Current status and progress of organic functionalization of CNT based thermal interface materials for electronics cooling applications

Paper in proceeding, 2017

The development of integrated circuitry has resulted in cheaper and more efficient computers being available every year. Unfortunately, this development comes at the expense of an exponential increase of power density that scales with miniaturisation of transistors. To counteract the hot spot issue that arises and results in poor reliability and reduced lifetime of microsystems, thermal interface materials (TIMs) can be used. TIMs play a key role in thermal management of microsystems by providing efficient thermal pathways between surfaces. Vertically aligned carbon nanotubes (CNT) have been suggested as a potential material for such TIM applications due to the combination of their high thermal conductivity, which has been reported to reach over 3000 W/mK, and unique mechanical properties. However, due to the poor interaction between individual CNT strands and the contact surface, large contact resistances are commonly measured in these interfaces. One solution to this issue is to anchor the CNT by covalent bonding using chemical functionalization which allows phonon propagation through the interface. In this paper various chemical functionalization solutions from recent literature for CNT in TIM applications will be summarized. By comparing the results from these studies to other TIM systems, CNT array based TIM hold some promise with thermal interface resistance values reaching as low as 0.6mm2K/W. However, experimental results regarding the reliability of these solutions are still uncommon and should be a suitable area for further investigations.