Constriction resistance at high signal frequencies

Constriction resistance arises in practical electrical interfaces because contact is made at discrete spots as defined by the surface roughness and contact pressure. This paper describes the dependence of constriction resistance on signal frequency. This dependence was calculated for circular constrictions ranging in diameter from 10 to 100 /spl mu/m, and for frequencies ranging from DC to 1 GHz. The results indicate that the magnitude of constriction resistance does not deviate appreciably from values predicted by Helm's classical analytical expression, as long as the skin depth is large compared with the constriction radius. For skin depths that are much smaller than the constriction radius, constriction resistance decreases with increasing frequency to an apparent limiting value independent of the constriction radius. At high frequencies, constriction resistance constitutes only one of two components of the total connection resistance measured in practice. The second component of connection resistance is determined by details of the geometry and dimensions of the contact interface, and increases with signal frequency.