通孔电镀中的折镀问题失效分析与改善

Failure Analysis and Improvement of Folding Plating Defect during PTH Hole Electroplating

针对在利用垂直沉铜与脉冲电镀组合工艺进行PCB通孔电镀过程中所发生的折镀问题进行了研究,借助扫描电镜对通孔折镀线及其两侧的铜晶格进行了对比分析,同时结合PCB通孔电镀的原理并基于DOE实验对可能引起"折镀"失效的各影响因素进行了验证。结果表明,折镀失效是因脉冲电镀过程中孔内折镀失效位置与周边位置铜原子结晶的成核与生长速率不同,二者之间铜晶格的致密性差异较大所致,而沉铜过程中除油剂三乙醇胺在孔壁严重粗糙处残留与脉冲电镀过程中高浓度的光亮剂协同作用是造成折镀失效位置与周边位置铜原子结晶的成核与生长速率不同的根本原因。

A research was investigated about folding plating defect which emerged during PTH hole electroplating process employing vertical electroless plating copper and pulse plating integrated technology. Meanwhile, a comparative analysis was conducted on copper lattice of the folding plating lines and their neighboring areas using SEM. Additionally, a confirmation of the factors which were attributed to folding plating defect was carried out based on PTH hole electroplating theory together with DOE experiments. It was turned out that folding plating defect could be attributed to the prominently different copper atom crystalizing and growing rates of folding plating spots and their surrounding areas during pulse plating, which led to a big copper lattice difference between them. It was also found that triethanolamine residue used as degreaser in electroless plating copper process in severe roughness spots of hole wall would performed a synergistic effect with high concentrated brightener, which was the fundamental reason leading to the prominently different copper atom crystalizing and growing rates of folding plating spots and their surrounding areas during pulse plating.