Patent ID: 6454958
Filing Date: 2002-09-24
Classification: C23F

Abstract:
A method for operating an etching bath comprising:dipping a metal workpiece in the etching bath, the etching bath containing an etching medium, the metal being oxidized by a chemical reaction between the mete and the etching medium and converted into a complexed metal ion dissolved with the etching medium; removing a mixture of the dissolved complexed metal ion and the etching medium from the etching bath at a concentration of the dissolved complexed metal that is below a saturation limit of the dissolved complexed metal ion; separating the etching medium from the mixture via a nanofiltration using a principle of reverse osmosis so as to provide recovered etching medium and a residue while concentrating the complexed metal ion in the residue; reusing the recovered etching medium in the etching bath; and performing a recovery process on the dissolved complexed metal ion.