展开

Industry dynamic

Products / 产品展示
Contact us / 联系我们
Home > News > Industry dynamic

Comparison of the choice of LED cooling material and the co

发布时间:2018.04.28 浏览:133

Heat dissipation is a major factor affecting the lighting intensity of LED lamps. The efficiency of LED lamp is 80% higher than the traditional incandescent  lamp,but LED components and drive circuit have huge heat dissipation.If the heat is not properly discharged, the luminous intensity and life of the LED lamps will fall  sharply.
The radiating fins can solve the problem of low illumination LED lamp.The manufacturers can produce 40W LED and 60W LED lamp as replacement.High brightness LED  lamp will meet the heat problem.A heat sink is unable to solve the heat dissipation problem of 75W or 100W LED lamps.
In order to achieve the ideal lighting intensity, we must use the active  cooling technology to solve the heat of the LED lamps.Some active cooling solutions such as fan, its life is not long with LED lamps.In order to provide a practical  cooling solution for high brightness LED lamps, the cooling technology must be low energy consumption.And can be applied to small lamps and lanterns; the life should  be similar or higher than the light source.
1、Heat dissipation material selection
To improve the luminous efficiency and service life of LED, the heat dissipation of LED products is one of the most important  issues in the present stage.LED industry development is also a high power, high brightness, small size LED products for its development focus.Therefore, to provide  high heat dissipation and precise size heat dissipation plate become the future trend in the development of LED cooling substrate.At this stage, aluminum substrate is  replaced by aluminum nitride substrate,Or eutectic or flip chip process to replace gold grain / substrate combination to achieve the promotion of LED luminous  efficiency is the mainstream of development.
1.1、  Material selection
Generally speaking, the ordinary air cooling radiator to choose the metal as the heat sink of the material.For the materials, it is hoped that it has high specific  heat and high thermal conductivity,as can be seen, silver and copper is the best heat conduction material, followed by gold and aluminum.But gold and silver are too  expensive, so the heat sink is made of aluminum and copper.In comparison, copper and aluminum alloy two have their own advantages and disadvantages at the same  time:The thermal conductivity of copper, but the price is more expensive, processing more difficult, weight and copper radiator heat capacity is relatively small, and  easy to oxidation.Pure aluminum too soft on the other hand, can not directly use, the use of aluminum alloy in order to provide enough hardness, the advantages of  aluminum alloy is low price, light weight, but thermal conductivity worse than copper .So in the development of the radiator also appeared in the following several  materials of the product:
1.2、  Pure aluminum radiator
Pure aluminum radiator is the most common heat sink, its manufacturing process is simple, the cost is low, so far, pure aluminum radiator still occupy a considerable  part of the market. In order to increase the radiating area of the fins, the most commonly used means of processing pure aluminum radiator is aluminum extrusion  technology, and the evaluation of the main indicators of a pure aluminum radiator is thickness and Pin-Fin ratio of the heat sink. Pin refers to the radiator fin  height, Fin refers to two adjacent pieces of fin distance. Pin-Fin ratio is the height of Pin (not including the base thickness) divided by Pin-Fin,  the larger  Pin- Fin means that the more effective heat radiating area, the more advanced aluminum extrusion technology.
1.3、Copper radiator
The thermal conductivity of copper is 1.69 times that of aluminum, so under the premise of the same other conditions, copper radiator can quickly heat away from the  heat source. But the texture of copper is a problem, a lot of "pure copper radiator" is not the real 100% copper.
 
In the list of copper, the copper content of more than 99% is known as the non acid copper, the next grade of copper is copper content of 85% below. In the market most  of the copper radiator are between them. And some low-quality copper radiator copper volume even  less than 85%, although the cost is very low, but the heat conduction  ability is greatly reduced, the impact of the heat dissipation. In addition, copper also has obvious shortcomings, high cost, difficult to process, the quality of the  radiator is too much to hinder the application of the whole copper heat sink. Hardness of copper is not like luminum alloy al6063, some mechanical processing, such as  cutting groove not good as  aluminum; the melting point of copper than aluminum much higher, is not conducive to the extrusion (extrusion) and so on and so forth.
1.3、  Copper radiator
The thermal conductivity of copper is 1.69 times that of aluminum, so under the premise of the same other conditions, copper radiator can quickly heat away from the  heat source. But the texture of copper is a problem, a lot of "pure copper radiator" is not the real 100% copper.
 
