Improvement in Contact Characteristics by Atmosphere Control for Sealed Contacts

Takeshi AOKI

IEICE TRANSACTIONS (1976-1990)   Vol.E73    No.8    pp.1399-1404
Publication Date: 1990/08/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Components

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Miniaturized sealed contacts can be made highly reliable by controlling the atmosphere. This paper studies the effects of oxygen concentration on adhesion and contact resistance characteristics as well as those of oxygen dissipation for silver-palladium alloy and gold-palladium alloy contact. There is a permissible oxygen concentration range where adhesion is prevented and contact resistance is also stable. This range depends on the corrosive resistance of the contact materials. Oxygen concentration varies not only due to air leakage, but also due to oxygen dissipation caused by the oxidation of contact metals in sealed contact enclosures. If the most suitable contact materials and oxygen concentration are selected, the oxygen concentration range can be wide enough to allow changes in oxygen concentration within the enclosures. Switches where silver-palladium alloy mating with gold-palladium alloy contacts are sealed in a nitrogen atmosphere containing about 5% oxygen are confirmed to have characteristics that satisfy the conditions required for practical speech path equipment. This confirms that atmosphere control is a practical way to produce highly reliable sealed contacts.