Leach-resistant solder alloys for silver-based thick-film conductors

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%...

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Bibliographische Detailangaben
Hauptverfasser: CARTER BRADLEY H, YEH SHING
Format: Patent
Sprache:eng
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Beschreibung
Zusammenfassung: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.