Approximately 15 million gallons of excess acid cupric chloride etchant are generated each year and this amount is growing 12-15% annually. This project concerns an innovative, electrolytic, recovery process that reduces excess etchant generation by 53% for acid cupric chloride etchers who use chemical regeneration. It is targeted particularly at printed circuit (PC) board and leadframe etchers who employ chemical regeneration and require an etchant purge to hold down impurities like photoresist organics from PC boards, and the 4% nickel in popular leadframe alloy 7025, respectively. Even the simplest process version captures 91% of the copper etched as high-value plate, while reducing makeup HCl required for regeneration by 57%. Incorporating electrodialysis into the process lowers makeup HCl even more. Key to process success is recent availability of novel proton-selective membranes, which would separate anode and cathode compartments in recovery cells. Being selectively permeable to protons, the membranes do not pass other ionic species at an appreciable rate. Non-ionic species, the most important being water, are similarly prevented from cross-over. The overall objective of this Phase I project is to demonstrate feasibility of this process applied to both PC board fabrication and leadframe etching.
