Contact Behaviors of New Material for Micro Relays

Terutaka TAMAI  Tatsumi IDE  

IEICE TRANSACTIONS on Electronics   Vol.E87-C   No.8   pp.1235-1240
Publication Date: 2004/08/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on IS-EMD2003--Recent Technical Trend of Electro-Mechanical Devices)
Category: New Technology and Automotive Applications
contact resistance,  adhesion,  sticking,  Ag-Pd-Mg alloy,  Ag-Pd alloy,  contact material,  micro relay,  

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Ag(40 wt%)-Pd(60 wt%) alloy has been widely applied to contact materials installed in various electromechanical devices. However, in application to the down sized relays, failure due to contact resistance is caused easily by both growth of oxide film on the contact surface and low contact force. To solve the increase in contact resistance, an overlay of thin Au or thin Au-Ag (8-10 wt%) has been used on the alloy. Despite this, cleanliness and low hardness of these overlays cause adhesion, or sticking, at contact interface. Increase in contact resistance and sticking are contrary to each other. In order to eliminate these contrary properties, the author studied improving the Ag-Pd alloy with a dopant. Low level of contact resistance for both static and dynamic contacts of Ag-Pd with Mg doping was found even if the contact surface was covered with an oxide contaminant film. This paper presents the excellent contact resistance and adhesion behaviors of Ag-Pd-Mg alloy and their mechanisms, and also presents in the later part, surface contamination behaviors for organic gases.