无氰金-锡合金电镀液的成分优化及电流密度确定

Composition Optimization and Determination of Current Density of Electroplating Solution for Non-cyanide Au-Sn Alloy

以室温下稳定的Ivey无氰金-锡合金镀液为基础,用EDTA代替柠檬酸铵作为金离子络合剂,焦磷酸钾作为锡离子络合剂,将镀液pH值从6.0调整到8.0,新开发了一种高温下稳定的无氰金-锡合金镀液(50℃保温5 h不分解);研究了该无氰镀液中氯金酸钠浓度和电流密度D对镀液稳定性和镀层成分及生长速度的影响。结果表明:当温度为45℃时,保持镀液中其他成分及其浓度不变,氯金酸钠质量浓度为10 g.L-1时,合金镀层的生长速度最快且镀液的稳定性也较好;当D在6～10 mA.cm-2范围内时,随着D的增大,镀层晶粒尺寸不断增大,镀层生长速度先增大后减小,在7 mA.cm-2时镀层生长速度最快,达24μm.h-1;应用此镀液在蒸镀有金种子层并用光刻胶刻蚀出图形的硅片上电镀得到了金-锡凸点,凸点形状规则,内部成分均匀。

Based on the stable Ivey non-cyanide Au-Sn alloy plating solution at room temperature,a new stable non-cyanide Au-Sn alloy plating solution at high temperatures was developed which could kept stable at 50 ℃ for 5 h without decomposition,using EDTA which was instead of ammonium citrate as gold ion complexing agent,potassium pyrophosphate as tinion complexing agent and adjusting the plating solution pH value from 6.0 to 8.0.The effects of NaAuCl4·2H2O concentration and current density（D） on the solution stability,coating composition and the growth rate of the non-cyanide plating solution were investigated.The results show that at 45 ℃ and kept the other composition as well as the concentration of the solution stable,the fastest growth rate of the coating was obtained and its stability was good when the NaAuCl4·2H2O concentration was 10 g·L-1.When the D value was in the range of 6-10 mA·cm-2,with the increasing of D the grain size of the coating increased and the growth rate of the coating increased first and then decreased.When the D value was 7 mA·cm-2,the growth rate was the fastest which increased to 24 μm·h-1.Au-Sn bumps electroplated on Si substrate（vapor plating with Au seed layer） in the plating solution had regular shape,and the composition was homogeneous.