Leach-resistant solder alloys for silver-based thick-film conductors
US6630251B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 23, 2002 |
| Grant date | Oct 7, 2003 |
| Priority date | — |
| Expiry date | Sep 23, 2022 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/12896
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A tin-lead solder alloy containing copper and/or nickel and optionally silver, palladium, platinum and/or gold as its alloying constituents. The solder alloy consists essentially of, by weight, about 5% to about 70% tin, up to about 4% silver palladium, platinum and/or gold, about 0.5% to about 10% copper and/or nickel, the balance lead and incidental impurities. The presence of copper and/or nickel in the alloy has the beneficial effect of inhibiting the dissolution and leaching of silver from a silver-containing thick-film, such as a conductor or solder pad, into the molten solder alloy during reflow. In addition, solder joints formed of the solder alloy form a diffusion barrier layer of intermetallic compounds that inhibit solid-state interdiffusion between silver from a silver-containing thick-film and tin from the solder joint.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.