Electrokinetic Imaging: A New Electrostatic Printing Process for Liquid Toners

Abstract

This paper describes a new printing/imaging technique for depositing liquid toner in which electrophoresis, in a non-aqueous medium, is used to fill the cavities of a masked substrate with functional toner. The substrate is laminated with a patterned mask that is capable of storing electrostatic charge. The mask material is similar to that used in the printed wiring board and flex circuit industries. The substrate is held in moderate proximity to a counter electrode between which an electric field will be established. The substrate/counter electrode assembly is immersed in a bath of functional liquid toner that is mechanically agitated. The substrate can be imaged in as little as 5 seconds, typically 15 to 20 seconds. The toner is a conventional liquid toner based on hydrocarbon diluents. The functional materials can be in the range of a few microns to 100 microns in diameter range.Possible applications of Electro-kinetic imaging include any product where there is a need to build a microstructure like the ribs of a plasma display panel. Such microstructures include building of posts, spheres or cavities on electronic parts and the building of fine metal wiring structures. The process can be viewed more as a building process rather than one for printing micron thick ink layers, though it can operate in that region too.