Thermal characterization of a copper microchannel heat sink for power electronics cooling

An investigative prototype of a single-phase cooling system based on the microchannel heat sink with water as the heat transfer medium was developed to study the fluid flow and forced-convection heat transfer characteristics for the cooling of electronics microprocessors with extremely high heat fluxes. The microchannel heat sink was made from copper with a high fin aspect ratio of 17.5. In the experiment, pressure losses through the heat sink and thermal characteristics of the cooling section under different heat fluxes (25 to 200W from 7 x 7 mm2 and 11 x 13 mm2 heat sources) and coolant flow rates (1.7 to 15 cm3=s) were studied. Under similar test conditions, minimum cold-plate thermal resistances Rcp of 0.11 and 0:33°C=W were achieved with 11 x 13 mm2 and 7 x 7 mm2 sources, respectively. Heat fluxes of up to 4:1 MW=m2 were effectively dissipated while maintaining a junction temperature below 100°C. With a 15 cm3=s (Re =150) coolant flow rate, maximum values of 5334 W=m2 · Kfor the convection heat transfer coefficient and 3.4 for the Nusselt number were achieved with a 3.3 kPa coolant pressure drop through the system. As an outcome of the present investigation, the copper water-based microchannel heat sink has proved to be a reliable cooling solution for high-end microprocessors.