Electrostatic Repulsion Between Highly Injecting Metals: An Experimental Investigation

Abstract

This paper is an experimental investigation of the major implications brought in the crossing resistance of mechanically contacted metals when operating in the high electronic injection regime, i.e., steady state interfacial voltage values greater than the max. acceptable level determined by specifications and less than the melting voltage. Under such operating conditions, monolayers of positive ions may be formed within interfacial cavities filled by the material from the surrounding space. The dominating ion neutralization process on the cathode controls the formation of "Helmholtz" inner layers at the metal cathode+oxide+gas interface. The presence of a positive ion monolayer over the cathode electrode will tend to reduce the field threshold required for electronic field emission and affect the overall currentvoltage characteristics.The response of contacts operating under high charge injection is monitored on an injected charge vs. interfacial field phase space, which clearly demonstrates non-linear conductivity phenomena and hysteresis effects for the examined structures. Experimental results indicate convincingly the importance of the dielectric media around highly injecting metal contacts. The excessive positive ion formation may also account for the experimentally observed electrostatic repulsion between highly injecting metal contacts. Under low contact pressure situations spontaneous separation of the current carying electrodes may occur. During a spontaneous contact breaking process, the transient current and voltage profiles across the metal contacts have been monitored using state-of-the-art data logging systems. The importance of the oxide capacitance and (time varying) gap capacitance on V(t) and I(t) profiles has been discussed. The obtained results provide evidence for the positive ion layer formation over the cathode electrodes.

Corrosion effects on the electrical performance of silver metal contacts

“…Contact resistance measurements were stored in steps of 10 iterations for up to 1000 iterations. Whenever required, each iteration cycle could be applied by multiple contact make-break transitions to investigate the accelerated induced degradation by synergy effects, such as (a) mechanical contact bounce and (b) spontaneous contact opening effects induced by magnetic blow open forces (Shea et al, 1994) or plasma formation in interfacial cavities (Dervos, 1995(Dervos, , 1997 (Dervos and Fitsilis, 1994;Dervos and Michailides, 1997;Dervos et al, 1993).…”