Test of IGBT Junction-Case Steady State Thermal Resistance and Experimental Analysis

A common theoretically erroneous is to assume that the power electronic devices junction-case steady state thermal resistance is a constant. Based on theoretical qualitative analysis and experimental research, the junction-case steady state thermal resistance is varies as a function of the heat current, heat sink condition, sample time and ambient temperature. The conception of the thermal resistance and the physical structure of the IGBT module and the thermal impedance test principle are briefly introduced. The transient thermal impedance curve and the junction-case steady state thermal resistance of a certain type of IGBT are obtained by the thermal resistance test experiments. It´s found that the junction-case steady state thermal resistance is probably a function of the heat current. When the high heat current reaches a certain level, the steady state thermal resistance becomes stable. In the cool-plate cooling condition, as the cooling condition improves, the junction-case steady state thermal resistance increases. The junction-case steady state thermal resistance decreases as the sample time decreases. Those research results could be helpful for the thermal model modeling and heat sink design for such electronics devices.