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In The Thermal Design Of Custom PCB Assembly, Which Aspects Should Be Considered For Its Heat Dissipation Scheme?

Views: 45     Author: Site Editor     Publish Time: 2021-08-13      Origin: Site

As the functions of electronic products become stronger and stronger, the issue of heat has gradually attracted everyone's attention. So, what angles should be considered when a new product is thermally designed? China custom assembly manufacturer - Giant will explain to you.

1. Power density

The power density can directly reflect the heat dissipation difficulty of the product, and calculating the power density has great reference value for estimating the severity of the heat dissipation problem of the product. Without any testing or thermal simulation, the power density of pcba processing companies can give a rough estimate of the fastest product feasibility.

1) The power density is less than 10W/L, which can basically be solved by natural heat dissipation solutions;

2) The power density is less than 80W/L, which can basically be solved by forced air cooling;

3) If the power density is more than 80W/L, special solutions such as liquid cooling and air conditioning need to be considered.

For example, for a set-top box, if its size is: 100mm×100mm×50mm, and the volume is 0.5L, so if the power density is 10W/L, the power consumption is less than 5W, and the natural heat dissipation solution can basically be used; If this is a microcomputer of the same size, if the power is within 40W, you can try the forced air cooling solution.

Of course, it needs to be understood that materials with different properties can actually change the above-mentioned power density limit to a certain extent. For natural heat dissipation, the use of materials with very low prices and poor thermal conductivity may not even achieve the power density of SW/L; if high thermal conductivity materials such as graphite sheets, carbon nanomaterials, and heat pipes are used, the power density is even It can be increased to 20W/L. Obviously, no matter what material is used, it is impossible to solve the power density of 100W/L with a natural heat dissipation solution. The specific limit to be adopted must be fine-tuned according to the product's heat source distribution, cost requirements, and use environment.

2. Allowable temperature rise of the product

In the thermal evaluation of the product, many people think that the environment in which the product should be used should be paid attention to. But in fact, the ambient temperature of use and the temperature requirements of the devices used should be considered comprehensively. Regarding the thermal design of products, a common misunderstanding is that people often think that the higher the temperature, the greater the risk of over-temperature of the device. In fact, this is not the case. A simple example is as follows:

The highest temperature requirement of ordinary bucket capacitor is 105, while the inductance is 125. When the temperature of the capacitor is 110 and the inductance is 115, although the temperature of the capacitor is lower, it is actually overheated and may malfunction in a short time. Although the temperature of the inductor is higher, it can still operate stably for a long time.

Therefore, in addition to the power density, what really determines the heat dissipation difficulty of the product is the allowable temperature rise of the product, that is, the difference between the applicable working environment temperature of the product and the maximum allowable temperature of the device. For example, the temperature requirement of the key device used is 100, and the product requirement meets the use environment of 55, then the temperature rise will be 45. Obviously, assume that all other conditions remain the same.

3. The use environment of the product

The environment in which the product is used does not only include the surrounding air temperature and humidity. In some special application scenarios, products need to be designed for protection, such as waterproof, dustproof, and insect-proof. Some requirements are more special, such as outdoor wireless base stations, because they need to be installed on high towers, their weight needs to be considered.

In some cases, the use environment also limits the heat dissipation scheme, and the heat dissipation means can also be fully combined with the use environment to save design costs. For example, pcba products immersed in water must not use forced air cooling, but because the surrounding water temperature may be low, heat can be transferred to the water for heat dissipation.

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