Thermal Stress Analysis Comparison in IGBT Power Modules between DC and Switching Power Cycling
Zoubir Khatir, R. Lallemand, Ali Ibrahim, Damien Ingrosso
Abstract
The purpose of this article 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta {T}_J$</tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta T$</tex-math></inline-formula> than compared to the switching mode and to a slightly lower lifetime. The results of the experimental tests were corroborated by electrothermomechanical simulations with which the difference in lifetime between the two modes was evaluated.