Selectively stripping tin or tin-lead alloys from copper substrates
US4004956A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 14, 1974 |
| Grant date | Jan 25, 1977 |
| Priority date | — |
| Expiry date | Aug 14, 1994 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K3/067
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
Acidic solutions for selectively stripping tin or tin-lead alloys from copper substrates comprising an aqueous solution of at least one nitro-substituted aromatic compound; an inorganic acid capable of readily reacting with tin and lead to form water-soluble salts thereof and incapable of reacting with tin and lead to form a water-insoluble compound film on the tin or tin-lead alloy surface, preferably fluoboric acid; a thiourea; an organic acid of the formula RCOOH wherein R is 1-2C alkyl or hydrogen; and a haloacetic acid wherein the halogen is chloro or bromo. The haloacetic acid in combination with the acid of the formula RCOOH result in a pronounced synergism in accelerating the rate of stripping the tin or tin-lead alloy deposit from the copper substrate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.