Investigation on reproduction of IGBT die-attach solder degradation with finite element thermal-mechanical simulation

In order to investigate the aging and failure mechanism of IGBT, finite element (FE) simulation is a crucial analytical instrument that is extensively employed. The results obtained from conventional finite element (FE) simulations indicate that the die-attach solder's stress distribution is predominantly localized within the initial voids. As a result, it is commonly postulated that the die-attach undergoes aging through the initiation and propagation of cracks from the initial voids. However, empirical findings obtained under prolonged on/off time conditions contradict this view. This issue is specifically examined and evaluated in this paper. Even with additional mesh size refinement, the simulation results continue to fall short of accurately representing the actual aging process. The primary reason may be that FE is incapable of reflecting the creep-dominated microscopic changes of die-attach solder. This research will significantly influence the reliability assessment of IGBTs, given that creep is a critical determinant of solder deterioration in real-world scenarios.