• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.868-870
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• 2009

이 연구에서는 암반에 마이크로 파일을 그라우팅하여 시공할 경우에 암반과 그라우트 접촉면에 발생되는 부착력을 특수 제작된 부착력실험용 몰드와 만능시험기를 이용하여 측정하고 그라우팅 방법(압력식, 중력식)을 달리하여 비교 분석하였다. 실험결과 압력식의 부착력과 일축압축강도가 중력식보다 크게 나타났다.

• 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 Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.94-97
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• 2002

Micromolding methods are most suitable for mass production of plastic microlens and lens array with low cost. Among the procedures related with micromolding of microlens array, fabrication of mold insect which contains micro cavity of lens shape is the most important stage. In this study, nickel mold inserts for 45 $\mu\textrm{m}$ and 95 $\mu\textrm{m}$ diameters lens way were fabricated using electroforming process. The mother for metal mold inset was made using reflow method. A micro compression molding with polymer powders was used to test the qualities of the metal mold insets. Micro lens profile and surface roughness was measured by interferometric technique and AFM, respectively. The final molded lens replicated the mother well, and had good surface quality.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.6
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• pp.271-275
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• 2001

We investigated preparation of 1-3 PZT composites for medical ultrasonic transducer array (briefly UTA) using micro pressing method. The proposed process was using pressing PZT green sheet by PMMA micro mold obtained from X-ray lithography. Microstructures, electriacl and electro-mechanical properties of fabricated composites were analyzed. Dielectric constant at 1kHz and thickness mode electro-mechanical coupling coefficient of $6.2mm{\times}6.2mm{\times}422{\mu}m$ UTA sample were 1754 and 51%, respectively. Microstructures of sintered PZT showed dense and uniform. And PZT phases were well crystallized. Micro pressing method is a mass productive process in case of using injection molded PMMA by batch type LIGA process.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.2
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• pp.85-89
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• 2014

We propose the new fabrication method of a 70 nm half-pitch wire grid polarizer with high performance using magnetic soft mold. The device is a form of aluminium gratings on a PET(Polyethylene phthalate) substrate whose size of $3cm{\times}3cm$ is compatible with a TFT_LCD(Tin Flat Transistor Liquid Crystal Display) panel. A magnetic soft mold with a pitch of 70 nm is fabricated using two-step replication method. As a result, we get a NWGP pattern which has 70.39 nm line width, 64.76 nm depth, 140.78 nm pitch, on substrate. The maximum and minimum transmittances of the NWGP at 800 nm are 75% and 10%, respectively. This work demonstrates a unique cost-effective solution for nanopatterning requirements in consumer electronics components.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.2
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• pp.65-70
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• 2023

Nanoimprint lithography (NIL) has attracted much attention due to its process simplicity, excellent patternability, process scalability, high productivity, and low processing cost for pattern formation. However, the pattern size that can be implemented on metal materials through conventional NIL technologies is generally limited to the micro level. Here, we introduce a novel hard imprint lithography method, extreme-pressure imprint lithography (EPIL), for the direct nano-to-microscale pattern formation on the surfaces of metal substrates with various thicknesses. The EPIL process allows reliable nanoscopic patterning on diverse surfaces, such as polymers, metals, and ceramics, without the use of ultraviolet (UV) light, laser, imprint resist, or electrical pulse. Micro/nano molds fabricated by laser micromachining and conventional photolithography are utilized for the nanopatterning of Al substrates through precise plastic deformation by applying high load or pressure at room temperature. We demonstrate micro/nanoscale pattern formation on the Al substrates with various thicknesses from 20 ㎛ to 100 mm. Moreover, we also show how to obtain controllable pattern structures on the surface of metallic materials via the versatile EPIL technique. We expect that this imprint lithography-based new approach will be applied to other emerging nanofabrication methods for various device applications with complex geometries on the surface of metallic materials.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.25-29
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• 2015

Demand for a low-cost, high-throughput, and high-resolution patterning method for fabricating devices continues to increase. The roll-to-roll (R2R) imprint lithography technique has received a great deal of attention as a means of fabricating next-generation devices. In this paper, we propose a fabrication method for polymeric planar lightwave circuit (PLC) devices that uses R2R imprint lithography. The proposed technique uses an elastomeric polydimethylsiloxane (PDMS) mold. A Si wafer with micro patterns is used as the Si master. The PDMS mold is then replicated from the Si master. By applying a precise web tension and at a given web speed, we fabricated a micro-patterned PLC device. The insertion losses were 4.0 dB for a $1{\times}2$ optical splitter. As such, the proposed method of fabricating a PLC device by the R2R process was shown to be an effective solution.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.17-20
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• 2003

The EMC's rheological effects on molding process are evaluated in this study. When considering mold processing for IC packages, the major concerning items in current studies are incomplete fill, severe wire sweeping and paddle shifts etc. To simulate EMC's fast curing rheokinetics with 3D mold flow behavior, one should select appropriate rheometry which characterize each EMC's rheological motion and finding empirical parameters for numerical analysis current studies present the new rheometry with parallel plate rheometry for reactive rheokinetic experiments, the experiment and numerical analysis is done with the commercial higher filler loaded EMC for the case of Thin Quad Plant Packages (TQFP) with package thickness below 1.0 mm. The experimental results and simulation results based on new rheometry matches well in point of the prediction of wire sweep, filling behavior of melt front advancement and void trapping position.

• Korean Journal of Metals and Materials
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• v.50 no.8
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• pp.591-597
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• 2012

This paper presents regularly micro-textured glass surfaces ensuring the superhydrophobic properties in the Cassie-Baxter regime. The proposed surfaces were fabricated simply and efficiently by filling the glass material into a silicon micro-mold with periodic micro-cavities based on a thermal-reflow process, resulting in a successful demonstration of the textured glass surface with periodically-arrayed micro-pillar structures. The static and dynamic wetting properties of the micro-textured glass surfaces were characterized by measuring the static contact angle (SCA) and contact angle hysteresis (CAH), respectively. In addition, the surface wettability was estimated theoretically based on Wenzel and Cassie-Baxter wetting theories, and compared with the experimental ones. Through the experimental and theoretical observations, it was clearly confirmed that the proposed micro-textured glass surfaces showed the slippery superhydrophobic behaviors in the Cassie-Baxter wetting mode.

• Design & Manufacturing
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• v.15 no.4
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• pp.57-64
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• 2021

In recent materials industry, researches on the technology to manufacture super hydrophobic surface by effectively controlling the wettability of solid surface are expanding. Research on the fabrication of super hydrophobic surface has been studied not only for basic research but also for self-cleaning, anti-icing, anti-friction, flow resistance reduction in construction, textile, communication, military and aviation fields. A super hydrophobic surface is defined as a surface having a water droplet contact angle of 150 ° or more. The contact angle is determined by the surface energy and is influenced not only by the chemical properties of the surface but also by the rough structure. In this paper, maskless lithography using DMD, electro etching, anodizing and hot embossing are used to make the polymer resin PMMA surface super hydrophobic. In the fabrication of microstructure, DMDs are limited by the spacing of microstructure due to the structural limitations of the mirrors. In order to overcome this, maskless lithography using a transfer mechanism was used in this paper. In this paper, a super hydrophobic surface with micro and nano composite structure was fabricated. And the wettability characteristics of the micro pattern surface were analyzed.