-04-01

460

Passive Piezoelectric Prosthesis for the Inner Ear.  

National Technical Information Service (NTIS)

A tubular prosthesis formed by an assembly of electrode segments enclosing an elongated inner chamber, is inserted into the inner ear of a patient for piezoelectric generation of electrical impulses and localized injection thereof in response to externall...

S. A. Fisher A. S. DeReggi

1997-01-01

461

Piezoelectric Sensor Pen for Dynamic Signature Verification.  

National Technical Information Service (NTIS)

The concept of using handwriting dynamics for electronic identification is discussed. A piezoelectric sensor pen for obtaining the pen point dynamics during writing is described. Design equations are derived and details of an operating device are presente...

E. P. EerNisse C. E. Land J. B. Snelling

1977-01-01

462

NMR and optical studies of piezoelectric polymers  

SciTech Connect

Progress is reported in several areas dealing with piezoelectric (electroactive) polymers (mostly vinylidene fluoride, trifluoroethylene, copolymers, PVF[sub 2]) and liquid crystals. Optical studies, neutron scattering, NMR, thermal, theory and modeling were done.

Schmidt, V.H.; Tuthill, G.F.

1993-01-01

463

Linear Elasticity and Piezoelectricity in Pyroelectrics.  

National Technical Information Service (NTIS)

A new, first-principles theory of linear elasticity and piezoelectricity in pyroelectrics, materials including ferroelectrics, which possess a spontaneous polarization is presented. The constitutive relations for the polarization, the electric displacemen...

D. F. Nelson M. Lax

1975-01-01

464

Classical Piezoelectricity: Is the Theory Complete.  

National Technical Information Service (NTIS)

This paper cites experimental evidences which show that the classical theory of piezoelectricity is not complete in describing the responses of ferroelectric ceramics. There are also some preliminary evidences to show that the theory as applied to piezoel...

P. J. Chen

1985-01-01

465

Simulation of Piezoelectric Jellyfish Power Generator  

NASA Astrophysics Data System (ADS)

The energy problem is getting increasingly serious. As such, unused energy recovery technology is crucial for environmental protection, which has been investigated extensively. Several methods have been developed to utilize scavenged energy from the environment, such as waste heat, solar energy, wind energy, and tides energy to convert into useful power. There is a new idea of piezoelectric jellyfish generator which combines the utilization of sea wave and vibration energy. When sea wave passes through the jellyfish, the wave causes the tentacles to vibrate. The tentacles is made of piezoelectric polymer which can convert the strain energy into electrical energy. This paper discusses about the piezoelectric jellyfish's tentacles being disturbed by wave in the sea. We employed the commercial CFD software CFD-ACE+ 2006 to simulate this phenomenon. The parameters including its tentacle length (L) and wave propagating function (Y) are studied which affect the piezoelectric jellyfish capacity to generate power.

Wu, Yeong-Jen; Lai, Wei-Hsiang

466

Calvarial bone harvesting with piezoelectric device.  

PubMed

We introduce the use of a piezoelectric device in order to harvest calvarial bone grafts. The vibration frequency of the instrument allows for the efficient cutting of bone without the risk of accidentally damaging the dura. PMID:17993887

Gonzalez-Lagunas, Javier; Mareque, Javier

2007-11-01

467

Studying insect motion with piezoelectric sensors  

NASA Astrophysics Data System (ADS)

Piezoelectric materials have been widely used in applications such as transducers, acoustic components, as well as motion, pressure and airborne sensors. Because of the material's biocompatibility and flexibility, we have been able to apply small piezoelectric sensors, made of PVDF, to cockroaches. We built a laboratory test system to study the piezoelectric properties of a bending sensor. The tested motion was compared with that of the sensor attached to a cockroach. Surface characterization and finite element analysis revealed the effects of microstructure on piezoelectric response. The sensor attachment enables us to monitor the insects' locomotion and study their behaviors. The applications of engineering materials to insects opens the door to innovating approaches to integrating biological, mechanical and electrical systems.

