铟对金电镀的影响

Influence of Indium on Gold Plating

在柠檬酸盐镀金体系中，加入少量硬化元素Ｉｎ，形成Ａｕ－Ｉｎ合金镀层，从而改变了镀层的色泽和增加光亮度；电流密度比纯金电镀提高２～４倍，缩短了电镀时间。当Ｉｎ浓度为０．５～４ｇ／Ｌ、Ａｕ浓度为１０ｇ／Ｌ时，在３０～４０℃，电流密度０．２～１Ａ／ｄｍ２等参数下电镀，镀层中Ｉｎ含量随着镀液中Ｉｎ浓度的增加而略有增加，而Ｉｎ浓度＞４ｇ／Ｌ时，镀层中Ｉｎ含量明显增加。镀层硬度较纯金镀层提高一倍，Ｈｖ近２００。导电率不因Ｉｎ的引入而降低。耐盐雾腐蚀与纯金相同。可作为硬金镀层用于电器产品和防护装饰性电镀。

Au-In alloy deposit was prepared by the addition of a small amount of In as an addition agent to the normal citrate gold electrolyte. As a result, improvements on color and brightness of the deposit were achieved. The current density during the plating process was 2～4 times greater than that of the pure gold plating, and the perriod of the process was shortened. When the concentrations of In were 0.5～4g/L, temperatures 30～40℃ and current densities 0.2～1A/dm^2, the result about In content of tested deposits showed a little increase with the increase of the concentration of In in the electrolyte, but showed a great increase with the concentrations exceeding 4g/L. The hardness of the deposit was tested to be one more time greater than that of the pure gold deposit, Hv nearly 200. The conductivity was not be reduced with the addition of In. The result of salt spray test was the same as that of the pure gold deposit. This technique can, therefore, be applied to the electronic industry, protecting and decorative fields.