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The use of environmentally friendly lead-free solder in electronic assembly requires a higher process temperatures that double
the saturated steam pressure inside the electronic package. We studied the interfacial delamination fractures created by the
trapped steam inside the defect voids in packages by computationally modeling the steam diffusion and evaporation processes
and the hygrothermal fracture behaviors. These results were compared with results from the conventional saturated steam pressure
approach. The comparisons revealed that the saturated steam approach is appropriate for small defects, while the evaporative-diffusion
approach is suited for delamination analyses of small and large defects. Our results showed that the strain energy release
rate increased with initial defect growth, but reached a defect-size independent plateau when the defect had grown larger
than the temperature-dependent critical defect size. To control delamination in packages undergoing lead-free solder reflow,
the interfacial fracture energy release rate should be engineered to be above this plateau by controlling the interfacial
adhesion, and the applied strain energy release rate should be reduced by reducing the diffusion and evaporation rate of water
in the materials. 相似文献
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《Electronics Packaging Manufacturing, IEEE Transactions on》2008,31(3):227-239
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Wenxing Dong Yaowu Shi Yongping Lei Zhidong Xia Fu Guo 《Journal of Electronic Materials》2009,38(9):1906-1912
In the present work, solidification cracks in Sn-Ag-Cu solder joints were investigated. Experimental results indicate that
solidification cracks existed in significant numbers in the miniature Sn-Ag-Cu solder joints. In order to create solidification
cracks in the miniature solder joints during solidification and evaluate the susceptibility of Sn-Ag-Cu alloys to solidification
cracking, a copper self-restraint specimen was designed, which can simulate the process of solidification crack formation.
The solidification crack susceptibility of the Sn-Ag-Cu solder alloy was evaluated using the total crack length of the solder
joint. In addition, the effect of trace amounts of elemental additions on solidification cracking of Sn-Ag-Cu solder joints
was studied. It was found that adding trace amounts of Ni or Ce could depress the solidification cracks in Sn-3.0Ag-0.5Cu
solder joints. However, P additions aggravated the formation of solidification cracks. 相似文献
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A large number of lead-free Sn-Ag-Cu controlled collapse chip connection (C4) solder joints (∼100 μm in diameter) in flip-chip microelectronic packages were studied by electron backscatter diffraction (EBSD) in order to describe
the statistical distribution of grain size and coincident site lattice boundaries associated with 60 deg twins in the Sn phase,
as a function of silver content. It is shown that lower silver content results in smaller grains, and a lower propensity for
grains to exhibit twinning symmetries. Indirect measurements of the creep properties of these joints were also obtained as
a function of silver content, showing that, in the strain rate and temperature conditions that are the most relevant to the
microelectronic industry, solder joints with low silver content are more susceptible to creep deformation. 相似文献
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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. 相似文献
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Crystallographically faceted void (CFV) formation in lead-free solder joints has been observed after solidification and during subsequent solid-state aging. Such voids have not previously been reported in the literature. This paper gives a preliminary report on observations of voids which tend to be associated with, and adjacent to, intermetallic compounds in the solder bulk and near-substrate interface region. It has been observed that CFVs are correlated with β-Sn crystallographic orientation and form in a tetragonal shape. Aging promotes CFV clustering and growth. 相似文献
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《Components and Packaging Technologies, IEEE Transactions on》2009,32(2):302-308
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Y. S. Chen C. S. Wang T. C. Wang W. H. Chan K. C. Chang T. D. Yuan 《Journal of Electronic Materials》2007,36(1):6-16
This study investigates the reliability of flip chip ball grid array (FCBGA) components with three types of solder materials:
eutectic solder with a composition Sn63Pb37 and the lead-free solders SnAg3.0Cu0.5 and SnAg4.0Cu0.5. Two substrate-side solder
mask (S/M) opening sizes, 0.4 mm and 0.525 mm, were used. Both the monotonic and cyclic mechanical four-point bend tests are
conducted for the reliability assessment. It is found that the FCBGA components with SnAg3.0Cu0.5 solder have the best durability
during the cyclic bend test, yet the eutectic solder is the strongest during the monotonic bend test. Besides, the FCBGA components
with 0.525-mm S/M opening have around 3 times more life cycles than those with the 0.4-mm S/M opening in the cyclic bend test.
It is also noteworthy that the lead-free solder materials have much variation in the failed cycles during the cyclic test.
Moreover, the failure locations for those components with 0.4-mm S/M openings are found to be at the interface between the
package side metal pad and the solder ball, and those with an S/M opening of 0.525 mm are observed to be failed mostly at
the interface between the printed circuit board (PCB) side metal pad and the solder ball. 相似文献
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P. Darbandi T.R. Bieler F. Pourboghrat Tae-kyu Lee 《Journal of Electronic Materials》2013,42(2):201-214
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. 相似文献
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无铅化电子组装中,由于原材料的变化带来了一系列工艺的变化,随之产生许多新的焊接缺陷。针对“黑盘”现象进行了产生机理分析,并给出了相应的解决措施。 相似文献
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无铅化电子组装中,由于原材料的变化带来一系列工艺的变化,随之产生许多新的焊接缺陷.针对表面裂纹、表面发暗及二次回流等缺陷进行了机理分析,并给出了相应的解决措施. 相似文献
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元器件的微型化和产品的多功能化,驱动了产品安装设计的高密度化和立体化.其特点是焊点越来越密集;焊点尺寸越来越微小;间距越来越细.焊接缺陷是影响电子产品质量的主要因素,针对回流焊接工艺中常见的几种缺陷进行分析,并给出相应的解决措施. 相似文献
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无铅化电子组装中,由于原材料的变化带来了一系列工艺的变化,随之产生许多新的焊接缺陷.针对电迁移和Kirkendall空洞等缺陷进行了产生机理分析,并给出了相应的解决措施. 相似文献