Formation and performance of ohmic contact electrodes on BaTiO3-based thermistors by localized electroless Cu-plating

Ohmic contact electrodes with high performance were formed on the surface of BaTiO3-based thermisitors by localized electroless Cu-plating and the physical properties of the coated thermistors were investigated. The adhesive force between the electroless plated layer and the substrate, the voltage-resistance, the resistance, the ageing-resistance properties, and the solderability, all met the industrial production requirements for thermistors. The structure and morphologies of these NiP–Cu composite electrodes as well as the ceramic substrates were characterized by X-ray diffraction and atomic force microscopy, verifying that the film contains a typical Cu crystal structure with preferred orientation of the copper grains.