添加剂对无氰电镀白铜锡工艺的影响

Effects of additives on cyanide-free white copper-tin alloy electroplating

研究了多种胺类高分子添加剂对焦磷酸盐体系无氰电镀白铜锡工艺及镀层微观形貌的影响。基础镀液的组成为:K4P2O7·3H2O200～250g/L,Cu2P2O7·3H2O16～19g/L,Sn2P2O712～15g/L,pH8.5～8.7。以IEP(水性阳离子季铵盐)、DPTHE(多胺高分子聚合物)和JZ-1(胺类化合物)作添加剂时,均可在较宽的电流密度范围内得到白亮铜锡合金镀层。以IEP作添加剂时,电镀白铜锡的电流密度上限最高为3.70A/dm2;以DPTHE作添加剂时,电镀白铜锡合金镀层的电流密度下限最低为0.09A/dm2,可抑制低电流密度区形成金黄色低锡铜锡合金。以IEP和DPTHE作添加剂时,均可使白铜锡合金镀层持续增厚,电镀50min可得到白亮、无裂纹的镀层,且IEP具有更明显的整平和细化晶粒作用。

The effects of different kinds of additives on the plating process and surface morphology of white copper–tin alloy coatings were studied in a cyanide-free pyrophosphate plating bath. The basic bath composition is as follows： K4P2O7·3H2O 200-250 g/L, Cu2P2O7·3H2O 16-19 g/L, Sn2P2O7 12-15 g/L, and pH 8.5-8.7. Bright white copper-tin alloy coatings can be obtained over wide range of current density when using IEP （a water-soluble quaternary ammonium salt cation）, DPTHE （a high-molecular-weight polyamine） and JZ-1 （an amine compound） as the additive. The upper limit of current density for white copper-tin alloy plating is up to 3.70 A/dm 2 while using IEP. The lower limit of current density for white copper-tin alloy plating is 0.09 A/dm 2 when using DPTHE. DPTHE can inhibit the forming of golden low-tin copper–tin alloy at low current density area. The white copper–tin alloy coatings can be thickened continually when using IEP and DPTHE, and are still brightly white and crack-free after plating for 50 min. IEP has more obvious leveling and grain-refining effects.