Shadow mask of the nickel-iron type having specific composition

摘要

A method of manufacturing a shadow mask of the nickel-iron type, in which an aperture-patterned sheet of a nickel-iron alloy comprising 35-37% by weight of Ni and less than 0.1% by weight of each constituent of the group of Mn, Cr and Si and at most 0.9% by weight of Co is given a thermal treatment for obtaining an ASTM grain number of >/=7, and the sheet thus obtained is given the desired shape of a shadow mask having a thermal expansion coefficient of