Integral liquid cooled (ILC) high power module for efficient heat extraction

This paper describes an innovative method for the removal of heat from semiconductor power modules operating with high power losses. In linear applications, for example, losses are often so high that air cooling is inadequate and liquid cooling must be used. Traditionally, this is achieved by bolting a standard module onto a liquid-cooled heat exchanger. While more effective than air cooling, a thermal barrier still exists between the module base plate and separate heat sink and this contributes significantly to the total junction to ambient thermal resistance. To eliminate this barrier, APT Europe has engineered an integral liquid cooled (ILC) power module package, where the module base plate doubles as the liquid cooled heat exchanger´s upper lid. In this way the cooling medium is in direct contact with the module base plate and there is no interface. To illustrate the dramatic improvement in performance made possible by this approach, the thermal performance of a dual 200 V, 7 mohm MOSFET module operating in linear mode is analysed. A detailed description of the ILC construction as well as the influence of flow rate on thermal resistance are presented