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Metallurgical System for Gold to Tin Or Solder Contacts

IP.com Disclosure Number: IPCOM000062004D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Sullivan, JF: AUTHOR

Abstract

A metallurgical system is shown in the drawing in which tin or solder contacts gold plated leads in a plug-in connection or socket. A socket spring contact is plated with hard gold (knoop 200-225) and is 80-100 micro inches thick. The gold need not be pure - a purity level of 90% is acceptable. The gold is also smooth to 20 micro inches center line average. A barrier material of 100-125 micro inches of nickel separates the gold the spring, which may be a copper alloy or any spring material. Only the contact area need be plated with gold and nickel. This is extremely cost effective.

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Metallurgical System for Gold to Tin Or Solder Contacts

A metallurgical system is shown in the drawing in which tin or solder contacts gold plated leads in a plug-in connection or socket. A socket spring contact is plated with hard gold (knoop 200-225) and is 80-100 micro inches thick. The gold need not be pure - a purity level of 90% is acceptable. The gold is also smooth to 20 micro inches center line average. A barrier material of 100-125 micro inches of nickel separates the gold the spring, which may be a copper alloy or any spring material. Only the contact area need be plated with gold and nickel. This is extremely cost effective.

This materials system can be used with tin or solder dipped (and plated) circuit board or module lead pins.

The gold is hard (hardened with nickel or cobalt) so that any tin by lead oxide formation will be removed during the insertion or wipe action of the socket spring. The gold plating must also be smooth for easy wipe. The nickel acts as a barrier material to prevent the underlying spring material from diffusing to the gold.

Intermetallic formation of gold tin metallics should not occur at operating conditions or at normal room temperature for at least 25 years. Even at 125OEC, metallic formation is slow and may be insignificant to 10 years or more. Stress testing at 500 hours of 85OEC/81% RH has shown no degradation of electrical performance and no intermetallic formation.

Disclosed anonymously.

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