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The purpose of this paper is to compare the abilities of two kinds of solder joints (63Sn37Pb and 96.5Sn3.0Ag0.5Cu) to resist thermal fatigue, and to predict their thermal fatigue lives. First, ten 2D simplified models of PBGA (Plastic Ball Grid Array package) structure with different shape of solder joints, which are obtained from surface mount experiments, are established using finite element software. Then, the stress-strain response of solder joints is obtained. Finally, according to the modified Coffin-Manson's empirical formula, the thermal fatigue lives of solder joint above mentioned are predicted. The result shows the fatigue life of lead-free solder joints is as 3.5 times as SP solder joints'.

In this paper, Surface mount experiment of Sn-Pb and Lead-Free solder joints under different thermal reflow profile was aimed at statistical analysis of the reflowed cross-section contour and shape parameters (height, diameter and contact angle). The results as follows: Reflowed solder joints was a pot-shaped body which the top pad is slightly smaller than the bottom pad, and the maximum diameter of solder joints in the side was under the central position; Solder joint shapes obtained from different thermal reflow profiles have greatly differences; The smaller heating factors, the higher height and the smaller diameter and contact angle of solder joint formed by welding.

With the deep research of the reliability of electronic package, more and more investigator realizes that the study on the high strain rate behavior of materials is necessary. Drop impact reliability has become an important criterion when assessing the reliability of portable electronics. The quality of solder joints directly determines the drop-impact reliability of the product. Therefore, to study the dynamic stress-strain constitutive relationship and the fracture/failure behavior of the solder material due to an external impact rate loading become important. Solder balls, as a structural member of the electronic product, are used to connect the microchip and the associated printed circuit board by a proper joining technique such as the surface mount technology (SMT). The static compressive properties of Sn3.0Ag0.7Cu3.0Bi lead-free solder are studied through quasi-static compression testing. In addition, The mechanical behavior of the two lead-free alloy, at strain rates ranging from 3×102 to 1.2×103s−1 and temperatures between 25°C and 140°C, was investigated with the compressive split-Hopkinson pressure bar (SHPB). The dynamic property of Sn-3.0Ag-0.7Cu-3.0Bi alloy was assessed by means of split Hopkinson pressure bar test technique. The strain rate sensitivity of the lead-free solder is characterized using a modified split Hopkinson pressure bar system. The experimental results indicate that, the strain rate sensitivity parameter increases along with increasing strain and strain rate, but decreases with increasing temperature. The addition of Bi delays the sensitivity of strain rate of the lead-free solder. The influence of the addition of Bi on the dynamic stress — strain constitutive relationship and the fracture/failure behavior of the solder material is investigated. The activation energy varies inversely with the flow stress, and has a low value at high deformation strain rates or low temperatures. In this paper, Quasi-static and high strain rate properties of the lead-free solder with temperature are given. Basing on these experimental data, the constitutive relation of Johnson-cook model for this kind of material was built up.

In this paper, dynamic properties of EMC were studied sat different temperatures and different strain rates. Firstly EMC was investigated by quasi-static tests. Secondly a series of dynamic compressive experiments of EMC were conducted using the Split Hopkinson Pressure Bar (SHPB) at high strain rates. Corresponding measurements were conducted at temperatures ranging from 20°C to 200°C. The results indicate that the yield strength and flow stress of EMC increase remarkably with the increase of strain rate. However, the yield strength of EMC is almost unchanged with the increase of temperature which is ranging from 20°C to 200°C.

In this paper, according to the condition B in the drop test standard of JEDEC, create 3D finite element model of VFBGA (very-thin-profile fine-pitch BGA) packages in drop and impact, the material model of solder joints can be indicated by Cowper-Symonds model obtained from experiment data, taking into the consideration of strain rate and temperature effect. Comparing with traditional elastic for solder balls, this material model has better correlation with experimental measurement of dynamic strain, PCB center deflection. For conducting reliable analysis of VFBGA packaging in board-level drop condition, impact acceleration curve is applied to numerical simulation in input-G method.

