Akira Sugawara

Effect of Se Content in High-Cyanide Silver Plating Solution on {200} Crystal Plane Orientation Ratio of Electrodeposited Silver Layer

Electrodeposited silver layers obtained from high-cyanide silver plating solution are widely applied for connectors and switches of automobiles. However, few groups have discussed the relationship between the crystal structure of silver layers and their properties. In this study, the effect of the concentration of Se, added as a brightener to high-cyanide silver plating solution, was investigated by XRD and EBSD analysis for electrodeposited silver layers with {200} orientation. By optimizing the concentration of Se in the silver plating solution, the {200} orientation ratio of the silver layer was increased to as high as 94%. Since the diffusion of Cu from the Cu substrate used in this study into the silver layer was inhibited, the silver layer with the high {200} orientation ratio exhibited good electrical contact resistance of the surface of 1.3mΩ after a heating test performed at 200°C for 74h. In addition, the silver layer had good bend formability. The results of XRD analysis confirmed that the recrystallization of the electrodeposited silver layer occurred at room temperature within several hours, thus increasing the {200} orientation ratio of the silver layer.

Effect of Prior Cold-Working on Strength and Electrical Conductivity of Cu-Ti Dilute Alloy Aged in a Hydrogen Atmosphere

Aging solution-treated Cu-Ti alloys in a hydrogen atmosphere significantly improved their electrical conductivity without degradation of the mechanical strength, compared to conventionally aged alloys. In this study, the influence of prior deformation on the mechanical and electrical properties of Cu-4.2 at.% Ti alloys aged in a hydrogen atmosphere was examined. The Vickers hardness of the solution-treated specimen increased from 127 kgf/mm2 to 265 kgf/mm2 by aging at 673 K for 180 h in a hydrogen atmosphere of 0.8 MPa, while that of the deformed specimen achieved a maximum of approximately 280 kgf/mm2 by aging for 100 h in the same atmosphere. Prior deformation resulted in a more rapid increase in conductivity during aging than that without deformation. The conductivity at the peak-hardness of the deformed specimen was 22% IACS (International Annealed Copper Standard), which exceeded that for the solution-treated specimen. Thus, prior deformation assisted in a significant improvement of the mechanical and electrical properties during aging in a hydrogen atmosphere.