Tin coatings incorporating selected elemental additions to reduce discoloration
AssigneeOlin Corporation
InventorsSzuchain Chen, Julius Fister, Christopher Laurello
Life of this patent
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Abstract
A tin coated electrical or electronic component has enhanced resistance to oxidation and tarnishing as well a smaller increase in contact resistance when exposed to elevated temperatures. These benefits are achieved by depositing a relatively thin, on the order of 5-50 angstroms thick, layer of zinc on the tin coating prior to heating. A subsequent step of heating the sample to a temperature and time effective to convert all free tin to an intermetallic imparts the additional advantage of reducing the coefficient of friction.
Claims7
A method for reducing the coefficient of friction of an article having a tin or tin base alloy layer coating a copper or a copper base alloy substrate, comprising the steps of:
- forming said tin or tin base alloy layer to a thickness of between 15 and 200 microinches;
- and
- coating said tin or tin base alloy layer with a zinc containing layer, said zinc containing layer having a thickness in excess of 5 angstroms.
A heat aged article having electrical or electronic applications, comprising:
- a copper or copper base alloy substrate;
- a tin containing layer overlying said substrate, wherein substantially all tin contained within said tin containing layer is in the form of a non-oxidized tin containing intermetallic;
- and
- a zinc containing layer overlying said tin containing layer, wherein, the contact resistance of said article is less than 10 milliohms following heat aging in air at a temperature of 150° C. for at least seven days.
Dependencies are inferred from the claim text.