Complexing agent for displacement tin plating
US5196053A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 27, 1991 |
| Grant date | Mar 23, 1993 |
| Priority date | — |
| Expiry date | Nov 27, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K2203/073
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An environmentally innocuous effective replacement for thiourea is disclosed for use as a complexing agent in displacement plating processes in which the plating solution is applied to the substrate surface to be plated by immersion or by spraying, cascading, pouring and the like. The replacement complexing agent is an imidazole-2-thione compound having the formula: ##STR1## wherein A and B are the same or different --R--Y groups, wherein R is linear, branched or cyclic alkenyl group containing 1 to 12 carbon atoms and Y is a hydrogen, halogen, cyano, vinyl, phenyl, or ether moiety. Of this class of compounds, 1-methyl-3-propyl-imidazole-2-thione is preferred for immersion tin plating. This class of complexing agents is particularly useful in spray displacement tin plating for the manufacture of printed circuit boards wherein free tin metal is added to the plating solution.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.