对LED进行应力加速老化实验及分析可以对器件可靠性做出最快、最有效的评估。本文将相同的6 V高压功率白光LED分为两组, 一组施加180 mA电流应力和85 ℃温度应力进行高温老化实验, 另一组施加180 mA电流应力、85 ℃高温和85%相对湿度进行高温高湿老化实验。在老化过程中, 测试了LED光电参数随老化时间的变化规律。实验结果表明: 高温大电流应力下的样品的光退化幅度为0.9％～3.4％, 高温高湿大电流应力下的样品的光退化幅度为25.4％～27.8％, 高温高湿下样品的老化程度远高于高温老化下样品的老化程度, 湿度对LED可靠性有显著的影响。退化的原因包括荧光粉的退化和器件内部欧姆接触退化等。

The stress accelerated aging test and analysis are the most efficient and effective way to analysis the reliability of the devices. In this paper, the same 6 V LED modules were divided into two groups for aging. 180 mA stress current and 85 ℃ high temperature were applied for one group, and 180 mA stress current and 85 ℃/85%RH moisture condition for another. During the aging time, the optical and electrical characteristics of the LEDs were measured and analyzed. The experimental results show that the degradation rate of the samples which under high temperature and high current stress is 3.4%-0.9%, and the degradation rate of the samples which under high humidity, high temperature and high current stress is 25.4%-27.8%. The degradation of LEDs under high temperature and high humidity condition is more serious than that under high temperature. So it is strong evidence that the humidity badly affects the reliability of LEDs. The failure reasons include the degradation of the phosphor and the Ohmic contact in the devices.