The issue of heat accumulation caused by the low thermal conductivity (TC) of polymers widely used in electronic devices has become a block for chip development. Enhancing the overall TC by adding high-TC fillers to polymers to create composites is considered one of the promising solutions. However, adding a single filler to the polymer may lead to issues such as high interfacial thermal resistance between fillers. Here, we developed a boron nitride@carbon particle (BN@C) hybrid filler by in situ growth of carbon particles on the surface of BN and constructed BN@C/epoxy composites. The presence of carbon bridged the BN and prevented its agglomeration, forming a smooth and efficient thermal conduction network. Consequently, the TC of the composite reached 1.69 W m−1 K−1 at a 60 wt% load. Additionally, it exhibited excellent thermal stability, mechanical and dielectrical properties, and breakdown strength. This study provides an effective strategy for manufacturing high-TC polymeric composites for electronic devices.
