Metal dissolution process using H.sub.2 O.sub.2 --H.sub.2 SO.sub.4 etchant
US4395302A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 10, 1981 |
| Grant date | Jul 26, 1983 |
| Priority date | — |
| Expiry date | Dec 10, 2001 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23F1/46
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
An improved process for dissolution of metals by etching, and particularly the etching of copper in printed circuit board processing or the like, using an aqueous H.sub.2 O.sub.2 --H.sub.2 SO.sub.4 etching solution, in which the concentration of H.sub.2 SO.sub.4 in the etching solution is allowed to decrease during use of the etching solution from an initial, relatively high level at the time the etching solution is put into use, to a final, relatively low level. When a predetermined concentration of dissolved etched metal exists in the etching solution, the etching solution is removed from use, H.sub.2 SO.sub.4 is added to increase the concentration of H.sub.2 SO.sub.4 in the etching solution to approximately the initial, relatively high level, and the metal is precipitated out of the etching solution.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.