Mika, Bartosz; Lee, Hyungoo; Gonzlez, Jorge M.; Vinson, S. Bradleigh; Liang, Hong

2007-04-01

468

Piezoelectric response of epitaxial ferroelectric heterostructures  

NASA Astrophysics Data System (ADS)

The electromechanical response of epitaxial oxide heterostructures can be used to probe novel properties arising from nanoscale structural confinement. To resolve the layer-by-layer origin of piezoelectric responses of ferroelectric/dielectric superlattices, we performed time-resolved x-ray microdiffraction studies of a 2(BaTiO3)/4(CaTiO3) superlattice in an applied electric field. The contributions of individual components to the overall piezoelectric response are deduced using kinematic x-ray diffraction calculations. We found that the dielectric CaTiO3 component has an equal piezoelectric response and remnant polarization to the ferroelectric BaTiO3 component, in good agreement with predictions of piezoelectric coefficient (50 pm/V) and local polarization distribution based on density functional theory calculations.

Jo, Ji Young; Sichel, Rebecca; Lee, Ho Nyung; Nakhmanson, Serge; Dufresne, Eric; Evans, Paul G.

2010-03-01

469

Cymbal piezoelectric composite underwater acoustic transducer.  

PubMed

The working principle of Cymbal piezoelectric composite underwater acoustic transducer was studied in this paper. PZT-5A piezoelectric ceramic disk was used as piezoelectric phase and brass foil was used as end cap electrode of the Cymbal transducer. The silicon rubber was used as the insulated proof layer of the underwater acoustic transducer. The properties of this transducer used as hydrophone, such as operation frequency, free-field voltage receiving sensitivity and directivity, were investigated. Several kinds of prototype of this transducer were fabricated and the properties of this transducer used as hydrophone were tested. The results show that the properties of this transducer used as hydrophone depend on the dimensions of Cymbal transducer because the piezoelectric properties of this transducer are dependent on the dimensions of Cymbal transducer's end caps. The appropriate dimensions for getting higher free-field voltage receiving sensitivity with -184.7 dB were obtained. PMID:16793099

Li, Denghua; Wu, Min; Oyang, Peixi; Xu, Xiaofei

2006-06-06

470

Monolithic Low Noise Preamplifier for Piezoelectric Sensors.  

National Technical Information Service (NTIS)

This patent application discloses a preamplifier for a piezoelectric sensor requiring a high-impedance, low noise interface circuit. The preamplifier is a single, monolithic integrated circuit that can be mounted directly onto or inside a miniature sensor...

T. B. Straw

1993-01-01

471

Numerical homogenization techniques applied to piezoelectric composites.  

PubMed

With the recent availability of piezoelectric fibers, the design and the analysis of piezoelectric composites needs new modeling tools. Therefore, a numerical homogenization technique has been developed, based on the ATILA finite element code, that combines two techniques: one relying upon the representative volume element (RVE) the other relying upon the wave propagation (WP). The combination of the two methods allows the whole tensor of the homogenized properties of the piezoelectric composite to be found. Considering a fiber embedded in epoxy, the numerical results are compared to the results obtained using previous analytical models, thus validating the models. Even if the method is presented in a particular case, its extension to any piezoelectric composite is straightforward. PMID:12597177

Lenglet, Eve; Hladky-Hennion, Anne-Christine; Debus, Jean-Claude

2003-02-01

472

PIEZOELECTRIC MICRO POWER GENERATOR FOR ENERGY HARVESTING  

Microsoft Academic Search

A thin film lead zirconate titanate Pb(Zr,Ti)O3 (PZT), power generating device is developed. It is designed to resonate at specific vibrational frequencies from an ambient, vibrational energy source, thereby creating electrical energy via the piezoelectric effect. The energy harvesting device uses the piezoelectric d33 mode and is fabricated with three mask steps. Our cantilever device was designed to have a

R. Sood; Y. B. Jeon; S. G. Kim

473

Powering neon lamps through piezoelectric transformers  

Microsoft Academic Search

An investigation of the piezoelectric high-voltage ratio transformer as a potential component for powering neon lamps is discussed. The attractiveness of the piezoelectric technology is primarily the extreme simplicity of the resulting components, which are easy to reproduce in mass production, compared to the widely-used wire-wound ferrite transformers. Furthermore, on account of the electric network behaviour of a piezotransformer, the

