Compressible Gas-Cooled Micro-channel Heat Sink Board (Substrates)

Thermal management of high power electronic components (chips) with high heat dissipation ratings using air as the cooling fluid clearly demands non-traditional means to be successful. Many different approaches have been attempted in the past with varying degrees of success. One method utilizes heat sinks made of channels. For the case of air cooled channels, substantial increases in heat removal rates were made by designing for laminar conditions, which results in lower pressure drops. This has been recorded in detail in the literature. For gas cooled systems, the push for higher heat transfer rates is making designers opt for higher flowrates. In order to remove relative high amounts of heat, these heat sinks must allow for relatively high fluid flowrates and consequent relative high pressure drops. Although high speed internal gas flows is not efficient (high pumping power), higher gas speed allows for higher heat transfer rates and, therefore, higher air cooling rates. The goal of this paper is to present a design for a board made of channels within which a gas (air, for example) flows at speeds much higher than normal (higher than 50 m/s) but low enough that the compressibility effect penalty is not fully felt. Results indicate that the thermal performance of such heat sink substrate is very good (over 50% improvement). These limits are imposed by the onset of choking (both frictional and thermal) in the system and pumping power. It effect will be assessed and discussed.