Phase-Change Wetting Functional Layer for Reducing Interfacial Thermal Resistance in Carbon-Based Thermal Interface Materials
Interfacial contact resistance often dominates the total resistance of thermal interface materials (TIMs), limiting the benefits of highly conductive yet mechanically stiff filler networks. Here, we introduce a phase-change wetting functional layer onto a vertically aligned carbon-fiber TIM to improve interfacial conformity under low assembly pressure. The layer consists of polyethylene glycol (PEG) and copper particles confined within a crosslinked polydimethylsiloxane (PDMS) network. Upon heating across the phase transition, PEG melting promotes interfacial wetting and filling of microscopic voids, thereby increasing the real contact area. Meanwhile, the PDMS network suppresses macroscopic flow and leakage while preserving surface compliance. At 50 °C and 30 psi, the modified TIM reduces total thermal resistance from 97.8 to 45.4 K·mm²·W⁻¹ relative to the unmodified TIM, a 53.6% decrease. It achieves at 30 psi a thermal resistance comparable to the unmodified TIM at 50 psi, corresponding to a 40% reduction in assembly pressure. At 40 psi, heating from 40 to 50 °C reduces the thermal contact resistance at both interfaces from 41.3 to 25.3 K·mm²·W⁻¹. This 38.7% decrease highlights the contribution of improved interfacial contact to thermal enhancement. The TIM maintains low thermal resistance after 100 thermal cycles and 20 assembly-disassembly cycles. This phase-change-assisted, elastomer-confined architecture offers a practical route to low-resistance, leak-resistant, and reusable TIMs for pressure-sensitive electronics.
