Influence of grain size and microstructure on dynamic response of solder joints

Pb40/Sn60 is the most commonly used solder alloy for microelectronics packaging. It is well understood that, heat generated by the circuits when a semiconductor device is on and the coefficient of thermal expansion mismatch between the soldered layers lead to the thermal fatigue of the solder joints. On the other hand, there is very little research done to understand failure mechanics of solder joints when microelectronics devices are subjected to vibrations. In this study, it is shown that dynamic stresses contribute to the failure mechanism and in certain circumstances they can become the dominant failure cause when semiconductor devices are used in a vibrating environment. The purpose of this study is to understand the mechanics of the vibration induced damage in solder interconnects. A material nonlinear time domain dynamic analysis of a solder joint was performed using a damage mechanics based constitutive model. The analysis was done for isothermal condition and no thermal loads were considered. The study included a wide range of frequency and acceleration combinations.