NDLI: High temperature resistant galvanically deposited gold layers for switching contacts

Content Provider	IEEE Xplore Digital Library
Author	Johler, W. Weik, G. Poefel, K.
Copyright Year	2005
Description	Author affiliation: Tyco Electron. Axicom, Au-Waedenswil, Switzerland (Johler, W.)
Abstract	Due to new environmental requirements, all electronic components must be able to withstand peak soldering temperatures up to 265 /spl deg/C. In the worst case scenario, this temperature is applied 3 times. In order to make electromechanical relays resistant to the soldering heat during manufacture, the products are pre-aged by applying the same peak temperature, but usually for a longer duration. This temperature stress results in a high risk of oxidation of gold alloys, e.g. when they are galvanically deposited, as only a limited number of alloys can be deposited using galvanic processes, and a gold-gold combination is not suitable for switching contacts due to a high tendency towards cold welding. A method of protecting galvanically deposited gold alloys from oxidation has been developed. In order to prevent the formation of nickel- or cobalt-oxides, the gold layers were protected by a very thin layer of palladium (0.075/spl mu/m). In addition, a further improvement can be achieved by adding an even thinner layer of pure gold (0.005/spl mu/m). These layers make AuNi and AuCo alloys resistant to temperatures of 265 /spl deg/C, so no significant changes in contact resistance were observed any more, even during prolonged storage at high temperatures. Due to the minimum thickness no significant precious metal costs are involved. Adding a thin Pd layer hardens the pure gold layer and efficiently prevents from cold welding. The performance during service life at temperatures up to 110 /spl deg/C was not affected by the additional layers.
Sponsorship	Components, Packaging and Manufacturing Technol. Soc. of the Instit. of Electr. and Electron. Eng. Inc
Starting Page	48
Ending Page	54
File Size	409140
Page Count	7
File Format	PDF
ISBN	0780391136
DOI	10.1109/HOLM.2005.1518222
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2005-09-26
Publisher Place	USA
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Temperature Galvanizing Gold alloys Soldering Oxidation Welding Protection Electronic components Relays Manufacturing
Content Type	Text
Resource Type	Article

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