Shadow mask for a color picture tube

摘要

A shadow mask for a color picture tube is formed from a nickel-iron alloy steel sheet made of a nickel-iron alloy containing 35.0% to 37.0% by weight of nickel and 0.01% to 0.06% by weight of carbon. The alloy preferably has no more than 0.30% of silicon, 0.10% to 0.60% of manganese, no more than 0.020% of phosphorous and no more than 0.020% of sulphur. The nickel-iron alloy steel sheet is provided with apertures by etching using a pattern provided on the sheet. The mask is free from image degradation due to a rise in temperature.