大功率白光LED作为新一代照明光源的优势越来越明显，但其光衰机制综合了YAG荧光粉、LED芯片以及封装散热多重因素，衰减机理复杂。为研究LED芯片与荧光胶的相互热影响，基于蓝光LED器件基板温度可控实现蓝光LED器件温度稳定，并通过外部加热（以此作为LED热量作用于荧光胶）的方式控制荧光胶、荧光粉、硅胶的温度。重点研究了温度从27 ℃升高到220 ℃对三者光衰、主波长特性的影响。对荧光胶与LED芯片的近距离相互热影响进行了测试，结果表明荧光粉涂覆量会引起光功率的降低，而且随着光功率的降低，LED芯片结温呈现指数升高。实验证明荧光胶层与LED芯片是一个相互影响的复合热源模型。

The lighting advantages become more and more obvious for the white high power light emitting diode (HP-LED) as the next generation lighting source. But the light decay mechanism is complicated because of the compositions of the LED chip, YAG phosphor and even the thermal management of packaging. In order to investigate the light decay mechanism of the white HP-LED, the effects of temperature on the silicone-gel with phosphor, YAG phosphor particles and the silicone-gel are studied, respectively. The optical properties of the blue LED chip are kept in steady state by the HP-LED substrate temperature controlling. The silicone-gel with phosphor, YAG phosphor particles and the silicone-gel is heated by a heating source respectively. The tested results show that the optical radiant power decreases as an exponential relation with the temperature increasing from 27 ℃ to 220 ℃. The thermal properties of the phosphor layer coated on the HP-LED are studied. Results show that the phosphor layer coating can affect the radiant power and the pn junction temperature of the HP-LED. The above results show that the white HP-LED is a heat source interacted both with the LED chip and the YAG phosphor particles.