The main reason is the heat dissipation technology of L […]
The main reason is the heat dissipation technology of LED. Heat dissipation is a major factor affecting the lighting intensity of LED lamps. Heat sink can solve the heat dissipation problem of low illumination LED lamps. A radiator can
not solve the heat dissipation problem of 75W or 100W LED lamps. In order to achieve the ideal lighting intensity, active cooling technology must be used to solve the heat released by the LED lamp components. Some active cooling
solutions, such as fans, have less life than LED lamps. In order to provide a practical active cooling solution for high brightness LED lamps, heat dissipation technology must be low energy consumption; and can be applied to small lamps;
its life should be similar to or higher than the lamp source.
Generally speaking, according to the way of taking heat away from the radiator, the radiator can be divided into active and passive heat dissipation.
Passive heat dissipation means that the heat of the heat source LED light source is naturally emitted into the air through the heat sink. Its heat dissipation effect is proportional to the size of the heat sink, but because of the
natural heat dissipation, the effect is of course greatly discounted. It is often used in equipment that does not require space, or for parts with little heat, such as some popular motherboards, which are also adopted on the North
Bridge. Active heat dissipation is the most active type of heat dissipation. Active heat dissipation is forced to take away the heat emitted by the fins through fans and other heat dissipation equipment. Its characteristics are high heat
dissipation efficiency and small size of the equipment.
Active heat dissipation can be divided into air-cooled heat dissipation, liquid-cooled heat dissipation, heat pipe heat dissipation, semiconductor refrigeration, chemical refrigeration and so on. Air-cooled air-cooled heat dissipation is
the most common way of heat dissipation, but also a cheaper way. Air-cooled heat dissipation is essentially the use of fans to take away the heat absorbed by the radiator. The utility model has the advantages of relatively low price and
convenient installation. But it depends on the environment, for example, when the temperature rises and overfrequency, its heat dissipation performance will be greatly affected.his method is more common in laboratories or extreme
At present, the heat dissipation of LED lamps mainly includes the following ways:
1. Liquid cooling
Liquid cooling heat dissipation takes away heat of radiator by forced circulation of liquid driven by pump. Compared with air cooling, it has the advantages of quiet, stable cooling, less dependence on environment and so on. The price of
liquid cooling is relatively high, and the installation is relatively troublesome. At the same time, the best heat dissipation effect can be obtained by installing according to the instructions as far as possible. For the sake of cost
and ease of use, water is usually used as heat conducting liquid, so liquid-cooled radiator is often called water-cooled radiator.
2. Heat pipes
Heat pipe is a kind of heat transfer element. It makes full use of the principle of heat conduction and the fast heat transfer property of refrigerant. It transfers heat through evaporation and condensation of liquid in a fully enclosed
vacuum tube. It has a series of advantages, such as high thermal conductivity, good isotherm, arbitrary change of heat transfer area on both sides of the cold and heat, long-distance heat transfer, temperature control and so on. The heat
exchanger has the advantages of high heat transfer efficiency, compact structure and low fluid resistance. Its thermal conductivity has far exceeded that of any known metal.
3. Semiconductor Refrigeration
Semiconductor refrigeration is to use a special semiconductor chiller to produce temperature difference when electrified. As long as the heat at the high temperature end can be effectively dissipated, the low temperature end will be
continuously cooled. Temperature difference occurs on each semiconductor particle. A chiller consists of dozens of such particles in series, thus forming a temperature difference on the two surfaces of the chiller. The excellent heat
dissipation effect can be obtained by using this temperature difference phenomenon and coordinating with air/water cooling to cool the high temperature end. Semiconductor refrigeration has the advantages of low refrigeration temperature
and high reliability. The cold surface temperature can reach below -10 C, but the cost is too high, and it may cause short circuit because of low temperature. Moreover, the technology of semiconductor refrigeration wafer is not mature
and practical enough.
