ABSTRACT

An Au–Ag coating has been envisaged as an alternative to the conventional Au–Co electrodeposit. In this study, an Au–Ag coating was electrodeposited on Cu substrates pre-coated with a Ni layer. The contact resistance of the Au–Ag coating was observed to be lower than that of the Au–Co coating. Under extended aging, the Au–Ag coating demonstrated a slightly increased contact resistance, while the contact resistance of the Au–Co coating increased significantly. Additionally, the solderability of the Au–Ag coating surpassed that of the Au–Co coating. Qualitative analyses demonstrate that, in the case of Au–Co coating, a considerable amount of Ni diffused through the Au layer to react with O₂ in the air to form oxides during aging. The Co elements also oxidised due to aging. The formation of the oxide layer induced an increased contact resistance and diminished solderability. In addition, the Au–Co coating consisted of finer grains than the Au–Ag coating, promoting the Ni diffusion through the Au layer.

摘要

Au-Ag 涂层已被设想为传统 Au-Co 电沉积的替代品。在这项研究中，Au-Ag 涂层被电沉积在预涂有 Ni 层的 Cu 基底上。观察到 Au-Ag 涂层的接触电阻低于 Au-Co 涂层的接触电阻。在长时间老化下，Au-Ag 涂层的接触电阻略有增加，而 Au-Co 涂层的接触电阻显着增加。此外，Au-Ag 涂层的可焊性超过了 Au-Co 涂层。定性分析表明，在 Au-Co 涂层的情况下，大量 Ni 扩散通过 Au 层与 O _2反应老化时在空气中形成氧化物。Co元素也因老化而氧化。氧化层的形成导致接触电阻增加和可焊性降低。此外，Au-Co 涂层由比 Au-Ag 涂层更细的晶粒组成，促进了 Ni 通过 Au 层扩散。