研究了电流和温度应力因子及其共同作用时对GaN基白光LED可靠性的影响, 并从LED结构方面探究了各应力下LED的失效机理。结果表明, 以电流作为加速应力时, 荧光粉退化为其主要的失效方式, 同时LED出光的相关色温上升, 红色比减少; 在热应力下,主要是LED芯片结构发生变化, 峰值波长蓝移, 光通量衰减, 同时支架出现老化现象。电流和温度应力共同作用时, 温度应力对LED光通量的影响大于电流应力。电-热应力下的光通量衰减大于电、热应力单独作用时的衰减之和, 即电-热应力作用时, 光衰不具有线性叠加性。

The effects of current-temperature stress on the reliability of LED were investigated, and the failure mechanism was analyzed from the structure of LED. It is found that the current and temperature have different influences on the reliability of LED. When LEDs are applied current accelerating stress, the degradation of phosphor is the main failure mode which can cause the increasing of correlated color temperature and decreasing of red ratio. When LEDs are applied temperature accelerating stress, the structure of chip would change, which leads to the blueshift of peak wavelength. In addition, the structure of housing also appears aging at high temperature. The temperature stress has greater effect on the reliability than current stress when the current stress and temperature stress are applied together. The attenuation of luminous flux under current-temperature stress is greater than the sum of current and temperature stress working alone, which namely implies that the current and temperature stress do not have the features of linear superposition.