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Cooling technology is a key to winning LED products

As the LED materials and packaging technology evolves, prompted increasing brightness LED products, LED application is more and more widely, the LED as a back light display, especially the recent hot topic, mainly techniques in different kinds of LED back light color, brightness, life, power consumption and environmental protection demands are more advantages than the traditional cold cathode tube (CCFL), thus attracting industry actively. 
The power is not high, the original single chip LED calorific value is limited, thermal problem is not big, so the encapsulation method is relatively simple. But in recent years, as the LED materials technology constantly breakthroughs, LED packaging technology is also changed, from the early single chip type of ammunition packaging gradually developing into a flatter, more widespread type chip packaging module; The working current of low power LED to early about 20 ma, about 1/3 of the progress so far to 1 a high power LED, the input power of the single star LED up to more than 1 w, or even to 3 w, 5 w encapsulation mode is more evolution. 
Due to the high brightness were, thermal dissipation of high power LED system will affect the product function is key, advantages and disadvantages to the LED component the calorific value of rapid discharge to the surrounding environment, must first from the package hierarchy (L1 and L2) thermal management. Current industry practice is to the LED chip to solder or thermal conductive paste, in a soaking through soaking piece reduce the thermal impedance of encapsulated module, which is currently on the market the most common LED encapsulation module, main sources of Lumileds, OSRAM, Cree and Nicha LED international well-known manufacturers. 
Many applications of terminal products, such as mini projector, automotive lighting and light source, under the specific area of the required amount of lumens need more than thousands of lumen or tens of thousands of lumen, alone obviously not enough to cope with the single chip packaging modules and multichip LED encapsulation, and chip directly gelling substrate is a development trend in the future. 
Heat dissipation problem is in LED the main impediment to development is used as the lighting objects, the use of ceramic or discharge pipe is an effective way to prevent overheating, but thermal management solution to make the rising costs of materials, the purpose of high power LED thermal management design is effectively reduced the thermal resistance between the chip cooling to the final product, R junction - to - the case is one of the material solution, provides a high conductivity, low thermal resistance but by chip attached or hot metal solutions to transfer heat from the chip directly to encapsulate the outside of the shell. 
And, of course, the LED heat dissipation component similar to CPU heat dissipation, are made of heat sink, heat pipe, fan and thermal interface materials composed of air-cooled module is given priority to, of course, water is one of the hot countermeasures. At current the most popular in terms of the large size of the LED TV backlight module, 40 inches and 46 inch LED back light input power is 470 w and 550 w, respectively in view, 80% of them into heat needed around the heat dissipating capacity of 360 w and 440 w. 
So how will the heat take away? At present the industry useful water for cooling, but with a high price and reliability concerns; Also useful heat pipe with heat sink and fan for cooling, for example Japan giant SONY's 46 "LED back light liquid crystal TV, but the fan power consumption and noise problems still exist. Therefore, how to design the cooling way, without the fan may be important to decide who can win the future. 
The following is to introduce several kinds of thermal radiation and thermal material. 
The cooling way 
Generally speaking, according to the way of heat can be taken away from the radiator can be divided into active cooling and passive cooling radiator. So-called passive cooling, it is to point to through the radiator to heat source, the LED light source as natural heat into the air, the heat dissipation effect is proportional to the size of heat sink, but because it is a natural send out quantity of heat, the effect of course, is often used in those without the requirements of the equipment to the space, or used to heat cooling small parts, such as part of the affordable motherboard also take passive cooling on north bridge, the vast majority of taking active cooling type, active cooling is through the fan cooling device, such as compulsive to heat away from the heat sink, its characteristic is high cooling efficiency, small volume and equipment. 
Active cooling, segmentation from the cooling mode, can be divided into water cooling, surface cooling, heat pipe cooling, semiconductor refrigeration, chemical, refrigeration, etc. 
Air-cooled water cooling is the most common way of heat dissipation, by comparison, is also relatively cheap way. Air cooling heat dissipation from the essence is to use fan away the heat absorption by the radiator. With a relatively low price, easy installation, etc. But higher dependence on environment, such as temperatures and its heat dissipation when overclocking performance will be affected. 

----------Archled Technology Co.,Limited

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