IGBT module setup with integrated micro-heat sinks

Chances of liquid cooling integrated into power modules were investigated during an extended research project. It turned out that a flowing liquid yields better characteristics than a boiling liquid and that water offers superior thermal properties compared to electrical isolating fluids although the latter would allow to omit the isolating ceramic layer. Experimental investigations as well as numerical simulations revealed that the coefficient of heat transfer from solid to liquid can be increased by more than an order of magnitude compared to usually given numbers. To this goal a suited geometry of flow channels and a sufficiently high velocity of the liquid have to be chosen. A corresponding micro-heat sink for double sided cooling of an IGBT and a diode was constructed. The height of the total setup amounts to about 9 mm and with a 12/spl times/12 mm/sup 2/ test chip a thermal resistance of 0.087 K/W was achieved.