In the list of copper, the copper content of more than 99% is known as the non acid copper, the next grade of copper is copper content of 85% below. In the market most  of the copper radiator are between them. And some low-quality copper radiator copper volume even  less than 85%, although the cost is very low, but the heat conduction  ability is greatly reduced, the impact of the heat dissipation. In addition, copper also has obvious shortcomings, high cost, difficult to process, the quality of the  radiator is too much to hinder the application of the whole copper heat sink. Hardness of copper is not like luminum alloy al6063, some mechanical processing, such as  cutting groove not good as  aluminum; the melting point of copper than aluminum much higher, is not conducive to the extrusion (extrusion) and so on and so forth.
1.4、  Copper aluminum combined technology
In consideration of the respective disadvantage of copper and aluminum in these two kinds of material, at present high-end market often usd copper aluminum combined  the manufacturing process, these fins are usually applied to copper metal base, and radiating fin is used aluminum alloy, of course, in addition to the copper bottom,  heat sink copper column method, is also the same principle. With higher thermal conductivity, copper bottom surface can be quickly absorbed CPU release heat; aluminum  fins can by means of complex processes made the most beneficial to the heat dissipation of the shape, and provide greater heat storage space and quick release, this in  all aspects found a equilibrium point.
2、Comparison of heat dissipation
Generally speaking,Take the heat from the radiator in a way,The radiator can be divided into active cooling and passive cooling。So-called passive cooling,Refers to the heat source LED light source heat naturally distributed to the air through the heat sink, The effect of the heat dissipation is proportional to the size of the heat sink,But because it is a natural heat, Effect of course greatly reduced, Often used in devices that do not require space, Or used to heat the heat of a component, As part of the popularity of the motherboard in Beiqiao also take the passive cooling, The vast majority take the initiative type cooling type, Active cooling is through the fan and other heat dissipation device to heat the heat away from the heat, Its characteristics are high thermal efficiency, and the device is small.
 Active cooling,Subdivision of heat dissipation, Can be divided into air cooling, liquid cooling, heat pipe cooling, Semiconductor refrigeration, chemical refrigeration, etc。
2.1 air cooling
Air cooling cooling is the most common method of heat dissipation, By comparison, it is also a cheaper way. Air cooling heat dissipation is essentially the use of fans to take away the heat absorbed by the radiator. With relatively low prices, Easy installation, etc.. But the environmental dependence is relatively high For example, when the temperature rise will overclocking cooling performance greatly affected.
2.2 liquid cooling
Liquid cooling by liquid in the pump driven by forced circulation away heat radiator, Compared with air cooling, Has the advantages of quiet, stable, stable, small, etc.. The relatively high price of liquid And the installation is relatively trouble. At the same time, it can be installed in accordance with the instructions to install the best way to get the best heat dissipation effect. Consideration of cost and ease of use, Liquid cooling usually adopts water as heat transfer fluid, It is often called the liquid cooling radiator radiator.
2.3 heat pipe cooling
Heat pipe is a heat transfer element, It makes full use of the fast heat conduction principle and cooling medium heat transfer property, Heat transfer by evaporation and condensation of liquid in the vacuum tube, With high thermal conductivity, Good isothermal, Heat transfer area can be arbitrarily changed on both sides of the hot and cold sides. Long distance heat transfer, Can control the temperature and a series of advantages, And the heat exchanger is composed of heat pipe with high heat transfer efficiency. Compact structure, small fluid resistance, etc. ts thermal conductivity has been far more than any of the heat conduction ability of any known metal.
2.4 semiconductor refrigeration
Semiconductor refrigeration is the use of a special type of semiconductor refrigeration chip in the power generation to produce a temperature difference, As long as the high temperature of the heat can be effectively distributed, Then the low temperature is kept constant.
Temperature difference on each semiconductor particle, A chip is made in series with dozens of such particles, So as to form a temperature difference between the two surfaces of the cooling plate. Using this temperature difference phenomenon, Cooperate with air cooling / water cooling to cool the high temperature, Can get excellent cooling effect. Semiconductor refrigeration has low refrigeration temperature, High reliability, The surface temperature can reach minus 10 degrees celsius, But the cost is too high, And it may cause a short circuit due to the low temperature, And now the semiconductor refrigeration film technology is not mature, Not practical enough.
2.5 chemical refrigeration
So-called chemical refrigeration, Is to use some of the ultra low temperature chemical, Use them to absorb a lot of heat to reduce the temperature when it is melted. It is common to use dry ice and liquid nitrogen. Such as the use of dry ice can decrease the temperature to minus 20 degrees celsius, Some more "abnormal" players use liquid nitrogen to drop the CPU temperature below 100 degrees below zero (theoretically), Of course, due to the expensive price and duration is too short, This method is more common in the laboratory or extreme overclocking enthusiasts.