• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.06a
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• pp.19-20
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• 2001

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.12
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• pp.1194-1199
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• 2007

A unique fabrication method for a copper micromesh is proposed and demonstrated. A PDMS mold was fabricated using a microcasting process and then used as a flexible mold in copper electroplating. The fabricated copper micromesh was well formed and connected without any cracks within the entire mold area. The experimental results verified that the fabricated features of the copper micromesh accurately followed the shape of the microstructures of the PDMS mold. This unique fabrication method provides an easy yet precise means of producing three-dimensional metal microstructures.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.1-7
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• 2015

In the present study, copper micromolds with a microhole array were precisely manufactured by a synchrotron LIGA process. Like in the traditional LIGA process, a deep X-ray lithography based on a synchrotron radiation was employed as the first manufacturing step. Due to the excellent optical performance of the synchrotron X-ray used, cylindrical micropillar arrays with high aspect ratio could be efficiently obtained. The fabricated microfeatures were then used as a master of the subsequent copper electroforming process, thereby resulting in copper micromolds with a microhole array. Thermoplastic hot embossing experiments with the copper micromolds were carried out for imprinting cylindrical microfeatures onto a polystyrene sheet. Through the hot embossing, the effect of embossing temperature and usefulness of the present manufacturing method could be verified.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.5
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• pp.419-423
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• 2008

A new polymer replication technology using ultrasonic vibration is proposed and demonstrated. A commercial ultrasonic welder has been used in this experiment. Two different types of nickel molds have been fabricated: pillar type and pore type microstructures. Polymethyl methacrlylate (PMMA) has been used as the replication material and the optimal molding time was 2 sec and 2.5 sec for pillar-type and pore-type micromolds, respectively. Compared with the conventional polymer micromolding techniques, the proposed ultrasonic micromolding technique has the shortest processing time. In addition, only contact area between micromold and polymer substrate is melted so that the thermal shrinkage can be minimized. The fabricated PMMA microstructures have been very accurately replicated without vacuum. The proposed ultrasonic molding technique is a good alternative for high volume production.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.156-157
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• 2007

나노임프린팅 기술을 이용하여 원기둥형 나노 패턴을 갖는 도광판을 제작하였다. 나노 임프린트 공정을 이용하기 위해서는 니켈 스탬퍼가 필요하기 때문에 이를 제작하기 위하여 실리콘 웨이퍼 상에 건식식각을 이용하여 실리콘 몰드를 제작하였다. 제작된 실리콘 몰드를 전주도금을 이용하여 니켈 스탬퍼를 제작하였다. 제작된 니켈 스탬퍼를 사용한 나노임프린트 공정을 통해 원기둥 나노패턴을 갖는 도광판을 제작하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.71-71
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• 2012

Memory 반도체 Test공정에서 사용되는 Probe Card의 Probing Area가 넓어지면서 종래에 사용되던 Cantilever제품의 사용이 불가능하게 되고, MEMS공정을 사용한 새로운 형태의 Advanced제품이 시장에 출현을 하였다. MEMS형의 제품은 다수의 Micro Spring을 MLC(Multi Layer Ceramic)위에 MEMS 공정을 사용하여 생성하는 방식으로서 MLC는 좁은 지역에 다수의 Pin을 생성 할 수 있는 공간을 만들어 주며, 또 다른 이유는 전기적 특성인 임피던스를 맞추고 다수의 Pin의 압력에 의하여 생기는 하중을 Ceramic기판으로 지탱하기 위한 목적도 있다. 이에 MLC와 같은 전기적 특성을 임피던스를 맞춘 RF-CPCB를 사용하여 작은 면적에 다수의 Pin접합이 가능한 방법을 마련한 후, 이 RF-PCB를 부착하여 Pin의 하중을 받는 Wafer와 유사한 열팽창을 갖는 Substrate를 사용하여 MLC를 대체하여 다양한 온도 조건에서 사용이 가능하며, 복잡하고 공정비가 많이 드는 MEMS 공정에 의한 일괄 Micro Spring 생성 공정을 전주 도금 또는 2D방식의 도금 Pin으로 대체하였으며, Probe Card의 중요한 물리적 특성인 Pin들의 정렬도를 마련하기 위해 Photo Process를 사용한 Wafer로 만든 Wafer Pin Array Frame을 사용하여 2D 제작 Pin을 일괄 또는 부분 접합이 가능한 방법으로 Probe Array Head를 제작하여 이들을 부착하여 Probe Array Head를 이전의 MEMS공정 방법에 비해 쉽고 빠르게 만들어 probe Card를 제작 할 수 있게 되었다.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.12
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• pp.13-20
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• 2004

