Electrical contact is an important issue to high power microwave sources, pulsed power systems, field emitters, thin film devices and integrated circuits, and interconnects, etc. Current crowding, which leads to intense local heating, is a well known phenomenon associated with contact resistance for the above areas. This paper summarizes recent development on the accurate evaluation of contact resistance for both horizontal [1–3] and vertical [3,4] contacts. By horizontal (vertical), we mean a current flow that is parallel (perpendicular) to the base of a contact member. The contact members may possess vastly different electrical resistivities, and arbitrary aspect ratios. The analytic calculations are validated by the MAXWELL codes. Current partitions in different regions are displayed. Current crowding is shown to occur within a distance of 0.44h of the rim of an electrode that is made in horizontal contact with a thin film of thickness h, regardless of the electrode shape [1,3]. A novel relation between AC bulk contact resistance and DC thin film contact resistance was discovered [3]. General scaling laws are presented.
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