What is the difference between thermal grease and thermal silicone?

Fri May 13 2022 JITAI

One, refer to different
1. Thermal grease: Thermal grease is a thermally conductive silicone grease-like compound made of silicone as the main raw material, adding materials with excellent heat resistance and thermal conductivity.
2. Thermally conductive silica gel: It is a high-end thermally conductive compound.

Second, the characteristics are different
1. Thermal grease: high thermal conductivity, excellent thermal conductivity, good electrical insulation (only for insulating thermal grease), wide operating temperature, good use stability, low consistency and good construction performance.
2. Thermally conductive silica gel: Through the condensation reaction of moisture in the air, low molecules are released to cause cross-linking and curing, and vulcanized into high-performance elastomers. It has excellent anti-cold and heat alternating performance, anti-aging performance and electrical insulation performance. And has excellent moisture resistance, shock resistance, corona resistance, leakage resistance and chemical resistance properties.
3. Different uses
1. Thermal grease: used for heat conduction and heat dissipation of electronic components such as power amplifiers, transistors, tubes, CPUs, etc., so as to ensure the stability of the electrical performance of electronic instruments and meters.
2. Thermally conductive silica gel: widely used in various electronic products, the contact between the heating body (power tube, thyristor, electric heating stack, etc.) and heat dissipation facilities (heat sink, heat sink, shell, etc.) in electrical equipment Surface, play the role of heat transfer medium and moisture-proof, dust-proof, anti-corrosion, shock-proof and other properties.

Thermal silica
Thermally conductive silicone rubber is a one-component dealcoholized room temperature curing silicone rubber, which has the functions 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, which is beneficial to the heat conduction between the heat source and its surrounding heat sinks, motherboards, metal shells and outer casings. It has the advantages of high thermal conductivity, good insulation performance and easy use. It has good adhesion to metals including copper, aluminum and stainless steel. The curing form is dealcoholized, and it does not corrode metal and non-metal surfaces. Compared with thermal grease, it is much lower, and once cured, it is difficult to separate the bonded objects. Generally, it can only be used in graphics cards and memory heat sinks. If it is used on the CPU, it will cause overheating, and it is difficult to remove the heat sink. Pulling it down forcibly may directly damage the CPU or CPU socket. However, if you pull down the silicone-bonded graphics card heat sink forcibly, it is possible to pull the display chip off the PCB.
thermal grease
Thermal grease, also known as silicon paste, is a grease-like, non-adhesive, non-drying, special formula produced by compounding metal oxides with good thermal conductivity and insulating properties with organosiloxane. become. The product has excellent thermal conductivity, good electrical insulation, wide use temperature (working temperature -60 ° C ~ 300 ° C), good use stability, low consistency and good construction performance, this product has no Poisonous, non-corrosive, odorless, non-drying, insoluble. Silicone grease is used for lubrication and can be applied under high load. The appearance is similar to big butter, and we generally have less contact. And what we usually call thermal grease should be called silicon paste, which is composed of silicone oil + filler. The filler is very finely ground powder, and the composition is ZnO/Al2O3/boron nitride/silicon carbide/aluminum powder, etc. The silicone oil ensures a certain fluidity, while the filler fills the tiny gaps between the CPU and the heat sink, ensuring thermal conductivity. Since silicone oil is less sensitive to temperature, it does not thicken at low temperature, it does not become thinner at high temperature, and it is not volatile, so it can be used for a long time. Some high-grade thermal greases now use silver powder or aluminum powder as fillers, which take advantage of the high thermal conductivity of metals.
By understanding the definitions of thermal grease and thermally conductive silicone, we know that although silicone grease and silicone are only literally one word apart, and they are both thermally conductive materials, they are completely different things. Relatively speaking, silicone grease has a wider scope of application and is suitable for almost any heat dissipation conditions; and because silicone is difficult to remove once glued, it is mostly used in occasions that only require one-time bonding, such as Graphics card heat sink, etc.
In the application of heat dissipation and heat conduction, even two planes with very smooth surfaces will have gaps when they are in contact with each other. The air in these gaps is a poor conductor of heat, which will hinder the conduction of heat to the heat sink. Thermal grease is a material that can fill these voids and make heat conduction more smoothly and quickly. There are many types of silicone greases on the market today, and different parameters and physical properties determine different uses. For example, some are suitable for CPU heat conduction, some are suitable for memory heat conduction, and some are suitable for power supply heat conduction.
Therefore, thermal grease is similar to thermal silica gel in that both have thermal conductivity and insulation, and they are both thermally conductive interface materials.

What is the difference between thermal grease and thermal silicone?