Etchant Recovery System

Cupric chloride etchant is in wide use 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 and disposed of. The device under development 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. An electrolytic system we have already developed for ferric chloride etchant will generate chlorine gas if utilized on cupric chloride etchant. The Phase I program was intended to develop ways of modifying the existing device so that the chlorine gas could be utilized to regenerate the etchant, and would not escape into the environment. We were ultimately successful in developing a sealed electrodeposition cell which accomplished this goal. With no chlorine escape, we recovered at least 90% of the theoretical amount of copper, recovered 99.8% pure copper, and regenerated the etchant based on oxidation reduction potential (ORP) values. We have a customer in the circuit board business who has offered to help us further evaluate the experimental cell developed during Phase I. In order to accomplish this, we will modify the existing cell to increase its capacity for copper collection and throughput. We will then evaluate the capabilities of the cell on the customer¿s production etching line. Following this study, we will design and build a small prototype working unit. The same customer has agreed to help us evaluate the small prototype unit, and will purchase the unit if all goes as planned. VTO will be performed on this working model. Test 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 our anticipated range of system cost. The cost of electricity needed for our system is well below the current normal cost of 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 is also a major benefit for our potential customers, and recognized as such by the customers contacted in the independent survey.