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LED heat dissipation, error analysis and the method to deal with
2014-03-26 15:45:16

LED heat dissipation, error analysis and the method to deal with

 

LED heat dissipation, error analysis and the method to deal with
 
With the widely application of the LED, LED heat dissipation problem is becoming more and more attention. LED the cooling performance is good or bad will directly affect the service life of LED products, therefore, solving the problem of the LED heat dissipation is imperative. This paper analyses some misunderstandings LED heat dissipation, and share some questions about the LED heat dissipation method to cope with the situation, hope to be of help. 
 
First : Error analysis of LED heat dissipation
 
The LED heat dissipation myth is mainly manifested in the following aspects:
 
1. The internal quantum efficiency is not high. In composite, the electrons and holes is not 100% produces photons, which is commonly referred to as the "leaks" and reduce PN area carrier recombination rate. Leakage current is multiplied by the voltage, the power of this part is converted into heat energy, but it does not occupy a main component part, because now the internal efficiency of photon is close to 90%.
 
2. The inside of the photons to all injection to chip external and finally converted into heat. This part is mainly because the current is called external quantum efficiency is only 30%, mostly is converted into heat.
 
3. The excessive dependence on thermal conductive materials. What because use high-tech materials can scatter heat out. Actually using ordinary aluminum radiator, after multiple tests, the temperature of the heat sink is only higher than the bottom of the radiator for 3 to 5 degrees Celsius. That is to say, if I can use to a thermal conductivity, good material, under the condition of the thermal resistance is zero, also can reduce the temperature for 3 to 5 degrees Celsius.
 
4. Superstition heat pipe. Heat pipe with good heat conduction ability, this is beyond doubt. But derived from heat sink thermal eventually need to go through the tropical air convection. If there is no cooling fins, heat pipes will soon reach thermal equilibrium, the temperature rise together with the heat sink. And if the increase in heat pipe radiator fins, eventually with fins heat dissipation. And fins and heat pipe contact point but not as good as other ways to contact. As a result of high cost, the cooling effect is not improving. But heat pipe used in integrated LED heat conduction or useful, but the structure is reasonable!
 
5. Take some manufacturer propaganda nano radiation material. Radiation temperature in the LED lamps and lanterns of 50 degrees Celsius under the condition of share can be ignored. Propaganda and manufacturer of radiation coating even as their propaganda has good radiation effect, even achieve blackbody radiation ability of radiation, the heat dissipation ratio but a few percent. And coating itself will hinder hot export, thus affecting the heat convection. 
 
Second, the LED heat dissipation problem approach
 
Let's take a look at about LED heat dissipation problem approach.
 
Method 1, aluminum radiator fins
 
This is the most common way of heat dissipation, use aluminum radiator fins as a part of the shell to increase the cooling area. 
led heat dissipation
 
Method 2, thermal plastic shell
 
Using the LED heat insulation plastic instead of aluminum alloy heat dissipation, can significantly improve the ability of thermal radiation.  
LED heat insulation plastic
Method 3, air fluid mechanics
 
Using the lamp shell shape, make air convection, this is the lowest cost way of strengthening heat dissipation.
led corn bulb
 
Methods 4, liquid ball bubble
 
Using liquid ball bubble packaging technology, high thermal conductivity of transparent liquid filled in the ball bubble lamp body. This is in addition to the reflective principle, only use smooth thermal conductivity, heat dissipation of the LED chip technology. 
 
Methods 5, the use of lamp holder
 
In the home of small power LED lights, often using the internal space of the lamp holder, the driver circuit part or all of the heat into. So that you can use like screw base has a large lamp holder of the metal surface heat dissipation, because lamp holder is contact base metal electrode and the power cord. So part of the heat can be derived 
 
Methods 6, heat insulation plastic instead of aluminum alloy
 
LED heat insulation plastic
Heat insulation plastic instead of aluminum alloy heat dissipation, the LED heat insulation plastic, while maintaining the heat dissipation capacity and aluminum alloy flat, to improve thermal radiation ability by 4 to 8 times. Made of the heat dissipation material LED heat dissipation energy boost overall heat dissipation effect. 
LED heat insulation plastic led bulb light
 
Methods 7, heat conduction heat integration - the use of high thermal conductive ceramics
 
Lamp shell cooling purpose is to reduce the working temperature of the LED chip, due to the LED chip expansion coefficient with the metal thermal conductivity, heat dissipation material expansion coefficient difference is very big, the LED chip can not be directly welding, to avoid high and low temperature thermal stress damage LED chip. The latest high thermal conductive ceramic material, the thermal conductivity is close to aluminum, expansion system can be coordinated to be synchronous with the LED chip. So it can be heat conduction, heat integration, reduce the thermal conductivity of the intermediate links.  

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