Two‐Step Grafted AlN /Silicone Composites Thermal Interface Materials With Balanced Thermal Conductivity and Electrical Insulation for Thermal Management

In this study, tris(2‐methoxyethoxy)vinylsilane was grafted onto aluminum nitride (AlN) fillers to improve interfacial compatibility with silicone oil and reduce interfacial thermal resistance. A two‐step covalent bonding strategy, combining surface grafting with subsequent curing, was developed to fabricate AlN‐Vi/silicone composites with high thermal conductivity and excellent electrical insulation. XPS, FTIR, and SEM confirmed successful grafting and uniform filler dispersion. The optimized composite (G‐240) achieved a thermal conductivity of 2.723 W m −1 K −1 at 240 wt% loading, approximately 6.8 times that of neat silicone, with volume resistivity exceeding 1.0 × 10 14 Ω cm and dielectric breakdown strength of 15.33 kV mm −1 , significantly outperforming the unmodified composite. Accelerated aging tests further demonstrated that the grafted silane layer may suppress AlN hydrolysis and preserve thermal performance. This work offers a simple and effective route for high‐performance silicone composite thermal interface materials in electronic packaging and 5G applications.