Computer Simulation of Thermo-Mechanical Fatigue of Solder Joints Including Microstructure Coarsening

Thermo-mechanical cycling (– 30°/130°C) tests were performed on 63Sn37Pb solder joints with cycle periods of 12–48 min. The effect of phase (grain) size was incorporated into the integrated matrix creep damage concept to take into account the coarsening which occurred during the thermal cycling. It was thereby determined that failure (50 percent load drop) results at a total integrated matrix plastic strain (creep) of 1.39 and that the measured fatigue life is only 21 percent of that predicted assuming no coarsening. The coarsening during the thermo-mechanical cycling was in reasonable accord with the cubic coarsening law. However, it was more rapid than occurred during isothermal aging at zero stress.