Apparatus for controlling electroless plating bath

摘要

A method and an apparatus for controlling an electroless plating bath such as an electroless nickel plating bath capable of using the bath for an extended period of time without remake are disclosed. The method comprises the steps of continuously or intermittently measuring the concentration of at least one consumable ingredient in the electroless plating bath, and automatically adding to the plating bath a first replenishing composition essentially consisting of consumable ingredients after detecting that the measured value has reached a predetermined concentration; while continuously or intermittently measuring the consumed amount of at least one consumable ingredient of the electroless plating bath to determine the degree of aging of the bath, and automatically discharging the predetermined volume of the plating solution and automatically adding to the plating bath a second replenishing composition containing nonconsumable ingredients in an amount essentially corresponding to a lost amount by the discharging after detecting that the consumed amount of the consumable ingredients has reached a predetermined value.