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Manufacture of microscale random pattern using indentation machining technology
Je-Ryung Lee,Seung Hwan Moon,Tae-Jin Je,Doo-Sun Choi,Hwi Kim,Eun-chae Jeon 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.6
The display industries recently demand new microscale dot-type patterns for thinner and brighter displays with high energy efficiency, which are randomly distributed with irregular separation distances and have uniform optical characteristics. We developed a new program to generate the coordinates of the controlled microscale random patterns considering their diameter and the distance to the nearest pattern for preventing overlap of each pattern. Then the microscale random patterns were machined on a metal mold using the indentation machining which is a simple and low-cost machining method. We decreased the total machining time by the optimization of machining order of the random patterns. The coordinates, the diameter and the fi ll-factor of the machined patterns by the indentation machining were much consistent to the designed values. The controlled microscale random patterns had uniform optical characteristics over all areas of the manufactured optical fi lm. Moreover, if optical films have the same diameters and fi ll-factor, they showed the same optical characteristics even they have totally different coordinates of random microscale patterns. This technology is expected to reduce the number of the optical films and the light sources in the display, which can save much energies.
감광성 에칭 레지스트의 잉크젯 인쇄를 이용한 인쇄회로 기판 제작
박성준(Sung-Jun Park),이로운(Ro-Woon Lee),정재우(Jaewoo Joung) Korean Society for Precision Engineering 2007 한국정밀공학회지 Vol.24 No.5
A novel selective metallization process to fabricate the fine conductive line based on inkjet printing has been investigated. Recently, Inkjet printing has been widely used in flat panel display, electronic circuits, biochips and bioMEMS because direct inkjet printing is an alternative and cost-effective technology for patterning and fabricating objects directly from design without masks. The photosensitive etching resist used in this process is an organic polymer which becomes solidified when exposed to ultraviolet lights and has high viscosity at ambient temperature. A piezoelectric-driven ink jet printhead is used to dispense 20-30 pm diameter droplets onto the copper substrate to prevent subsequent etching. Repeatability of circuitry fabrication is closely related to the formation of steady droplets, adhesion between etching resist and copper substrate. Therefore, the ability to form small and stable droplets and surface topography of the copper surface and chemical attack must be taken into consideration for fine and precise patterns. In this study, factors affecting the pattern formation such as adhesion strength, etching mechanism, UV curing have been investigated. As a result, microscale copper patterns with tens of urn high have been fabricated.
REDUCTION OF PISTON SKIRT FRICTION USING THE MICRO-SCALE PATTERNED SURFACE
강종대,이종훈,김동립,박성욱 한국자동차공학회 2023 International journal of automotive technology Vol.24 No.1
The purpose of this study is to determine whether piston friction can be reduced by applying a micro-pattern to the skirt portion of the piston, which accounts for the largest proportion of engine parts. The roughness of the ready-made pistons was reduced before etching the micro-scale pattern onto the piston skirt. The micro-patterns were screen-printed on the piston skirt, and kept uniform through etching. The friction reduction effect of the piston was confirmed through an engine experiment using a 1.6 L four-cylinder gasoline engine to remove parts. A hexagonal shape that is representative of bionic textures was selected for the micro-pattern, and circular and cross-hatch patterns were additionally produced for comparison. The friction experiments with the patterning pistons confirmed that friction was reduced by up to 6.74 % by adjusting the spacing of the hexagonal pattern. It was also confirmed that friction was reduced in the cross-hatch pattern by up to 5.28 %. The friction reduction effect may vary depending on the parameters used for a specific pattern.
윤성원,Kenta Suzuki,Hideki Takagi,Hiroshi Hiroshima,Yoshinori Kinoshita,Katsuhiro Hayashi 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.8
High-aspect-ratio microstructures (HARMS) of polyimides have many applications, such as components of microelectromechanical systems and X-ray gratings. This study demonstrates the fabrication of HARMS with vertical and smooth sidewalls in a thick, soluble block-copolymer polyimide (SBCP) film by an UV-assisted thermal imprint process. A preheating condition was controlled as a parameter that dominated the imprint pattern fidelity. After investigating a proper prebaking condition, patterns with a width of 3.4 μm and a height of 35.1 μm with a high-aspect ratio of 10 were successfully structured in an SBCP film that has a thickness of approximately a hundred micrometers. The process has potential as a low-cost fine pattern fabrication process for polyimide-based polymers.