细间距器件SnAgCu焊点热疲劳性能研究

通过试验和数值模拟两种方法分析细间距器件SnAgCu焊点的热疲劳寿命。采用-55～125℃温度循环试验,发现SnAgCu焊点疲劳寿命约为1150次。基于Anand方程和Wong方程两种本构模型,针对两类疲劳寿命预测方程进行对比研究。结果显示,基于两种模型计算的SnAgCu焊点应力时间历程曲线具有相类似的趋势,但是应力值有较大差别。针对两类疲劳寿命预测方程,结合试验研究分析焊点的疲劳寿命,基于Wong方程结合双蠕变模型计算的疲劳寿命值和试验结果吻合良好,而基于Anand方程结合Engelmaier修正的Coffin-Mason方程计算的疲劳寿命略高于试验结果。

Thermal Fatigue Behavior of SnAgCu Soldered Joints in Fine Pitch Devices

This paper presents the fatigue life of fine pitch devices with SnAgCu soldered joints calculated by experiments and numerical simulation. Special test vehicles were selected with SnAgCu soldered joints for testing, and thus the fatigue life of the SnAgCu soldered joints was 1150 cycles under -55-125 ℃ test condition. On the other hand finite element code ANSYS was used to simulate the stress-strain response and fatigue life of lead free soldered joints based on two sorts of constitutive models: Anand equation and Wong equation, plus two life prediction models. It is found that the similar tendency can be seen in the stress history course curves based on these constitutive models, and the values of stress based on these constitutive equation are different from each other. Two life prediction equations, comparing with thermal cycling experiments, were employed to analyze the fatigue life of fme pitch devices with SnAgCu soldered joints under thermal cycling test. It is seen that the life calculated by fatigue life prediction equations with two creep mechanism based on Wong model coincide well with that of the test data, and the life calculated by Engelmaier-modified Coffin-Mason equation calculated based on Anand model is slightly higher than that of the actual result.