Controllable construction and performance response regulation of diamond@EGaInSn-based bicontinuous phase thermal interface materials

The relentless miniaturization and 3D integration of high-power electronic devices have created an urgent demand for thermal interface materials (TIMs) that simultaneously achieve high thermal conductivity and mechanical compliance. Here, diamond@EGaInSn (Eutectic gallium indium tin alloy)/polysiloxane bicontinuous phase (BCP) thermal pads with high thermal performance and excellent elasticity were fabricated via molding combined with low-temperature vacuum infiltration. Remarkably, microstructural analysis confirms the formation of interpenetrating diamond@EGaInSn and polysiloxane 3D networks, where EGaInSn alloy uniformly coats diamond surfaces and forms liquid bridges to create continuous thermal pathways. This thermal pad achieves a high thermal conductivity of 25.85 W/(m·K) and ultralow interfacial contact thermal resistance (ICTR) of 0.35 K·mm²/W, significantly outperforming commercial TIMs. The BCP thermal pads achieves exceptional compressive properties and mechanical robustness (deformation less than 20 μm) through EGaInSn’s dual functionality as both thermal conductor and deformable matrix. The bending stiffness of BCP thermal pads increases with applied pressure due to reduced interparticle spacing and enhanced mechanical interlocking between diamond reinforcements. Heat dissipation test results show that the BCP thermal pad exhibits superior thermal conductivity to commercial TIMs. In summary, this bicontinuous phase design provides a new paradigm for multifunctional TIMs.