P. J. M. Smidt; J. L. Duarte

1996-01-01

474

Piezoelectric properties of lithium borosilicate glass ceramics  

Microsoft Academic Search

Glass ceramics in the system Li2O-SiO2-B2O3 with oriented crystallites were prepared by crystallizing the glasses in a temperature gradient. Piezoelectric and electromechanical properties of the glass ceramics are reported. Some of the compositions exhibit low temperature coefficient of resonance, comparable to LiTaO3 single crystals. Advantages of fabricating glass-ceramic piezoelectric resonators are described and the possibility of using them in surface

A. Halliyal; A. S. Bhalla; R. E. Newnham; L. E. Cross

1982-01-01

475

Half-Heusler Semiconductors as Piezoelectrics  

NASA Astrophysics Data System (ADS)

We use a first-principles rational-design approach to demonstrate the potential of semiconducting half-Heusler compounds as a previously unrecognized class of piezoelectric materials. We perform a high-throughput scan of a large number of compounds, testing for insulating character and calculating structural, dielectric, and piezoelectric properties. Our results provide guidance for the experimental realization and characterization of high-performance materials in this class that may be suitable for practical applications.

Roy, Anindya; Bennett, Joseph W.; Rabe, Karin M.; Vanderbilt, David

2012-07-01

476

Half-Heusler semiconductors as piezoelectrics  

NASA Astrophysics Data System (ADS)

We use a first-principles rational-design approach to demonstrate the potential of semiconducting half-Heusler compounds as a previously-unrecognized class of piezoelectric materials. We scan a large number of compounds, testing for insulating character and calculating structural, dielectric, and piezoelectric properties. Of the 792 compounds considered, 234 are found to be nonmetallic, of which 189 are further found to be elastically stable. We compare the computed structural parameters to available experimental values for the half-Heusler compounds considered that have been experimentally studied, as reported in the Inorganic Crystal Structure Database. Calculated piezoelectric coefficients (d14) and electromechanical coupling factors (k14) are often high enough to compare favorably with those of piezoelectrics currently in use. We analyze how factors such as electronegativity and ionic radius influence the piezoelectricity of the compound. Moreover, we show that even if toxic or expensive elements are excluded, we are still left with many combinations having reasonably high piezoelectric response. Our results provide guidance for the experimental realization and characterization of high-performance materials of this class that may find practical applications.

Roy, Anindya; Bennett, Joseph W.; Rabe, Karin M.; Vanderbilt, David

2012-02-01

477

Size effect in mesoscopic epitaxial ferroelectric structures: Increase of piezoelectric response with decreasing feature size  

NASA Astrophysics Data System (ADS)

An epitaxial 200 nm thick film of Pb(Zr0.40Ti0.60)O3 (PZT) has been deposited by reactive rf magnetron sputtering on conductive Nb-doped SrTiO3 (100) (STO). The patterning process involved electron-beam lithography of polymethylmethacrylate, fabrication of a 75 nm thick Cr hard mask layer by means of a lift-off process, and dry etching of PZT. The smallest PZT features obtained were 100 nm in lateral dimensions. Piezoelectric sensitive scanning force microscopy in the contact mode revealed a strong increase of the piezoelectric response for feature sizes with lateral dimensions below 300 nm. It is proposed that this behavior is mainly due to vanishing a domains.

Bhlmann, S.; Dwir, B.; Baborowski, J.; Muralt, P.

2002-04-01

478

Study of Constant Torsion Assembly Method of Piezoelectric Transducer Based on PC Control  

Microsoft Academic Search

The piezoelectric transducer plays a key role in the ultrasonic equipment. In the assembly process of piezoelectric transducer with traditional method, the torsion and the pressure have some fluctuations, and as a result, in the process of using the piezoelectric transducer, the electric-acoustic transformation efficiency of the piezoelectric transducer gets lower, the temperature of the piezoelectric transducer rises, piezoelectric ceramic

Zhang Yundian; Yu Fang; Chen Yan; Zhang Zhixiao

2006-01-01

479

High-bandwidth macro/microactuation for hard-disk drive  

NASA Astrophysics Data System (ADS)

The track density of hard disk drives had been increasing of 30%/year in these last years. The increase in bandwidth is limited by the presence of mechanical resonance modes and other nonlinear in the voice coil motor (VCM) actuators. One approach to overcoming the problem is by using a dual-stage servo mechanism. Dual stage actuator systems composed of a micro actuator and a conventional actuator (VCM)-macro actuator may enable such high track densities to be attained. In this paper, a novel piezoelectric microactuator was successfully designed and mounted on the suspension in hard disk drives. The microactuator is based on the deformation in piezoelectric effect, and drives the head suspension assembly. The paper describes the structure of macro/micro actuators, its principles of operation and mechanical characteristics. The actuators system in hard disk has a high bandwidth, simple structure, and low cost.

