Effect of Aspect Ratio on the Hydraulic and Thermal Performance of Ladder Shape Micro Channels Employed Micro Cooling Systems

Abstract

The success of an IC cooling system or heat sink for ULSI depends on the ability to achieve effective heat transfer rate to the flowing liquid and superior flow performance of the micro channels. The effective heat transfer requires large substrate area that is in contact with the flowing liquid and availability of large mass of fluid to carry away the heat. Conventionally a collection of parallel rectangular micro channels have been used to achieve this. However, there is a practical maximum limit on the number of channels that can be imbedded in the back surface of the substrate by bulk etching. A collection of parallel ladder shape micro channels with rectangular cross section have been introduced and extensively studied by the authors for heat sinking in ULSI circuits. It has been shown that the substrate area extended by the link channels effectively decrease the thermal resistance and increases heat transfer coefficient. The flow performance of these ladder shape micro channels have also been studied using COMSOL MULTIPHYSICS with three different geometrical dimensions (Device -A, Device -B, Device -C) and the comparison of the flow and thermal performance indicating parameters of the collection of ladder shape micro channels show that the high performance heat sinking can be designed using only when the aspect ratio is smaller