| 摘要 |
PURPOSE:To obtain a silver plating soln. having long pot life at ordinary temp. and capable of rapidly depositing silver and forming a homogeneous silver film even when allowed to stand for a long time after preparation, by using EDTA or an alkali metal salt or NH4 salt thereof and a reducing agent besides silver nitrate. CONSTITUTION:A compd. (complexing agent) forming a complex compd. of Ag, e.g., an aq. NH3 soln. is added to a silver plating soln. contg. silver nitrate preferably at 2.5-4.5 g/l concn. EDTA or an alkali metal salt or NH4 salt thereof as an additive and a reducing agent are further added to the plating soln. The proper amt. of the additive used is 30-40g per 1l plating soln. and that ot the reducing agent is nearly equivalent to the amt. of the silver nitrate. Since Ag ions in the silver plating soln. are chelated by the additive, the reduction reaction of Al ions at ordinary temp. is decelerated and the pot life of the plating soln. is prolonged. By heating the plating soln. to about 45-55 deg.C, the reduction reaction is quickly initiated. |
