Studies on Liquid Flow and Heat Transfer for Cooling of Integrated Circuits Using Microchannels

Abstract

The past couple of decades has witnessed a rapid progress in the applications of Integrated Circuits (ICs) forcing the size of these circuits to decrease drastically with high demand on increased operating speeds and package densities. These factors have lead to high die temperatures which are detrimental to circuit performance and reliability. A need has therefore arisen for new and innovative techniques for the development of embedded cooling solutions, IC-level integration of thermal sensors and heat sinks, and systematic synthesis techniques for ICs that contain embedded heat dissipation mechanisms. Microchannels and minichannels based heat sinks, which provide large surface to volume ratio, are the obvious choice for this task as they provide a large heat transfer surface area per unit fluid flow volume. The large surface to volume ratio leads to a high rate of heat transfer, making these micro devices as excellent cooling systems. Microchannels provide an efficient means to remove heat from a surface but pose certain challenges in bringing the fresh coolant to the heated surface and returning it to the cooling system before the coolant reaches the stringent temperature limits; however, this can be achieved at the cost of higher pressure drop per unit length. This problem is interlinked with the performance issues of the systems being cooled, which dictate a lowering of the surface temperature to increase reliability, speed of the processor units, or other system considerations. Various researchers have studied the option of using liquid flow based microchannel heat sink (MCHS) as a solution for thermal management. An MCHS has an inlet plenum, from where the fluid is supplied to an array of micro-channels, and an outlet plenum, where it is collected after being made to pass through the microchannels.