What performance parameters do we need to know when purchasing thermal conductive silicone grease

THERMAL GREASEIt is a high thermal conductivity insulating silicone material that almost never solidifies and can maintain its grease like state during long-term use at temperatures ranging from -50 ℃ to 200 ℃. It has excellent electrical insulation and thermal conductivity, as well as low ionization (approaching zero), high and low temperature resistance, water resistance, ozone resistance, and weather aging resistance.

But many people who have used thermal silicone grease have noticed a phenomenon: why does the thermal silicone grease purchased by others not solidify after being used for so long, while the one purchased by oneself solidifies and becomes a powder after a period of time? What is the reason for this? Below, Advanced Institute Technology will introduce several factors that affect the performance of thermal conductive silicone grease.

The difference between silicone and silicone grease

Silicone and silicone grease are both materials that help with system heat dissipation. The difference is that silicone has good thermal conductivity and insulation properties, and does not lose its stickiness at high temperatures. It is mainly used to stick heat sinks on the surface of equipment; Silicone grease, on the other hand, does not have viscosity and is an emulsion or paste. Its function is to fill the gap between the chip and the heat sink, improving the thermal conductivity efficiency. Many high-end fans nowadays have already been coated with thermal conductive silicone grease at the bottom, which is dry and different from the commonly used paste and emulsion silicone grease.

Affects the performance parameters of thermal conductive silicone grease

1. Working temperature

The working temperature of thermal conductive silicone grease is an important factor in the curing time of thermal conductive silicone grease. The working temperature is an important parameter to ensure that the thermal conductive material is in a solid or liquid state. If the temperature exceeds the temperature that the thermal conductive silicone grease can withstand, the silicone grease will be converted into a liquid. If the temperature is lower than the minimum temperature of silicone grease, it will transform into a solid due to the increase in viscosity. Both of these situations are not conducive to heat dissipation.

2. Thermal conductivity coefficient

The thermal conductivity coefficient of thermal conductive silicone grease is basically the same as that of a radiator, and its unit is: W/m.K， The larger the value of thermal conductivity, the faster the thermal conduction speed of the material, and the better the thermal conductivity performance, which is a performance indicator.

3. Thermal resistance coefficient

The thermal resistance coefficient refers to the hindering effect of an object on heat conduction, and the concept of thermal resistance is similar to that of resistance. The lower the thermal resistance, the lower the temperature of the heating object. The size of the thermal resistance is closely related to the material used by the thermal grease manufacturer.

4. Dielectric constant

Compared to some CPUs without metal top cover protection, dielectric constant is a very important parameter, which is related to whether there is a short circuit problem inside the computer. The commonly used thermal conductive silicone grease is made of materials with good insulation wire, but some special silicone grease, such as silver containing silicone grease, has a certain degree of conductivity. But nowadays, most CPUs are equipped with metal top covers for thermal conductivity and core protection, so there is no need to worry about short circuits caused by thermal grease overflow.

5. Viscosity

Viscosity is the viscosity that guides the thermal silicone grease. Generally speaking, the IDE viscosity of thermal silicone grease needs to be around 68 to be within the normal range. Some thermal silicone greases on the market are exceptionally cheap because of their low viscosity and low thermal conductivity components.

4. Solid content

The coefficient in thermal grease refers to the mass percentage of the remaining portion after drying the grease under specified conditions. Actually, it is more accurate to call it 'non-volatile content'. The higher the solid content of silicone grease, the higher its viscosity and the harder it gives the impression.

5. Oil content

Generally speaking, the lower the oil content of thermal conductive silicone grease, the better, because silicone grease with a higher oil content will separate some oils and fats after a slightly longer storage time, which will to some extent hinder the conduction of heat. Therefore, when replacing thermal grease, we need to first remove the grease separated from the grease to prevent a decrease in the performance of the thermal grease.