GB1209380A - Image plane plate - Google Patents

Abstract

1,209,380. Image plane plates. PPG INDUSTRIES Inc. 27 Sept., 1968 [29 Sept., 1967], No 45912/68. Heading C1M. [Also in Division G2] A pattern in an ultra-violet-light-responsive substrate is produced by: (i) producing a plate of glass having selected portions of one surface thereof stained by migration into the glass of metal ions so as to be opaque to U.V. light in said portions, (ii) applying the plate to a substrate whereon said pattern is to be produced in a photoresist material developable by exposure to U.V. light and subsequent subjection to a solvent, and passing U.V. light through the plate on to the photoresist and treating with the solvent. The stained glass plate is preferably made by first staining all one side of the plate, by either simply coating one side, or masking one side and dipping in the stain material, or by dipping the plate unmasked and removing the coating on one surface of the plate. The metal ion is preferably silver, applied by using a staining material comprising silver chromate and titania in an appropriate vehicle, which material is applied and fire at, e.g. 1150‹ F. for 7 minutes, resulting in a stain of depth about 0.001 inch in the plate. This gives 8-10% transmission of visible light with substantially zero transmission of U.V. The optical density of the surface may be improved by treating with, e.g. forming gas, SO 2 or H 2 S. The stained plate is then coated with an etch-resistant coating, and the desired pattern scribed in said coating. The plate is then etched in the scribed zones, so as to remove selected portions of the opaque zone, and the etch resistant coating then removed. Such a plate has the desired pattern scribed in it, necessitating the use of a negative resist material on the substrate. In an alternative method, the plate is first coated and scribed, and the scribed areas rendered U.V.-opaque as above. The coating is then removed, leaving a plate in which the opaque regions give the desired pattern, allowing the use of a positive resist on the substrate.