What are the performance criteria for thermal conductive silicone grease?

Thermal conductive silicone grease is a high-conductivity, insulating silicone material that never solidifies and can remain in a paste state for extended periods between -50°C and 200°C. It boasts excellent electrical insulation and thermal conductivity, along with low levels of ionization (nearly negligible), and resistance to extreme temperatures, water, ozone, and weathering. The distinction between silicone and silicone grease Both silicone and silicone grease aid in system heat dissipation. The distinction lies in the fact that silicone, with its good thermal conductivity and insulating properties, maintains its viscosity even at elevated temperatures and is primarily used to attach heat sinks to equipment surfaces. In contrast, silicone grease lacks viscosity and is an emulsion or paste, its function is to bridge the gap between the chip and the heat sink to enhance thermal conductivity. Currently, many premium fans are already coated with thermal conductive silicone grease at their bases, which is dry and distinct from the conventional paste and emulsion liquid types.

However, many users of thermal conductive silicone grease have observed a phenomenon: why does the thermal conductive silicone grease others use last for so long without solidifying, while the one they use tends to solidify and turn into powder after a while? What causes this? Below, the HANAST editor will discuss several factors that influence the performance of thermal conductive silicone grease.

Operating Temperature The operating temperature of thermal grease is a crucial factor influencing the curing and aging process. It is a vital parameter for maintaining the material in either a solid or liquid state. When the temperature exceeds the maximum tolerable limit for the thermal grease, it transforms into a liquid. Conversely, if the temperature drops below the minimum operating temperature, the grease will solidify due to an increase in viscosity, both of which negatively impact heat dissipation. Thermal Conductivity The thermal conductivity of thermal grease is roughly consistent with that of a heat sink. Its unit is W/m·K. A higher thermal conductivity coefficient indicates a faster heat transfer rate and better thermal performance. Thermal Resistance Thermal resistance refers to the resistance to heat conduction, akin to electrical resistance. A lower thermal resistance coefficient means a lower temperature for the heating object, which is closely related to the material used in the thermal grease.

Dielectric constant In contrast to some CPUs that lack metal top cover protection, the dielectric constant is a crucial parameter that influences the likelihood of short circuits within the computer. The commonly used thermal greases are made from materials with good insulation properties, although some specialized greases, like those containing silver, exhibit a certain degree of electrical conductivity. However, most contemporary CPUs are now equipped with metal top covers for thermal and core protection, negating the concern of short circuits due to thermal grease spillage. Viscosity The viscosity of thermal grease is a measure of its stickiness. Typically, the viscosity of thermal grease IDE should be around 68 to fall within the normal range. Some thermal greases on the market are exceptionally affordable due to their low viscosity and low thermal conductivity components. Solid content In thermal grease, this coefficient refers to the mass percentage of the dried grease over the total. It's more accurately termed "non-volatile content". Greases with a higher solid content tend to be more viscous and feel harder. Oil content Generally speaking, the lower the oil content in thermal grease, the better, as greases with higher oil content tend to separate some fats over time, which can impede heat conduction to some extent. Therefore, when replacing thermal grease, it's essential to remove the separated fats to prevent a decline in its performance.