Quantitative analysis of organic additives in acid copper plating solution

Due to the decomposition, condensation, and invalidation of organic additives in acid copper plating solution, it is hard to identify the effective concentration of additives, which causes difficulties in the prediction and grasping of the electroplating effect. To solve this problem, this paper established the linear relationship between absorbency and the concentration of organic additives based on the principle of ultraviolet spectrophotometry and the luminescence mechanism of the chromogenic agent and three organic additives after eliminating the interference of copper and hydrogen ions in the plating solution. The concentrations of polyethylene glycol (PEG), bis-(sodium sulfopropyl)-disulfide(SPS), and gelatin in the solution were analyzed quantitatively according to Law of Lambert-Beer. According to the results, the linear relationship between PEG’s mass concentration and absorbency can be described as y = 0.01057 + 0.01372x, with a linear correlation of 0.9982, a relative error of about 0.56%-3.7%, and a minimum detection limit of 1 mg/L. The method adopted for detecting the SPS content records a relative error of around 0.817%-4.202% with the minimum detection limit of 2 μmol/L. The linear relationship between gelatin concentration and absorbancy is expressed as y = 0.02165x + 0.00932, in which the linear correlation r = 0.9906.