Method for analyzing the addition agents in solutions for electroplating

Abstract

A method for measuring concentrations of addition agents in solutions of additive mixtures, namely for monitoring additives in PbSn plating solutions, comprising the steps of: (a) preparing a basis solution which contains an electroactive species whose electroreduction reaction is sensitive to the additive of interest; (b) preparing calibration standard sample solutions comprising appropriate concentrations of all species other than the additive; (c) preparing the working solution whose additive concentration is to be determined; (d) applying a pulse voltammetry technique, at a hanging Hg drop electrode, to a sample of the basis solution located in a cell of a polarographic analyzer; (e) thereafter measuring the polarographic peak height for the indicator reaction in the basis solution; (f) adding a measured amount of the working solution to the basis solution sample in the cell; (g) thereafter measuring the peak height for the indicator reaction in the mixed solution of step (f); and (h) repeating steps (f) and (g) until the peak height has dropped to a constant value.