Thermal greases with exceptionally high thermal conductivity and low thermal resistance

Abstract

The need for higher performance thermal interface materials has been spurred by the higher thermal demands of new microprocessors, MCMs and other high speed devices. These devices typically produce 10-40 watts of heat. Many applications require the use of a removable interface material along with the need to minimize the bond line and thermal resistance. In addition, greases can compensate for surface nonplanarity approaching 3-4 mils for heat sinks and device packages. In the past several years, a number of diamond filled greases, with claims of high thermal conductivity, have been reported but these products were not practical for low cost consumer applications such as severs, desktop and laptop computers. Other fillers such as boron nitride and aluminum nitride have also been used but most of the previous available fillers were optimized for use in producing ceramic substrates and not for use in polymer based systems. We would like to present our results on the development of a series of high thermal conductivity, cost effective, easy to use greases. In addition to thermal, physical and electrical properties, we will summarize reliability test data including temperature cycling, temperature/humidity exposure and high temperature aging.