• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.371-374
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• 2007

A method for metal nano powder imprinting is proposed as a patterning process for conductive tracks that is inexpensive and scalable down to the nanoscale. Conductive tracks with line widths of $0.5{\sim}20{\mu}m$ were fabricated using this method. The processing conditions were optimized to avoid various types of defects, and to increase the degree of sintering and electric conductivity of the imprinted conductive tracks. The mean electric resistivity of the conductive tracks imprinted under optimum conditions was $8.95{\mu}{\Omega}{\cdot}cm$, which is in the range required for practical applications.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.125-126
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• 2008

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.105-108
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• 2006

It has been issued to fabricate nano-scale patterns with large-scale in the field of digital display. Also, large-scale fabrication technology of nano pattern is very important not only for the field of digital display but also for the most of applications of the nano-scale patterns in the view of the productivity. Among the fabrication technologies, UV nano imprinting process is suitable for replicating polymeric nano-scale patterns. However, in case of conventional UV nano imprinting process using flat mold, it is not easy to replicate large areal nano patterns. Because there are several problems such as releasing, uniformity of the replica, mold fabrication and so on. In this study, to overcome the limitation of the conventional UV nano imprinting process, we proposed a continuous UV nano imprinting process using a pattern roll stamper. A pattern roll stamper that has nano-scale patterns was fabricated by attaching thin metal stamper to a roll base. A continuous UV nano imprinting system was designed and constructed. As practical examples of the process, various nano patterns with pattern size of 500, 150 and 50nm were fabricated. Finally, geometrical properties of imprinted nano patterns were measured and analyzed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.237-240
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• 2005

The demand of micro electrical mechanical system (MEMS) bio/chemical sensor is rapidly increasing. To prevent the contamination of sensing area, a filtration system is required in on-chip total analyzing MEMS bio/chemical sensor. A nano-filter was mainly applied in some application detecting submicron feature size bio/chemical products such as bacteria, fungi and so on. We suggested a simple nano-filter fabrication process based on replication process. The mother pattern was fabricated by holographic lithography and reactive ion etching process, and the replication process was carried out using polymer mold and UV-imprinting process. Finally the nano-filter is obtained after removing the replicated part of metal deposited replica. In this study, as a practical example of the suggested process, a nano-dot array was replicated to fabricate nano-filter fur bacteria sensor application.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.6
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• pp.153-159
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• 2004

In this study, a new process to pattern directly on a thin metal layer using improved nano replication printing (nRP) process is suggested to evaluate the possibilities of fabricating a stamp for nano-imprinting. In the nRP process, any figure can be replicated from a bitmap figure file in the range of several micrometers with nano-scaled details. In the process, liquid-state resins are polymerized by two-photon absorption which is induced by femto-second laser. A thin gold layer was sputtered on a glass plate and then, designed patterns or figures were developed on the gold layer by newly developed top-down building approach. Generally, stamps fur nano-imprinting have been fabricated by using the costly electron-beam lithography process combined with a reactive ion-etching process. Through this study, the effectiveness of the improved nRP process is evaluated to make a stamp with the resolution of around 200nm with reduced cost.

• Design & Manufacturing
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• v.17 no.2
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• pp.55-61
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• 2023

