白光LED封装材料的变色模式与机理分析(下)

Discoloration Modes and Mechanism Analysis of White-LED Packaging Materials(Ⅱ)

近年来固体照明技术发展迅速,尤其在白光LED照明领域。但白光LED在长期使用中,受到高温、光照或外来污染物的影响,容易出现明显的变色现象,降低LED的出光效率或导致色温漂移。变色可能发生在LED的各种封装材料当中,不同种类封装材料的变色机理并不一样。本文结合本实验室和其他相关实验室的研究,分别对反光杯、固晶胶、荧光粉及封装硅胶4种封装材料的变色模式和机理进行讨论分析。同时还设计了支架镀银层的变色机理验证实验,实验结果表明与理论相符合。

Solid state lighting technology has achieved great progress in recent years,especially in white light emitting diodes（LEDs）.However,influenced by high temperature,photon energy or external pollution,packing materials will be resulted in an obvious discoloration phenomenon which will adversely affect the light efficiency and color temperature of white LEDs.Discoloration may occur at various packaging materials of LEDs,and different materials have different discoloration mechanisms.In this paper,combining the studies by our lab and the other research groups,some major discoloration modes and mechanisms of four white LED packaging materials（reflector cup,die-attach adhesive,phosphor and silicone） were discussed,respectively.Moreover,some experiments about LED reflector cups were designed to verify the reasons of the reflector cup discoloration.