Synergistic enhancement of thermal conductivity for low dielectric constant boron nitride-polytetrafluoroethylene composites by adding small content of graphene nanosheets

Polymer composite with high thermal conductivity (TC) and low dielectric property has great applications in electronic packaging. Herein, we fabricated a series of boron nitride nanosheets-graphene nanosheets-polytetrafluoroethylene (BNNs-GNs-PTFE, BGP) composites, in which the GNs contents of composites were all constant at 1 wt%, via liquid mixing, followed by cold-pressing and sintering. The results demonstrated that the BGP composites possessed good crystallization, excellent thermal stability, high TC and low dielectric property. When BNNs-GNs content was 25 wt%, the BGP composite had a TC of 1.41 W m(-1) K-1. The synergetic effect of BNNs and GNs on the enhancement of composite's TC was investigated with a modified effective medium theory (EMT) model. In addition, we found that the dielectric constant and dielectric loss of BGP composites remained at a low level. The study indicated that adding small content of GNs into BNNs-PTFE composite can significantly enhance the composite's TC, while maintaining its low dielectric constant.