印制电路板通孔电镀铜添加剂的优化

Optimization of additives for copper electroplating of through holes on printed circuit board

采用由75 g/L CuSO4?5H2O、230 g/L硫酸和添加剂组成的酸性镀铜液,在温度(22±3)°C、电流密度1.7 A/dm^2和空气搅拌的条件下,对印制电路板(PCB)通孔进行电镀铜填孔。以填孔率、凹陷值、面铜厚度和通孔截面为指标,研究了Cl^?、聚乙二醇(PEG-10000)、聚二硫二丙烷磺酸钠(SPS)和2,2′?二硫代二吡啶(2-PDS)4种添加剂对填孔效果的影响。得到较优的添加剂组合为:Cl?50~70 mg/L,PEG-10000 200~300 mg/L,SPS 8~11 mg/L,2-PDS 9~13 mg/L。采用该组合添加剂时填孔率高达91.7%,镀层均匀、细致、平整,抗高温循环和耐浸锡热冲击性能良好,满足PCB的可靠性要求。

The filling of through holes on print circuit board(PCB)were carried out by copper electroplating in an acidic bath comprising 75 g/L CuSO4·5H2O,230 g/L H2SO4,and some additives at temperature(22±3)°C and current density 1.7 A/dm^2 under air agitation.The effects of four types of additives including Cl^?,polyethylene glycol(PEG-10000),3,3′-dithiodipropane sulfonate(SPS),and 2,2′-dithiopyridine(2-PDS)on the hole filling were studied by evaluating the filling efficiency,dimple,copper coating thickness on the surface,and cross-sectional morphology of the filled through hole.The combination of additives was optimized as follows:Cl?50-70 mg/L,PEG-10000 200-300 mg/L,SPS 8-11 mg/L,and 2-PDS 9-13 mg/L.The hole filling efficiency was up to 91.7%when electroplating with the optimized combination of additives.The copper coatings obtained were uniform,compact,and smooth,and had good resistance to thermal shock in temperature cycling and tin immersion tests,meeting the requirements of reliability for PCB application.