Method for treating spent tin/lead stripping solution
US6685820B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Apr 26, 2002 |
| Grant date | Feb 3, 2004 |
| Priority date | — |
| Expiry date | Jul 26, 2022 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P10/20
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The present invention relates to a method for treating spent tin or tin/lead stripping solution used in the electronic industry, particularly in the manufacture of printed circuit boards or a lead frames. Said method comprises (i) electrolytically reducing copper ions in the solution to copper at a low temperature; (ii) electrolytically oxidizing Sn2+ and Pb2+ in the solution at a high temperature to form solid tin and lead oxides and hydroxides; (iii) separating solid tin and lead oxides and hydroxides from the solution; (iv) dissolving tin and lead oxides and hydroxides obtained in step (iii) in a strong alkali or acidic solution; and (v) electrolytically reducing the alkali or acidic solution obtained in step (iv) at a high temperature to recover metallic tin and lead. Also, the filtrate obtained in step (iii) above is useful for preparing fresh tin or tin/lead stripping solution.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.