高温下荧光粉层的位置对LED光效衰减的影响  

Effect of phosphor layer's location on LED's luminous depreciation under elevated temperature

作　　者：陈奇[1] 陈全[2] 罗小兵[1] 

机构地区：[1]华中科技大学能源与动力工程学院,武汉430074 [2]武汉纺织大学电子与电气工程学院,武汉430073

出　　处：《科学通报》2017年第12期1302-1306,共5页Chinese Science Bulletin

基　　金：国家自然科学基金(51576078;51376070)资助

摘　　要：荧光粉的性能在很大程度上可以影响到LED产品的光效.关于荧光粉涂覆工艺如何影响LED的光效已经有很多研究,但是关于荧光粉层的位置对LED热学和光学性能的研究还比较少.本文采用了一种在线测试的方法,研究了高温加速实验中荧光粉层位于不同位置时对LED光效衰减的影响.通过制备荧光粉片,实现LED模块中荧光粉层的不同位置分布.对比实验结果表明,采用荧光粉片的LED模块光效衰减较小,在散热条件良好的情况下,荧光粉的发热对其光效影响不大.对于普通涂覆的大功率LED模块而言,要提高性能,其封装内部需要更好的热设计.High power white light-emitting diode（LED） has been widely used in our daily life due to its extraordinary characteristics of high luminous efficiency, low power consumption, long lifetime and environment protection. Among all the technologies to produce white light, phosphor converting scheme is most popular. In this mode, part of the blue light emitted by LED chip is converted into yellow light by phosphor layer. Then a white output light of blue and yellow light mixture is obtained. The conversion ability of phosphor layer can determine LED＇s performance parameters including luminous efficiency, correlative color temperature, angular color uniformity, etc. When one of the parameters does not meet the requirement（like relative light output drops below 70%）, the LED fails. Therefore, LED＇s reliability is greatly affected by phosphor layer＇s property. Previous study shows that the conversion efficacy of phosphor exhibits exponential degradation as temperature increases. The decrease of phosphor＇s conversion efficacy can induce light output decrease and deteriorate the reliability. Thus, for phosphor converted LED（pc-LED）, thermal management is of great importance. In conventional phosphor coating process, phosphor gel is directly dispensed onto the LED chip. When the LED is working, heat generated by the chip is accumulated due to the poor heat conduction of phosphor layer, resulting in the phosphor temperature rise. Besides, the phosphor＇s self-heating can also cause phosphor temperature rise. To solve this problem, some researchers used remote phosphor coating to reduce the influence of heat produced by chip. The phosphor layer was moved away from the chip to avoid contact. It means that the phosphor layer＇s location can have an effect on pc-LED＇s reliability. In this paper, the phosphor layer＇s location was further controlled by phosphor slice. The phosphor slices were prepared by mold to keep specific size. An online testing method was adopted to investigate the effect of phosphor

关 键 词：LED 光效衰减 加速实验 荧光粉位置 在线测试 

分 类 号：TN312.8[电子电信—物理电子学]