Study of Electrical Contacts Fatigue and Degradation Evaluation for Press-Pack IEGT Under Power Cycling Tests

The electrical contact status between metal layers in a press-pack injection enhanced gate transistor (PP-IEGT) is essential information for the reliability of the whole device. This article employs the numerical method, microscopic detection, and power cycling test (PCT) to qualify the contact degradations and performance in PP-IEGT. First, the contact status of metal pair aluminum–molybdenum in a single-chip module is described through the finite element method (FEM). Then, the contact fatigue of the single-chip module is estimated by the microdetection of the chip surface and the monitor of contact resistance during PCT. Finally, PCTs are conducted on parallel branches to explore contact degradation under different contact statuses. The results show that the chip is subjected to fretting wear and cracks due to the periodic expansion and shrink. In the aging process, the contact resistances display a linear growth trend and have a significant impact on the electrical parameter shift. Moreover, the degradation of the branch with insufficient contact is more serious, especially under smaller clamping force and longer heating duration.