Electrochemical refractory metal stripper and parts cleaning process

Abstract

An electrochemical process for removing deposited tungsten from metal parts is described. The electrolyte solution is a basic solution containing a polydentate ligand. The solution is typically comprised of water, ammonium or alkali base, and a chelating or sequestering agent. The parts to be cleaned are biased anodically. The cathodes are preferably constructed of nickel. As hydroxide tungsten complexes and chelated tungsten complexes are formed, oxidation and dissolution of the deposited tungsten is promoted. The oxides form a thin layer on the metal parts, thus protecting the underlying metal part from the electrochemical reaction itself. Once the oxides are formed, that is, once the reaction has reached an end, the parts are removed. The oxides are wiped off, leaving a metal part surface with a high luster, thus improving the performance of the deposition equipment parts.