Extension of air cooling for high power processors

Air cooling limits for a high power CPU with high local power density were explored through a thermal model. The thermal model included a 20 mm×20 mm die that was assumed to have power dissipation of 160 W and a local power density of 100 W/cm². Package size is assumed to be 50 mm×50 mm, and the heat sink volume is 100 mm (flow length)×100 mm (width)×45 mm (height). The heat sink base is 5 mm thick. The effects of various package materials and configurations; thermal interface material between package and heat sink; heat sink base configurations, parallel plate fin geometries; and air flow conditions on the overall thermal performance have been investigated. Analytical methods are used to predict heat transfer and pressure drop for the parallel plate fin heat sink. Entropy generation rate minimization is applied in the optimization of the fin geometries and flow conditions. Finally, numerical model and heat sink performance results are used to predict air cooling limit.