Thermal interface materials - a review of the state of the art

The past few decades have seen an escalation of power densities in electronic devices, and in particular in microprocessor chips. Together with the continuing trend of reduction in device dimensions this has led to dramatic increase in the thermal issues within electronic circuits. Thermal management is therefore becoming increasingly more critical and fundamental to ensuring that electronic devices operate within their specification. Although a thermal management system may make use of all modes of heat transfer to maintain temperatures within their appropriate limits and to ensure optimum performance and reliability, conductive heat transfer is typically used to spread the heat out from its point of generation and into the extended surface area of a heat sink. To minimise the contact resistance, thermal interface materials (TIMs) are introduced to the joint to fill the air gaps and are an essential part of an assembly when solid surfaces are attached together. This paper reviews the conventional interface materials and then goes on to present a comprehensive review of the emerging state-of-the-art research in the use of carbon nanotube based materials. The paper also outlines the advantages and disadvantages of each TIM category and the factors that need to be considered when selecting an interface material