Alkyl methyl silicone phase change materials for thermal interface applications

Phase change materials (PCM) have shown several favorable characteristics as thermal interface materials (TIMs). Their main advantage is that they become flowable at the operation temperature, but are much less subject to pump-out than greases. As PCMs become flowable, voids on the substrate surfaces are filled and as a result the interfacial resistances are minimized. High performance PCMs are developed in Dow Corning from silicone organic polymers and thermally conductive fillers. Silicone organics are made from functionalized siloxane polymers and organic materials. By selecting the size of the organic molecule and the structure of siloxane polymer, silicone organics with desirable melting temperature and melt viscosity can be synthesized. Compounds of silicone organics and thermally conductive fillers, particularly aluminum oxide, show excellent thermal conductivities in bulk and very low thermal impedance in thin bondline. Bulk thermal conductivities of the melted PCM are typically around 5 W/mK, and the thermal impedance test in thin bondline is in progress. Details of each measurement method and stability studies will be discussed.