Gold separable manner and update manner null of non electrolysis gold-plating

摘要

PROBLEM TO BE SOLVED: To simply renew an electroless gold plating bath contg. soluble gold salt and a reducing agent at a low cost without recovering gold from the bath by reducing the pH of the bath and depositing and separating gold. ;SOLUTION: After the use of an electroless gold plating bath of pH about 12.5 to 14.0 contg. soluble gold salt such as kaU(CN)₂ and a reducing agent such as dimethylamine borane, which is mixed with an acidic soln. such as an aq. soln. of sulfuric acid to reduce the pH thereof to ≤12.5. In this way, the reducing power of the plating bath is increased to deposite gold by approximately the total content. Next, the top part contg. no gold components is removed. The obtd. coarse gold is mixed with an oxidizing agent such as KCN and sodium nitrobenzenesulfonate, which is redissolved, thereafter, newly, the plating soln. or a replenishing soln. contg. required components other than gold is added, and new electroless plating bath is made up.;COPYRIGHT: (C)1997,JPO