Method for preventing lead from dissolving from a lead-containing copper-based alloy
US7067068B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 13, 2002 |
| Grant date | Jun 27, 2006 |
| Priority date | — |
| Expiry date | Aug 28, 2023 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23F1/00
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A lead-containing copper-based alloy is immersed into a weak acidic or neutral etching solution having a buffer effect which is formed by adding an organic acid into a complexing agent having a high ability to form a complexing ion with lead, and lead particles present on the surface of the lead-containing copper-based alloy are then removed. The complexing agent is one of an organic ammonium salt such as ammonium acetate, or ammonium citrate, or may be an organic sodium salt such as sodium acetate, sodium tartrate, and sodium citrate. Preferably, an immersion temperature of the alloy to the etching solution falls within a range of from 10 to 50° C. The etching solution is agitated with oxygen or a gas containing oxygen blown thereinto during the immersion of the alloy into the etching solution. An extremely low voltage of −0.3 to +0.2 V vs. NHE is applied from outside to the lead-containing copper-based alloy as an anode.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.