Examining the evolution of metals utilized in printed circuit boards

ABSTRACT

Management of waste electrical and electronic equipment (WEEE) has recently attracted worldwide attention because of high metal concentrations in them. Evolution of toxic and precious metals utilized in WEEE can not only reflect the adventure of eco-design, but can also guide the final recycling option. Pb, As, Cu, Au, Sn and Ag were determined in 10 composite samples of printed circuit boards of cathode ray tube televisions (TV–PCBs) that were produced between 1980 and 2005. The obtained results indicated that average metal concentrations in all TV–PCBs were – Cu: 10.6 ± 4.1%, Sn: 4.21 ± 0.90%, Pb: 3.15 ± 0.54%, Ag: 0.0215 ± 0.0068%, Au: 0.0068 ± 0.0049% and As: 0.0007 ± 0.0004%. No remarkable difference was found in compositions of Pb and Sn over the years, suggesting that there were no major modifications of Sn/Pb solder used in joining the circuitry system. The average composition of Cu fluctuated between 5.10% in 1980 and 12.8% in the mid-1990s and decreased afterwards. The decreases in Ag and Cu compositions could possibly be associated with thinner layers of these metals in newer model products.

KEYWORDS:

• Printed circuit board
• e-waste
• cathode ray tube
• composition
• metals

Acknowledgements

The authors also appreciate the South-South cooperation program between the Basel Convention Regional Centre for the Asia and the Pacific Regions (BCRC-AP) in Beijing, China and Basel Convention Coordination Centre for Training and Knowledge Transfer for the African Region (BCCC-Africa) in Ibadan, Nigeria, for creating a platform for this study to be carried out in China. The authors finally appreciate the constructive criticisms and contributions of the anonymous reviewers of this manuscript. The reviewers’ comments indeed improved the quality of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCiD

Xianlai Zeng http://orcid.org/0000-0001-5563-6098

Additional information

Funding

The work was financially supported by the National Natural Science Foundation of China (71373141), and the National Key Technology R&D Program (2014BAC03B04).