Method for producing base for metal masks, method for producing metal mask for vapor deposition, base for metal masks, and metal mask for vapor deposition

A method for manufacturing a metal mask substrate, the method comprising:

• preparing a rolled metal sheet having a length extending from one end to an opposing end of the rolled metal sheet and the rolled metal sheet including an obverse surface and a reverse surface that is a surface located opposite to the obverse surface, at least one of the obverse surface or the reverse surface being an object to be processed;
• reducing a thickness of the rolled metal sheet, along the length of the rolled metal sheet, to 10 μm or less by etching the object to be processed by 3 μm or more by use of an acidic etching liquid such that a maximum thickness of the rolled metal sheet is 10 μm or less, and
• roughening the object to be processed so that the processed object becomes a resist formation surface that has a surface roughness Rz of 0.2 μm or more, wherein a metal mask sheet is configured for through holes to be formed in areas of the metal mask sheet having a thickness of 10 μm or less.