Method for measuring the relative etching or stripping rate of a solution

Abstract

A pair of relatively inert metal electrodes 14 and 16 are immersed in a metal processing solution 10. The metal processing solution 10 is of the type that oxidizes a metal dissimilar from that of the electrodes from the elemental state to the ionic state. A predetermined potential is applied for a predetermined time across the electrodes to create a direct current through the solution, thereby plating a determinable quantity of the metal ionic species on one of the electrodes as a metal. After the potential is removed from the electrodes, the elapsed time required for essentially all of the metal to be reoxidized to the ionic state by the processing solution is measured. Since the plated metal is dissimilar from that of the electrode, a galvanic cell is formed. Thus, the elapsed time can be measured, for example, by coupling an external load in series with the two electrodes and noting the elapsed time during which a current flows through the load. The elapsed time thus measured provides a direct indication of the etching or stripping rate of the solution.

Dependencies are inferred from the claim text.