1. Analysis of the misunderstanding of LED heat dissipation
The misunderstanding of LED heat dissipation is mainly reflected in the following aspects:
1. The internal quantum power is not high
That is to say, when electrons and holes recombine, photons cannot be generated 100%, which is generally referred to as "current leakage", which reduces the recombination rate of carriers in the PN region. The leakage current multiplied by the voltage is the power of this part, which is converted into heat energy, but this part is not a major component because the internal photon power is now close to 90%.
2. The photons generated inside cannot be fully emitted to the outside of the chip and finally converted into heat
Some of this is important, because the current called external quantum power is only about 30%, and most of it is converted into heat.
3. Excessive reliance on thermal conductivity materials
Because of the use of high-tech materials, the heat can be dissipated. In fact, ordinary aluminum is used for heat dissipation. After repeated tests, the temperature of the heat sink is only 3-5 degrees Celsius higher than the bottom of the radiator. That is to say, if a material with excellent thermal conductivity can be used, the temperature can be lowered by 3-5 degrees Celsius when the thermal resistance is zero.
4. Superstition Heat Pipe
There is no doubt that heat pipes have excellent thermal conductivity. But the heat derived from the heat sink ultimately needs to be removed by air convection. Without fins to dissipate heat, the heat pipe would quickly reach thermal equilibrium and the temperature would rise along with the heat sink. And if heat dissipation fins are added to the heat pipe, the heat dissipation is still finned after all. And the touch points of fins and heat pipes are not as good as other methods. The result is that the cost is high, and the heat dissipation effect has not been improved. However, it is still useful to use heat pipes to conduct heat on integrated LEDs, but the structure must be reasonable!
5. Believe in the nano-radiation information promoted by some manufacturers
The proportion of radiation heat dissipation in the current LED lamp temperature is about 50 degrees Celsius can be ignored. And the radiation coating that the manufacturer promotes has excellent radiation effect as they promote, even if it reaches the radiation capacity of black body radiation, the proportion of heat dissipation is only a few percent. And the coating itself will hinder the export of heat, thus affecting the heat dissipation of convection.
2. Solutions to LED heat dissipation questions
Let's take a look at the solutions to LED heat dissipation problems.
Method 1. Aluminum cooling fins
This is the most common heat dissipation method, using aluminum heat dissipation fins as part of the shell to increase the heat dissipation area.
Method 2, thermally conductive plastic shell
The use of LED insulating heat-dissipating plastics instead of aluminum alloys to manufacture heat-dissipating bodies can greatly improve the heat radiation capacity.
Method 3. Aerodynamics
Using the shape of the lamp housing to create convection air, which is the lowest cost way to enhance heat dissipation.
Method 4, liquid bulb
Using the liquid bulb packaging technology, the transparent liquid with high thermal conductivity is filled into the bulb of the lamp body. In addition to the principle of reflection, this is the only technology that uses the light-emitting surface of the LED chip to conduct heat and heat.
Method 5, the use of lamp holder
In household-type smaller-power LED lamps, the inner space of the lamp head is usually used, and some or all of the heating drive circuits are placed. In this way, it is possible to use a lamp cap with a large metal surface such as a screw cap to dissipate heat, because the lamp cap is closely connected to the metal electrode of the lamp holder and the power cord. Therefore, some heat can be dissipated from this.
Method 6. Insulating and heat-dissipating plastics instead of aluminum alloys
The insulating and heat-dissipating plastic replaces the aluminum alloy to make the heat-dissipating body. This LED insulating and heat-dissipating plastic, while maintaining the same heat dissipation capacity as the aluminum alloy, improves the heat radiation capacity by 4-8 times. The LED heat sink manufactured with this heat dissipation material can greatly improve the overall heat dissipation effect.
Method 7. Integration of heat conduction and heat dissipation - the application of high thermal conductivity ceramics
The purpose of heat dissipation of the lamp housing is to reduce the working temperature of the LED chip, because the expansion coefficient of the LED chip is far away from the expansion coefficient of our commonly used metal thermal conductivity and heat dissipation materials, and the LED chip cannot be directly welded to avoid damage to the LED due to high and low temperature thermal stress. chip. The latest high thermal conductivity ceramic material, the thermal conductivity is close to that of aluminum, and the expansion system can be adjusted to synchronize with the LED chip. In this way, heat conduction and heat dissipation can be integrated, and the intermediate links of heat conduction can be reduced.
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