四羟丙基乙二胺和EDTA·2Na盐化学镀铜体系研究

Electroless Copper Plating in the Presence of THPED and EDTA·2Na as the Dual-Chelating Agent

为了降低成本、提高镀层质量和镀液的稳定性，以混合配位体（EDTA-2Na）代替THPED（四羟丙基乙二胺），系统研究了THPED和EDTA·2Na盐双配住体化学镀铜体系。对镀速、镀液稳定性及镀层附着力的研究结果表明，镀速随EDTA·2Na盐、硫酸铜和甲醛浓度的增加先升高后降低；随THPED浓度的增加先降低后升高；随溶液pH值和镀液温度增加而升高；添加剂亚铁氰化钾、α，α′-联吡啶和2-MBT虽均使镀速减慢，但能使镀层外观变好；聚乙二醇-1000（PEG-1000）对镀速影响较小，但能使镀层质量变好。其化学镀铜最佳条件为THPED 10．0g／L，EDTA·2Na 8．7g／L，CuS04-5H2O 12．0g／L，甲醛（37％-40％）16．0mL／L，α，α′-联吡啶10．0mg／L，亚铁氰化钾40．0mg／L，PEG-1000 1．0g／L，2-MBT（二巯基苯骈噻唑）0．5mg／L，pH值13．2及镀液温度50℃。在最佳条件下获得的镀层外观红亮、表面平整，镀液稳定，镀速达到4．05μm／h。由SEM分析可知，镀层表面平整、光滑、晶粒细致。

N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine (THPED) and ethyl-diamine-tetra acetic acid (EDTA·2Na) dual-chelating-agent system was introduced to decrease the costs and increase the stability of the bath and quality of the plating for electroless copper plating.Thus a systematical investigation was carried out with respect to the technology and plating performance based on the THPED-EDTA·2Na dual-chelating agent system.The optimized plating technology was determined,while the morphologies of the resulting platings were observed using a scanning electron microscope.Results indicated that the plating rate firstly increased and then decreased with increasing concentration of EDTA·2Na,while it firstly decreased and then increased with increasing concentration of THPED.Moreover,the plating rate firstly increased and then decreased with increasing concentration of CuSO-4· 5H-2O and HCHO,while it increased with increasing the pH value and temperature of the plating bath.Besides,the additives including 2-MBT,2,2-dipyridyl and K-4Fe(CN)-6·3H-2O had great effects on the plating rate and surface qualities of the copper coating,so did the additive polyethyleneglycol-1000(PEG-1000),although it had little effect on the plating rate.The optimized bath for the electroless copper plating was suggested to be composed of 10.0 g/L THPED,8.7 g/L EDTA·2Na,16.0 mL/L HCHO,12.0 g/L CuSO-4 5·H-2O,40.0 mg/L K-4Fe(CN)-6·3H-2O,10.0 mg/L 2,2′-dipyridyl,1.0 g/L PEG-1000,0.5 mg/L 2-MBT; and the optimized plating parameters were suggested to be pH value 13.2 and bath temperature 50 ℃.The plating bath showed good stability at the optimized plating conditions and the plating rate in a duration of 30 min was as high as 4.05 μm/h.The resulting copper coating was smooth and bright,showing good surface quality.