Sucrose-Assisted Interface Engineering of Boron Nitride for BT-Based High-Frequency Electronic Packaging Substrates with Low Dielectric Loss and Enhanced Thermal Conductivity.

The rapid evolution of high-frequency communication, heterogeneous integration, and high-power-density packaging technologies has imposed increasingly stringent requirements for low-loss signal transmission and efficient heat dissipation on polymer-based packaging substrates. Herein, a BN interfacial engineering strategy combining sucrose-assisted mechanochemical activation with silane coupling was developed, and the resulting functionalized BN (f-BN) and SiO2 were incorporated as hybrid fillers into glass fiber fabric-reinforced bismaleimide-triazine (BT) resin composites. The results reveal that sucrose-assisted ball milling generated a hydroxyl-rich active layer on the BN surface, enabling the subsequent grafting of phenylamino silane and thereby improving the dispersion and interfacial bonding of f-BN within the composites. With the partial replacement of SiO2 by thermally conductive f-BN, the f-BN45 composite achieved an extremely low dielectric loss (Df) of 0.003 at 10 GHz and a through-plane thermal conductivity of 1.53 W m-1 K-1, which was 86.9% higher than that of the composite filled only with SiO2. In addition to its low Df and enhanced heat-conduction capability, f-BN45 also exhibited improved dimensional stability of the composites, as reflected by an X-axis CTE of 7.2 ppm/°C, while maintaining stable dielectric performance over a wide temperature range. Practical power device heat-dissipation evaluation and finite element simulations further confirmed the advantage of f-BN45 in chip thermal management. This work highlights sucrose-assisted surface activation combined with silane coupling as an effective route to tailoring the BN/resin interface, offering a feasible paradigm for high-performance BT-based composites in high-frequency electronic packaging and thermal management applications.