| Manufacture of the Invar Fine Metal Mask Using an Electroforming Technique I.g. Kim1; Y.b. Park2; 1, Suncheon, Republic of South Korea; 2SUNCHON NATIONAL UNIVERSITY, Suncheon, Republic of South Korea; PAPER: 31/Manufacturing/Regular (Oral) SCHEDULED: 16:45/Wed. 30 Nov. 2022/Saitong ABSTRACT: In the manufacturing processes of red-green-blue (RGB)-type organic light emitting diode (OLED) displays, Invar (Fe-36 wt.% Ni alloy) is used as a material for the fine metal mask (FMM), which guides the evaporated diode materials through its small holes onto the correct positions of the substrate glass. Because the hole size of the FMM should not change during the evaporation process, Invar, whose thermal expansivity approaches zero[1], must be used for the FMM material. For high-quality color images in the display, the thickness of the FMM needs to be thinner [2]. Contrary to the conventional top-down method of producing Invar, a bottom-up approach of electroforming is a promising technology for producing very thin FMMs. The present authors have recently presented that the electroformed Invar via sophisticated heat treatment exhibits the coefficient of thermal expansion (CTE) lower than that of the conventional Invar [3]. The current work has been aimed at investigating the effect of the microstructure evolution on the CTE during heat treatment in electroformed Invar. Finally, we propose optimal process conditions to manufacture the Invar FMM applied for an ultra high definition (UHD) grade of the OLED display. References: [1] Guillaume, C.É. Recherches sur les aciers au nickel. Dilatations aux températures élevées; résistance électrique. Comp. Rend. Acard. Sci. 1897, 125, 235–238. [2] Kim, C.W.; Kim, K.S.; Park, J.K.; Kim, D.H.; Jung, K.R. FMM Material and Manufacturing Process for UHD Resolution AMOLED Displays, SID 2019 DIGEST. 2019, 1079-1082. [3] Park, Y.B.; Kim, I.G. The Gain of Low Thermal Expansivity via Phase Transition in Electroformed Invar, Coatings. 2018, 8, 169. |
