Power cycling on press-pack IGBTs: measurements and thermomechanical simulation

Press-pack IGBTs are increasing their market-share, especially for traction applications. As packaging performance is a key factor for a successful product, there is a great interest in defining optimal solutions in terms of geometry, materials and mechanical loading. To support IGBT reliability assessment we developed a testing rig for accelerated testing of a single chip under controlled pressure conditions. In parallel, we created a thermomechanical simulation of the chip/testing rig assembly for the determination of internal stresses and strains due to actual operation. Test results and preliminary failure analysis following power cycling show the possibility of predicting the degradation according to different mechanisms induced by the combined effect of pressure and temperature fluctuation.