METHOD FOR CONTROLLING COPPER SULFATE PLATING BATH

摘要

PURPOSE:To keep the stability of a copper sulfate plating bath and to prevent defective plating by determining the concn. of an additive in the bath, calculating a deficient amount in the additive from the result, replenishing the deficient amount and further filtering off the by-product by activated carbon. CONSTITUTION:A fixed amt. of the plating soln. is sampled from a copper sulfate plating tank 1 and sent to an automatic additive analyzer 2. The additive concn. in the plating soln. is determined by the potential-scanning stripping method using a rotary electrode. A deficiency in the additive is calculated by a controller 3 from the additive concn. The deficiency is replenished to the tank 1 from an additive tank 4a through a fixed delivery pump 4. An activated-carbon filtration circulating pump 6 is operated in accordance with the integrated supply of the additive to circulate the plating soln. through an activated-carbon tank filter 5, and the by-product in the plating bath is filtered off by the activated carbon. Consequently, the additive concn. in the bath is kept in a specified range, the stability of the bath is maintained, and defective plating is prevented.