Investigation on the aging characteristics of high-power white LEDs under different stresses

We used two types of 1-W white LEDs, both of which had the structure of GaN chip with phosphor covered and packaged in metal PCB boards with laminated aluminum. Of the two types of packaging lens, one is made of hard silica gel, and the other is made of soft plastic. The purpose of this paper is to analyze the aging characters of high-power white LEDs under stresses. In accelerated life tests, the two types of white LEDs were treated with high temperature and DC current distinctively. The tendencies of the decay of luminous flux in the two conditions were basically the same, while the changing trends of the color temperature were different. The hard silica gel had better stability.