Pure Indium thermal pad is, in many cases, the premium thermal interface material. As long as some compressive force can be applied holding the parts together, it offers far greater thermal conductivity of 81.8 W/m-k compared to graphite sheets or 8 W/m-k for thermal grease. It seeps into the microscopic grooves between your parts and provides a lifetime of service with no risk of degradation or drying out. It operates in a wide spectrum of temperatures from cryogenic up to its melting point of 156°C. It also makes disassembly mess-free. For supreme results, clean all the parts with a dilute acid solution (e.g., 5% HCl) before mating.