Current flow in a typical aluminum contact interface occurs only where metallic junctions form at cracks in the insulating aluminum oxide. When the total metallic conducting area is small, current density may be high enough to initiate electromigration failure. These experiments use a solid aluminum specimen having a constricted current path, representing a single metallic contact junction. Tests are conducted at two current levels, with alternating or direct current flow. There is no significant change of potential drop during an initial stable period, after which the specimens fail abruptly as the failure occurs in both AC and DC specimens.
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