The heat dissipation of LEDs is now more and more important to people. This is because the light decay of LEDs or their lifetime is directly related to their junction temperature. The heat dissipation is not good, the junction temperature is high, and the lifetime is short. According to the Arrhenius rule, the temperature is per A 10°C reduction in life will be extended by a factor of 2. It can be seen from Cree's relationship between light decay and junction temperature (Fig. 1) that if the junction temperature can be controlled at 65 °C, the lifetime of light decay to 70% can be as high as 100,000 hours! This is the life expectancy that people dream of, but can it really be achieved? Yes, as long as you can seriously deal with its heat dissipation problem, it is possible! Unfortunately, the actual heat dissipation of LED lights is far from this requirement! As a result, the life of LED lamps has become a major problem affecting their performance, so it must be taken seriously!
If the luminescence at a junction temperature of 25 degrees is 100%, then when the junction temperature rises to 60 degrees, the luminescence amount is only 90%; when the junction temperature is 100 degrees, it drops to 80%; 140 degrees is only 70%. It can be seen that improving heat dissipation and controlling junction temperature are very important things.
In addition to this, the heating of the LED will also cause its spectral shift; the color temperature will increase; the forward current will increase (at constant voltage supply); the reverse current will also increase; the thermal stress will increase; the phosphor epoxy aging accelerates, etc. All kinds of problems, so the heat dissipation of LEDs is the most important issue in the design of LED lamps.
Figure 1. Relationship between light decay and junction temperature
Figure 2. Relationship between junction temperature and luminescence
If the luminescence at a junction temperature of 25 degrees is 100%, then when the junction temperature rises to 60 degrees, the luminescence amount is only 90%; when the junction temperature is 100 degrees, it drops to 80%; 140 degrees is only 70%. It can be seen that improving heat dissipation and controlling junction temperature are very important things.
In addition to this, the heating of the LED will also cause its spectral shift; the color temperature will increase; the forward current will increase (at constant voltage supply); the reverse current will also increase; the thermal stress will increase; the phosphor epoxy aging accelerates, etc. All kinds of problems, so the heat dissipation of LEDs is the most important issue in the design of LED lamps.
SHENZHEN YINZHIGUAN DIGITAL TECHNOLOGY CO.,LTD , http://www.yzgmusiccrown.com