This presentation will describe the use of the RTA (Technic, Inc.) system for control of a Cu plating bath in a SC productization environment. This tool is a robust, in-situ sensor that analyzes all the components of the bath by a variety of electroanalytical techniques. It consists of a probe that stays continually immersed in the main bath module of the plater, with the appropriate electronics and PC controller located within 25 ft. of the probe. A complex factory calibration scheme provides accurate measurements. The internally generated reference electrode and the rigorous electrochemical cleaning procedures provide long-term repeatability and reliability. Measurements of all 5 components are performed in ~ 15 minutes, making repeated measurements easy. Long-term sensor stability has been demonstrated. After a year of continuous use, this sensor has required no recalibration and virtually no maintenance. Bath control is greatly facilitated by the accuracy, repeatability and reliability of this sensor. Its CoO is minimal, there is no need for any standards or test solutions and its cleanroom footprint is no larger than a PC. Further development of this system, aimed to provide information over and above simple bath control, will also be described.