High Performance Roll-to-Roll Refractive Index Matched to Optically Clear Adhesive ITO Coating Films for Projected-Capacitive Touch Screens Application

摘要

After the Apple iPhone hit the market, projected capacitive touch technology gained momentum in the mobile computing manufacturing industries. A constant reflectance at the touch screen surface, as light plays across the surface, is a requirement for ITO patterned materials used by projected capacitive touch screens. To meet this requirement, refractive index matched ITO coatings, on glass or plastic substrates, is essential. This paper describes the design, fabrication, and characterization of high performance refractive index matched to optically clear adhesive (OCA), roll-to-roll ITO on polyethylene terephthalate (PET) coating. In this work, a mixed nanoparticle chemical wet web coating has been selected as the under layer of ITO for ITO index matching to the OCA. The mechanical advantages for using the chemical web wet coating are shown in this paper. This paper also shows how to achieve index matching to OCA with different ITO surface sheet resistance based on the same chemical wet web undercoating by changing the ITO sputtering process parameters. This is achieved due to the optical constants (n and k) of the ITO coating varying as the ITO sputtering process parameters are changed.