In Situ Cross-Linked Thermal Interface Materials with Paraffin-Assisted Viscosity Enhancement for Efficient Device Cooling

Efficient thermal management in modern electronic devices requires thermal interface materials (TIMs) that integrate high bulk thermal conductivity with excellent interfacial wettability. However, conventional high-filler-loading TIMs often exhibit elevated interfacial thermal resistance due to poor processability and limited surface conformity. Herein, we present an in situ cross-linked TIM system based on hydroxyl-terminated polybutadiene and amino resin, incorporating a small amount of paraffin as a processing aid. The paraffin not only enhances interfacial wettability but also increases the composite viscosity from ∼3000 to 11,000 Pa·s (0.1 s–1), facilitating improved surface conformity and enabling the effective reorganization of the ZnO/Al2O3 hybrid filler network. This strategy supports an ultrahigh filler loading of 94 wt % and achieves a bulk thermal conductivity of 7.47 W m–1 K–1. Practical device-level cooling tests demonstrate a temperature reduction of 47.6 °C compared with a bare chip and a 12.4 °C improvement over a commercial thermal grease. These findings underscore the effectiveness of this approach in simultaneously minimizing bulk and interfacial thermal resistances, providing a cost-effective and scalable route for next-generation electronic thermal management.