Application of ORNL Modified Strain Hardening to Primary Creep for thermal fatigue evaluation of Al Wire Bonding Al in Power Module

Abstract

Power modules are key devices in power converters. An important part of the power module is the bonding area between the wires and the semiconductor chip. This bonding area is subject to damage due to cyclic thermal loading caused by short-cycle operation of the power module. Thermal-elastic-plastic creep analysis is required to accurately analyze this phenomenon. Al wire shows a transient creep phenomenon for a short time, and a recovery phenomenon of creep strain has been reported. The conventional strain-hardening rule cannot sufficiently represent these creep phenomena, and it is necessary to apply a modified strain-hardening rule based on ORNL. In this study, thermo-elastic-plastic creep analysis was performed for the phenomenon of delamination due to crack propagation in wire bonds of power modules subjected to repetitive thermal loading, and the ORNL modified strain-hardening rule was applied to the transition creep. The results of applying nonlinear fracture mechanics parameters in post-processing are reported.