Compact air-cooled heat sinks for power packages

The main findings of theoretical and experimental work carried out in the development of compact air-cooled heat sinks tailored for spot-cooling of power packages are presented. After formulating the particular cooling task, the thermal issues and practical constraints of a compact heat exchanger design are matched to yield three structures, i.e., microchannel, woven wire screen and porous metal fibre, to be viable candidates. A simplified analytical model is developed to allow performance analyses and optimizations of microchannel and woven wire screen heat sinks operated in impingement mode. Based on the simulation results, five novel heat sinks are fabricated and tested. An experimental setup is built to investigate the effects of heat sink structure, mass-flow rate of air, power dissipation and mounting conditions on heat sink performance. In the measurements the source-gate voltage of the selected MOSFET is used as temperature sensitive electrical parameter (TSEP) to obtain the peak junction temperature. Dissipated base plate and volumetric heat fluxes of 15 W/cm² and 5 W/cm³ are achieved, along with reasonable pressure and pumping power requirements as well as accompanying acoustic noise. Obtained results yield a fivefold enhancement in heat removal capability compared to traditional forced air-cooling schemes