Contact Resistance Characteristics of Improved Conductive Elastomer Contacts for Contaminated Printed Circuit Board in SO2 Environment

Terutaka TAMAI  Yasushi SAITOH  Yasuhiro HATTORI  Hirosaka IKEDA  

IEICE TRANSACTIONS on Electronics   Vol.E91-C   No.8   pp.1192-1198
Publication Date: 2008/08/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e91-c.8.1192
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Recent Development of Electromechanical Devices(Selected Papers from IS-EMD2007))
Category: Contact Phenomena
silicone rubber,  elastomeric contacts,  contact failure,  PCB,  contact resistance,  SO2 environment,  

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Characteristics of conductive elastomer that is composed of silicone rubber and dispersed carbon black particles show conductive and elastic properties in one simple material. This material has been widely applied to make-break contacts of panel switches and connectors of liquid crystal panels. However, since surface state of the contact is very soft, it is difficult to remove contaminant films of contaminated opposite side contact surface and to obtain low contact resistance owing to break the film. This is an important problem to be solved not only for the application of make-break switching contact but also static connector contacts. This study has been conducted to examine some complex structures of the elastomer which indicate removal characteristics for contaminant films and low contact resistance. As specimens, six different types of elastomer contacts composed of different type of dispersed materials as carbon and metal fibers, metal mesh, and plated surfaces were used. The contacts of opposite side were Au and Sn plated contact surface on a printed circuit board (PCB) which is usually used in the static connector and make-break contacts. In order to contaminate contact surfaces of PCB, the surfaces were subjected to exposure in an SO2 gas environment. The elastomeric contacts contained hard materials showed lower contact resistance than only dispersed carbon particles in the elastomer matrix for both contaminated PCB contact surfaces.