Analysis of crack growth in solder joints

Understanding crack growth in solder joints is important for predicting the fatigue life of solder interconnects. In this paper, crack propagation in solder joints made of two solder alloys, 62Sn/36Pb/2Ag (by weight), a commonly used solder paste for SMT reflow applications, and 96.5Sn/3.5Ag (by weight), a lead‐free solder alloy, was examined during thermal cycling. Based on these observations, the rate of crack propagation was estimated. Microstructural changes in the solder during thermal cycling were also studied.