Thermal Stress Analysis Comparison in IGBT Power Modules between DC and switching Power Cycling

The purpose of this paper is to show and highlight the observed differences in power cycling test results between DC and switching modes. The focus is done in the generated thermal stresses in IGBT power modules where degradations concern the bond-wire contacts and interconnections. It has been found that for the same ΔT j test conditions, the necessarily higher load current in DC mode leads to a higher thermal stress in the bond wires than in switching mode. Consequently, the bond-wire contacts experience locally a slightly higher ΔT than compared to the switching mode and to a slightly lower lifetime. The results of the experimental tests were corroborated by electro-thermo-mechanical simulations with which the difference in lifetime between the two modes was evaluated.