Fluid-to-fluid spot-to-spreader (F2/S2) hybrid heat sink for integrated chip-level and hotspot-level thermal management

An innovative heat sink design aimed at meeting both the hotspot and large background heat flux requirements of next generation integrated circuits is presented. The heat sink design utilizes two separate, unmixed fluids to meet the cooling requirements of the chip with one fluid acting as a fluidic spreader dedicated to cooling the hotspots only, while the second fluid serves as both a coolant for the background heat fluxes as well as an on-chip regenerator for the hotspot fluid. In this paper we present the conceptual heat sink design and explore its theoretical capabilities through optimization calculations and computational fluid dynamics (CFD) simulations. We have shown that through close coupling of the two thermal fluids the proposed hybrid heat sink can theoretically remove hot spot heat fluxes on the order of 1 kW/cm² and background heat fluxes up to 100 W/cm² in one compact and efficient package. Additionally, we have shown that the F2/S2 design can handle these thermal loads with a relatively small pressure drop penalty, within the realm of existing micro-pump technologies. Finally, the feasibility of the F2/S2 design was demonstrated experimentally by modifying a commercially available, air-cooled aluminum heat sink to accommodate an integrated hotspot cooling system and fluidic spreader. The results of these experiments, where the prototype heat sink was able to remove hotspot heat fluxes of up to 365 W/cm² and background heat fluxes of up to 20 W/cm², are reported.