Power cycling and stress variation in a multichip module

The effect of inelastic (creep and plastic) deformation of solder joints during power cycling of a specific multichip module is presented here. The utilized finite element technique allows one to account for the stress redistribution in the module as a function of time while the deformation/creep of the solder joints occur. It is shown that a nonuniform stress distribution exists in the module during power cycling, which affects and controls the inelastic deformation and fatigue life of solder joints. It is also shown that the choice of a suitable material and geometry for different components contained in the module plays a very important role in enhancing the fatigue life of solder joints