Analysis of the Machining Depth over Time in Wet Etching for Fabrication of Invar Thin Film Shadow Mask

Invar is made up of 64% iron and 36% nickel. Invar has a characteristic of low thermal expansion coefficient that hardly causes a change of dimension according to temperature change. It is used for shadow mask fabrication by using this feature. Shadow mask is an important element for enhancing the pixels of the display. Therefore, Wet etching is an important machining technique because it is economical and mass-producible to make shadow mask. In this study, the machining depth was compared and analyzed with the machining time by using a 30μm invar thin film. As the machining time increased, the machining depth of the hole increased and a perfect hole array occurred when the machining time was 5 minutes. Through the same processing conditions, a 5.5-inch large-area shadow mask with uniform hole size was fabricated.