Manufacturing method of metal mask and metal mask thereof

A manufacturing method of a metal mask, comprising:

• providing a metal plate having a first surface and a second surface opposite to each other, wherein the first surface has a plurality of preset opening regions, and each of the preset opening regions has a first area;
• forming a first photoresist layer on the first surface of the metal plate, wherein the first photoresist layer has a plurality of first apertures, and each of the first apertures has a second area;
• the first apertures correspond to the preset opening regions respectively, and each of the preset opening regions is partially exposed to each of the first apertures, wherein the second area is 75%-100% of the first area;
• forming a second photoresist layer on the second surface of the metal plate, wherein the second photoresist layer has a plurality of second apertures, and the second surface is exposed to the second apertures;
• forming a plurality of first etching parts on the first surface, wherein the first etching parts correspond to the first apertures respectively;
• each of the first etching parts has a first opening, and each of the first openings is located in each of the preset opening regions;
• and
• forming a plurality of second etching parts on the second surface, wherein the second etching parts correspond to the second apertures respectively.