Factors affecting heat dissipation（air cooling）
Efficiency of heat transfer:
The heat transfer efficiency is the key to heat dissipation. The factors that affect the heat transfer efficiency are as follows.
1. The number and thickness of heat pipes: the more heat pipes, the better, generally 2 pipes are good enough, 4 pipes are enough, 6 and above are high-end radiators; the thicker the copper pipe, the better (mostly 6mm, but also 8mm of).
The size of the contact area between the fin and the air
The fin is responsible for heat dissipation. Its task is to dissipate the heat sent by the heat pipe into the air. Therefore, the fin must be in contact with the air as much as possible. Some manufacturers will carefully design some bumps to be as large as possible. Increase the surface area of the fins.
Air volume
The air volume represents the total volume of air that the fan can send out per minute, generally expressed in CFM. The greater the air volume, the better the heat dissipation. The parameters of the fan also include: speed, wind pressure, fan blade size, noise and so on. Most fans now have PWM intelligent speed regulation. What we need to pay attention to is air volume, noise, etc.
Process of heat transfer base:
① Heat pipe direct contact: The base of this scheme is very common, and the general radiator of one hundred yuan and below is this kind. In order to ensure the flatness of the contact surface with the CPU, this solution will flatten and polish the copper tube, which makes the already thin copper tube thinner. Over time, unevenness will appear, which will affect the efficiency of heat conduction. Regular large factories will polish the copper tube very flat, so that the contact area with the CPU is larger and the heat conduction efficiency is high. The copper pipes of some copycat manufacturers are uneven, causing some copper pipes to not touch the CPU at all when they are working, so no matter how many copper pipes they are, it is just a fancy.
② Copper bottom welding (mirror polishing): The base of this scheme is slightly more expensive, because the heat transfer base is directly made into a mirror surface, which has a higher contact area and better heat conduction effect. So mid-to-high-end air-cooled radiators use this scheme.
③Heat plate: This is a rarely seen scheme. The principle is similar to that of a heat pipe. It also transfers heat by evaporating the liquid when it meets heat and then liquefies when it meets cold. This scheme conducts heat evenly and has high efficiency, but the cost is very high. , So it's rare.
3. Thermal conductive grease: Due to manufacturing process problems, it is impossible to have a completely flat contact surface between the radiator base and the CPU (even if you look flat, you can see unevenness under a magnifying glass), so you need to Apply a layer of silicone grease with higher thermal conductivity to fill in these uneven areas to help conduct heat.
The thermal conductivity of silicone grease is much lower than that of copper, so just apply a thin layer evenly. If the coating is too thick, it will affect the heat dissipation. The thermal conductivity of general silicone grease is between 5-8, and the more expensive thermal conductivity is 10-15.
4. The process at the junction of the radiating fins and the heat pipe: the heat pipe is interspersed between the fins and must transfer heat to the fins, so the processing technology at the junction will also affect the thermal conductivity. The current processing technology has two kind:
① Reflow soldering: is to solder the two together. This solution has a high cost, but has good thermal conductivity, and is very firm, and it is not easy to loose the fins.
②Wearing fin: also called "finishing" process. It is to make holes in the fins, and then insert the thermally conductive copper tube into the fins with the help of external force. This kind of process is low cost, although simple, but it is not easy to do it well, because you have to consider problems such as poor contact and loose fins (if you pick it up, the fins will slide on the heat pipe, and the heat conduction effect can be imagined. And got it).
