Method for manufacture of printed circuit boards
US4804615A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 3, 1986 |
| Grant date | Feb 14, 1989 |
| Priority date | — |
| Expiry date | Sep 3, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K2203/043
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Printed circuit boards having solder coated pads and through-holes and bare copper traces protected by a directly applied solder mask or by a coating of non-reflowable metal and a solder mask thereover, are manufactured by a process which avoids the need for tin-lead stripping and the need for separate application and leveling of molten solder. In the preferred process, liquid resists are applied to circuit boards having tin-lead over copper plated holes and pads so as to define and etch-protect bare copper traces of desired pattern circuitry (as well as other desired configurations). Copper areas other than those protected by the etch-resist and tin-lead plating are etched away, the etch-resist removed and solder mask applied over the bare copper traces or other desired bare copper areas or, alternatively, to bare copper first coated with a non-reflowable metal. The tin-lead plating is then preferably reflowed and solidified to provide the pads and through-holes with solder coating.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.