Process for removing tin and tin-lead alloy from copper substrates
US5035749A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 6, 1990 |
| Grant date | Jul 30, 1991 |
| Priority date | — |
| Expiry date | Aug 6, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K3/067
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
Disclosed is a method for removing a layer of tin or tin-lead alloy from a copper substrate of a printed circuit board employing the two different reagents in a two-step procedure without damaging the substrate, and at the same time, preventing formation of whitish precipitates in the treating solution. In the first step, the layer of tin or tin-lead alloy is selectively removed with the first reagent having a comparatively mild oxidation capability, then in the second step the intermetallic layer consisting of tin and copper is removed with the second reagent having a comparatively strong oxidation capability. This process ensures a smooth and effective operation in the production of high quality printed circuit boards.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.