Manufacture Shadow masks are made using a photochemical machining process. It starts out with a sheet of steel or invar alloy that is coated with photoresist, which is baked to solidify it, exposed to UV light through photomasks, developed to remove unexposed resist, the metal is etched using liquid acid, and then the photoresist is removed. One photomask has larger dark spots than the other, this creates tapered apertures. The shadow mask is installed to the screen using metal pieces or a rail or frame that is fused to the funnel or the screen glass respectively, holding the shadow mask in tension to minimize warping (if the mask is flat, used in flat screen CRT computer monitors) and allowing for higher image brightness and contrast. Bimetal springs may be used in CRTs used in TVs to compensate for warping that occurs as the electron beam heats the shadow mask, causing thermal expansion.
Manufacture Shadow masks are made using a photochemical machining process. It starts out with a sheet of steel or invar alloy that is coated with photoresist, which is baked to solidify it, exposed to UV light through photomasks developed to remove unexposed resist, the metal is etched using liquid acid, and then the photoresist is removed. One photomask has larger dark spots than the other, this creates tapered apertures. The shadow mask is installed to the screen using metal pieces or a rail or frame that is fused to the funnel or the screen glass respectively, holding the shadow mask in tension to minimize warping (if the mask is flat, used in flat screen CRT computer monitors) and allowing for higher image brightness and contrast. Bimetal springs may be used in CRTs used in TVs to compensate for warping that occurs as the electron beam heats the shadow mask, causing thermal expansion.