Metallic ion concentration on Ni-W planting bath had little influence on the thickness of Ni-W films. On the other hand, concentration increasing of metallic ion decreased the content rate of W in Ni-W film and suppressing nodules on Ni-W film. Ni-W plating bath with a metallic ion concentration of 0.75 M was largely similar to that of 1.0 M in content rate of W in Ni-W film and surface shape of Ni-W film. Since the content rate of W in Ni-W film and suppression of nodules are in the relationship of trade-off, it is necessary to search a metallic ion concentration that achieves high content rate of W and suppression of nodules at the same time
