The reason for the heating of the LED display is that the electrical energy is not all converted into light energy, but partly converted into heat energy. LED light efficiency only 100lm W, its electro-optic conversion efficiency is about only $number. That means about 70% of the electricity is turned into heat.
Specifically, led junction temperature is caused by two factors:
1. The internal quantum efficiency is not high, that is, when the electron and the hole are compounded, the photon is not 100%, which is usually called the "leakage of the current", which reduces the compound rate of the PN region carrier. The leakage current times the voltage is this part of the power, which is converted to thermal energy, but this part does not constitute the main component, because the internal photon efficiency has nearly 90%.
2. The internal photons cannot be emitted entirely outside of the chip and eventually converted to heat, which is mainly because this is called the external quantum efficiency of only about 30%, most of which translates into heat.
Thermal solution of LED display:
The solution of LED cooling, mainly from two aspects, packaging before and after the package, can be understood as LED chip cooling and LED lighting cooling. LED chip cooling mainly with the substrate and the selection of the circuit and the process, because any LED will be made of lamps, so the heat generated by the LED chip is always through the shell of the lamp to disperse into the air. If the heat dissipation is not good, because the thermal capacity of the LED chip is very small, a little bit of heat accumulation will make the chip's junction temperature quickly increased, if the long period of work in the state of high temperature, its life will be shortened quickly. However, these calories need to be able to really guide the chip to the outside air, to go through many ways. Specifically, LED display chip generated by the heat, from its metal radiator block out, first through the solder to the aluminum substrate PCB, and then through the thermal adhesive to aluminum radiator. Therefore, the cooling of LED lamps actually includes two parts of conduction heat and heat dissipation.
