IR Camera Validation of IGBT Junction Temperature Measurement via Peak Gate Current

Infrared measurements are used to assess the measurement accuracy of the peak gate current (I-G (Peak)) method for Insulated-gate bipolar transistor (IGBT) junction temperature measurement. Single IGBT chips with the gate pad in both the center and the edge are investigated, along with paralleled chips, as well as chips suffering partial bondwire lift-off. Results are also compared with a traditional electrical temperature measurement method: the voltage drop under low current (V-CE ((low))). In all cases, the I-GPeak method is found to provide a temperature slightly overestimating the temperature of the gate pad. Consequently, both the gate pad position and chip temperature distribution influence whether the measurement is representative of the mean junction temperature. These results remain consistent after chips are degraded through bondwire lift-off. In a paralleled IGBT configuration with nonnegligible temperature disequilibrium between chips, the I-GPeak method delivers a measurement based on the average temperature of the gate pads.