| 摘要 |
PURPOSE:To easily produce a shadow mask having fine hole of a required shape free from a defect without necessitating a backing stage by utilizing etching liquid having concn. difference and simultaneously photoetching both surfaces of a metallic plate for a base material. CONSTITUTION:A photoresist 3 is provided on both surfaces of a metallic plate 1 of a base material for a shadow mask. Then the metallic plate 1 is etched simultaneously from both surfaces by applying high-concn. etching liquid 6 on one surface and applying low-concn. etching liquid 7 on the other surface. In this case, the high-concn. etching liquid 6 is higher in viscosity and lower in etching velocity and on the other hand, the low-concn. etching liquid 7 is higher in etching velocity. After etching treatment is finished at a point of time when a prescribed through-hole has been formed, the photoresist 3 is removed. Thereby the fine hole having such a cross-sectional shape that irregular reflection of the electron beam is not caused in the side of the hole is perforated by one time of etching without performing backing and the shadow mask is obtained with good yield. |
