Process for etching workpieces
US5076885A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jul 10, 1990 |
| Grant date | Dec 31, 1991 |
| Priority date | — |
| Expiry date | Jul 10, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K3/068
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Workpieces containing copper, in particular copper laminated printed circuit boards, are etched in an alkaline etching agent which contains a copper tetramine complex as the active component. After etching, the workpieces are washed with a mainly neutral washing liquid consisting of a solution of the salt required for regeneration of the etching agent. This regeneration salt mainly contains ammonia ions and chloride ions. In a regeneration system connected to the etching machine the etching agent is on the one hand set to the correct pH value with ammonia gas and on the other hand diluted with the neutral mixture resulting from the washing process.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.