| 摘要 |
<p>METHOD FOR PRODUCING AN APERTURED WORK PIECE An apertured work piece, such as a shadow mask for a color television picture tube, is produced by coating opposite major surfaces of a thin metal sheet with etchresistant patterns. One pattern comprises an array of larger open areas surrounded by etch-resistant material, and the other pattern comprises smaller open areas of similar shape and registered with the larger open areas. Each of the smaller open areas has therewithin a stillsmaller solid area of etch-resistant material. The coated sheet is etched from both sides to produce the desired apertures, and then the coatings are removed from the sheet.</p> |
