Lifetime of Bonded Contacts on Thin Film Metallizations

Gold beams and wires are microwelded to a stable gold/platinum/titanium thin-film sandwich on silicon wafers. The contacts are subjected to simultaneous thermal and mechanical loads. The measured times-to-fracture are analyzed by mechanisms of creep-crack propagation. A creep rupture equation contains the stress exponent and the thermal activation energy of plastic f low as the material-specific parameters. The time-to-fracture is strongly affected by the texture of the beams and wires and by the geometry of the welded contact. The equation can be used for extrapolation in a temperature interval between 300 and 650K.