PCB通孔电镀层剥离失效原因分析及改进

Reason analysis on delamination between electroplated copper coatings of through holes and corresponding improvement measures

针对高厚径比印制电路板(PCB)通孔的镀层剥离问题,先通过分析镀层剥离部位的微观形貌和元素组成推测相关因素,再通过试验进行验证。结果发现,镀层剥离位于两次加厚铜镀层之间,主要是因为一次电镀层氧化,造成二次沉铜过程中微蚀效果不佳,引起镀层间结合力下降。改用连续两次沉铜后再连续两次电镀的工艺后,上述问题得以解决。

As for the delamination problem between copper coatings of through holes with a high aspect ratio on printed circuit board(PCB),the corresponding factors were speculated by analyzing the micromorphology and elemental composition of delaminated parts of coating firstly,and then verification experiments were conducted.It was found that the delamination occurred between the firstly and secondarily electroplated copper coatings.The primary causes are concluded as follows:the slight etching effectiveness during secondarily copper electroplating was poor due to the oxidation of firstly electroplated copper coating,leading to weak adhesion between two layers of copper coatings.The problem could be solved after adopting a modified process:electroless copper plating successively twice followed by copper electroplating successively twice.