白光LED阵列结温检测以及寿命预测分析

发布时间：2018-04-01 00:03

本文选题：白光LED阵列　切入点：结温　出处：《中国科学院长春光学精密机械与物理研究所》2017年博士论文

【摘要】：LED照明产品因其绿色、节能、寿命长等优势正逐步取代传统照明产品。虽然人们对其节能、环保等优势已普遍认可,但对其长寿命和高可靠性方面一直存在质疑。在LED可靠性方面很关键的问题之一在于解决LED器件PN结的热学问题。LED结温的升高会直接导致其发光效率和寿命的降低,从而阻碍其在照明领域的发展与推广。针对目前LED产品大功率、大密度的特点,LED产品的结温成为影响LED可靠性以及使用寿命的关键因素,因而LED产品的结温准确测量以及寿命预测具有重要意义。本论文主要完成了以下4个方面的工作。1、研究了白光LED阵列结温检测技术,对传统正向电压法以及基于蓝白比的光学方法分别进行了研究。1)搭建了正向电压法LED结温测试平台,分析了结温测试的不确定度。当LED阵列工作于实际照明系统中时,针对LED驱动电路输出电流的变化提出了结温修正方法。2)针对由单一荧光粉转化的白光LED,采用基于蓝白比W/B的结温测试方法,搭建了实验平台并完成了验证。结果表明W/B随结温变化具有较高线性度,拟合度R-square高于0.99。3)针对由两种荧光粉转化的白光LED,本论文基于光谱分解,提出了一种蓝白比(B+Y+R)/B的计算方法,给出了光谱分解以及计算过程中所产生的不确定度。结果表明采用(B+Y+R)/B计算结温,可将结温误差由5.7℃缩小为2.2℃。2、在LED温度加速老化实验中基于结温的测量,研究了LED在线测试与非在线测试两种方法在寿命预测上的差异。1)首先根据短期阶梯应力老化实验中LED结温的变化,确定温度应力的“突变点”,从而在不改变LED失效机理的前提下合理选择温度应力。2)在LED温度加速老化实验中,根据LED加载不同热沉时结温的变化,提出了LED在线测试与非在线测试的对比实验方法,给出了两种测试条件下LED光衰、色漂移以及寿命的对比分析结果。结果表明在线测试的寿命小于非在线测试,相差8%至13%。3针对LED加速老化过程中结温逐渐上升的现象,提出了结温修正的光衰退化模型,从而将LED的光衰退化归一到其初始结温下的变化,去除了结温变化对于推算寿命的影响。研究中5个LED测试样品,在80℃下老化3000小时,在环境温度25℃下的结温上升6℃至8℃,此结温的上升使得所预测的寿命偏低9%至21%。4提出了一种LED灯具中各组件的退化分析方法,将影响LED灯具光衰的组件分为LED驱动、灯罩和LED光源三部分,分别以输出功率、透过率和光通量作为三个组件的退化参数进行退化分析。对一款白光LED球泡灯进行了实验研究,结果表明,LED光源是影响LED灯具光衰退化最为严重的组件,占LED灯具整体退化量的70%左右;灯罩的退化则占灯具整体退化量的21%左右;LED驱动电路的退化对LED灯具的影响不大。本文对白光LED进行了结温测试、加速老化实验以及寿命预测分析,在相关方面取得了一定进展,对将来LED结温测试以及可靠性分析的标准制定具有一定的参考意义。
[Abstract]:LED lighting products for its green, energy saving, long life and other advantages are gradually replacing traditional lighting products. Although the energy saving, environmental protection and other advantages has been widely recognized, but the long life and high reliability there has been questioned. One of the key problems in LED reliability is the junction temperature of.LED thermal problem solving LED device the increase of PN junction will directly lead to reduce the luminous efficiency and service life, thus hindering its development and promotion in the lighting field. Aiming at the characteristics of high power LED products, high density, the junction temperature of LED products become the key factors influencing the LED reliability and service life, thus LED products and accurate measurement of junction temperature the life prediction has important significance. This thesis consists of the following 4 aspects of the work of.1, white LED array junction temperature detection technology, the traditional voltage method and based on the ratio of the light blue and white Study on the.1 method respectively) set up the voltage method LED junction temperature test platform, analyzes the temperature measurement uncertainty of LED array. When working in real lighting system, according to the changes of the driving circuit of LED output current of the junction temperature correction method for.2) by a single phosphor converted white LED the junction temperature test method, blue white ratio based on W/B experimental platform is built and verified. The results show that the W/B junction temperature change with high linearity, fitting degree R-square higher than 0.99.3) directed by two kinds of fluorescent powder into the white LED, this paper based on spectral decomposition, a blue and white ratio (B+Y+R) the calculation method of /B generated by the given spectral decomposition and calculation of uncertainty. The results show that the use of /B (B+Y+R) to calculate the junction temperature, the junction temperature error reduced from 5.7 DEG C to 2.2 degrees.2, the experiment in the LED accelerated aging temperature In the measurement of junction temperature based on the difference of.1 of LED online test and non online test of two methods in the life prediction of the first step) according to the short-term stress aging changes of LED junction temperature in the experiment, determine the temperature stress of "mutation", thus without changing the LED failure mechanism under the reasonable choice the temperature stress of.2) in the LED temperature accelerated aging experiment, according to the change of LED loaded with different heat sink when the junction temperature, the experiment method of LED online testing and non online test, given the two test conditions LED decay, contrast color drift and life analysis results. The results show that the online test of the life less than the online test, a difference of 8% to 13%.3 for the LED junction temperature rises gradually accelerated aging phenomenon in the process of decay, and puts forward the end temperature correction degradation model, which will be LED light degradation normalized to its initial node temperature change, go to In addition to junction temperature change for calculation of life. 5 LED test samples in the study, aged for 3000 hours at 80 DEG C, the junction temperature at ambient temperature under 25 DEG C to rise 6 to 8 DEG C, the rise in junction temperature makes the predicted life is low to 9% 21%.4 presents a degradation analysis method LED the lamps of various components, will affect the assembly lumen LED lamps are divided into LED drive, LED light shade and the three part respectively to the output power, as the degradation parameters of three components of the transmittance and luminous flux degradation analysis. On a white LED bulb lamp was studied, the results show that the LED light source is the degradation effect of LED lamp is the most serious decay component, accounting for about 70% of the amount of LED light degradation; the degradation of the whole lamp shade accounted for about 21% of the amount of degradation; LED degradation effect on the driving circuit of LED lamp. The little white LED for over temperature measurement Accelerated aging test and life prediction analysis have made some progress in related aspects. It has a certain reference value for the future LED junction temperature test and reliability analysis.

【学位授予单位】：中国科学院长春光学精密机械与物理研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN312.8

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