LAUSR

Abstract An Au-coated Ag alloy (ACAA) wire was fabricated in this work. Microstructure and bonding performance including characteristics of free air ball (FAB) and heat affected zone (HAZ) of the ACAA wire was investigated. The wire is coated by Au layer with an average thickness about 110 nm continuously via physical method. During bonding, golf-clubbed FAB and asymmetrical distribution of Au on the section is observed. Sparking and heating from the side is suggested to be the reason and the schematic is illustrated. The ACAA wire experiences certain degree of grain growth in the HAZ. Tensile strength of the HAZ and base wire is 228.86 MPa and 232.43 MPa, respectively while elongation is 15.12% and 18.84%, meaning that the HAZ present slight tensile performance reduction. The ACAA wire presents better oxidation resistance, mechanical and electrical performance than the non-coated Ag alloy (AA) wire. Despite the golf-clubbed FAB, morphology of the bonded ball and bondability testing results of the ACAA wire meet the requirement of wire bonding.