CONSTITUENT MAINTENANCE OF A COPPER SULFATE BATH THROUGH CHEMICAL DISSOLUTION OF COPPER METAL

摘要

A copper electroplating bath is provided with a constant source of copper ions by monitoring the copper concentration in the bath. Copper metal is dissolved with sulfuric acid in the separate system which comprises one or more reactors that are electrically isolated from the bath. The reactors are pressurized with oxygen gas. Plating bath that is depleted of copper is transferred to a mixing tank where it is mixed with copper solution from the reactor(s). The replenished plating solution is filtered and is returned to the plating bath. The dissolution rate of the copper is determined by the rate of oxygen addition to the reactors which in turn is controlled by the pressure of the oxygen in the reactors and the use of a controller such as an ampere-time indicator which monitors the amount of electrical current applied to the plating tank during operation.