Method for fabricating printed circuits
US5235139A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 12, 1990 |
| Grant date | Aug 10, 1993 |
| Priority date | — |
| Expiry date | Sep 12, 2010 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/4921
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Conductive copper areas of printed circuits, such as through-holes, pads and lands, to which electronic components can thereafter be electrically connected by, e.g., wave soldering, are provided with a coating of nickel or cobalt, such as by electroless deposition from nickel-or cobalt-boron and nickel-or cobalt-phosphorous plating baths, or entirely or partly electrolytically, followed by a coating of a protective material which protects the nickel or cobalt coating from oxidation prior to the subsequent solder connection operation, is wettable by solder in the subsequent solder connection operation, and substantially dissolves in the solder in the subsequent solder connection operation without adverse effect on the solder joint between the electronic component and the through-hole, pad or land. A particular preferred protective material is gold, such as applied by deposition from immersion or electroless gold plating baths. The invention renders the so-treated areas readily susceptible to the soldering of components thereat, thereby avoiding the need for hot air solder levelling.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.