Abstract
We investigated the relationship between adhesion and internal stress to improve the adhesion of electroless pure Ni plating on a smooth alumina substrate, focusing on the energy balance in the interface between the substrate and the film. We measured both parts for unified energy (J/m2) and found the ideal adhesion energy. In the measured results, peel energy Gp is dependent on film thickness, and thicker film reduced the Gp of the Ni plating. Since the thickness of columnar crystal pure Ni plating film is more than 0.2 μm, columnar crystal pure Ni plating is highly adhesive on smooth alumina substrates. Interfacial adhesion energy Gad which is the ideal adhesion energy is not simply the sum of peel energy Gp (adhesion) and internal strain energy Gin (internal stress); we also must consider bending energy Gbend, elastic energy Gel, and fracture energy Gf. The gains achieved reflect the high adhesion property of columnar crystal pure Ni plating compared to nano crystalline pure Ni plating. In this study we successfully controlled both the appearance of the void for the interface between the substrate and the film to minimize internal strain energy Gin, and the strength around the interface between the substrate and the film to minimize elastic energy Gel and fracture energy Gf.
