板级焊点结构的热疲劳及机械疲劳性能分析

Thermal Fatigue and Mechanical Fatigue Behavior of Board Level Solder Joint

采用实验测试与数值模拟相结合的方法对锡铅钎料和无铅钎料SAC305板级焊点分别在热疲劳和机械疲劳载荷作用下的破坏规律进行比较研究。结果表明:相对于传统锡铅钎料而言,常用无铅钎料(SAC305)焊点结构具有较为优异的抗热疲劳性能,然而其抗机械疲劳性能相对较差。由此,采用有限元方法分析了两种钎料焊点结构在热疲劳和机械疲劳过程中的塑性应变和蠕变应变演变过程,以探讨表面贴装板级焊点结构热疲劳和机械疲劳破坏过程的本质区别。

The thermal fatigue behavior and mechanical fatigue behavior of board level solder joint were investigated by experimental testing and numerical simulation. And two kinds of solder materials, including traditional eutectic lead-tin solder and SAC305 lead-free solder, were considered. Results show that the lead-free solder （SAC305） joint has a longer thermal fatigue lifetime, but a shorter mechanical fatigue lifetime than the eutectic solder joint. Therefore, the evolutions of inelastic strains, including creep and plastic strain, caused by thermal fatigue and mechanical fatigue loading in the solder joint were analyzed by a finite element method. And the difference of solder joint＇s thermal fatigue and mechanical fatigue behavior was presented.