Patent ID: 6562249
Filing Date: 2003-05-13
Classification: H01J

Abstract:
A method of etching apertures in a thin metal sheet to form a shadow mask for a color picture tube, said thin metal sheet having a first acid-resistant stencil on one major surface thereof and a second acid-resistant stencil on the other major surface thereof, both said first acid-resistant stencil and said second acid-resistant stencil having openings therein at locations of intended apertures in said sheet, said method comprising:magnetically holding said thin metal sheet with a flat magnetic assembly, said flat magnetic assembly including a magnetic layer that is supported on an acid-resistant board, moving said flat magnetic assembly through an etching chamber while said flat magnetic assembly magnetically holds said thin metal sheet thereto, said etching chamber having an insulative strip passing therethrough, said thin metal sheet being positioned under said insulative strip with said first acid-resistant stencil facing downward, said magnetic assembly being located on top of said insulative strip with said magnetic layer facing downward to magnetically hold said metal sheet against said insulative strip, as said insulative strip, with magnetic assembly and metal sheet thereon, is moved through said etching chamber, partially etching into the metal sheet from the bottom side thereof to form a partially etched metal sheet, transferring said partially etched metal sheet to a second magnetic assembly which magnetically holds it thereto, placing said second magnetic assembly on the top of said insulative strip with the second acid-resistant stencil on said metal sheet facing upward, and passing said second assembly and metal sheet through a second etching chamber, wherein etch-through of apertures in said metal sheet is completed.