| Recovery of Copper from Printed Circuit Board Etchant | United States | - | Full scale |
COMMUNICATION EQUIPMENT AND APPARATUS # 14
Background
In the manufacturing of printed circuit boards, the unwanted copper is etched away by acid solutions of cupric chloride. As the copper dissolves, the effectiveness of the solution falls and it must be regenerated. The traditional way of doing this is to oxidize the cuprous ion produced with acidified hydrogen peroxide. During the process the volume of solution increases steadily and the copper in the surplus liquor is precipitated as copper oxide and usually landfilled.
Praegitzer Industries Inc, founded in 1981, is a leading designer and manufacturer of advanced circuit boards. The company employs 500 people in three locations.
FSL was founded in 1967 to supply automated etching machines for the large scale production of printed circuit boards. They have a staff of 55 in the UK, have subsidiary companies in Germany and the USA and export through agencies to many countries throughout the world.
Cleaner Production Principle
Recovery, Reuse and Recycle
Cleaner Production Application
The original proposal for recovering the copper in high quality form came from the UK Electricity Research Council. Using an electrolytic technique involving a divided cell, simultaneous regeneration of the etching solution and recovery of the unwanted copper is possible. A special membrane allows hydrogen and chloride ions through, but not the copper. The copper is transferred via a bleed valve and recovered at the cathode as pure flakes.
The development of a suitable cell dividing material. The process development where the excess etchant is pumped to the recovery circuit and the copper is obtained in a recoverable form. Control of the process by means of the oxidation-reduction potential.
Environmental and Economic Benefits
Project benefits include,
| The quality of the circuit boards is improved. |
| The disposal costs are virtually eliminated. |
| The etching solution is maintained at its optimum composition. |
| The copper is recovered in high value form. |
| There are no hazardous chemicals to be handled. |
Cost saving are based on 50 tons of copper recovered per year.
| US$/year | |
| Copper | 50,000 |
| Materials | 80,000 |
| Disposal | 25,000 |
| TOTAL | 155,000 |
Capital investment was US$ 220,000. The payback period was 18 months.
Constraints
None reported.
Contacts
Review Status
This case study was originally published in the UNEP IE document "Cleaner Production Worldwide". In the process of preparing the document the case study underwent a technical review.
Subsequently the case study has undergone another technical review by Dr Prasad Modak at Environmental Management Centre, Mumbai, India, in September 1998.