Fabrication of multilayer Graphene-coated Copper nanoparticles for application as a thermal interface material

A process to fabricate a thermal interface material (TIM) was developed to coat graphene, which is chemically stable and thermally conductive, on the surface of copper nanoparticles (CNPs) to prevent their oxidation while promoting heat dissipation. The CNPs were synthesized using the polyol method to convert polyvinylpyrrolidone (PVP) into multilayer graphene (MLG) via chemical vapor deposition (CVD). For optimization, CVD temperature, the amount of additional PVP solution, and PVP molecular weight (MW) in polyol process were varied. The results showed that thermal properties degraded with increasing residual PVP, and an increasing I_D/I_G ratio confirmed improved MLG quality. The optimal MLG coating conditions were found to be a CVD temperature of 880℃, 50 wt% additional PVP solution and using K30 PVP in polyol process (MW: 45,000). These conditions provided the highest thermal conductivity of 19.66 W/m∙K. Thermogravimetric analysis established that oxidation began at 150℃, which is higher than the upper temperature limit of electronic components. Therefore, MLG-coated CNPs would be suitable as TIM.