Apparatus for automatically replenishing an electroless plating bath

摘要

An apparatus for maintaining the consumable components of an electroless plating solution at predetermined concentration in a plating tank containing the plating solution while workpieces are being processed in the tank. The apparatus measures the concentrations of the consumable components in a sample stream of the electroless plating solution and based on these measurements, meters the required amounts of the components into the plating solution. A portion of the apparatus provides for the introduction of plating solution poison into the sample stream to prevent autocatalytic decomposition and deposition of the plating metal, e.g., copper, onto to the walls and sensors of the apparatus.