Whisker resistant tin coatings and baths and methods for making such coatings
AssigneeOlin Corporation
InventorsIgor V. Kadija, Julius C. Fister, Joseph Winter, Arvind Parthasarathi
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Abstract
The present invention relates to an addition to tin coating solutions for inhibiting the growth of tin whiskers. The addition comprises a concentration of a metal salt selected from the group consisting of palladium salt, silver salt, nickel salt, iron salt, cadmium salt, platinum salt, gold salt, indium salt, ruthenium salt and cobalt salt. In a preferred embodiment, the metal salt addition is either a palladium salt such as palladium chloride or a silver salt such as silver sulfate.
Claims18
A method for inhibiting tin whisker growth on a substrate material having a tin containing coating, said method comprising:
- preparing a tin coating solution containing a metal salt selected from the group consisting of palladium salts, silver salts, nickel salts, iron salts, cadmium salts, platinum salts, gold salts, indium salts, ruthenium salts, and cobalt salts;
- and
- said preparing step comprising providing an initial tin containing solution and adding said metal salt to said initial solution in a concentration above the saturation point of the initial solution to form a metal salt saturated solution;
- and
- applying said tin coating solution to said substrate material.
A tin coating solution for imparting tin whisker formation resistance to a substrate material coated with a tin containing material, said solution comprising a tin containing solution having a concentration of a palladium salt, the palladium being present in an amount greater than about 50 ppm.
A composite structure for use in electrical and electronic applications comprising:
- a metal or metal alloy substrate;
- a whisker resistant tin coating on at least one surface of said substrate, said tin coating consisting essentially of from about 0.1 w/o to about 20 w/o palladium for inhibiting tin whisker growth and the balance essentially tin;
- and
- said tin coating having an essentially smooth surface and a relatively fine grain structure of less than about 1 micron with said substrate being formed from copper or a copper base alloy.
A composite structure for use in electrical and electronic applications comprising:
- a metal or metal alloy substrate;
- and
- a whisker resistant tin coating on at least one surface of said substrate, said tin coating consisting of from about 0.1 w/o to about 20 w/o palladium for inhibiting tin whisker growth and the balance essentially tin.
Dependencies are inferred from the claim text.