Etchant Recovery System

Cupric chloride etchant is widely used in the etching of copper, particularly in the manufacture of printed circuit boards. Currently, hazardous oxidants such as chlorine are used to regenerate this etchant. In addition, the hazardous waste generated must be hauled away for disposal. In Phase II, Republic Anode Fabricators, Inc., will develop a device that will electrolytically regenerate the etchant without the addition of oxidizing chemicals. Additionally, it will recover copper metal and eliminate the formation of hazardous waste products. Republic Anode Fabricators already has developed an electrolytic system for ferric chloride etchant that will generate chlorine gas if used on cupric chloride etchant. Phase I of this research project was intended to develop ways of modifying the existing device so that chlorine gas could be used to regenerate the etchant and would not escape into the environment. Republic Anode Fabricators ultimately was successful in developing a sealed electrodeposition cell that accomplished this goal. With no chlorine escape, at least 90 percent of the theoretical amount of copper and 99.8 percent pure copper were recovered. In addition, the etchant was regenerated based on oxidation reduction potential (ORP) values. Republic Anode Fabricators has partnered with a firm that will help evaluate the experimental cell developed during Phase I. To accomplish this, the existing cell will be modified to increase its capacity for copper collection and throughput. The capabilities of the cell then will be modified on the customer’s production etching line. Following this study, Republic Anode Fabricators will design and build a small prototype working unit. The partnering firm will help evaluate the small prototype unit and will purchase the unit if all goes as planned. VTO will be performed on this working model. Tests will include copper purity, copper collection efficiency, ORP rate of increase, thermal effects, reliability and robustness of the unit, and economic considerations. Following this investigation, a larger prototype unit will be designed, built, customer-tested, evaluated, and sold. An independent marketing survey indicates a large potential market and an acceptable selling price within the anticipated range of system costs. The cost of electricity needed for the system is well below the current normal cost of the chemicals for etching copper. In addition, the recovered copper can be sold for more than the cost of etching. The elimination of hazardous waste production and hauling also is a major benefit for potential customers and recognized as such by the customers contacted in the independent survey.