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Materials 2018, 11(1), 160; https://doi.org/10.3390/ma11010160

Quadrilateral Micro-Hole Array Machining on Invar Thin Film: Wet Etching and Electrochemical Fusion Machining

Department of Mechanical Engineering, Inha University, Incheon 402-751, Korea
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Received: 11 December 2017 / Revised: 3 January 2018 / Accepted: 17 January 2018 / Published: 19 January 2018
(This article belongs to the Section Manufacturing Processes and Systems)
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Abstract

Ultra-precision products which contain a micro-hole array have recently shown remarkable demand growth in many fields, especially in the semiconductor and display industries. Photoresist etching and electrochemical machining are widely known as precision methods for machining micro-holes with no residual stress and lower surface roughness on the fabricated products. The Invar shadow masks used for organic light-emitting diodes (OLEDs) contain numerous micro-holes and are currently machined by a photoresist etching method. However, this method has several problems, such as uncontrollable hole machining accuracy, non-etched areas, and overcutting. To solve these problems, a machining method that combines photoresist etching and electrochemical machining can be applied. In this study, negative photoresist with a quadrilateral hole array pattern was dry coated onto 30-µm-thick Invar thin film, and then exposure and development were carried out. After that, photoresist single-side wet etching and a fusion method of wet etching-electrochemical machining were used to machine micro-holes on the Invar. The hole machining geometry, surface quality, and overcutting characteristics of the methods were studied. Wet etching and electrochemical fusion machining can improve the accuracy and surface quality. The overcutting phenomenon can also be controlled by the fusion machining. Experimental results show that the proposed method is promising for the fabrication of Invar film shadow masks. View Full-Text
Keywords: wet etching; electrochemical machining; fusion machining; Invar film; micro-hole array wet etching; electrochemical machining; fusion machining; Invar film; micro-hole array
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Choi, W.-K.; Kim, S.-H.; Choi, S.-G.; Lee, E.-S. Quadrilateral Micro-Hole Array Machining on Invar Thin Film: Wet Etching and Electrochemical Fusion Machining. Materials 2018, 11, 160.

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