A damage integral approach to solder joint fatigue

Abstract

The application of a damage integral approach which provides numerical accounting of the accumulated fatigue damage in solder joint is reviewed. The instantaneous fatigue damage rate is determined by the solder stress state, temperature and environment using a phenomenological crack growth law. The stress is calculated using state variable constitutive relations for inelastic deformation. The material parameters for the crack growth law are determined from isothermal fatigue data. Representative damage integral calculations are used to illustrate the application of the approach. Finally, the significance of failure criteria on the apparent fatigue life is discussed in terms of the damage integral approach.