LED heat dissipation technology
LED heat dissipation technology
LED lighting heat is affecting the strength of a major factor. Heat sink to solve low-light LED lamp heat. A heat sink can not be solved 75W or 100W LED lamp heat problem.
In order to achieve the desired lighting intensity, active cooling techniques must be used to solve the LED lighting components release heat. Some active cooling solutions such as LED lighting fan life is not high. High-brightness LED lamps in order to provide a useful active cooling solutions, heat must be low-power technology; and can be applied to a small lamp; its life with the light source similar to or higher than the light source.
Cooling methods
Generally speaking, in accordance with the radiator to remove heat from the way, the radiator can be divided into active cooling and passive cooling. The so-called passive cooling, is through the heat sink to heat LED light source of natural heat into the atmosphere, the cooling effect and heat sink size is proportional to, but because it is the natural distribution of heat, the effect is of course greatly reduced, often used in those spaces does not require the equipment, or used to heat small components heat, as some universal also take the Northbridge motherboard passive cooling, the vast majority take an active cooling type, active cooling is forced through the fan and other cooling equipment issued to the heat sink of the heat away, which is characterized by high thermal efficiency, and small equipment.
Active cooling, heat the way from the subdivision, can be divided into air-cooling, liquid cooling, heat pipe cooling, semiconductor refrigeration, chemical refrigeration and so on.
Air-cooled air-cooling is the most common cooling method, comparatively speaking, is the cheaper way. Air-cooling fan from the essence is to use the heat absorbed by the radiator away. With relatively low prices, convenient installation. However, relatively high dependence on the environment, such as its temperature increases and cooling when overclocking performance will be greatly affected.
Liquid
Liquid cooling liquid in the pump is driven by forced circulation of the heat sink away, compared with air-cooled, with a quiet, cool and stable, a small dependence on the environment and so on. Relatively high price of liquid cooling, and the installation is relatively trouble some. At the same time try to follow the instructions to guide the installation method to install to get the best cooling effect. For cost and ease of use considerations, liquid cooling is usually used as the thermal conductivity of liquid water, so liquid cooling radiator is also often referred to as water-cooled radiator.
Heat pipe
Heat pipe is a form of heat transfer components, which make full use of the principle of heat transfer medium and cooling properties of the rapid heat transfer through the liquid within the closed vacuum evaporation and condensation to transfer heat, with a high thermal conductivity, good isothermal sex, hot and cold sides of the heat transfer area can be arbitrarily changed, be long-distance heat transfer, temperature control and a series of advantages, and the composition of the heat pipe heat exchanger with high efficiency, compact structure, small resistance loss of fluid, etc. . Its thermal capacity has far exceeded the capacity of the thermal conductivity of any known metal.
Semiconductor cooling
Semiconductor refrigeration is the use of a specially designed semiconductor chip in the power generated when the refrigerant temperature to cooling, as long as the high temperature side of the heat can be effectively dissipated, the low temperature side to be cooled constantly. In the semiconductor particles are produced each temperature, a cooling film by the dozens of such particles in series, thereby cooling the surface of a piece of the two temperature. Using this temperature phenomenon, with the air / water cooled high-temperature side, to get good heat dissipation. Semiconductor refrigeration with refrigeration temperature is low, high reliability, cold temperatures can reach minus 10 ℃, but the cost is too high, the temperature is too low and may lead to cause a short circuit, and now film semiconductor refrigeration technology is not mature enough and practical.
Chemical cooling
The so-called chemical refrigeration, is to use some of the ultra-low-temperature chemical substances, the use of their time in the melt to absorb large amounts of heat to reduce temperature. Use this area to dry ice and liquid nitrogen is more common. Such as the use of dry ice can reduce the temperature to minus 20 ℃ below, there are some more "abnormal" players use liquid nitrogen to the CPU temperature dropped to minus 100 ℃ the following (in theory), of course, due to their cost and duration is too short, this methods common in the laboratory or extreme overclocking enthusiasts.
