| 摘要 |
PURPOSE:To produce a high-fineness shadow mask in high yield in case of producing the shadow mask for a high-fineness color picture tube by making both the surface roughness of a thin steel sheet for stock and a mean interval of ruggedness of the surface roughness to specified value and forming a resist film thereon and boring it by means of etching. CONSTITUTION:A thin aluminum killed low carbon soft steel sheet having 0.2mm thickness is used as a stock of a shadow mask and surface roughness Ra (surface roughness indication by TIS, B, 0601) is regulated to 0.2-0.7mum and a mean interval Sm of ruggedness of the surface roughness is regulated to <=100mum by dull finish or furthermore crystalline particle size is regulated to >=8.0 in particle size number. After subjecting this thin soft steel sheet to degreasing treatment, photosensitive liquid is coated thereon to form a resist film and a mask pattern is closely stuck and subjected to etching treatment via exposure to light, development, drying and burning and a high-fineness hole formed on the pattern is bored. The high-fineness shadow mask can be produced in excellent product yield.
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