Ma, Jianxu; Ang, Marcelo H.

2000-10-01

480

Modeling and Control of a Dual Stage Actuator Hard Disk Drive  

NASA Astrophysics Data System (ADS)

A data-based approach is presented for modeling and controller design of a dual-stage servo actuator in a hard disk drive. The servo actuator in this hard disk drive consists of a conventional voice coil motor and a piezo-electrically actuated suspension. A weighted Hankel matrix based realization algorithm that uses frequency domain data is applied to estimate a discrete-time model of the voice coil motor and the piezoelectric actuator. Based on the discrete-time models, different dual-stage track-following controllers were designed using classic and H? loop shaping techniques. The controllers were implemented in real-time in the investigated hard disk drive. A stable feed-back control and good agreement between measurements and simulations show the promising result of data based modeling and control.

Boettcher, Uwe; Callafon, Raymond A. De; Talke, Frank E.

481

Dielectrophoretically structured piezoelectric composites with high aspect ratio piezoelectric particles inclusions  

NASA Astrophysics Data System (ADS)

Piezoelectric composites were prepared by dielectrophoretic alignment of high aspect ratio piezoelectric particles in a thermosetting polymer matrix. A high level of alignment was achieved in the cured composite from a resin containing randomly oriented high aspect ratio particles. Upon application of an electric field during curing of the resin, the particles were found to rotate with their long axes in the direction of the electric field, before coalescing to form chains. The dielectric and piezoelectric properties of the structured composites are well described by an analytical model for composites containing particles arranged into chains. The influence of degree of rotation and aspect ratio of the individual particles as well as their spacing is described with this model. The results correlate with the experimental values for both permittivity and piezoelectric constants in the poling direction. Dielectric and piezoelectric properties were significantly improved with respect to randomly dispersed piezoelectric ceramic powder-polymer composites and the maximum g33 was shifted to a lower volume fraction. The results could have implications for development of dielectric and piezoelectric (nano-)fiber composites for dielectrics such as embedded capcitors, as well as piezoelectrics for sensing and energy harvesting applications.

van den Ende, D. A.; van Kempen, S. E.; Wu, X.; Groen, W. A.; Randall, C. A.; van der Zwaag, S.

2012-06-01

482

Design and characterization of piezoelectric ultrasonic motors  

NASA Astrophysics Data System (ADS)

This thesis presents modeling and prototype fabrication and characterization of new types of piezoelectric ultrasonic micromotors. Our approach in designing these piezoelectric motors was: (i) to simplify the structure including the poling configuration of piezoelectric elements used in the stator and (ii) to reduce the number of components in order to decrease the cost and enhance the driving reliability. There are two different types of piezoelectric motors designed throughout this research. The first of these designs consists of a metal tube, on which two piezoelectric ceramic plates poled in thickness direction, were bonded. Two orthogonal bending modes of the hollow cylinder were superimposed resulting in a rotational vibration. Since the structure and poling configuration of the active piezoelectric elements used in the stator are simple, this motor structure is very suitable for miniaturization. Moreover, a single driving source can excite two bending modes at the same time, thus generate a wobble motion. Three types of prototypes are included in this design. The piezoelectric stator structure is the same for all. However, the dimensions of the motors are reduced by almost 50 percent. Starting with a 10 mm long stator, we reached to 4 mm in the last prototype. The initial diameter was 2.4 mm, which was reduced to 1.6 mm. In the final design, the rotor part of the motor was changed resulting in the reduction in the number of components. In terms of driving circuit, a single driving source was enough to run the motors and a conventional switching power supply type resonant L-C circuit was used. A simple motor structure with a simple driving circuit were combined successfully and fabricated inexpensively. The second design is a shear type piezoelectric linear motor. The behavior of a single rectangular piezoelectric shear plate was analyzed and after optimizing the dimensions and the mode characteristics, a prototype was fabricated. The prototype co