As two main branches of CAE technology, the appearance and application of optimization design and virtual prototyping (VP) caused the CAE technology at that time to achieve the unprecedented new heights respectively. The collaborative simulation technology can support VP from three levels, namely, the tools teamwork between CAD/CAE softwares, the coupling simulation analysis collaboration of multidisciplinary fields, and the long-distance collaborative simulation & cooperation design. They can also be regarded as pre-processing technology of modern generalized optimization design. Because VP and the collaborative simulation technology have the advantages of being highly efficient to simulate, analyze & calculate and of multidisciplinary collaborative work, it is very convenient to apply them to modern generalized optimization design to do multidisciplinary & multiple-objective optimization design. However, because VP and the collaborative simulation technology are not mature enough, the consequential data losing and systematic error caused by them will be inevitably brought into the modern generalized optimization design whose basis is collaborative virtual prototype technology. (5 pages)

The creep behavior of Zeolite molecular sieves has been investigated in this research by using a nanoindentation test. In the holding time, creep curves were obtained. The results show that the penetration depth during constant load phase is time-dependent. After analysis, creep stress exponents of Zeolite molecular sieves were determined from In vs .InH curves. Given a secondary creep material model, the indention processes of Zeolite molecular sieves were simulated with the ANSYS finite element code by force loading. The simulative results were consistent with experimental creep curves through modulating the constant C of creep constitutive equation. Therefore, the creep constitutive equations of Zeolite molecular sieves were determined.

Lamination failure as “popcorn” form of plastic electronic packages under thermal stress induced by heat mismatch and vapor pressure induced by the moisture during the solder-reflow process is studied. When plastic electronic packages are made of thermohyperelastic materials, using the theory of cavity formation and unstable void growth in incompressible hyper-elastic material, we gained a analytical relationship between void growth and the sum of the vapor pressure and thermal stress. Numerical analyses show that plastic electronic packages will produce popcorn failure when the vapor pressure maintains saturation state during the solder-reflow process on condition that plastic electronic packages absorb a lot of moisture; popcorn failure won’t occur when the moisture in voids is in single vapor phase during the solder-reflow process on condition that plastic electronic packages absorb little moisture.

In order to explore more mechanical properties of zeolite Ferrierite (FER) single crystal, a method of determining its mechanical properties—nanoindentation reverse analysis—was obtained based on the nanoindentation experiment and numerical simulations, and this will be presented in this paper. The yield stress and the characteristic work-hardening rate were gained if its stress-strain relation was a bilinear constitutive relation. The mechanical parameters obtained by reverse analysis have been compared with ones gained by nanoindentation finite-element numerical simulations.

In this paper, a representative material cell containing a single microvoid is used to investigate void growth under combined vapor pressure and thermal stress. The plastic IC packaging material is assumed to be Gent-Thomas thermohyperelastic materials. Using the theory of cavity formation and unstable void growth in incompressible hyper-elastic material, we gained an analytical relation between the applied traction and the change of temperature. Numerical analysis is given of such polymers electronic packaging materials occurred "Popcorn" critical load burst. Numerical results indicate that the critical stress for unstable void growth is very sensitive to the change of temperature. The critical stress for unstable void growth at reflow temperature is likely to be much lower than that at room temperature.

TiNi composite thin films were fabricated using a closed-field unbalanced magnetron sputtering system equipped with optical emission spectroscopy monitor (OEM). The thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and nanoindentation. Results show that the TiNi films are amorphous, and their composition varies approximately linearly with the OEM value. Thus, the film composition could be controlled by in situ real-time OEM. The structure of the single B2 parent phase was observed in the annealed TiNi film. The hardness and elastic modulus of the films increased because of the precipitation of the Ti 3 Ni 4 phase in the single B2 parent phase.

