A temperature-independent method for monitoring the degradation of bond wires in IGBT modules based on transfer characteristics

Abstract

Various electrical parameters have been previously proposed for the condition monitoring (e.g., junction temperature, degradation level) of IGBT modules. However, It is a challenge that these parameters are both junction temperature and degradation level dependent, making it complicated to use them for either junction temperature estimation or degradation level assessment. This paper validates the IGBT chip related parameters is independent with the degradation of IGBT module and proposes a junction temperature independent indicator for the degradation level monitoring of bond wires in IGBT modules. It is based on a specific operation point in transfer characteristics curves of IGBTs, where the collector current reduces with the degradation of bond wires and keeps constant under different junction temperature. The principle of the proposed method is discussed. Experimental results based on an IGBT module at different degradation levels from power cycling test verify the effectiveness of the proposed concept.