一种基于焊点形态的可焊性分析方法

通过扫描电镜对润湿不良（不充分）焊盘进行分析，背散射电子图像下在焊料润湿边界处可观察到一条带状区域，在此称之为润湿过渡层。经过大量观察分析发现润湿过渡层是焊料在焊盘表面润湿焊接界面反应的起始位置，因而其形态随着焊接条件以及焊盘的状态变化而变化。文章通过对回流贴装焊接过程中回流温度、老化引起的润湿过渡层形态差异变化的分析，总结出通过润湿过渡层形态观察对被焊面润湿性进行焊接后评估的方法，为可焊性失效分析提供新的分析思路。

A solderability analysis method based on the form of welding spot

In the backscattered electron image of scanning electron microscopy （SEM）, a strip zone can be observed at the solder wetting boundaries of the poor wetting pads after delfux. It is the starting position of the interface reaction in the welding process, so the form of the wetting transition layer changes with the condition changes of relfow process and the pads. In this paper, based on the analysis of the different forms of the wetting transition layer formed in different relfow temperature or PCB aging condition in relfow process, a new method for judging the wetting ability after soldering was established and a new way for solderability failure analysis was provided.