基于Anand模型SnAgCu-X焊点疲劳寿命预测

Anand模型采用有限元法模拟WLCSP器件Sn3.8Ag0.7Cu-X（Ce，Fe）无铅焊点在热循环载荷条件下的应力-应变响应，借助蠕变应变疲劳寿命预测模型SnAgCu，SnAgCuCe，SnAgCuFe焊点疲劳寿命.结果表明，在服役器件整体器件出现明显的变形现象，电路板翘曲严重.从中心到拐角焊点变形-应力-应变逐渐增加，芯片下拐角焊点成为整个结构潜在的危险区域.通过计算WLCSP器件SnAgCu、SnAgCuCe和SnAgCuFe三种焊点的疲劳寿命，证实了SnAgCuCe和SnAgCuFe焊点寿命明显高于SnAgCu焊点，证明了在SnAgCu中添加一定量的铈和铁可以显著提高SnAgCu焊点的使用寿命，分析结果为新型无铅钎料的研发提供理论支撑.

Fatigue life prediction of SnAgCu-X solder joints based on Anand model

Based on Anand model, finite element method was used to analyze the stress-strain response of Sn3.8Ag0.7Cu-X(Ce,Fe) solder joints in WLCSP device, and the fatigue life of solder joints were calculated using fatigue life prediction model. The results indicated that deformation of the WLCSP device in service was found, and the significant warp of the PCB can be observed, the deformation-stress-strain in the ball array increased obviously from central solder joint to corner solder joint, the corner solder joints under the chip become the danger area of the whole device. The fatigue lives of SnAgCu, SnAgCuCe and SnAgCuFe solder joints were calculated, it was found that the fatigue life of SnAgCuCe and SnAgCuFe were higher than SnAgCu solder joints, which demonstrated in theory that the addition of Ce and Fe can improve the fatigue life of SnAgCu solder joints, which can provide the theory support for the researches of lead-free solders.