板级跌落试验下BGA焊球的疲劳裂纹行为研究

Study on Fatigue Behavior of BGA Soldering Under Board Level Drop Test

BGA焊球内部裂纹的生长是跌落可靠性试验中焊球失效的根本原因。比较和研究了无铅及有铅焊球在板级跌落试验下疲劳裂纹的行为。通过跌落试验获得了BGA焊球在不同加速度水平下的平均寿命,接着在同一加速度水平下跌落不同次数,使用荧光染色法观察焊球内部裂纹的生成和扩展行为,得到无铅及有铅BGA焊球内部裂纹随跌落次数增加的不同生长规律。根据观察结果分析和讨论了跌落试验下裂纹随跌落次数增加时的扩展行为及其原理,进一步阐明了BGA焊球的失效原因和失效机制。

The crack extending inside the BGA soldering is considered as the root cause of the fatigue failure. The fatigue behavior of the BGA leaded and lead-free soldering under board level drop test was studied. The life of soldering in drop test was measured under different acceleration levels. The different rules of crack propagation of leaded and lead-free soldering were observed by dropping different times under fixed acceleration level. The initiation and propagation of soldering cracks were characterized using fluorescence-dye method. The principle of crack propagating and extending under this circumstance were analyzed and discussed for the better understanding the failure cause and mechanism of the BGA soldering.