Analysis on the abilities of solder joints to resist thermal fatigue and service life prediction

The purpose of this paper is to compare the abilities of two kinds of solder joints (63Sn37Pb and 96.5Sn3.0Ag0.5Cu) to resist thermal fatigue, and to predict their thermal fatigue lives. First, ten 2D simplified models of PBGA (Plastic Ball Grid Array package) structure with different shape of solder joints, which are obtained from surface mount experiments, are established using finite element software. Then, the stress-strain response of solder joints is obtained. Finally, according to the modified Coffin-Manson's empirical formula, the thermal fatigue lives of solder joint above mentioned are predicted. The result shows the fatigue life of lead-free solder joints is as 3.5 times as SP solder joints'.