高出光品质LED封装:现状及进展

发布时间：2018-06-05 11:33

本文选题：LED封装 + 热设计　；参考：《中国科学:技术科学》2017年09期

【摘要】：发光二极管(light-emitting diode,LED)具有电光转换效率高、节能环保、体积小等优点,被誉为21世纪绿色照明光源.随着LED在越来越多的照明场合的应用推广和人们对于光源质量的要求的提高,LED出光品质越来越被重视.评价LED出光品质的指标主要有效率、空间颜色均匀性和显色指数,这些参数和LED封装密切相关.LED封装是将芯片和其他封装材料集成在一起形成最终的照明产品,起着机械保护、外部信号和电连接、散热和光学参数调控等关键性功能.本文从封装的角度,对LED的效率、空间颜色均匀性和显色指数的调控技术进行了系统阐述.具体到封装中的关键技术,主要包含以下3方面:(1)热设计.LED在工作过程中约有60%的输入电能被转化为热量,如果产生的热量不能及时有效地散到环境中,将会造成LED的温度急剧升高,导致LED的效率下降并带来可靠性问题.(2)光学设计.LED的光从芯片有源层中通过电子-空穴复合的方式产生后,在经过芯片、荧光粉、封装胶和透镜等材料后,由于散射和折射等作用,光的传播方向和路径会发生改变.此外由于吸收作用,部分的光被吸收并转换成热量.因此通过光学设计不仅可以调控LED光源能量分布,还可以减少光在封装材料中的吸收从而提高光效.(3)荧光粉涂覆.相比于多色发光LED芯片组合获得期望出光品质LED的封装形式,将单色或者多色荧光粉涂覆在单色LED芯片上的封装形式具有更强的相关色温可调性和工艺灵活性而被广泛应用于LED工业生产中.对于荧光粉结合芯片的白光LED封装形式,荧光粉涂覆起着调控空间颜色均匀性和显色指数的关键作用.
[Abstract]:Light emitting Diode (LED) has the advantages of high efficiency of electro-optic conversion, energy saving and environmental protection, small volume and so on. It is praised as the green lighting source in the 21st century. With the application of LED in more and more lighting occasions and the improvement of the quality of light source, more and more attention has been paid to the quality of LED. The main indexes to evaluate the light quality of LED are efficiency, spatial color uniformity and color rendering index. These parameters are closely related to LED packaging. It is the integration of chips and other packaging materials to form the final lighting product, which plays an important role in mechanical protection. External signal and electrical connection, heat dissipation and optical parameter control and other key functions. In this paper, the efficiency, spatial color uniformity and color rendering index of LED are systematically described from the point of view of encapsulation. Specifically, the key technologies in packaging include the following three aspects: 1) Heat design. About 60% of the input electric energy of LED is converted into heat in the process of operation. If the generated heat can not be effectively distributed to the environment in a timely and effective manner, This will cause a sharp rise in the temperature of LED, resulting in a decrease in the efficiency of LED and a reliability problem. (2) Optical design. Led light is generated from the active layer of the chip by electron-hole recombination, after passing through the chip, the phosphor. After encapsulating materials such as glue and lens, the direction and path of light propagation will change due to scattering and refraction. In addition, part of the light is absorbed and converted into heat due to absorption. Therefore, the optical design can not only regulate the energy distribution of LED light source, but also reduce the absorption of light in packaging materials, thus improving the light efficiency. Compared with the combination of polychromatic luminescent LED chips, the desired optical quality LED packaging form can be obtained. The packaging of monochromatic or polychromatic phosphors coated on monochromatic LED chips has been widely used in the industrial production of LED because of its strong correlation color temperature tunability and process flexibility. For the white LED packaging of phosphor binding chip, phosphor coating plays a key role in controlling spatial color uniformity and color rendering index.
【作者单位】：华中科技大学能源与动力工程学院;
【基金】：国家自然科学基金(51625601,51576078,51606074)资助项目
【分类号】：TN312.8

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