What Is Thermal Silicone?

What Is Thermal Silicone?

Thermal silicone, also known as thermally conductive adhesive, thermally conductive silicone rubber, etc., is made of organic silicone as the main body, added with fillers, thermal conductive materials and other polymer materials, and has good thermal conductivity and electrical insulation properties.

Ordinary thermal conductive silica gel is added with aluminum oxide, etc., and high thermal conductive silica gel is added with thermal conductive substances such as boron nitride. Manufacturers of thermally conductive silicone adhesives or potting materials can generally make different thermal conductivity, curing speed, viscosity, color, hardness, etc. according to their needs.

As a silicone rubber matrix with excellent insulation and shock absorption properties, its thermal conductivity is only about 0.2W/m.K, but by adding high-performance thermal conductive fillers to the matrix, including metal fillers (such as Al, Cu, MgO, AIN , BN) and non-metallic materials (such as SiC, graphite, conductive carbon black, etc.), the thermal conductivity can be improved several times or even dozens of times. The thermal conductivity of thermal silicone materials is ultimately determined by the silicone rubber matrix, filler properties, filler ratio, filler distribution, and processing technology.

Thermal silicone includes room temperature vulcanized and high-temperature vulcanized silicones. Such silicones generally include thermal silicone adhesives, thermal potting compounds, and thermal conductive gaskets that have been vulcanized into a certain shape.

Generally, the thermal conductivity of high-temperature vulcanized thermal conductive silicone is slightly worse than that of room-temperature vulcanized thermal silicone. , heat dissipation, insulation and sealing, etc., thermal silicone can provide the high elasticity and heat resistance required by the system, and can quickly transfer the heat of the system.

The thermal conductivity of different thermal silicones varies greatly. The cost price difference is also huge (but if insulation is not required, the production cost can be greatly reduced and a high thermal conductivity can be achieved).

Thermal silicone is a high-end thermal compound. The non-conductive properties of the product can avoid risks such as short circuits; it has the effect of cooling and bonding electronic devices. It can be cured to a higher hardness elastomer in a short time. After curing, it is closely attached to its contact surface to reduce thermal resistance, thereby facilitating the heat conduction between the heat source and its surrounding heat sinks, motherboards, metal shells and outer shells. Thermal conductive silica gel has the advantages of high thermal conductivity, good insulation performance and easy use. It has good adhesion to metals including copper, aluminum, stainless steel, etc., and the curing form is dealcoholized, which does not corrode metal and non-metal surfaces.

Thermally conductive silica gel can be widely applied to various electronic products, the contact surface between the heating element (power tube, thyristor, electric heating stack, etc.) It plays the role of heat transfer medium and moisture-proof, dust-proof, anti-corrosion, shock-proof and other properties. It is suitable for surface coating or overall potting of various microwave devices such as microwave communication, microwave transmission equipment, microwave special power supply, and regulated power supply.

It is widely used to replace thermal grease and thermal pads for filling bonding and heat dissipation between CPU and radiator, thyristor intelligent control module and radiator, transistor and thermistor connection, high-power electrical module and radiator. After using this glue, the traditional connection method of card and screw can be removed, and the result is more reliable filling and heat dissipation, simpler process, and more economical cost.

Such as: integrated circuits that can be widely used in personal portable computers, microprocessors, memory modules, cache memories, sealed integrated chips, DC/AC converters, IGBTs and other power modules, semiconductors, relays, rectifiers and transformers, etc. package. Fixing of electronic and electrical components and flame retardant, thermal conductivity, insulation, shock-proof, moisture-proof sealing. Heat dissipation of high-power LED products. It is especially suitable for bonding and sealing with high requirements on thermal conductivity.

Correct use of thermal silicone

  1. Clean the surface: Clean the surface of the sticky or coated object to remove rust, dust and oil.
  2. Gluing: Unscrew the cap of the hose, first pierce the seal with the tip of the cap, squeeze the glue onto the cleaned surface to make it evenly distributed, and close and fix the glued surface.
  3. Curing: When the coated parts are placed in the air, the phenomenon of skin formation will occur slowly, and any operation should be completed before the surface skin formation. The curing process is a curing process from the surface to the inside. Within 24 hours (room temperature and 55% relative humidity), the glue will be cured to a depth of 2 to 4 mm. If the part is deep, especially in the part that is not easy to touch the air, The time to complete curing will be extended, and if the temperature is lower, the curing time will also be extended.
  4. Do not move, use or pack the operated parts until they have reached sufficient strength.
  5. Storage: Unused glue should be tightened immediately and sealed.


After the operation is completed, the unused glue should be tightened immediately and the cap should be tightly sealed. When using it again, if there is a little crust on the seal, it can be removed without affecting normal use. During the storage process of the glue, there may be a small amount of curing phenomenon at the mouth of the nozzle. After removing it, it can be used normally without affecting the performance of the product.
This product will release a small amount of by-products during the curing process, which is slightly irritating to the skin and eyes. It is recommended to use it in a well-ventilated place. In case of accidental contact with the skin, wipe it clean, and then rinse with water; in case of accidental contact with eyes, immediately rinse with water and go to the hospital for examination.

The above is an introduction to the definition, characteristics, functions and usage of thermal silicone. Only with a sufficient understanding of thermal silicone can we more accurately select the thermal silicone solution and achieve better performance in practical applications. Now, there are many manufacturers of thermal silicone on the market, and they are widely used. They are mainly used in the optoelectronic industry, computer industry, network industry, home appliance industry, semiconductor lighting industry, etc. At present, 5G and new energy are another development trend, and thermal silicone is It is an indispensable thermal conductive material in electronic heat dissipation materials. It can be seen that the development trend of thermal conductive silica gel is even more immeasurable, and the future is bright.

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