DocumentCode :
1464545
Title :
Inside front cover
Author :
Dervos, Constantine T. ; Michaelides, Joseph M.
Author_Institution :
Dept. of Electr. & Comput. Eng., Nat. Tech. Univ. of Athens, Greece
Volume :
21
Issue :
4
fYear :
1998
Abstract :
This paper investigates experimentally the significance of the effective contact capacitance, i.e., the interfacial capacitance during the current flow, for a wide range of stationary metal contacts operating under high charge injection rates. The effective capacitance of metallic interfaces depends on the ratio between the apparent contact area (which is optically determined) and the effective contact area (which injects the electronic charges). Silver contacts having series resistance values significantly less than the contact resistance were subjected to ac high current densities (up to 500 A/mm/sup 2/). The obtained i(t) and v(t) profiles were further analyzed to obtain I-V curves. Due to the phase shift between i(t) and v(t) profiles the I-V curve within a single period of the stimulating current will produce a closed loop. The area of the loop determines the interfacial electrical energy. According to the obtained results the electrical energy storage at a given metal contact, increases at: (1) higher ampacity values; (2) lower operating temperatures; (3) higher clamping forces between the joints (elastic deformation regime) each of the above parameters acting independently. The experimental results were obtained for AgSnO/sub 2/ and OFHC contacts operated in a wide temperature range, varying between -130/spl deg/C and +40/spl deg/C. The observed response of the electrical contacts is mainly characterized by the implications of the asperity contact model and dominating charge transport processes across the metallic interfaces. When standard simple equivalent circuits are used to determine contact impedance, the effective capacitance of current carrying metal contacts acquires exceptionally high values.
Keywords :
capacitance; charge injection; elastic deformation; electrical contacts; equivalent circuits; -130 to 40 degC; AgSnO/sub 2/; OFHC contacts; ac high current densities; ampacity values; apparent contact area; asperity contact model; charge injection rates; charge transport processes; clamping forces; contact capacitance; contact impedance; current-voltage characteristics; effective contact area; elastic deformation regime; electrical energy storage; equivalent circuits; interfacial capacitance; operating temperatures; series resistance values; stationary metal contacts; stimulating current; Capacitance; Capacitance-voltage characteristics; Chemical processes; Contact resistance; Current-voltage characteristics; Dielectrics; Electrons; Oxidation; Surface cleaning; Surface reconstruction;
fLanguage :
English
Journal_Title :
Components, Packaging, and Manufacturing Technology, Part A, IEEE Transactions on
Publisher :
ieee
ISSN :
1070-9886
Type :
jour
DOI :
10.1109/95.740043
Filename :
740043
Link To Document :
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