LED照明灯具的色漂退化机理及其可靠性建模研究

Color shift (CS), as one of the critical failure modes of LED luminaires, has become a research focus on systematically evaluating the reliability of LED luminaires. This project aims at the major demand of LED lighting industry, and carries out the research on the CS degradation mechanisms and their reliability modeling for LED luminaires. First, adopting highly accelerated stress-limit decay testing, the SC stress limit of LED luminaires is investigated in order to obtain an accelerated testing stress limit that ensured with the consistency of CS mechanisms; the key factors that cause CS of LED luminaires and their interaction mechanisms are studied experimentally based on the step-stress accelerated decay testing models with a subsystem isolated acceleration pattern; and the theoretical analysis method of the step-stress accelerated decay testing for the color shift process of LED luminaire is established. Second, statistics analysis models for CS paths are established by analyzing experimental CS laws of lamp system; the statistics models are associated with the CS decay mechanisms under different testing stresses; consequently, a reliability evaluation model for lamp system CS procedure is established, and life-span characteristics of LED lamp CS failure are analyzed. Furthermore, the CS induced mechanisms and accordingly main characteristic parameters for the key CS factors are explored deeply; the effect rules of lamp CS induced by key CS factors are then elucidated, and the correlation mechanisms between characteristic parameters of key CS mechanisms and environmental stresses are illustrated; consequently, a Reliability prediction model focused on the key CS mechanisms of LED luminaires is developed. The project study results are of important scientific meaning and application value on LED product design, manufacturing and reliability evaluation.

色漂是LED照明灯具的关键失效模式之一，已成为系统评估LED灯具可靠性的研究重点。本项目针对LED照明产业的重大需求，开展LED灯具色漂退化机理及其可靠性建模研究。首先采用高加速极限应力退化试验，进行灯具的色漂极限应力研究，获得可保证色漂机理一致的加速试验极限应力；结合子系统隔离加速的步进应力加速衰减试验模型，试验研究引起灯具色漂的关键因素及其相互作用机制，建立灯具色漂的步进应力加速试验理论分析方法。然后分析灯具系统色漂轨迹的漂移规律，建立基于色漂退化机理的色漂轨迹统计分析模型，建立灯具系统色漂的可靠性评估模型，分析灯具色漂失效的寿命特征；进而深入研究灯具色漂关键因素的色漂诱导机理及其主要表征参数，阐明关键因素诱导灯具色漂的作用规律，揭示关键色漂机理与环境应力的关联机制，建立基于关键色漂机理的LED灯具可靠性预测模型。研究成果将对LED产品设计、制造及可靠性评估具有重要科学意义和应用价值。

高可靠性和高光学性能是LED产品进入普通照明领域的重要保障。色漂是LED照明灯具的关键失效模式之一，是系统评估LED灯具可靠性的研究重点。本项目针对LED照明产业的重大需求，研究LED灯具色漂退化机理及其可靠性建模。.采用高加速极限应力试验，进行了LED灯具、器件、封装部件的色漂极限应力研究，获得了可保证色漂机理一致的加速试验极限应力；结合子系统隔离加速的步进应力加速衰减试验模型，试验研究明确了引起灯具色漂的关键因素及其相互作用机制，建立了灯具色漂的步进应力加速试验理论分析方法；分析灯具、器件、封装部件老化引起的色漂规律，建立了适用色漂退化机理的色漂轨迹统计分析模型，对典型加速试验灯具、封装建立了色漂可靠性评估预测模型，并分析了色漂的寿命特征；进行了灯具色漂关键因素的主要表征参数分析，建立了关键色漂机理影响因素的可靠性模型，并进行寿命特征分析。此外针对影响LED产品光色可靠性的界面失效模式，建立功率封装质量特征的无损表征、检测分析方法。.揭示了LED灯具关键色漂机理关联因素及其与环境应力的关联机制。研究结果表明高加速极限应力试验获得的试验极限热应力能有效确保灯具色漂退化机理保持一致，并且经由提出的线性幂轨迹分析模型检验灯具色漂机理假设常量，能有效检验LED产品色漂机理改变过程；步进应力加速色漂衰减试验结果表明LED灯具、器件及关键部件所呈现的色漂轨迹均与试验环境应力加载历史无关，仅与当前加载的应力有关；白光LED封装的荧光粉成分对灯具色漂贡献非常大，随着试验应力水平提高其作用更突出。LED封装透镜老化对灯具色漂影响贡献仅次于荧光粉影响，且受荧光粉影响很大，其受氧化、吸潮影响黄化，严重影响透光性能。可靠性建模分析结果表明基于实际服役条件对LED器件、关键色漂因素的可靠性评估结果能更有效反映灯具实际色漂性能特征。.本项目提出了LED灯具色漂的高加速极限应力检测方法，并建立了步进应力加速色漂可靠性试验评估方法及建模分析理论，对LED灯具系统可靠性分析具有重要参考意义和应用价值；同时针对色漂轨迹统计需求提出线性幂轨迹分析模型，为LED灯具产品可靠性分析提供了一种新的建模思路。研究成果对LED灯具的设计、制造、应用及可靠性评估提供了依据。