无氰电镀白铜锡工艺与镀层性能

Process for cyanide-free white cooper-tin alloy plating and the coating properties

通过赫尔槽试验与方槽试验研究了镀液组成和工艺条件对白铜锡电镀层外观与组成的影响。最佳镀液组成与工艺条件为:Cu2P2O7·3H2O16～19g/L,Sn2P2O712～15g/L,K4P2O7·3H2O200～250g/L,K2HPO460～80g/L,有机胺类添加剂JZ-11.2～1.8mL/L,pH=8.5～8.7,温度20～25°C,阴极电流密度1.0A/dm2。采用该工艺对基体施镀20min可得到厚度为5.09μm、锡的质量分数为40%～50%的均匀白亮的Cu-Sn合金镀层。Cu-Sn合金镀层的晶体结构以CuSn和Cu41Sn11为主,结晶细致、无微裂纹,显微硬度为372HV,耐蚀性能比相同厚度的光亮镍镀层好。

The effects of composition of plating bath and process parameters on the appearance and composition of white copper-tin coating were studied by Hull cell test and square cell test. The optimal composition of plating bath and process parameters are as follows： Cu2P2OT·3H20 16-19 g/L, SnzP207 12-15 g/L, K4P2OT·3H20 200-250 g/L, KzHPO4 60-80 g/L, organic amine additive JZ-1 1.2-1.8 mL/L, temperature 20-25℃, pH 8.5-8.7, and current density 1.0 A/dm2. Under the given process conditions, a uniformly white Cu-Sn alloy coating of 5.09 μm thick and containing Sn 40wt%-50wt% is obtained. The crystal of Cu-Sn alloy coating is mainly of CuSn and Cu41Sn11 1-based structure. The coating is compact and microcrack-free with a micro- hardness of 372 HV and better corrosion resistance than bright nickel coating with the same thickness.