Power-cycling-stability of IGBT-modules

Insulated gate bipolar transistors (IGBT) play a leading role in industrial power converter applications. They also reach traction applications where GTOs and thyristors are the predominant switching devices. In this application, power cycling stability and temperature cycling stability are especially very important requests for the long-term stability of such switching devices. Since the mounting technology in wire bonded IGBT-modules is completely different to pressure contacted GTOs and thyristors, in this presentation a special focus is brought to the power cycling stability. Concerning this topic, customer requests are compared to the current state in power cycling stability of Siemens- and eupec-IGBT modules. Principle device structures and mounting technology as well as predominant failure mechanisms are introduced. The improvement in the power cycling stability in the last few years are demonstrated by comparing results of different mounting and bonding technologies. The power cycling test equipment and a test method which allows online monitoring during the power cycling test are shown. This method is based on the change of the forward voltage of the IGBTs caused by a change of the thermal resistance of the chips and the change of the ohmic resistance of the bond wire contact on the chip. The dependence of the IGBT-module's power cycling stability on its temperature swing as well as on its absolute temperature are demonstrated.