New and clean strategy for the determination of Cu2+ in electroless copper plating baths

This article concerns a new and clean strategy for the determination of Cu2+ in electroless copper plating baths with differential spectrophotometry. With this strategy, the problem of too high absorbance of Cu2+ under plating conditions has been solved. We investigated the influence of copper sulfate, sodium hypophosphite, nickel sulfate, sodium citrate, polyglycol, temperature and pH on the absorption spectrum of Cu2+ in electroless copper plating baths. Five grams per litre of CuSO4·5H2O solution was selected as the reference solution. Experimental results prove that, this strategy has the merits of fast and high accuracy compared to the traditional techniques. Linearly dependent coefficient of the working curve is 0.9999 and the components in the formula have no obvious effect on the detection of Cu2+ under experimental conditions. Therefore, we can directly move solutions from the EC plating baths for detection, after that the sample can still go back to the baths without any pollution from the plating process to the environment.