US Patent 11396030 Mask frame assembly for depositing thin film

A mask frame assembly includes: a mask frame; at least one mask sheet arranged on the mask frame; a plurality of first support sticks extending in a first direction; and a plurality of second support sticks extending in a second direction, wherein a mask frame transformation index is within a range from about −1000 to about +1000 based on mask frame transformation index=Σ (tensile force of first support sticks/tensile rate of first support sticks)−Σ (tensile force of second support sticks/tensile rate of second support sticks), where tensile force of respective first or second support stick is given by thickness (T)×width (W)×elastic coefficient (E)×tensile rate (δ/L