Coating dense silicon carbide layer on artificial graphites to achieve synergistically enhanced thermal conductivity and electronic insulation of polymer composites

As a potential thermal conductive filler, spherical graphite (SG) has high thermal conductivity, low density, and a good spherical shape structure. However, the poor electrical insulation of SG will seriously limit its application in highly integrated electronic device packaging. Herein, through a simple liquid–solid chemical reaction, the surface of the SG particle is firmly covered by a uniform silicon carbide (SiC) ceramic coating. Subsequently, a polycarbosilane precursor is immersed into the pore channels of the SiC layer and pyrolyzed at a high temperature to densify the coating. As compared to the original SG thermal pad, the SiC‐coated SG‐derived pad exhibits significantly enhanced electrical insulation and even higher thermal conductivity. As a result, the SiC‐coated SG‐based composite displays a high thermal conductivity of 3.36 W m−1 K−1, a satisfactory resistivity of 7.10 × 1010 Ω cm accompanied with a low density of 1.65 g/cm3. This work could provide the instructional designing protocol of the highly thermal conductive carbon‐based particles by coating ceramic layers for potential application in electronic packaging.