Abstract
Precision coating is a very important process in manufacturing of thin films. Among many coating techniques, slot coating may be the most promising in developing high precision coating process due to its versatility and controllability. Fundamentals of slot coating have been studied by many pioneer researchers. However, two topics: use of polymer additives and discrete operation remained relatively largely uninvestigated, especially in terms of their basic mechanisms. These two topics are studied in this thesis using theoretical analysis and experimental methods. The second order fluid perturbation model is used to analyze viscoelastic effects on coating limits. It is found that the first normal stress can induce or avoid coating defects under different conditions. The predictions of this model are supported by analyzing the curvatures of upstream /or downstream menisci using microphotography. Transient flow effects due to the formation and growth of boundary layers are analyzed; and it is found the response time is extremely short. Therefore the main reason of the front edge coating defects is that the coating conditions are out of the coating window when the coating flow builds up. The relations between discontinuous and continuous coating are established and many practical operation guidelines are developed and confirmed by experiments. A practical instrument design of patch coater was also performed in this research. By integrating knowledge in coating engineering, mechanical engineering, and electrical engineering, a precision patch coater is designed, set up and tested. Besides new theories and experimental tools, the most special achievement in our research is the patch coater. This research is the first mechanical design that applies coating engineering to patch coating. Our achievements push the coating technology of Taiwan on the top of the world.