亚硫酸盐／硫代硫酸盐体系无氰镀铜

Cyanide-free copper electroplating in sulfite/thiosulfate bath

采用黄铜和不锈钢为基体，以SO3^2-／S2O3^2-为还原剂和配位剂，胺化合物为配位剂，研究了一价铜无氰镀铜工艺，其镀液组成和操作条件为：CuCl2．2H2016．0～21．3g／L，SO3^2-／S2O3^2-0．475mol／L，胺化合物0．76mol／L，H3BO3 36g/L，葡萄糖0．38mol／L，光亮剂（有机胺类化合物）0．04mL／L，温度40℃，pH8（以KOH调节），搅拌，电流密度0．5～2．0A／dm^2。讨论了温度、pH、铜离子质量浓度和光亮剂体积分数对镀层质量及电流效率的影响，分别采用扫描电镜和x射线衍射表征了镀层的表面形貌和结构。结果表明，控制合适的条件可使电流效率超过90％。使用本工艺电镀时，应采用较高的镀液pH，但镀液在存置时宜控制在较低的pH。添加剂能提高镀液的整平性能，使铜镀层只出现（111）和（200）晶面，光亮度提高，晶粒更细小、致密，颗粒分布均匀。

A cyanide-free copper electroplating process with sulfite/thiosulfate as reducing and complexing agents, amine compound as complexing agent and cuprous ions as main salt was studied using brass and stainless steel as substrates. The bath composition and operation conditions are CuCl2·2H2O 16.0-21.3 g/L, sulfite/thiosulfate 0.457 mol/L, amine compound 0.76 mol/L, H3BO3 36 g/L, glucose 0.38 mol/L, brightener （organic amine compound） 0.04 mL/L, temperature 40 ℃, pH 8 （adjusted with KOH）, agitation, and current density 0.5-2.0 A/dm^2. The effects of temperature, pH, mass concentration of copper ions and volume fraction of brightener on the deposit quality and current efficiency were discussed. The structure and surface morphology of the deposit were characterized by SEM and X-ray diffraction,respectively. The results showed that the current efficiency can reach over 90% by appropriately controlling the conditions. The bath pH should be relatively high in operation, but relatively low during storage. The additive can improve the leveling performance of the bath, lead to the unique formation of （111） and （200） oriented faces of copper deposit, increase the deposit brightness, and make grains smaller, more compact and more uniformly distributed.