Thermally conductive 3D binetwork structured aggregated boron nitride/Cu-foam/polymer composites

A 3D filler network structure can significantly improve the thermal conductivity of a composite. In addition, a spherically shaped filler is advantageous for high packing density and filler connectivity compared to other shapes. Here, to achieve a high thermal conductivity, epoxy composites were fabricated using spherically aggregated boron nitride (A-BN) and Cu foam as hybrid fillers. To defoam the composites, A-BN was first incorporated into the matrix with Cu foam by a vacuum impregnation process, followed by a curing process. As the A-BN loading increased up to 25 wt%, the thermal conductivity of the composite also increased due to the formation of a heat path. However, when the filler loading exceeded 25 wt%, the thermal conductivity decreases because of filler aggregation. Thus, the composite containing 25 wt% A-BN exhibited the maximum thermal conductivity (2.017 W/mK), with an enhancement of 940% compared with that without filler. In addition, the incorporation of A-BN is beneficial for increasing the volume resistivity of the composite, allowing its practically insulation (1.21 x 10(13) Omega cm). This study shows that the formation of 3D network structures with binary fillers is advantageous for the heat management of electronic devices.