Different manufacturers produce the LED Products, and they have different degree of light decay. It has something to do with the temperature. and the determined factors are the LED chip, phosphor and packaging technologies. Currently, the White LED light decay may be one of the most important issues to enter into the LED  lighting market. There are two reasons why the LED show light decay.

1. LED Quality Problem

1)  The LED itself quality is not good and the brightness decrease rapidly;

2) During production, The LED’s heat could not dissipate from the PIN feet, leading to the LED chip attenuation;

2. The Conditions of usage

1) LED is constant current driver, but some customers use Voltage drivers, which may result in the light decay of lighting;

2) The driver current > the Rated driver conditions
In fact,  there are many reasons of light decay. the most important reason is the heat dissipation.  Although many led manufacturers don’t pay more attention to the problem of heat dissipation, but in the long run, the light decay  is faster that the good led products with better heat dissipation.

Besides, The thermal resistance of LED, the heat dissipation of PCB, as well as colloidal and gold thread of the LED will lead to the light decay.