电子封装SnPb钎料和底充胶的材料模型及其应用

采用统一型粘塑性Anand模型描述SnPb钎料的非弹性力学行为，基于试验数据和弹塑性蠕变本构模型，确定了92.5Pb5Sn2.5Ag和60Sn40Pb两种钎料Anand模型的材料参数。采用线性粘弹性Maxwell模型，描述了一种倒装焊底充胶U8347-3材料的模量松弛和体积松弛，得到了相应的松弛参数，研究对所给出的材料模型和参数进行了验证。另外，利用有限元法模拟了倒装焊在热循环条件下的应力应变行为，分析了SnPb焊点的塑性应变和热循环寿命。结果表明，采用上述材料模型和参数，可以合理描述SnPb钎料和底充胶的力学本构，并可应用于电子封装的可靠性模拟和分析。

MATERIAL MODELS FOR SnPb SOLDERS AND UNDERFILL IN ELECTRONIC PACKAGING AND THEIR APPLICATION

The unified viscoplastic Anand model is employed to represent the inelastic deformation behavior of SnPb solders. Based on the eXPerimental data and the elsto-plasto-creep model, the material parameters of Anand model for 92. 5Pb5Sn2. 5Ag and 60Sn40Pb solders are determined. The linear viscoelastic Maxwell model is applied to describe the modulus and volume relaxation of a underfill material U8347-3 in flip chip package and the relaxation coefficients are obtained. In addition, the stress/strain resPOnses of flip chip package under thermal cycling are simulated with finite element method. The viscoplastic strain and thermal fatigue lifetimes of SnPb solder joints are analyzed. The results show that the viscoplastic Anand and the linear viscoelastic Maxwell models can be used to represent the mechanical behaviors of SnPb solders and under fill material, respectively. The material models can be applied to the reliability simulation and analysis of electronic packages.