Corrosion Behavior of the Nickel/nickel Interface During the Copper Sacrificial Layer Releasing Process in Micro-Electroforming

The corrosion behavior of the Ni/Ni interface during the Cu sacrificial layer releasing process in micro-electroforming has been investigated. The XPS and SEM results reveal that the pre-existing passive layer and interfacial defects exist on the Ni/Ni interface. Compared with Ni base, the interface is prone to be attacked. Pitting corrosion occurs along interface boundary, which contains three main processes, pit initiation, pit growth and pits fusion, leading to a commensurate reduction in interfacial adhesion strength and ultimately structural integrity. The combination of the substrate modification and heat post treatment is an effective solution to avoid the localized corrosion. We believe that both the surface activation and thermally induced diffusion have worked.