"Heat-conducting silica gel sheet" is a kind of heat-conducting medium material synthesized by a special process based on silica gel, adding various auxiliary materials such as metal oxides. In the industry, it is also called heat-conducting silica gel pad, heat-conducting silicon film, soft Thermally conductive pads, thermally conductive silicone gaskets, etc., are specially designed for the use of gaps to transfer heat. They can fill the gaps, open up the heat channel between the heat-generating part and the heat-dissipating part, effectively improve the heat transfer efficiency, and at the same time play a role in insulation and lightening. It can meet the design requirements of miniaturization and ultra-thinness of equipment. It is extremely manufacturable and usable, and has a wide range of thickness. It is an excellent thermal conductivity filling material.
The production process of thermally conductive silica gel sheets mainly includes: raw material preparation→plasticizing, kneading→molding vulcanization→trimming and cutting→inspection, etc. The following is a brief introduction to the production process of thermal silica gel sheets:
1. Raw material preparation
The thermal conductivity of ordinary organic silica gel is usually only about 0.2W/m·K. However, mixing thermally conductive fillers in ordinary silicone can improve its thermal conductivity. Commonly used thermally conductive fillers are metal oxides (such as Al2O3, MgO, BeO, etc.), metal nitrides (such as SiN, AlN, BN, etc.). The thermal conductivity of the filler is not only related to the material itself, but also closely related to the particle size distribution, shape, interface contact, and degree of bonding inside the molecule of the thermally conductive filler. In general, fibrous or foil-shaped thermally conductive fillers conduct heat better.
2. Plasticizing and mixing
Masticating and kneading are a process of silica gel processing, which refers to the use of mechanical or chemical methods to reduce the molecular weight and viscosity of raw rubber to improve its plasticity and obtain appropriate fluidity to meet the needs of further processing of kneading and molding. The raw materials for making thermal silica gel sheets are generally destroyed by mechanical high-speed stirring. After color mixing and mixing, the milky white silica gel is transformed into flakes of various colors.
3. Forming vulcanization
If you want to make a soft, elastic and tensile thermally conductive silicone sheet, you need to use secondary vulcanized silicone. Vulcanization can actually be called curing. After the liquid heat-conducting silica gel is heated and formed in the first stage, its cross-linking density is not enough, and further vulcanization reaction is required to increase the tensile strength, resilience, hardness, swelling degree, density, and thermal stability of the heat-conducting silica gel sheet. Vulcanization has been greatly improved. If the secondary vulcanization is not carried out, the performance of the thermally conductive silicone sheet produced may be affected to a certain extent, and products with better performance cannot be obtained. The product parameters after primary vulcanization are different from those of secondary vulcanization, which is also related to the actual operation process and steps.
4. Trimming and cutting
The heat-conducting silicone sheet after high-temperature treatment needs to be placed for a period of time to allow it to cool naturally before cutting into different sizes and specifications, instead of other rapid cooling methods. Otherwise, it will directly affect the product performance of the thermal pad.
5. Finished product testing
The main items that need to be tested for finished products include: thermal conductivity, temperature range, volume resistivity, withstand voltage, flame retardancy, tensile strength, hardness, thickness, etc.
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