Accuracy estimation of low-current voltage drop method for junction temperature monitoring under DC power cycling

A thorough accuracy estimation of the well-known low-current voltage drop method is carried out in this paper. A high-performance infrared camera is utilized as the reference in a DC power-cycling test on a commercial IGBT power module. The result shows that the low-current voltage drop method produces generally a higher temperature than the actual, in particular at the bond wire's joint point. However, a simple compensation method with a linear function can be easily adopted to compensate the temperature difference. After compensation, the maximum error of temperature swing is 0.28 degrees C.