Three-dimensional network of hexagonal boron nitride filled with polydimethylsiloxane with high thermal conductivity and good insulating properties for thermal management applications

Electronic components tend to fail due to heat accumulation during use. As a result, thermally conductive and insulating polymer-matrix composites (PMCs) are in great demand in the electronics packaging industry. This study proposes a new hard-template approach for the construction of a three-dimensional hexagonal boron nitride foam (3D-BN) using PMMA microspheres as sacrificial materials. The 3D-BN is then filled with polydimethylsiloxane (PDMS) to create 3D-BN/PDMS composites with high thermally conductivities and good insulating properties. The results of various characterization analyses and 3D finite element simulation show that the 3D-BN is the fundamental factor in improving the thermal conductivity (TC) of the composites. Compared with nanoscale h-BN (nBN), micron h-BN (mBN) is more organized along the pore walls in 3D-BN, better utilizing the in-plane TC of h-BN while reducing the interface thermal resistance (ITR). The obtained lightweight composite exhibits a high TC of 1.868 Wm −1 K −1 and an ultrahigh volume electrical resistivity of 3.66 × 10 13  Ω m at 18.33 vol% mBN loading. This research provides a promising strategy for designing and fabricating thermal management PMCs.