测试和比较了大功率白光lEd在高温耐电(HTCd)和高温存储(HTS)两种老化条件的光热性能变化。结果表明,在HTCd老化下,光通量衰减达到40~60%;而HTS下的衰减只有10~14%。这说明,电流应力对lEd的寿命影响比较大。利用热阻瞬态响应法测试和结构函数理论分析两种高温老化条件下lEd的热特性,结果表明,在HTCd老化下lEd热阻的变化较HTS更为明显,并且热阻变化大多体现在导热Ag胶层。这主要是由于高温条件下电流应力引起Ag颗粒的空间分布不均,使粘结界面产生空隙导致热阻发生不同程度的改变。In this paper,high temperature current driving(HTCD) stress and high temperature storing(HTS) stress are applied to study the degradation and thermal characteristics of high power LEDs.The results show a larger light dimming of 40%-60%under temperature-current-combined stress,and only 10%-14% dimming under temperature-only stress,demonstrating more obvious influence of the current stress on LED′s lifetime.The junction-to-case thermal resistance has changed a little under both degradation methods,with a larger change under the temperature-current-combined stress.The change mainly happens in the die attachment layer of the power LED,i.e.,the silver layer.The reason is that the inhomogeneous spatial distribution of silver particles results in gaps in the bonding interface under the high temperature.国家“863”计划(2006AA03A175);福建省科技计划(2008J0030);厦门大学基础创新科研基金(中央高校基本科研业务费专项资金)(2011121046)资助项
