| 摘要 |
<p>A metal sheet is embossed by a special embossing tool to provide regions in the sheet of minimum thickness at the intended aperture locations thereon. Following embossing, the sheet is shaped into a desired mask contour and the embossed side of the sheet is coated with a stop-off substance to prevent subsequent removal of material from that side. The regions of minimum thickness are then removed, such as by etching the uncoated side of the sheet, to provide the apertures.</p> |