The choice of material
Heat transfer coefficient (unit: W / mK)
Silver 429
Copper 401
Gold 317
Aluminum 237
Iron 80
34.8 Lead
1070 Aluminum Alloy 226
1050 Aluminum Alloy 209
6063 Aluminum Alloy 201
6061-type alloy 155
In general, the general air-cooled radiator natural to choose the metal as a heat sink material. On the choice of materials, I hope it also has high heat and high thermal conductivity, can be seen from, silver and copper are the best thermal conductivity material, followed by gold and aluminum. But gold, silver is too expensive, so now the main heat sink made of aluminum and copper. In contrast, while both copper and aluminum have their advantages and disadvantages: the thermal conductivity of copper is good, but expensive, more difficult process, excessive weight, and the copper heat sink thermal capacity is small and easily oxidized . The other hand, aluminum is too soft, can not be directly used, are used in order to provide sufficient rigidity aluminum, aluminum has the advantage of low cost, light weight, but the thermal conductivity than copper would be much worse. So in the history of the radiator, there have been several materials products:
Aluminum radiator
Early aluminum radiator is the most common radiator, its manufacturing process is simple, low cost, so far, aluminum radiator continues to occupy a considerable portion of the market. Its fins to increase heat dissipation area, aluminum radiator is the most common means of processing aluminum extrusion technology, and evaluation of an aluminum radiator is the main indicators of the heat sink base thickness and Pin-Fin ratio. Pin fin heat sink is the height, Fin is adjacent to the distance between two fins. Pin-Fin height than is Pin (not including base thickness) divided by the Fin, Pin-Fin heat sink than the larger effective heat dissipation means that the larger the area, on behalf of the more advanced aluminum extrusion technology.
LED lighting heat is affecting the strength of a major factor. Heat sink to solve low-light LED lamp heat. A heat sink can not be solved 75W or 100W LED lamp heat problem.
In order to achieve the desired lighting intensity, active cooling techniques must be used to solve the LED lighting components release heat. Some active cooling solutions such as LED lighting fan life is not high. High-brightness LED lamps in order to provide a useful active cooling solutions, heat must be low-power technology; and can be applied to a small lamp; its life with the light source similar to or higher than the light source.
Cooling methods
Generally speaking, in accordance with the radiator to remove heat from the way, the radiator can be divided into active cooling and passive cooling. The so-called passive cooling, is through the heat sink to heat LED light source of natural heat into the atmosphere, the cooling effect and heat sink size is proportional to, but because it is the natural distribution of heat, the effect is of course greatly reduced, often used in those spaces does not require the equipment, or used to heat small components heat, as some universal also take the Northbridge motherboard passive cooling, the vast majority take an active cooling type, active cooling is forced through the fan and other cooling equipment issued to the heat sink of the heat away, which is characterized by high thermal efficiency, and small equipment.
Active cooling, heat the way from the subdivision, can be divided into air-cooling, liquid cooling, heat pipe cooling, semiconductor refrigeration, chemical refrigeration and so on.
Air-cooled air-cooling is the most common cooling method, comparatively speaking, is the cheaper way. Air-cooling fan from the essence is to use the heat absorbed by the radiator away. With relatively low prices, convenient installation. However, relatively high dependence on the environment, such as its temperature increases and cooling when overclocking performance will be greatly affected.
Liquid
Liquid cooling liquid in the pump is driven by forced circulation of the heat sink away, compared with air-cooled, with a quiet, cool and stable, a small dependence on the environment and so on. Relatively high price of liquid cooling, and the installation is relatively trouble some. At the same time try to follow the instructions to guide the installation method to install to get the best cooling effect. For cost and ease of use considerations, liquid cooling is usually used as the thermal conductivity of liquid water, so liquid cooling radiator is also often referred to as water-cooled radiator.
Heat pipe
Heat pipe is a form of heat transfer components, which make full use of the principle of heat transfer medium and cooling properties of the rapid heat transfer through the liquid within the closed vacuum evaporation and condensation to transfer heat, with a high thermal conductivity, good isothermal sex, hot and cold sides of the heat transfer area can be arbitrarily changed, be long-distance heat transfer, temperature control and a series of advantages, and the composition of the heat pipe heat exchanger with high efficiency, compact structure, small resistance loss of fluid, etc. . Its thermal capacity has far exceeded the capacity of the thermal conductivity of any known metal.
Semiconductor cooling
Semiconductor refrigeration is the use of a specially designed semiconductor chip in the power generated when the refrigerant temperature to cooling, as long as the high temperature side of the heat can be effectively dissipated, the low temperature side to be cooled constantly. In the semiconductor particles are produced each temperature, a cooling film by the dozens of such particles in series, thereby cooling the surface of a piece of the two temperature. Using this temperature phenomenon, with the air / water cooled high-temperature side, to get good heat dissipation. Semiconductor refrigeration with refrigeration temperature is low, high reliability, cold temperatures can reach minus 10 ℃, but the cost is too high, the temperature is too low and may lead to cause a short circuit, and now film semiconductor refrigeration technology is not mature enough and practical.
