The invention relates generally to an apparatus for cooling a heated surface and, more particularly, to a double side cooled power module using power overlay technology to interconnect semiconductor power devices in a planar manner.
The development of higher-density power electronics has made it increasingly more difficult to cool power semiconductor devices. With modern silicon-based power devices capable of dissipating up to 500 W/cm2, there is a need for improved thermal management solutions. When device temperatures are limited to 50 K increases, natural and forced air cooling schemes can only handle heat fluxes up to about one (1) W/cm2. Conventional liquid cooling plates can achieve heat fluxes on the order of a twenty (20) W/cm2. Heat pipes, impingement sprays, and liquid boiling are capable of larger heat fluxes, but these techniques can lead to manufacturing difficulties and high cost.
An additional problem encountered in conventional cooling of high heat flux power devices is non-uniform temperature distribution across the heated surface. This is due to the non-uniform cooling channel structure, as well as the temperature rise of the cooling fluid as it flows through long channels parallel to the heated surface.
One promising technology for high performance thermal management is micro-channel cooling. In the 1980's, it was demonstrated as an effective means of cooling silicon integrated circuits, with designs demonstrating heat fluxes of up to 1000 W/cm2 and surface temperature rise below 100° C. Known micro-channel designs require soldering a substrate (with micro-channels fabricated in the bottom copper layer) to a metal-composite heat sink that incorporates a manifold to distribute cooling fluid to the micro-channels. Further, these known micro-channel designs employ very complicated backside micro-channel structures and heat sinks that are extremely complicated to build and therefore very costly to manufacture.
Although power overlay technology (POL) has been employed to provide double-sided cooling, these known structures have not utilized micro-channel features to enhance thermal performance of POL modules. Further, known POL technology generally requires smoothing, brazing and/or soldering operations in order to satisfactorily bond heat sinks to the POL.
In view of the foregoing, it would be desirable to provide a double side cooled power module using power overlay technology that employs cooling channel features to enhance thermal performance of POL modules and that is relatively simple to assemble and that does not compromise cooling-channel features in subsequent processing operations following construction of substrate cooling-channels. It would also be advantageous if the double side cooled power module using POL technology could be implemented without use of smoothing, brazing, or soldering operations.