Preparation of graphene/aligned carbon nanotube array composite films for thermal packaging applications

Vertically aligned carbon nanotube arrays (VACNTs) have been successfully achieved by CVD. The carbon nanotubes were almost triple-walled. Furthermore, the graphene/VACNT composite films have been prepared as thermal interface materials, using photolithographic and densification processes. Compared with pure epoxy resin, the longitudinal thermal conductivity of the composite films was obviously improved, which confirmed that VACNTs provided additional longitudinal heat transfer channels in the films. Furthermore, their longitudinal thermal conductivity was largely dependent on the distribution of VACNTs. The transversal thermal conductivity of the composite film with a pattern size of 300 m was about seven times higher than that of pure epoxy resin. This indicated that graphene provided additional horizontal heat transfer channels to achieve the enhancement of transversal thermal conductivity in composite films.