Electroless Plated Ni-P on Hole Surface and Mechanism of Deposition

The surface morphology and composition of Ni-P coating were analyzed by SEM and EDS. The deposition rate of Ni-P coating was measured by weight gain method. The surface morphology showed axial grains in the initial stage and cellular structure after forming continuous film. The chemical composition of cellular structure was different from that of the half sphere nuclei nucleated on it. The depositing rate decreased with the decrease of hole height when the height of through hole and blind hole was less than 1.76 mm and 2.2 mm respectively.