Several misunderstandings about LED heat dissipation and how to deal with it

Misunderstanding analysis of LED heat dissipation

The misunderstanding of LED heat dissipation is mainly reflected in the following aspects:

1. The internal quantum efficiency is not high. That is, when electrons and holes recombine, photons cannot be generated 100%, and it is generally called "current leakage" to lower 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, but this part does not occupy the main component, because the internal photon efficiency is now close to 90%.

2. The internally generated photons cannot be completely emitted to the outside of the chip and finally converted into heat. This part is the main one, because the current external quantum efficiency is only about 30%, and most of it is converted into heat.

3. Over-reliance on thermally conductive materials. Because of the high-tech materials used, the heat can be dissipated. Its practical ordinary aluminum 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. The heat pipe has a good thermal conductivity, which is beyond doubt. But the heat that is derived from the heat sink eventually needs to go tropical through air convection. If there are no fins that dissipate heat, the heat pipe will soon reach thermal equilibrium and the temperature will rise with the heat sink. If you add heat sink fins to the heat pipe, you will eventually use fins to dissipate heat. Moreover, the contact points of the fins and the heat pipes are not as good as other methods. The result is a high cost and no improvement in heat dissipation. However, it is useful to use heat on the integrated LED, but it must be structurally sound!

5. Believe in the nano-radiation materials promoted by some manufacturers. Radiation heat dissipation is negligible in the current temperature of LED lamps at around 50 degrees Celsius. The radiation coatings promoted by the manufacturers have a good radiation effect even if they are advertised, even if they reach the radiation capacity of black body radiation, the heat dissipation proportion is only a few percent. Moreover, the coating itself hinders the heat transfer, which affects the heat dissipation of the convection.

How to deal with LED heat dissipation problems

Below we will break down the response to the LED heat dissipation problem.