Monitoring Bond Wire Defects of IGBT Module Using Module Transconductance

Monitoring the defective insulated gate bipolar transistor (IGBT) module is a cost-effective approach to improve the quality of customer service. In general, the parasitic parameters of bond wires inside the IGBT module are affected by aging. Module transconductance reflects the characteristics of the IGBT module and contains information about bond wire health status. It is investigated as a precursor parameter to monitor the bond wire defects in this article. The mathematical model of module transconductance is deduced to establish the relationship between module transconductance and the parameter of bond wires, which indicates that the module transconductance decreases with the increase of bond wire defects. For accurate and safe measurement, the influence of temperature difference caused by bond wire defects during measurement and safety measurement area where the module operates in the active region are discussed. Based on the safety measurement area and the method to eliminate the difference in temperature, a pulse ramp drive circuit is proposed to extract module transconductance. The simulation and experiments are carried out to validate the feasibility of the measurement method and correctness of the theoretical analysis.