Etchant and process
US4144119A · kind A · utility
Inventors
Key dates
| Filing date | Sep 30, 1977 |
| Grant date | Mar 13, 1979 |
| Priority date | — |
| Expiry date | Sep 30, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K3/067
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
This invention is directed to an etchant and to a process for its use. The etchant comprises sulfuric acid activated with hydrogen peroxide or the synergistic combination of hydrogen peroxide and molybdenum. The etchant is characterized by a source of phosphate ions as an inhibitor against attack on tin, especially immersion tin, as well as several other metals such as nickel and alloys of nickel such as gold alloys. The etchant is especially useful for etching copper and its alloys in the presence of a tin etch resist, and therefore, provides a new procedure for the fabrication of printed circuit boards using immersion tin as an etch resist.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.