Effects of silicone lens aging on degradation kinetics of light-emitting diode package in various accelerated testing
Effects of silicone lens aging on degradation kinetics of light-emitting diode package in various accelerated testing
复制标题
各种加速测试中硅胶透镜老化对发光二极管封装降解动力学的影响
DOI：
10.1016/j.optmat.2020.110071
复制
发表时间：
2020-09-01
影响因子：
3.9
通讯作者：
Zhang, Guoqi
中科院分区：
文献类型：
--
作者：
Cai, Miao;Liang, Zhi;Zhang, Guoqi
有机硅由于其高透光率、大折射率和良好的热稳定性而通常用于发光二极管（LED）封装中作为透镜和/或封装。然而，硅胶透镜老化对LED封装的流明衰减和色偏的影响是封装级可靠性的一个相当大的问题。本研究实证研究了硅透镜老化对LED封装件在恒定应力加速老化试验、升压应力加速老化试验和降压应力加速老化试验（SDSADT）下的流明衰减和色偏的影响。结果表明，有机硅透镜老化大大有助于流明衰减和LED的颜色偏移，并显着影响LED封装的降解动力学。三种测试方法中老化硅胶样品覆盖的LED封装的色坐标在相同的45度方向上呈现稳定的泛黄变化规律。有机硅透镜老化主要是由于热氧化和水解反应的累积而降低其对蓝光的透过率，其对LED蓝光峰值强度的影响与分步应力加速降解试验（SSADT）的应力加载顺序无关。另外，硅胶透镜老化对LED流明和色偏的影响规律可以分别用指数和幂函数模型来表示。在SSADT中，管腔衰减和色移基本上与历史应力和加载顺序无关。与其他加速试验相比，SDSADT试验方式更能有效区分热应力水平的色移效应。这些发现被认为是有益的LED产品的设计和可靠性评估。
Silicone is commonly used in light-emitting diode (LED) package as lens and/or encapsulation owing to its high light transmittance, large refractive index, and good thermal stability. However, the effect of silicone lens aging on the lumen decay and color shift of LED package is a considerable concern for package level reliability. This study empirically investigates the effects of silicone lens aging on lumen decay and color shift of LED package under three accelerated tests, namely, the constant stress-accelerated degradation test, step-up stress-accelerated degradation test, and step-down stress-accelerated degradation test (SDSADT). Results reveal that silicone lens aging substantially contributed to lumen decay and color shift of LEDs and considerably influenced the degradation kinetics of LED package. The color coordinates of LED package covered with aged silicone specimen in three testing methods exhibit a steady yellowing shift law at the same 45-degree direction. Silicone lens aging primarily reduces its transmittance to blue light as accumulated thermal oxidation and hydrolysis reaction, and its effect on the blue peak intensity of LED is independent of the stress-loaded order of step stress-accelerated degradation testing (SSADT). In addition, the effect law of silicone lens aging on LED lumen and color shift could be presented with the exponential and power function models, respectively. Lumen decay and color shift are mostly independent of the historical stress and loaded order in SSADT. The SDSADT testing manner more effectively distinguishes the color shift effect of thermal stress level compared with other accelerated tests. These findings are assumed to benefit the design and reliability assessment of LED products.