LED典型失效机理

Typical Failure Mechanism of LEDs

鉴于LED芯片尺寸较小,散热和成本的压力,LED封装难度很大,暴露出来的可靠性问题也最多。LED失效后,往往能够通过电参数测试、内部形貌分析、剖面检查、SEM检查等方法暴露失效现象、分析出失效机理,最终提出改进意见,提高器件的良品率。根据失效分析实例剖析了LED典型失效机理:LED芯片缺陷和腐蚀;LED芯片粘结用导电胶腐蚀、使用不当导致开路或短路;LED芯片金丝键合损伤;LED封装结构设计不当,导致机械应力集中损伤芯片;LED器件使用不当——过流烧毁、ESD损伤、焊接不良或焊料迁移。并分别提出了相应的改进建议。

Because the LED size is only a few millimeters,and the requirements for the cost and cooling are higher,the LED packaging is more difficult.Thus the failure of LED package is the most common.The electrical parameter testing,internal visual,section inspection and SEM inspection are all helpful to find the failure phenomenon and conclude the failure mechanism.Then the solutions to improve the yield rate were found out. The failure mechanisms were analyzed,such as the defects and erosion of the LED chip;the erosion and misuse of electrically conductive adhesives（ECA）;the defects of gold wire bonding;the defects of package structure;the misuse of LED device,including over current,ESD injury,poor soldering,emission of soldering flux.And the advice were brought forward correspondingly.