白光LED荧光粉电泳沉积技术的研究

发布时间：2018-06-11 22:45

本文选题：电泳涂层技术 + 荧光粉涂覆技术　；参考：《电子科技大学》2016年硕士论文

【摘要】：白光LED(Light-Emitting Diode)作为新一代固态照明器件,由于白光LED自身具有的节能、环保、高效等特点,日渐进入人们的视野当中,其潜力也不言而喻。白光LED实现方式大致可分为三种,目前综合考虑多个因素,较常使用的是蓝光LED芯片上涂覆黄色荧光粉的方式。在LED工艺流程当中,荧光粉层的涂覆是当中一个主要步骤,本文研究方向就是对荧光粉涂覆技术的研究。评价一个荧光粉涂覆技术的优劣的重要参考是LED的发光效率和空间色温分布均匀性等参数。鉴于目前已有荧光粉涂层技术,本文在原有的电泳涂层技术的基础上,创新性的通过结合电泳涂层技术和自适应涂层技术,改进了原有白光LED电泳沉积荧光粉涂层工艺,目的是改善原有电泳涂层技术涂覆的LED的发光效率与空间色温分布均匀性。本文的主要工作是得出改进型白光LED电泳沉积荧光粉涂层结构的实验方案,并对LED蓝光芯片在经过新工艺各步骤后光通量、发光效率、相对光谱曲线和色温空间分布均匀性变化情况进行测试分析,之后对改进工艺的成品与原有EPD工艺成品进行对比分析,得出以下结论:首先,透明导电涂层是电泳涂层技术中不可缺少的,本实验中采用ATO(Antimony Tin Oxide)作为透明导电材料,较之前实验所用的ITO(Indium Tin Oxide)透过率有较为显著的提升。通过对喷涂ATO纳米分散液前后的蓝光LED芯片进行相对光谱、绝对光谱和空间色温分布的分析,可知ATO层对LED的色温分布没有影响,至少在本实验中用到的实验仪器的精度范围内没有。而ATO会降低LED芯片发光效率和光通量,降为未涂ATO的75.5%。并详细分析了由光谱仪和积分球显示的光谱数据不一致的原因是两仪器精度不同且不够。其次,在改进工艺步骤中,在经过第一步EPD(Electrophoretic Deposition)涂覆后,喷涂一层硅胶层后光效会有所提升;再经过自适应技术涂覆后,光效后有所下降;最后再进行灌胶封装后,光效提高。而光通量与光效的变化规律相同。再次,涂覆硅胶层可以提高蓝光抽取率而提高色温的作用,抽取率的大小与硅胶厚度正相关,但是硅胶的涂覆无法保证提升空间色温的均匀性,原因是色温变化灵敏度在各色温区间内是不同的。新工艺中的自适应工艺步骤确实起到了修正空间色温均匀性的作用,而且可以弥补中间硅胶层所造成的对空间色温均匀性不稳定作用的误差。然后,相对色温在3700K-5000K之间的样品短波区域波峰对应波长与长波区域波峰对应波长比值不变,为0.8;对应纵坐标比值规律为比值越大,色温越高,相对色温在4500K-4600K之间比值约为1。最后,对比了新工艺制成的样品与原有EPD工艺制成的样品的光效和空间色温分布,可以得知:光效较原有EPD工艺技术提高了6.17%,标准差降低了3.17%;LED色温为5000K左右时,色温分布标准差减少了17.67%。
[Abstract]:White LED Light-Emitting Diode) as a new generation of solid-state lighting devices, due to its own characteristics of energy saving, environmental protection, high efficiency, etc., it has gradually entered the people's field of vision, its potential is also self-evident. White LED implementation can be divided into three ways, currently considering a number of factors, more often used on the blue LED chip coated with yellow phosphors. In the LED process, the phosphor coating is one of the main steps, the research direction of this paper is to study the phosphor coating technology. The important reference for evaluating the quality of a phosphor coating technology is the luminous efficiency of LED and the uniform distribution of color temperature in space. In view of the existing phosphor coating technology, based on the original electrophoretic coating technology, this paper improved the original white LED electrophoretic deposition phosphor coating technology by combining the electrophoretic coating technology and adaptive coating technology. The aim of this paper is to improve the luminescence efficiency and the uniformity of color temperature distribution of LEDs coated with the original electrophoretic coating technology. The main work of this paper is to obtain the experimental scheme of the improved white LED electrophoretic deposition phosphor coating structure, and the luminous flux and luminous efficiency of the LED blue chip after the new process. The relative spectral curve and the change of color temperature spatial distribution uniformity were tested and analyzed. Then the finished product of the improved process and the original EPD process product were compared and analyzed. The following conclusions were obtained: first of all, Transparent conductive coating is indispensable in electrophoretic coating technology. In this experiment, ATOO antimony Tin Oxide is used as transparent conductive material, and the transmittance of ITOX Indium Tin Oxide is significantly improved compared with that of ITO / Indium Tin used in previous experiments. By analyzing the relative spectrum, absolute spectrum and spatial color temperature distribution of blue LED chip before and after spraying ATO nano-dispersion, we know that ATO layer has no effect on the color temperature distribution of LED. At least not within the precision range of the experimental instruments used in this experiment. ATO reduces LED chip luminous efficiency and luminous flux to 75. 5% of uncoated ATO. The reason for the inconsistency of spectral data displayed by spectrometer and integral sphere is that the accuracy of the two instruments is different and insufficient. Secondly, in the process of improvement, after the first step of EPD-Electrophoretic Depositioncoating, the light efficiency will be improved after spraying a layer of silica gel, then after self-adapting technology, the light efficiency will be decreased, and finally, the light efficiency will be improved after the encapsulation of glue. The change of luminous flux and light efficiency is the same. Thirdly, the coating of silica gel can improve the extraction rate of blue light and the effect of color temperature. The size of extraction rate is positively related to the thickness of silica gel, but the coating of silica gel can not guarantee the uniformity of color temperature in space. The reason is that the sensitivity of color temperature variation is different in each color temperature range. The adaptive process in the new process can correct the uniformity of space color temperature and make up for the error caused by the intermediate silica gel layer on the instability of spatial color temperature uniformity. Then, the ratio of the corresponding wavelength of the wave peak in the short wave region and the wave peak in the long wave region of the sample with the relative color temperature between 3700K-5000K and the corresponding wavelength of the wave peak in the long wave region is equal to 0.8, and the ratio of the corresponding longitudinal coordinate ratio increases with the increase of the color temperature, and the ratio of the relative color temperature between 4500K-4600K is about 1. Finally, the light efficiency and space color temperature distribution of the samples made by the new process and the original EPD process are compared. It can be seen that the light efficiency is 6.17% higher than that of the original EPD process, and the standard deviation is reduced by 3.17% when the color temperature of LED is about 5 000 K. The standard deviation of color temperature distribution decreased 17.67%.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM923.34

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