印制板局部电镀金悬边问题的研究

Study on edge suspension of local gold plating on PCB

文章重点阐述了局部电金板镍金悬边过大和悬边断裂的原因分析和改善方案,并运用电化学原理和金属腐蚀学的理论解释这种想象的产生成因,做到理论和实际相结合。蚀刻悬边过大主要与排风量大小(O_(2)供应)、蚀刻喷淋压力、氯离子含量有关;悬边断裂主要与Ni、Cu、Au三种金属在退锡液中发生的原电池腐蚀有关,同时退锡液中的护铜剂又影响了原电池腐蚀的位置与进程;最后也提出了另一种避免蚀刻悬边的方案。

This paper focuses on the cause analysis and improvement scheme of the excessive overhanging edge and the overhanging edge fracture of the partially electro gold plating,and explains the causes of this phenomenon by using the electrochemical principle and the theory of metal corrosion,so as to combine theory with practice.The excessive overhanging edge of the etching is mainly related to the exhaust volume(O2 supply),the etching spray pressure,and the chloride ion content.The hanging edge fracture is mainly related to corrosion of primary batteries of Ni,Cu and Au in the tin stripping solution,and concentration of the copper protecting agent in tin stripping solution affects the position and process of corrosion of primary batteries.At last,another method to avoid edge overhanging is proposed.