GB1332000A - Kinescope manufacture involving electroless deposition techni ques - Google Patents

Abstract

1332000 Making aperture masks for cathode ray tubes RCA CORPORATION 30 Dec 1970 [30 Dec 1969] 61848/70 Heading B3A A method of making an apertured colour selection mask for a colour television tube includes the steps of providing on one face of a thin sheet of metal a perforated pattern of catalytic electroless deposition initiating material, forming in said shut permanent apertures one end of each of which is partially closed by said catalytic material and electrolessly or electrolessly and electrolytically depositing on the catalytic material further material which is opaque or is subsequently rendered opaque to form temporary apertures smaller than said permanent apertures whereby said mask is adapted to be used in the printing of phosphor deposits on the tube screen. A metal substrate 42 with a catalytic layer 46, of e.g. palladium, copper, nickel, cobalt or chromium, has a perforated pattern 48 of etch resistant material applied to the layer 46, which step may (not shown) remove the catalytic layer at the apertures 50 of the pattern 48. A second perforated pattern 52 with apertures 54 aligned with the apertures 50 of pattern 48 is optionally applied to the other face of the substrate. Portions of the substrate, and of layer 46 if not already removed, aligned with the apertures 50, 54 and portions of the substrate only adjacent the apertures are then removed by etching to leave areas 58 of catalytic layer extending partly across openings 56 etched in the substrate. Material, preferably metallic and preferably a nickel-boron alloy, is electrolessly deposited at 62 on the exposed face of the areas 58. Other suitable metals are nickel-phosphorous alloys, copper, cobalt and nickel and alloys of these metals. The material may be rendered opaque after deposit. The etch resist pattern and the catalytic layer are preferably removed before the mask is used as a photographic master in printing phosphor deposits on a transparent substrate to form an image screen for a television tube. If such removal takes place, the electrolessly deposited layer 62, may be built up by further electroless deposition (62a), Fig. 6 (not shown) or by electroplating, Fig. 7 (not shown) which latter causes plating also of the walls of the apertures 56. After the screen-printing the opaque deposits are removed by electro-chemical stripping or chemical etching. The mask (30) and screen (8) are subsequently mounted in a colour television tube (10) Fig. 1 (not shown).