Thermal conductive silicone grease, also called thermal paste, is a product that uses silicone oil as a base, thermally conductive powder as filler, functional additives, and is mixed and ground. At present, the base oils used for thermal conductive silicone grease mainly include methyl silicone oil, methylphenyl silicone oil, chlorohydrocarbon-based modified silicone oil, chlorofluorocarbon-modified silicone oil, long-chain alkyl silicone oil, etc. Commonly used additives include antioxidants (such as iron octoate), corrosion resists (such as naphthenate), anti-wear agents (sulfur- and phosphorus-containing compounds) and lubrication promoters (mineral oil), etc., selected according to the requirements of thermally conductive silicone grease sexual addition.
The thermal conduction methods of solids are mainly divided into three categories: electrons, phonons and photons. There are no free electrons in polymer polymerization itself, and vibrations between atoms, groups or chain links occur intelligently, and the heat conduction method is mainly phonons. Silicone oil is a type of polymer, so the thermal conductivity of ordinary silicone grease is mainly phonon heat conduction, and the thermal conductivity is generally less than 0.2W/m.K. However, after adding thermally conductive fillers, the thermal conductivity of silicone grease is significantly improved. Therefore, the thermal conductivity of the filler itself and the dispersion in the matrix significantly affect the performance of thermally conductive silicone grease.
Thermal conductive silicone grease is also called heat dissipation paste. It is a paste-like heat dissipation material containing silicone oil; due to the limitations of the production process and clamping method, it is difficult to There are always milled pores between the device and the heat sink. The gaps are filled with air, and air is a poor conductor of heat. The thermal conductivity of air is very low, which seriously affects the overall heat dissipation effect of electronic components. Filling the gap between the component and the heat sink with thermally conductive silicone grease can ensure close contact between the component and the heat sink, increase the contact area, improve heat transfer efficiency, and spread the heat generated by the component studio quickly and evenly to the heat sink, and finally taken away by the fan to optimize heat dissipation performance. In recent years, with the rapid development of my country's intelligent and automated industries, for example, the central processing unit (CPU) used in computers has increased its heat generation as its computing speed has increased, and heat dissipation problems have become more and more prominent. LED chip technology has only 30% of the electrical energy is converted into light, and the other 70% of the electrical energy is converted into heat. If this heat cannot be effectively dissipated, the chip will be burned and the service life will be reduced. At present, the Chinese patent application publication number "cn104231634" discloses a high-efficiency insulating and thermally conductive silicone grease and its preparation method, including dimethyl silicone oil, hydroxyl-terminated silicone oil, alumina and coupling agent; the thermally conductive silicone obtained by this method Grease is a system with higher thermal conductivity. Thermal conductive silicone grease with insulation and low contact thermal resistance is added with coupling agent; the thermally conductive silicone grease obtained by this method is a thermally conductive silicone grease product with high thermal conductivity system, insulation and contact thermal resistance. Adding coupling agent can reduce The viscosity of the system, but the viscosity of the thermally conductive silicone grease obtained after mixing evenly is close to 350,000 centipoise, and the viscosity is still very high. The surface wettability of the thermally conductive silicone grease is poor, resulting in an increase in cross-sectional thermal resistance and a deterioration of the overall thermal conductivity effect, which is not conducive to Heat dissipation between electronic devices. ?
A thermally conductive silicone grease, the following components are by weight: 5-20 parts of dimethyl silicone oil, 50-80 parts of thermally conductive filler 0.5-2 parts of joint agent, 0.1-1 part of methyl silicone oil, 0.1-5 parts of gas phase silica gel, 0.1-3 parts. Preferably, the thermally conductive filler is one or any combination of aluminum oxide, zinc oxide, gallium nitride, and boron nitride. Preferably, the auxiliary agent is one or more of polyvinyl alcohol, hexamethyldisiloxane, tetraethyl silicate, ethyl silicate, and tetraethoxysilane. Preferably, it also includes one or any combination of nanographene, carbon nanotube, and nanocarbon fiber. Preferably, 1-3 parts of calcium carbonate powder are also included.