Bond Wire Damage Detection and State of Health Estimation of a 1200V, 900A Dual Pack IGBT Power Module using the RL-Equivalent Circuit

Electrical and environmental stresses are the two dominant contributors in aging and failure of power semiconductor devices. Insulated gate bipolar junction transistors (IGBTs) and metal-oxide semiconductor field effect transistors (MOSFETs) are two most commonly used switching devices in power converter circuits. A significant portion of research effort is given in inventing innovative methods to estimate the degradation and fatigue in these devices. Until today, no other existing techniques can determine the number of lifted bond wires and their locations in a live IGBT module, although this information is extremely helpful to understand the overall state of health of an IGBT power module. In this paper, we have proposed a reflectometry-based technique to overcome this hurdle. The RL-equivalent circuit to represent a bond wire has been developed for the device under test and simulated in CST Studio Suite to measure the reflection amplitudes. Experimental results were obtained using a prototype reflectometry hardware, and both the simulation and experimental results have been compared. These results prove that with these two sets of measurements, it is possible to locate the aged device inside a module and detect the number of bond wire lift-offs associated to that device.