Micro-channel thermal management of high power devices

Heat fluxes in semiconductor power devices have been steadily increasing over the past two decades, now approaching 500 W/cm² . This dissipation requires advanced thermal management in order to maintain device maximum junction temperatures below the Si limit of 150degC. Micro-channel cooling shows great promise for high heat flux removal, with the potential for greater than 750 W/cm² performance. As flow passages decrease in size to sub-millimeter scales, the surface area-to-volume ratio increases, allowing greater potential heat transfer area. However, the correspondingly higher pressure losses across the channel can quickly exceed the maximum pump performance at these small dimensions. A novel micro-channel heat sink was developed, featuring micro-channel passages fabricated directly into the active metal braze (AMB) substrate, minimizing the junction-to-fluid thermal conduction resistance. The heat sink performance was simulated using computational fluid dynamics models and the results show that heat fluxes above 500 W/cm² could be achieved for a 50degC device junction-to-coolant temperature rise. The heat sink was fabricated and tested using an array of power diodes, and infrared thermography measurements validated the simulation results. The demonstrated thermal performance is superior to any existing micro-channel heat sink with a comparable electrical assembly