Manufacturing process for the microfluidic device can include such sequential steps as master fabrication, electroforming, and injection molding. The laser ablation using masks has been applied to the fabrication of channels in microfluidic devices. In this study, manufacturing of polymer master and mold insert for micro injection molding was investigated. Ablation of PET (polyethylene terephthalate) by the excimer laser radiation could be used successfully to make three dimensional master fur nickel mold insert. The mechanism fur ablative decomposition of PET with KrF excimer laser $({\lambda}: 248 nm, pulse duration: 5 ns)$ was explained by photochemical process, while ablation mechanism of PMMA (polymethyl methacrylate) is dominated by photothermal process, the .eaction between PC (polycarbonate) and KrF excimer laser beam generate too much su.face debris. Thus, PET was adopted in polymer master for nickel mold insert. Nickel electroforming using laser ablated PET master was preferable for replication method. Finally, it was shown that excimer laser ablation can substitute for X-ray lithography of LIGA process in microstructuring.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.8-13
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• 2015

In this study, we fabricated and characterized a nanostructured surface based on a plastic injection molding with a local mold heating (LMH) system. A metal mold core with a closed packed nano convex array (CVA) was achieved by integrated engineering procedures: (1) master template fabrication by anodic aluminum oxidation (AAO), (2) nickel electroforming (NE) process, and (3) post-processing by precision machining. The nickel mold core was utilized to replicate a surface with a closed packed nano concave-array (CCA) based on injection molding using cyclic olefin copolymer (COC) as a plastic material. In particular, an LMH system was introduced to enhance transcription quality of the nano structures by delaying solidification of molten polymer near the surface of the mold core.

• Korean Journal of Metals and Materials
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• v.46 no.7
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• pp.420-426
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• 2008

By using electrodeposition, we developed a new method to produce Ni/Invar bimetal sheets, which have been used for the present study to investigate the texture evolution during annealing. The grains of electrodeposited Ni were columnar, while those of electrodeposited Fe-Ni alloy were nanocrystalline. These different parts of the bimetal underwent different evolution of textures and microstructures during annealing. In the nanocrystalline Invar, the as-deposited textures were of fiber-type characterized by strong <100>//ND and weak <111>//ND components, and the occurrence of grain growth resulted in the strong development of the <111>//ND fiber texture with the minor <100> // ND components. On the other hand, in the columnar-structured Ni part, the as-deposited <110>//ND fiber texture transformed to the <112>//ND fiber texture due to recrystallization occurring above $550^{\circ}C$. The development of microtextures which took place during annealing in the Ni/Invar interfacial regions was investigated by using the OIM analysis, and discussed in terms of the effect of atomic diffusion across the interfaces.

• 연구논문집
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• s.33
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• pp.183-190
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• 2003

Today, We have used many electronic equipment such as computer, TV, cellular phone and so on. These equipment radiate a large amount of EMI(Electromagnetic interference) which is occurred trouble of airplane, medical equipment, communicate equipment, and especially, human health. So, Ni mesh fabrication for EMI shielding by continuous electroforming process was investigated. Continuous electroforming apparatus was made by means of rotating cathode drum. And We investigated the characteristics of two types of Ni electroforming solution. One was made by laboratory and the other was produced by M cooperation. The grain size increased with increasing current density and bath temperature, and decreasing rotating speed of cathode drum. EDX results indicate that the Ni mesh electroformed by the KIMM solution is composed of pure Ni. But the Ni mesh electroformed by the M cooperation solution has Ni and S element. The incorporation of S element in the Ni mesh has a profoundly effect on mechanical properties such as hardness, internal stress and so on.