Expected Life and Failure Model in IGBT Modules under Vibration-Induced Stress: A Case Study

This article presents a case study on a gel-filled insulated gate bipolar transistor (IGBT) module under mechanical vibration, focusing on its failure mechanism and proposing a life model. First, we used finite element analysis (FEA) with ANSYS to predict the critical stress points, which turned out to be the bond wire feet. Second, we validated these findings to a high degree through experimental tests using a vibrating chamber. In both approaches, a strong correlation is found between the failure rate and the vibration profile, where wear rate increases as one approaches the bond wires' resonance frequency. In experimental tests, all samples happened to fail at the same location, i.e., the upper side foot of terminal bond wires. This result matches the simulation predictions, as these bond wires are the ones with the lowest resonance frequency, hence the closest to the real-world vibrations. A comparison between simulation and experimental results suggest that silicone gel adds to the system a beneficial low-pass behavior that is expected to extend bond wires lifespan.