Thermal management analysis of high-power electronic modules using Cu bonded AlN substrates

We have successfully developed a thermal management analysis technique that consists of computer simulation based on experimental data, to assume temperatures of high-power electronic modules using Cu bonded AlN substrates, which are used in electric vehicles (EVs) and hybrid electric vehicles (HEVs). An experimental system emulating a high power electronic module was assembled. With increasing electrical power, we observed a positive nonlinearity between the temperature on heaters and the input power. In order to explain this nonlinearity, we ascertained two important factors, the warpage of the substrate and the pore rate inside the Si-grease between the substrate and the Al plate. For ascertaining the warpage due to thermal stress, a movement of reflectance laser beam from a mirror put on the substrate was measured. We determined the pore rate of Si- grease by measuring the pore size inside the grease sandwiched between a clear glass plate and an Al plate on a heated plate. Inputting the pore rate into thermal-strain-interaction simulation, the calculated temperature was consistent with the experimental temperature within an error of less than 3 deg. C at a high power operation of 900 W.