Research on the power cycling aging mechanism and lifetime prediction of IGBT modules under low air pressure environment

IGBT modules operating in low-pressure environments experience significant performance degradation, impacting reliability. This study investigates the power cycling aging characteristics and mechanisms of IGBT modules under low-pressure conditions using a custom-built experimental platform. Results show accelerated aging in low pressure (54kPa), with a 5% on-state voltage drop increase occurring when a standard pressure module exhibits only a 3% increase. The maximum steady-state junction temperature increased by 12% under low pressure, compared to 7% at standard pressure. Disassembly of the aging module revealed that bonding quality and insulation degradation was more severe in low air pressure environments. A multi-physics (current-thermal-mechanical) model, incorporating low-pressure convective heat transfer corrections, was developed to analyze these effects. The model confirms that restricted heat dissipation in low pressure leads to increased junction temperatures and stresses (bond wire foot, solder layer edge, copper-ceramic interface), resulting in bond wire lift-off. Based on the coupling of air pressure, heat dissipation, and junction temperature, this paper establishes a lifetime model for IGBT modules under low-pressure conditions using experimental data and finite element modeling, enabling lifespan prediction at various pressures. These results provide references for safe operation and lifetime prediction of IGBT modules in low-pressure environments.