大功率LED的电流老化特性分析

基于一体化封装技术,先将铝基板进行硬质阳极氧化处理使其绝缘,后将蓝光LED芯片直接封装到铝基板上,分别制成大功率白光和蓝光LED,其中白光LED由蓝光芯片涂覆YAG∶Ce荧光粉制成。将白光和蓝光LED分别用500 mA和700 mA电流加速老化1 000 h,平均每间隔24 h测试其各种光学参数,对比蓝光LED与白光LED的衰减情况。白光LED的光通量衰减比蓝光严重,但白光光功率的衰减比蓝光慢。LED的衰减分为两个阶段:第一阶段芯片与荧光粉同时衰减;第二阶段主要是芯片的衰减,荧光粉衰减较慢。

The Accelerated Aging Characterization of High Power LED

Insulation layer of aluminum substrate for LED encapsulation was made by hard anodizing technology. White and blue GaN-based light-emitting diodes were encapsulated on the aluminum plate directly. White LED was fabricated by blue chip coated with YAG∶Ce phosphor, while blue LED didnt coated with phosphor. Accelerated aging tests at 500 mA and 700 mA were carried out for about 1 000 h on the new type of integrated high-power. Then optical parameters of LEDs were tested per 24 h. Compared with the blue and white LED, we could get the following conclusions: White LED luminous flux attenuates seriously than the blue LED, while optical power is opposite. There are two stages in LED attenuation: The chip and phosphor decay at the same time in initial stage of aging, well blue chip attenuation is dominant after a certain period of time.