The Bonding Characteristics of Gold in Ultrahigh Vacuum

The results are reported of a study of the factors which affect the solid-phase bonding of gold wire electrical leads. Gold surfaces were cleaned by sputtering and joined with precise control of mechanical and environmental variables. Contact resistance measurements as a function of load, coefficients of adhesion, and laser interference fringe photo-microtopographs were used as diagnostics to show the effects of cleaning, annealing, loading, and creep. Ultrahigh vacuum techniques and vibration isolation were essential to reproducibly forming and measuring the strengths of solid-phase bonds between gold samples and between gold and tungsten.