LED lumen attenuation is the weakening of the light signal during transmission. LED products made by global leading manufacturers at the present stage have lumen attenuation in different grades after used for a period of time and this phenomenon also exists in high power LEDs. Then, what causes LED attenuation? Lumen attenuation is directly related to the temperature, and is mainly determined by the chip, phosphor used and the packaging technology. At present, lumen attenuation has become the chief problem for white LED to march into civil lighting field. There are two main problems that cause LED lumen attenuation:
Ⅰ The quality of the LED product itself
1. The brightness of LED will attenuate quickly if the quality of the adopted LED chip is not good.
2. The production technology has some defects. If the heat generated by LED chips can not be exported out of the chip smoothly by the PINs, LED chips may be over heated and thus causing chip attenuation more serious.
Ⅱ The operating condition
1. LED should be drove by constant current, if drove by voltage, LED lumen attenuation will be caused.
2. If the driving current is larger than the rated value, LED lumen may easily get attenuated.
Among the various causes of LED products lumen attenuation, “heat” is the pivotal one. Many manufacturers pay little attention to the heat dissipation of the products, leading to a much more serious lumen attenuation compared to those products that dissipate heat properly. Besides, thermal resistance of the LED chip itself, silver colloid, the heat dissipation effect of the substrate and golden wire problems are also related closely to LED lumen attenuation.