4. Chemical refrigeration
The so-called chemical refrigeration is the use of some ultra-low temperature chemicals, using them to absorb a large amount of heat when melting to reduce the temperature. Dry ice and liquid nitrogen are commonly used in this area. For
example, using dry ice can reduce the temperature to below minus 20 degrees Celsius, and some more'perverted'players use liquid nitrogen to lower the CPU temperature to below minus 100 degrees Celsius (theoretically). Of course, because
of the high price and the short duration, this method is more common in laboratories or extreme overclocking enthusiasts.
Selection of heat dissipation materials. Generally speaking, ordinary air-cooled radiators naturally choose metal as radiator material. For the selected materials, it is hoped that they will have high specific heat and high thermal
conductivity at the same time. Silver and copper are the best thermal conductive materials, followed by gold and aluminum. But gold and silver are too expensive, so at present, radiators are mainly made of aluminum and copper.
Comparatively speaking, copper and aluminium alloy have their own advantages and disadvantages at the same time: copper has good thermal conductivity, but its price is more expensive, its processing is more difficult, its weight is too
large, and its heat capacity is smaller, and it is easy to oxidize. On the other hand, pure aluminium is too soft to be used directly. Aluminum alloys are used to provide sufficient hardness. The advantages of aluminum alloys are low
price and light weight, but their thermal conductivity is much worse than copper. So in the history of radiator development, there are also several kinds of products made of the following materials:
1. Pure aluminium radiator
Pure aluminium radiator is the most common radiator in the early period. Its manufacturing process is simple and its cost is low. So far, pure aluminium radiator still occupies a considerable part of the market. In order to increase the
heat dissipation area of fins, extrusion technology is the most commonly used processing method of pure aluminum radiator, and the main index of evaluating a pure aluminum radiator is the thickness of the radiator base and the ratio of
Pen-Fin. Pin refers to the height of fins of radiators, Fin refers to the distance between adjacent fins. Pin-Fin ratio is divided by the height of Pin (excluding the thickness of the base) by Fin. The larger the Pin-Fin ratio is, the
larger the effective heat dissipation area of the radiator is, the more advanced the aluminum extrusion technology is.
2. Pure copper radiator
The thermal conductivity of copper is 1.69 times that of aluminium, so under the same other conditions, pure copper radiator can take heat away from the heat source more quickly. But the quality of copper is a problem. Many of the "pure
copper radiators" are not really 100% copper. In the copper list, the copper content of more than 99% is called acid-free copper, and the next grade of copper is Dan copper with copper content of less than 85%. At present, the copper
content of most pure copper radiators in the market is between the two. The copper content of some inferior pure copper radiators is less than 85%. Although the cost is very low, the heat conduction capacity of some inferior pure copper
radiators is greatly reduced, which affects the heat dissipation. In addition, copper has obvious shortcomings, such as high cost, difficult processing and too large radiator quality, which hinder the application of all-copper radiators.
The hardness of red copper is not as good as that of aluminium alloy AL6063, and some mechanical processing (such as grooving) properties are not as good as that of aluminium. The melting point of copper is much higher than that of
aluminium, which is not conducive to extrusion forming and so on.
3. Copper-aluminium bonding technology
Considering the respective shortcomings of copper and aluminium, some high-end radiators in the market are usually manufactured by the combination of copper and aluminium. These radiators are usually made of copper metal base, while the
radiator fins are made of aluminium alloy. Of course, besides the copper base, there are also radiators using copper pillars and other methods, which are the same principle. With high thermal conductivity, copper bottom can absorb the
heat released by CPU quickly; aluminum fins can be made into the most conducive to heat dissipation shape by means of complex technology, and provide larger heat storage space and rapid release, which has found a balance point in all
In order to improve the luminous efficiency and service life of LED, and solve the problem of heat dissipation of LED products is one of the most important topics at this stage. The LED industry requires extremely strict alignment
accuracy of the circuit of the heat dissipation substrate itself, and needs the characteristics of high heat dissipation, small size and good adhesion of metal lines. Therefore, making thin film ceramic heat dissipation substrate by
using yellow light micro-shadow will promote the continuous development of LED. One of the important catalysts for high power upgrading.