Is the CPU coated with silicone grease or silica gel?

It's silicone grease, either silicone grease is the cheapest or two or three yuan a tube.

The information is as follows:

When purchasing heat dissipation materials, many users often only pay attention to the radiator and fan, but often ignore a very important thing-heat dissipation silicone grease, which often confuses silicone grease with silica gel. Although silicone grease and silica gel are only literally different, and they are both heat conducting materials, their characteristics are quite different. If used improperly, the consequences will be very serious.

Hot grease

Silicone grease is used for lubrication and can be used under high load. It looks like butter, and we usually have less contact with it. The thermal conductive silicone grease we usually say should be called silicone paste, and the composition is silicone oil+filler. The filler is ground powder, and its composition is ZnO/Al2O3/ boron nitride/silicon carbide/aluminum powder, etc. Silicone oil ensures a certain fluidity, while filler fills the tiny gap between CPU and radiator to ensure thermal conductivity. However, silicone oil has low sensitivity to temperature, does not thicken at low temperature, does not dilute at high temperature and does not volatilize, so it can be used for a long time. At present, some high-grade thermal conductive silicone grease uses silver powder or aluminum powder as filler, which takes advantage of the high thermal conductivity of metal. However, relatively speaking, the metal particles are relatively large, the filling effect is poor, and its performance is not greatly improved. Moreover, silicone grease is conductive, and improper use is easy to cause short circuit.

What we usually need to buy is thermal conductive silicone grease.

silica gel

The silica gel we are talking about is a kind of silicone rubber, which belongs to one-component liquid rubber vulcanized at room temperature. Once exposed to the air, the silane monomer in it condenses to form a network structure, and the system is cross-linked, unable to melt and dissolve, elastic and rubbery, and adheres to the object at the same time. Its thermal conductivity is slightly higher than that of ordinary rubber, but far lower than that of thermal conductive silicone grease, and once cured, the adhesive is difficult to separate, so it can only be used for graphics cards and memory radiators. If it is used on CPU, it will lead to overheating and it is difficult to take off the heat sink. Pulling down hard may directly damage the CPU or CPU socket. However, it is possible to pull the display chip off the PCB if the heat sink of the graphics card bonded with silica gel is forcibly pulled down.

Now you understand that silicone grease and silica gel are two different things, although they are only literally different, and they are both heat conducting materials. Relatively speaking, silicone grease has a wider application range and is suitable for almost any heat dissipation condition; However, once the silicone is stuck, it is difficult to take it off, so most of the time it is used in some occasions that only need one-time bonding, such as the heat sink of graphics cards. Okay, is that clear now? After figuring it out, let's not buy it wrong again.