Experimental study of the reliability of a power module

In use, electric vehicle power modules are submitted to harsh thermal loads. The resulting thermo-mechanical stresses have an effect on their lifetime. As specific mounting and cooling conditions have a strong impact on reliability, it is important to test power modules in their specific use conditions and verify that lifetime matches warranty duration requirements which may extend to 15 years. To provoke failures which are significant of application wear and aging, repeated stress cycles are applied to power modules. Stress levels correspond to worst case scenarios. To evaluate the degradation level, aging is characterized measuring electric and thermal parameters (emettor- collector voltage Vce, thermal resistance Rth). The test leading to lifetime assessment of various power module technologies are based on applying power cycles.