研究了常规荧光粉涂覆工艺和沉粉工艺COB封装白光LED的发光效率、色漂移及光通量等参数的电流依赖关系, 对实验结果进行了理论分析。研究结果表明, 采用沉粉工艺时, 更多的荧光粉集中在LED芯片表面, 理论上提供了更好的散热通道, 但是LED芯片电光转换时产生的热量和荧光粉光致发光产生的热量均集中在芯片附近, 导致芯片附近温度升高, 在几种效应的共同作用下, 沉粉工艺制作的COB LED的发光效率在不同电流下均低于常规工艺的3%~5%。

Studied is the dependence relationship of current with luminous efficiency, color drift, luminous flux of COB-packaged LED prepared by conventional phosphor coating and depositing process. And the experimental results are analyzed theoretically. The results show that, when depositing process is used, more phosphor will concentrate on the LED chip surface, providing a better heat dissipation channel, but the heat generated both by the electro-optical conversion of LED chip and by the photoluminescence of phosphor is concentrated near the chip surface, resulting in the temperature rise near the chip. Thus under several effects, the luminous efficiency of COB LED fabricated with deposited phosphor is 3%~5% lower than that prepared with conventional process under different current.