Evaluation of Copper Sulfate Electroplating Solution and Film Using a New Method of Fluorescence Measurement

Abstract

Control of plating bath conditions is an important issue on production lines. In this research, we developed a method for measuring and evaluating plating solutions using Janus Green B (JGB), a common additive, as a probe. It was discovered that when electricity was applied to a copper sulfate electroplating solution containing JGB as an additive, red fluorescence was generated. This is because the azo group of JGB is reductively cleaved by monovalent copper (Cu(I)) to produce a phenazine dye with red fluorescence. The fluorescence intensity depended on the energization current and time and was proportional to the concentration of JGB added. The fluorescence intensity indicates the rate of decrease in the concentration of JGB and can predict the deterioration of the quality of the plated film produced with the solution in a very early stage, and especially the occurrence of unevenness. Fluorescence is a simple and sensitive method of measurement that facilitates on-time and in-situ measurement and evaluation of plating baths at the production site and is a useful method of bath management.