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

Abstract 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.