添加剂对无氰电镀铜-锡合金(低锡)镀层性能的影响

通过赫尔槽试验与直流电解试验,研究了添加剂在焦磷酸盐溶液体系无氰电镀铜-锡合金(低锡)工艺中的作用。该体系镀液组成与工艺条件为:Cu2P2O7·3H2O25g/L,Sn2P2O71.0g/L,K4P2O7·3H2O250g/L,K2HPO4·3H2O60g/L,温度25℃,pH8.5,电流密度1.0A/dm2。采用扫描电镜(SEM)、X射线衍射(XRD)、能谱(EDS)、中性盐雾试验等方法研究了添加剂对镀层组成结构、外观、耐腐蚀性能及微观形貌的影响。结果表明,焦磷酸盐溶液体系无氰电镀铜-锡合金(低锡)时使用有机胺类添加剂可抑制Sn的析出,使合金镀层致密均匀,耐蚀性能好。镀层结晶主要为Cu13.7Sn结构,镀层中Sn含量为9%～11%。镀液中添加剂的使用量增加,则合金镀层中的Sn含量降低。

Effects of additives on properties of low-tin copper-tin alloy coating electroplated from a cyanide-free bath

The action of some additives on cyanide-free electroplating of low-tin Cu-Sn alloy in pyrophosphate bath was studied by Hull cell test and direct-current electrolysis experiment.The bath composition and process conditions are as follows:Cu 2 P 2 O 7 ·3H 2 O 25 g/L,Sn 2 P 2 O 7 1.0 g/L,K 4 P 2 O 7 ·3H 2 O 250 g/L,K 2 HPO 4 ·3H 2 O 60 g/L,temperature 25℃,pH 8.5,and current density 1.0 A/dm 2.The effects of additives on the constitution,appearance,corrosion resistance,and micro-morphology were studied by scanning electron microscopy (SEM),X-ray diffraction (XRD),energy-dispersive spectroscopy (EDS),and neutral salt spray test.The results showed that organic amine additive inhibits the deposition of Sn from the pyrophosphate bath,and makes the deposit more compact and uniform and presenting good corrosion resistance.The deposit is mainly of Cu 13.7 Sn structure,and content 9%-11% Sn.The content of Sn in Cu-Sn alloy deposit is decreased with increasing content of the additive in plating bath.