高速低シアン銀めっき浴の析出膜特性

概要

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The properties of silver deposits obtained by jet plating from low-cyanide baths were investigated. Deposits obtained from baths with and without the addition of selenocyanate at current densities lower than 50A/dm2 were matte, and were composed of randomly oriented small cristallites with very weak XRD patterns. The hardness of the deposits was around Hv 100. The amount of selenium codeposition in the matte deposits obtained from baths with selenocyanate was several times higher than that in the bright deposits obtained at 80-120A/dm2, which were composed of large crystallites strongly oriented to the (200) plane. Scanning ion microscopy revealed lines inclined 45° to the substrate, which are considered to be (111) plane stacking faults or twin crystals. The hardness of the deposits was around Hv 70. The matte and semi-bright deposits obtained by full-wave plating from selenocyanate-free baths were (111) oriented, and SIM showed many lines, which are considered as (111) planes, parallel to the substrate.Regardless of appearances, the wire bonding properties of all the deposits were virtually the same, and were satisfactory for application to semiconductor leadframes.