Abstract: For the manufacture of a color screen for a cathode ray tube a process is described which uses a single photolithographic mask for defining multiple patterns, so that said single mask may be used for determining the different areas where several different phosphor layers will be located. Masks used for conventional photolithographic processes normally comprise a pattern of regions that are either fully transparent or fully opaque to the radiation used for exposing the resist. The mask used as part of the present invention includes regions that are neither fully transparent nor fully opaque, having, instead, a grey scale of optical densities. Through careful control of both exposure and development time, selected parts of a layer of a positive photoresist, that were exposed through successively denser regions of the mask, can be successively removed.

Abstract: A method for forming a layer of particles on a substrate, such as a layer of phosphor particles on the inside of a CRT, is described. The depends on the use of a double-sided adhesive tape comprising a laminate of a dry adhesive between two protective layers. One of the protective layers is stripped away to expose one surface of the dry adhesive layer which is then pressed up against the substrate surface using a method such as rolling or autoclaving to bring about bubble-free adhesion. The other protective layer is then stripped away, thereby exposing the other surface of the adhesive layer. The particles that will comprise the final layer are then applied to the exposed adhesive surface by means of dusting. This is followed by the removal of any weakly adhering particles from the final particle layer. Finally, the dry adhesive layer is itself removed by means of a heat treatment, leaving in place a uniform layer of particles adhering to the substrate surface.