TiNi composite thin films were fabricated using a closed-field unbalanced magnetron sputtering system equipped with optical emission spectroscopy monitor (OEM). The thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and nanoindentation. Results show that the TiNi films are amorphous, and their composition varies approximately linearly with the OEM value. Thus, the film composition could be controlled by in situ real-time OEM. The structure of the single B2 parent phase was observed in the annealed TiNi film. The hardness and elastic modulus of the films increased because of the precipitation of the Ti3Ni4 phase in the single B2 parent phase.

Large zeolite SOD single crystals, of the largest size about 70×70×70μm, were synthesized using a near non-aqueous method. The characterizations of zeolite SOD and synthesis conditions were explained. Their mechanical properties have been measured by instrumented-nano indentation testing that can accurately measure the mechanical properties of small volumes of materials. The load-displacement curve, hardness-displacement curve and modulus-displacement curve of zeolite SOD were obtained. The values of the hardness and the elastic modulus were about 6GPa and 40GPa, respectively. The mechanical properties of zeolite SOD were compared with SiO 2 standard sample.

Infrared thermograph technology in the research of laser-matter interaction was discussed. The formation of molten pool and heat transfer and matter transfer in laser repairing cracks of components were investigated using infrared thermal imaging system. Because the software system of HWRX-3 thermovision is not compatible with the present computer and operation system, we discussed several methods, where the compatibility has been solved and the image processing system can be transformed to windows operation system by the redesign software. The friendly user interface and very high visibility of the optimized software have been testified during laser repairing cracks of components processing. One practical method of digital process for the investigation on heat transfer and matter transfer in laser repairing cracks of components has been developed.

Ti ( C , N ) coatings were prepared on stainless steel (SS) substrates by plasma surface alloying technique. Carbon–nitrogen co-doped titanium dioxide ( C - N - TiO 2) coatings were fabricated by oxidative of the Ti ( C , N ) coatings in air. The prepared C - N - TiO 2 coatings were characterized by SEM, XPS and XRD. Results reveal that the SS substrates were entirely shielded by the C - N - TiO 2 coatings. The C - N - TiO 2 coatings are anatase in structure as characterized by X-ray diffraction. The tribological behavior of the coatings was tested with ball-on-disc sliding wear and compared with substrate. Such a C - N - TiO 2 coatings showed good adhesion with the substrate and tribological properties of the SS in terms of much reduced friction coefficient and increased wear resistance.

A series of dynamic tests were conducted on a closed-cell aluminum alloy foams in order to determine experimental failure surface under impact loading conditions. Quasi-static tests have also been performed to investigate failure mechanism under different stress paths. Three typical types of deformation modes can be observed, which corresponds to the different failure mechanism. The failure loci of the foam in principal stress plane are explored from quasi-static to dynamic loading conditions. A significant strength enhancement is identified experimentally. The expansion of the failure locus from the quasi-static to the dynamic test is almost isotropic. A modified failure criterion for the metallic foam is proposed to predict failure locus as a function of strain rate. This rate-dependence failure criterion is capable of giving a good description of the biaxial failure stresses over a wide range of the strain rates.

This paper presents an experimental investigation on the yield behavior of Nomex honeycombs under combined shearcompression with regard to out-of-plane direction. Four different types of specimens were designed in order to investigate the influence of in-plane orientation angle on the yield behavior of honeycombs under combined loads. Two different failure modes of honeycomb specimens, i.e. the plastic buckling and the extension fracture of cell walls, are observed under combined shear-compression. The experimental results validate that the in-plane orientation angle has a significant influence on the developments of the experimental yield surface. The experimental yield surfaces are compared with a phenomenological yield criterion capable of accounting for anisotropic behavior. The comparative analytical results indicate the experimental yield surfaces are approximately consistent with the theoretical yield surfaces in the normal-shear stress space. These experimental results are useful to develop constitutive models of Nomex honeycombs under combined shear-compression.