为了对比研究新型低色温无荧光粉LED光源和低色温荧光粉LED光源的可靠性, 本文进行了85 ℃加速老化和温度步进应力实验, 测试了各光电参数在老化过程中的变化规律, 并分析了有无荧光粉低色温光源的老化衰减机理。实验结果表明, 在20 A/cm2工作电流密度、85 ℃的加速老化条件下, 两种类型的光源都表现出很好的稳定性, 但随着功率的增加, 无荧光粉光源展现出更好的光通量稳定性; 随着温度的升高, 无荧光粉光源在高达200 ℃左右仍表现出良好的可靠性, 而荧光粉光源则在175 ℃后出现了明显的光通量衰减和色温升高。电流应力或温度应力提升以后, 无荧光粉光源展现出更优异的可靠性。

For the comparative study of the reliability of the low color temperature light source made by phosphor-free LEDs and conventional phosphor-converted LEDs, 85 ℃ accelerated aging and temperature step-stress tests were carried out. The variation of each photoelectric parameters during the aging process was recorded, and the aging mechanism of the two different kinds light sources was analyzed. The results show that both types of light sources exhibit good stability under the accelerated aging at 85 ℃ with a current density of 20 A/cm2. However, as the current density increases, more obvious attenuation of luminous flux appears in phosphor-converted light sources. As the temperature increases, the phosphor-free light source still shows good stability up to about 200 ℃. However, the phosphor-converted light sources exhibit significant luminous flux attenuation and color temperature increase after 175 ℃. These results indicate that the phosphor-free light source shows excellent reliability when current stress or temperature stress increases.