A novel three-dimensional boron phosphide network for thermal management of epoxy composites

Recently, construction of effective three-dimensional (3D) heat transfer networks inside polymer has emerged as a promising design strategy to improve the isotropic thermal conductivity for electronic packaging materials. Hexagonal boron nitride (BN) sheets are popular carriers for constructing 3D networks. But removing overheat capability of BN was greatly sacrificed due to size limitation when constructing 3D network. Herein, a novel 3D heat-transferring network, interconnected boron phosphide (BP) grains in-situ growing on Ni foam, was designed to alternate 3D BN network. An isotropic 3D-BP@Ni network with high-quality and integrity was successfully fabricated by a simple high temperature treatment. The synthesized 3D-BP@Ni was incorporated into epoxy resin (ER) by infiltration to fabricate composites. ER/3D-BP@Ni composite, with strong interfacial adhesion between epoxy and 3D-BP@Ni, achieved a high thermal conductivity of 2.01 W/(mK), which corresponded to 908.53% and 402.00% enhancement compared to pure epoxy and ER/Ni composite. The coefficient of thermal expansion (CTE) of the composite reached as low as 26.95 x 10(-6)/degrees C, much smaller than epoxy of 60.69 x 10(-6)/ degrees C and ER/Ni composite of 59.42 x 10(-6)/ degrees C. The designed ER/3D-BP@Ni composite has distinguished heat removal and CTE with semiconductors from traditional polymer composites containing 3D BN network. This strategy is promising to promote the development of electrical packaging materials with high isotropic thermal conductivity.