An Economic, Environment-friendly Oxygen-Hydrochloric Acid Regeneration System for Ferric Chloride Etchants used in Photochemical Machining

This paper describes the implementation of a low-cost, environment-friendly, oxygen-based regeneration system into a commercial etching line. The system has been investigated from both technical and economic viewpoints. It has been demonstrated to be cheaper than alternative regeneration techniques but it is only feasible when etchant parameters are monitored and controlled on-line to prevent the precipitation of ferrous salts. From analysis of the system, it was discovered that the most important parameter to control is the etchant pH. This not only influences the ability to regenerate but also dictates the resultant surface finish of the etched product.