Monitoring and process control in roll coating

摘要

The applications of vacuum web coating demand ever more precise control of the coating process and product. For example, in the sputter roll coating of transparent conductive films such as ITO, the optical absorption properties of the coating, the electrical conductivity of the layer, and optical interference effects due to layer thickness must be simultaneously measured and controlled. Antireflective or index matching layers used in display applications require precise deposition of multiple layers of several materials. High volume applications such as barrier and decorative aluminizing also increasingly utilize precise process control to ensure high material efficiency, manufacturing throughput, and process reliability. To meet these demands, a variety of instruments have been developed to measure and display the optical and electrical properties of vacuum coatings, and provide feedback for adjustment of the process. Other methods look directly at the process variables. These techniques will be reviewed with emphasis on practical applications.