Thermal Properties of Power Terminals in High Power IGBT Modules

Power dissipation in the leads of IGBT modules has to be taken into account for modern inverter design. This is due to the fact that the total losses of the semiconductors are continuously decreasing while current density increases. This work analyzes the heat budget of the power terminals and the inverter interconnections. Different concepts are discussed for power terminals in high power IGBT modules. The internal connections between terminals and substrates by means of solder joints and wire bonds are compared in thermal and mechanical aspects. The basic concepts are illustrated with simulation models, and the most effective design for high current modules is deduced. The thermal and mechanical characteristics of the IHM A module and the next generation of IHM B modules are compared by both experiment and theoretical modeling. We discuss the necessity to dissipate heat from the power terminal to the heat sink and to the busbar. Static and transient design criteria for busbars are shown.