Strip material used for shadow mask having improved post-etching shape

Abstract

A mild steel or Fe--Ni alloy used for a shadow mask has TS / 0.2% YS .ltoreq.1.03. The cross sections S.sub.1 and S.sub.2 of a strip parallel and perpendicular to the rolling direction (RD), respectively, are subjected to the residual stress, which vary in the thickness direction. The maximum tensile residual stress (.sigma..sub.t) generated on a central portion of the cross sections S.sub.1 and S.sub.2 is adjusted to 50N / mm.sup.2 or less. A rectangle specimen elongated in the rolling direction (RD) is sampled from a rolled strip 1 shown at a central portion as seen in the width direction. Another rectangle specimen elongated in a direction perpendicular to the rolling direction (RD) is sampled from a rolled strip at a central portion as seen in the width direction. The rectangle specimens are clamped at one of the ends and are suspended downwards in a direction of the long sides thereof. Warp of the other non-clamped ends is 10 mm or less.

Description

BACKGROUND OF INVENTION[0001] 1. Field of Invention[0002] The present invention relates to a mild-steel strip or an Fe--Ni alloy strip used for a shadow mask having improved post-etching shape.[0003] 2. Description of Related Art[0004] A strip for a shadow mask of a Braun tube is usually produced by rolling. The strip for the shadow mask is degreased and then subjected to application of photo-resist on both surfaces. A pattern of through holes is delineated on the photo-resist layer which is then developed. Ferric chloride solution is sprayed on both surfaces of the strip to form through holes. The strip is then cut into shadow-mask segments (c.f. Materia (Journal of Japan Institute for Metals), Vol. 36 (1977), No. 11, pages 1070-1074). The shadow-mask segments are conveyed by an automatic conveying line during the etching process or the manufacturing process of a Braun tube. The etched shadow masks should not be caught on the conveyer so as to avoid conveying failure. The flatness ...

AI Technical Summary

Benefits of technology

[0011] It is an object of the present invention to provide an Al-killed-steel rolled strip or an Fe--Ni based-alloy rolled strip produced by straightening, but not stress-relief annealing, enabling reduction of residual stress and the post-etching warp.

Problems solved by technology

The residual stress (.sigma.) on both sides becomes therefore un-balanced, with the result that warp occurs.

However, in a highly precise shadow mask, since the non-symmetry mentioned above is considerable, large warp occurs under the influence of the residual stress.

However, the stress-relief annealing increases the production cost.

When the 0.2% YS becomes low, serious wrinkle is liable to occur in the subsequent etching process.

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