Thermo-Mechanically Activated Liquid Metal Bridging in Epoxy Composites for Next-Generation Electronic Packaging

Advanced semiconductor packaging demands epoxy molding compounds (EMCs) that strike an optimal balance between high thermal conductivity, low coefficient of thermal expansion (CTE), and strong electrical insulation. In this study, we present a highly efficient thermal management composite developed by mechanochemically modifying aluminum nitride (AlN) fillers with a liquid metal (LM) layer. During the thermo-compression process, the fluidic LM undergoes thermomechanical beading and pressure-induced oxide rupture. This allows the LM to merge at the filler interfaces, establishing a dynamically formed metallic bridging network. Consequently, this unique architecture significantly lowers the thermal contact resistance typical of polymer-ceramic composites, achieving remarkable thermal conductivities of 9.8 and 11.4 W m⁻¹ K⁻¹ at filler fractions of 60 and 80 vol%, respectively. Furthermore, this structural rearrangement minimizes interfacial micro-voids, preserving excellent electrical insulation and ensuring a low CTE (8.0–15.0 ppm K⁻¹) that rivals premium commercial EMCs (15.7 ppm K⁻¹). The densification driven by the LM also prevents moisture penetration, guaranteeing long-term reliability under severe 85 °C / 85% RH conditions. Practical infrared thermal imaging verifies that this LM-bridged composite dissipates heat far more effectively than conventional EMCs. Ultimately, this scalable interfacial engineering approach overcomes the typical limitations of highly filled polymer composites, presenting a promising pathway for next-generation electronic packaging.