低锡铜–锡合金无氰电镀工艺

Process of cyanide-free low-tin copper-tin alloy electroplating

通过赫尔槽试验研究了镀液组成、pH和温度对低锡铜-锡合金镀层外观的影响,并用方槽电镀试验研究了时间和电流密度对低锡铜-锡合金镀层的厚度与组成的影响,得到最佳镀液配方与工艺条件为:Cu2P2O7.3H2O25g/L,Sn2P2O71.0g/L,K4P2O7.3H2O250g/L,K2HPO4.3H2O60g/L,pH8.5,1.0A/dm2,25°C,20min,通气搅拌。采用最佳工艺配方制得的低锡铜-锡合金镀层为金黄色,表面均匀光亮,含铜量为85%～95%(质量分数),与基体的结合力好,抗变色性好。

The effects of bath composition, pH and temperature on the appearance of low-tin Cu-Sn alloy coating were studied by Hull cell test. The effects of deposition time and current density on the thickness and composition of coating were also studied by square cell plating test. The optimal bath composition and process parameters are as follows： ：Cu2P2O7·3H2O25g/L,Sn2P2O7 1.0g/L,K4P2O7·3H2O250g/L,K2HPO4·3H2O 60g/L, temperature 25℃, pH 8.5, current density 1.0 A/dm2, time 20 min, and aeration/agitation. Under the given process conditions, the Cu-Sn alloy coating obtained is golden, bright and uniform, containing copper 85wt%-95wt% and having the advantages of high tarnish resistance and good adhesion to substrate.