September 2000

Fregen - ELECTROCHEMICAL REGENERATION OF FERRIC CHLORIDE AND CUPRIC CHLORIDE ETCH SOLUTIONS

EDA has developed an electrochemical system for regeneration of common etch solutions and simultaneous removal oftrarnp metal. Laboratory work on spent etch solutions has shown that their performance is related to the ratio of concentration of the oxidized 10 reduced state of the active agent. This is measured and monitor· ed electrically and is known to analysts as the Oxygen Redox Potential (ORP). Electro~ chemical oxidation of the clehant solution and simultaneous removal of dissolved etched materials can be used to fully recover working solutions. Combining these two techniques, monilOring of the etchant strength and controlling the degree of electrochemical treatment can be used to maintain consistent petformances in the etch bath hour after hour. Our equipment has been rlln for several months at a nameplate manufacturing plant, demon· strating that Oxygen Redox Potential can be maintained at a high levels while extending the etch solution life by at least 6 times. Metal etched into solution from the workpiece is broadly in balance with plated tramp metal, which is removed from solution as dendritic, high-surface-area metal. The ability to maintain a more consistent, potent and long-lived etch is beneficial to the consistency, quality, performance and economics of the etching process.