A Review of the Performance and Characterization of Conventional and Promising Thermal Interface Materials for Electronic Package Applications

Thermal interface materials (TIMs) play a key role in reducing thermal resistance between jointed solid surfaces in order to increase thermal transfer efficiency. A TIM is a thermally conductive material which is applied between the interfaces of two components (such as circuit board and heat sinks) to enhance the thermal conductance between them. The present paper provides a detailed review in order to characterize conventional and advanced TIMs in terms of thermal performance. The paper also discusses the measurement of TIM performance using different techniques. It was found that greases are the most widely used TIMs and offer thermal resistance in the range of 0.1-1 cm(2)degrees C/W. However, greases are messy and difficult to apply and remove due to their high viscosity. Moreover, they have reliability issues such as pump-out, phase separation and dry-out, which limits their use as an efficient TIM. The thermal resistance of TIMs which contain carbon nanotubes (CNT) fall in the range of 0.01-0.19 cm(2)degrees C/W. However, the use of CNT as a TIM at high temperatures does not allow for uniform distribution of heat on cooling of electronic packaging systems. Although TIMs with the addition of nano--metal particles are considered promising, it is necessary to carry out extensive research on CNT as a TIM.