With femtosecond (fs) laser pulse irradiation on metals, various types of nano- and micro-scale structures can be naturally induced at the surface through laser-matter interaction. Two notable structures are laser-induced periodic surface structures (LIPSSs) and cone/spike structures, which are known to significantly modify the optical and physical properties of metal surfaces. In this work, we irradiate fs laser pulses onto various types of metals, cold-rolled steel, pickled & oiled steel, Fe-18Cr-8Ni alloy, Zn-Mg-Al alloy coated steel, and pure Cu which can be useful for precise molding and imprinting processes, and adjust the morphological profiles of LIPSSs and cone/spike structures for clear structural coloration and a larger range of surface wettability control, respectively, by changing the fluence of laser and the speed of raster scan. The periods of LIPSSs on metals used in our experiments are nearly independent of laser fluence. Accordingly, the structural coloration of the surface with LIPSSs can be optimized with the morphological profile of LIPSSs, controlled only by the speed of the raster scan once the laser fluence is determined for each metal sample. However, different from LIPSSs, we demonstrate that the morphological profiles of the cone/spike structures, including their size, shape, and density, can be manipulated with both the laser fluence and the raster scan speed to increase a change in the contact angle. By injection molding and imprinting processes, it is expected that fs laser-induced surface structures on metals can be replicated to the plastic surfaces and potentially beneficial to control the optical and wetting properties of the surface of injection molded and imprinted products.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.72-73
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• 2012

Metal line을 형성하는 방법에는 그라비아 인쇄, 잉크젯 인쇄, photo 공정 후 박막 증착 공정 등을 많이 사용한다. 본 연구에서는 Micro-imprinting 공정과 DFR photo lithography 공정을 통해 음각의 미세한 pattern을 형성한 후 sputtering과 printing을 이용하여 pattern의 filling을 통해 metal line을 구현하는 것을 목표로 하였다. Pattern을 형성한 후 RIE 공정을 통해 기판 표면의 친수성 처리를 하고, SAM 공정을 통해 코팅 막의 소수성 처리를 하였다. Sputtering과 전면 프린팅 및 건조 후 strip 공정을 통해 metal line을 형성하고, 이에 대한 표면 특성과 전기적 특성을 분석하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.655-656
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• 2005

In the future, plastic based system will play a crucial role in modem life, for examples, transparent display or disposable electronics and so on. In this paper, we introduced a new method to fabricate the metal line on the plastic substrate. Metal lines were fabricated by hot embossing and CMP process on PMMA (polymethylmethacrylate) substrates. A Si mold was made by wet etching process and a PMMA wafer was cut off from I mm thick PMMA sheet. A 100 nm thick Al was deposited on PMMA wafers. The Al deposited PMMA wafer and the Si mold carefully sandwiched which was directly imprinted by hot embossing. After imprinting process, a residual Al layer was removed by CMP process. Finally, we found the entire process may be very useful to fabricate the metal line on plastic substrates.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.11
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• pp.975-979
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• 2014

Transparent conductive films (TCF) with excellent electrical properties and high mechanical flexibility have been widely studied because of their potential for application in optoelectronic devices such as light-emitting diodes, paper displays and organic solar cells. In this paper, we report on low-resistance and high-transparent TCF for flexible device applications. To fabricate a high-resolution roll imprinted TCF, the following steps were performed: the design and manufacture of an electroforming stamp mold, the fabrication of high-resolution roll imprinted on flexible film, the manufacture of Ag-nano paste which was filled into patterned film using a doctor blade process. Also, we was demonstrated with the successful application(ITO free organic photovoltaic) of the developed flexible TCF.

• Transactions of Materials Processing
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• v.14 no.5 s.77
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• pp.473-476
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• 2005

The demand of on-chip total analyzing system with MEMS (micro electro mechanical system) bio/chemical sensor is rapidly increasing. In on-chip total analyzing system, to detect the bio/chemical products with submicron feature size, a filtration system with nano-filter is required. One of the conventional methods to fabricate nano-filter is to use direct patterning or RIE (reactive ion etching). However, those procedures are very costly and are not suitable fur mass production. In this study, we suggested new fabrication method for a nano-filter based on replication process, which is simple and low cost process. After the Si master was fabricated by laser interference lithography and reactive ion etching process, the polymeric mold was replicated by UV-imprint process. Metallic nano-filter was fabricated after removing the polymeric part of metal deposited polymeric mold. Finally, our fabrication method was applied to metallic nano-filter with $1{\mu}m$ pitch size and $0.4{\mu}m$ hole size for bacteria sensor application.