SBIR Phase I: Chemically Vapor Deposited Hydrophobic Dielectric Polymer Thin Films

This Small Business Innovation Research Phase I project will explore the failure mechanisms associated with hydrophobic dielectric coatings used in electronic paper (E paper) displays. Specifically, electrowetting (E paper) displays require such coatings in order to modulate the contact angle of colored fluids and produce visual images. In order to provide adequate electrical insulation, conventional dielectric coatings must be deposited at thicknesses that require high voltage operation. Conventional hydrophobic coatings deposited on top of these dielectrics are encumbered by electrolyte entrapment (which diminishes the electrowetting effect over time) and poor substrate conformality. We will design improved hydrophobic dielectrics that address the shortcomings of conventional offerings. Specifically, we will develop novel hydrophobic dielectric polymer coatings that exhibit the required combination of thinness, uniformity, and performance. The Phase I effort will identify promising coating recipes based on dielectric failure testing and electrowetting modulation testing. In Phase II, strategies will be developed for reducing dielectric coating defects to manufacturing levels, with an eye towards commercialization. The broader impact/commercial potential of this project is embodied in the project's anticipated advance of the state-of-the-art in thin dielectric coatings, which are used in a wide range of applications. Applications in which these coatings are simultaneously exposed to ionic solutions and electrical potentials are particularly challenging. Such applications include E paper (electrowetting) displays, implanted medical devices (e.g. neuroprosthetics, cardiac pacemakers), and military electronics. The need to prevent ingress of water and ions is acute in these applications, avoiding the short circuiting and corrosion of encapsulated electronics. Thin dielectric coatings are increasingly being viewed as viable alternatives to bulkier, more expensive hermetic packaging. While thin inorganic coatings have often been employed in similar cases, the attendant high cost and high processing temperatures associated with these materials may be prohibitive. Organic polymer encapsulants are generally not considered to be hermetic, but the assumption that electronic device hermeticity is required is often erroneous. It is anticipated that this project will facilitate both a better match between coating performance and actual device needs, and the manufacturing of reliable, lower cost electronics.