Is there an easy method for monitoring the concentration levels of organic additives in our plating baths? I now use a Hull cell to monitor the condition of my baths but would like to find a quantitative or at least semi-quantitative method. C.G.
I addressed a similar question in the context of copper plating earlier this year, but it is worthwhile discussing this again.
Yes, the Hull cell is a good place to start when monitoring the "health" of a plating bath, but the results are more of a qualitative nature. The results are also dependent on the skill and experience of the individual "reading" the results. An excellent way to get quantitative information about organic additives in plating baths is cyclic voltammetric stripping, CVS for short. CVS uses an electrochemical technique to monitor the additives. The concept is straighforward but does require instrumentation specifically designed for the method. Measurements using fresh additives are compared to those of the plating bath. The testing process is computer controlled, and results are expressed in terms of amount of additive present in the actual plating bath.
This type of instrumentation is used by almost all of the major manufacturers of printed circuit boards and semiconductors. Its use in other areas of the electroplating industry is a good idea.
Sources for CVS equipment can be found on the Suppliers page or in the 2002 Products Finishing Directory and Technology Guide under Analytical Equipment, automatic solution titration.