Chemical cooling
The so-called chemical refrigeration, is to use some of the ultra-low-temperature chemical substances, the use of their time in the melt to absorb large amounts of heat to reduce temperature. Use this area to dry ice and liquid nitrogen is more common. Such as the use of dry ice can reduce the temperature to minus 20 ℃ below, there are some more "abnormal" players use liquid nitrogen to the CPU temperature dropped to minus 100 ℃ the following (in theory), of course, due to their cost and duration is too short, this methods common in the laboratory or extreme overclocking enthusiasts.
The choice of material
Heat transfer coefficient (unit: W / mK)
Silver 429
Copper 401
Gold 317
Aluminum 237
Iron 80
34.8 Lead
1070 Aluminum Alloy 226
1050 Aluminum Alloy 209
6063 Aluminum Alloy 201
6061-type alloy 155
In general, the general air-cooled radiator natural to choose the metal as a heat sink material. On the choice of materials, I hope it also has high heat and high thermal conductivity, can be seen from, silver and copper are the best thermal conductivity material, followed by gold and aluminum. But gold, silver is too expensive, so now the main heat sink made of aluminum and copper. In contrast, while both copper and aluminum have their advantages and disadvantages: the thermal conductivity of copper is good, but expensive, more difficult process, excessive weight, and the copper heat sink thermal capacity is small and easily oxidized . The other hand, aluminum is too soft, can not be directly used, are used in order to provide sufficient rigidity aluminum, aluminum has the advantage of low cost, light weight, but the thermal conductivity than copper would be much worse. So in the history of the radiator, there have been several materials products:
Aluminum radiator
Early aluminum radiator is the most common radiator, its manufacturing process is simple, low cost, so far, aluminum radiator continues to occupy a considerable portion of the market. Its fins to increase heat dissipation area, aluminum radiator is the most common means of processing aluminum extrusion technology, and evaluation of an aluminum radiator is the main indicators of the heat sink base thickness and Pin-Fin ratio. Pin fin heat sink is the height, Fin is adjacent to the distance between two fins. Pin-Fin height than is Pin (not including base thickness) divided by the Fin, Pin-Fin heat sink than the larger effective heat dissipation means that the larger the area, on behalf of the more advanced aluminum extrusion technology.
Copper heat sink
Thermal conductivity of copper is 1.69 times that of aluminum, so in other conditions the same premise, pure copper heat sink faster in the heat away from the heat source. However, the texture of copper is a problem, self-styled "copper heat sink" is actually not true 100% of the copper. In the list of copper, copper more than 99% of the hormone known as acid-free copper, copper for the next grade copper content of 85% or less of Dan copper. Currently on the market most of the copper heat sink copper content in between. Some low-grade copper heat sink 85% copper content is not even that, although the cost is very low, but its ability to greatly reduce the thermal conductivity, affecting heat dissipation. In addition, copper also has obvious drawbacks, the high cost, processing difficulties, the quality of the radiator too have hindered the application of all-copper heat sink. Than the hardness of copper alloy AL6063, some mechanical processing (such as profile groove, etc.) perform as well as aluminum; copper is much higher melting point than aluminum, is not conducive to extrusion (Extrusion) and so on.
Copper and aluminum combined with technology
After considering both copper and aluminum material of their respective shortcomings, the current high-end market segments tend to use copper and aluminum radiator with manufacturing process, these heat sinks are usually made of copper metal base, and the heat sink is aluminum, of course, , in addition to copper base, but also the heat sink with studs and other methods, is the same principle. With a high thermal conductivity, copper bottom can quickly absorb the CPU to release the heat; aluminum fins can be made with the help of complex technology means most conducive to the shape of heat, and provide greater thermal storage space and quick release, which found in all aspects of an equilibrium point.
To improve efficiency and service life of LED light, LED products to solve the problem is the heat at this stage one of the most important issue, LED industry thermal substrate itself on the bit line is extremely stringent accuracy requirements, and the need to have high heat dissipation, small size, good adhesion of metal lines and other characteristics, therefore, making use of photolithography film ceramic substrate cooling, will be the promotion of high-power LED continuously to improve one of the important catalyst.
