Mechanism of Boron Codeposition in Electrodeposited Ni-B Alloy Films and Calculation of the Amount of Codeposited Boron

SUMMARYWe electrodeposited Ni-B ahoy films using a rotary electrode under various plating conditions and investigated the mechanism of the codeposition of B into the plated films by analyzing the relationship between the electrodeposition conditions and the composition of the plated films, as well as by analyzing electrochemical measurements. We reached the following conclusions: 1) In Ni-B alloy plating by electrodeposition, use of a rotary electrode expands the useful current density regions compared to a static bath.2) Unionized TMAB is present in the plating solution, and the deposition rate of B is related to the thickness of the diffusion layer at the cathode surface, regardless of the electrode potential. Accordingly, the amount of codedeposited B can he calculated from v0.7 and l/I, i.e., peripheral speed and current density.