Pulse plated nickel coatings on copper and copper alloys were investigated in view of their use as underlayer in Au/Ni/Cu or as external protective coatings. Deposition parameters were varied in order to determine their influence on the microstructure and consequently on the electrical contact properties of the electrodeposited Ni films. Roughness and hardness measurements as well as SEM studies were performed on these samples. Smooth and dense coatings were obtained for high pause-to-pulse ratio, 25-75 Hz pulse-plating frequencies and low current density. The contact resistances R/sub c/ of the as-deposited samples in approach and insert mode were measured versus load F/sub c/ in the range 0.1-10 N. It was found that initial contact resistance follows the power law R/sub c/=KF/sub c//sup -n/ where n is hardness and coating topography dependent. Moreover, aging samples in daily cyclic atmosphere shows an increase in contact resistance during the test, but ohmic behaviour prevails as verified by the current-voltage characteristics. Finally, the mechanical behaviour investigated by a fretting study shows that the pulse reverse condition improves contact resistance stability.
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机译：考虑到它们在Au / Ni / Cu中用作底层或用作外部保护性涂层，对在铜和铜合金上进行脉冲镀镍涂层进行了研究。改变沉积参数以便确定它们对微结构的影响，并因此确定对电沉积的镍膜的电接触性能的影响。对这些样品进行了粗糙度和硬度测量以及SEM研究。获得了光滑且致密的涂层，以实现高的暂停脉冲比，25-75 Hz的脉冲镀覆频率和低电流密度。测量了接近和插入模式下沉积样品的接触电阻R / sub c /，相对于负载F / sub c /在0.1-10 N范围内。发现初始接触电阻遵循幂律R / sub c / ＝ KF / sub c // sup -n /其中n是硬度和涂层形貌的依存性。此外，在日常循环气氛中老化的样品在测试过程中显示出接触电阻的增加，但是如电流-电压特性所证实的，欧姆行为占主导。最后，通过微动研究研究的机械性能表明，脉冲反向条件改善了接触电阻的稳定性。
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