A Study On A Kind Of New Conformal Phosphor Coating Structure And Industrialization

Green and low-carbon has become the main theme of global technology innovation and development. As the representative of semiconductor lighting technology, white LED has a lot of advantages, such as small size, high luminous efficiency, long life, security, reliability, energy conservation and environmental protection,so it is the ideal green lighting to replace the traditional light source. In order to generate white light, the most current method is the phosphor-converted white LEDs(pc-WLEDs). Phosphor coating has been thought as a main factor which influences the illumination quality of pc-WLEDs. In recent years, a great amount of effort has been devoted and some coating methods were proposed to improve the phosphor coating technology, for example, conformal phosphor coating, remote phosphor coating and self-adaptive phosphor coating.In the paper,based on the technology about self-adaptive phosphor coating, we explored that what is the phosphor coating impact of phosphor slip ritio at first, then the industrial scale researches of self-adaptive phosphor coating technology has been done, and finally, in order to improve ACU(Angular color uniformity) and luminous efficiency of WLEDs, we proposed conformal-remote phosphor coating structure.1. In the self-adaptive phosphor coating technology, the phosphor slurry ratio(the proportion of phosphor, PVA and ADC) directly affects the quality of the phosphor powder layer. After several experiments, we found an ideal ratio, put 400 mg phosphor(YAG: Ce3 +) into 1.4ml aqueous solution which is composed by 0.72 ml PVA aqueous solution(concentration of 5%) and 0.68 ml ADC aqueous solution(concentration of 0.26%), which can forming a good quality and high luminous efficiency of phosphor layer.2. In the industrial scale researches of self-adaptive phosphor coating technology, the CCTs distribution of sample are normally distributed, no matter whether the coating is conformal coating or remote coating. For all samples, the homogeneity of CCT were good, and the pass rate of 10% is more than 80%. In addition, the CCT homogeneity of remote phosphor coating is better than the CCT homogeneity of conformal phosphor coating, and the 10% pass rate of former is more than 90%.3. In this paper, we proposed a conformal-remote phosphor coating structure to improve ACU and luminous efficiency of WLEDs by self-adaptive technology. The experimental results show that the CCT deviation is 92 K of the self-adaptive conformal-remote phosphor coating, compared with the conventional phosphor coating and self-adaptive remote phosphor coating, it shows more uniformity. And the luminous efficiency of self-adaptive conformal-remote phosphor coating is increased about from 4.7% to 21.6% at driving current of 350 mA, compared with conventional phosphor coating. For the self-adaptive conformal-remote phosphor coating, the thickness of silicone layer absolutely had no affect on the luminous efficiency and angular color uniformity.