The traditional method to solve the heat dissipation of electronic equipment is to pad a layer of insulating medium between the heating element and the heat sink as a thermal conductive material, such as mica, polytetrafluoroethylene, and beryllium oxide ceramics. This method has certain effects. But there are disadvantages such as poor thermal conductivity, low mechanical properties, and high price. At present, some of the heat dissipation of electronic equipment is solved by various forms of radiators, but most of them must be solved by thermally conductive materials. Thermally conductive silicone rubber is the most important member of thermally conductive materials.
The mechanism of heat conduction of thermally conductive silicone rubber
Thermally conductive silicone rubber is a typical polymer composite material, and its thermal conductivity is mainly determined by the type of thermally conductive filler and its distribution in the silicone rubber matrix. Metal fillers (such as Al, Ag) have high thermal conductivity, but most of them are thermally and electrically conductive; inorganic non-metallic materials (such as AlN, SiC) also have high thermal conductivity, but they are quite expensive.
At present, metal oxides (such as Al2O3, ZnO) are mainly used as heat-conducting fillers. The heat-conducting mechanisms of various filler materials are different. Metal materials mainly conduct heat by electronic movement. The thermal conductivity of metals decreases with the increase of temperature. The thermal diffusion rate of is mainly determined by the vibration of adjacent atoms and the bonding group. In materials with strong covalent bonding, it is more efficient to conduct heat in the ordered crystal lattice. Therefore, when non-metallic materials are used as thermally conductive fillers, how to improve the thermal conductivity of the system is the main method to improve the thermal conductivity.