Sensors for ferric ion in plating solutions

Chemical sensors based on electrochemical principles and fabricated by microelectronic thick film metallization technique are being developed for the detection of ions in plating solutions. The results of earlier reported mathematical models were applied to the design of an optimal-performing array of gold band electrodes for the sensor. In this paper, the results of testing this sensor on quantitative detection of ferric ion in zinc-iron plating baths are described. A sensor response based on the transient current output following a cathodic potential step was found to be linear and reproducible with ferric ion concentration in the range of 0 to 0.1M. The sensor was stable and reproducible in a test lasting more than 26 days. The sensor output was not significantly affected by the presence of citric acid. A protecting shield eliminated any solution flow effects.