• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2007.05a
• /
• pp.199-204
• /
• 2007

Hot embossing, one of Nanoimprint Lithography(NIL) techniques, has been getting attention as an alternative candidate of next generation patterning technologies by the advantages of simplicity and low cost compared to conventional photolithographies. A typical hot embossing usually, however, takes more than ten minutes for one cycle of the process because of a long thermal cycling. Over the last few years a number of studies have been made to reduce the cycle time for hot embossing or similar patterning processes. The target of this research is to develop an induction heating apparatus for heating a metallic micro patterning mold at very high speed with the large-area uniformity of temperature distribution. It was found that a 0.5 mm-thick nickel mold can be heated from $25^{\circ}C$ to $150^{\circ}C$ within 1.5 seconds with the temperature variation of ${\pm}5^{\circ}C$ in 4-inch diameter area, using the induction heating apparatus.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.10a
• /
• pp.186-189
• /
• 2001

The main method in micro-etching process, used in manufacturing semiconductors, electronic components, circuits, is Photo Masking method that exposes and develops on the photo-sensitivity solutions or films. This method enables one to process highly precisely, $\pm$0.03 mm in end line location area. But this has limits in a high speed / wide width process, difficulties in endless masking, and the problem of high price. We have developed the direct masking method to make use of Gravure printing, widely used in grocery packing sheet printing. We made cylinder tools to influence the masking quality by laser stream process. We have confirmed that the end line location accuracy in the line width of the product is improved from 0.12 mm to $\pm$0.07 mm level, after etching process.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07b
• /
• pp.1419-1420
• /
• 2005

We have synthesized a photo patternable blue lightemitting polyfluorene (PF) derivative containing cross-linkable oxetane units. Poly(9,9-bis-(4-octyloxyphenyl)- fluorene-2,7-diyl-alt-9,9-bis-((3-hexyloxy-3'- ethyl)-oxetane)-fluorene-2,7-diyl) has been synthesized by Suzuki coupling polymerization. The relationship between patterning property and several variables such as the intensity of the exposed UV light, the concentrations of additives, has been studied by using optical microscope UV/visible spectroscopy, photoluminescence and scanning electron microscope (SEM). We obtained fine patterns with 10 mm resolution using the polymer film after exposure and development. This patterning method using conjugated polymers can be applicable to make fine pixels for PLEDs and OFETs.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.09a
• /
• pp.54-58
• /
• 2005

Femtosecond laser is the latest generation pulsed laser delivering shortest pulses. Any solid materials can be machined by it. Femtosecond laser micromachining allows highest precision and minimal heat influence within the workpiece. But due to the complex physical phenomena between the laser beam and the workpiece materials, it is very difficult to determine the optimal process conditions in the femtosecond laser micromachining. In this study, a method to simulate the femtosecond laser micromachining process was proposed. And femtosecond laser micro patterning processes of chromium thin film are simulated by the proposed method using a commercial FE code, LS-Dyna. Simulation results were compared with those of experiments.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.10
• /
• pp.2755-2756
• /
• 2010

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.24 no.1
• /
• pp.94-97
• /
• 2015

In this study, we introduce a yellowing phenomenon in silver nanowire laser patterning and attempt to understand the cause of this phenomenon. Silver nanowire is a promising alternative to indium tin oxide as a transparent electrode owing to its flexibility. Additionally, silver nanowire can be easily patterned by laser ablation, which is free of dangerous chemicals. However, a yellowish color change reducing visibility is observed on the patterned area of the silver nanowires, and this yellowing phenomenon prevents the use of silver nanowire as a transparent electrode material. We concluded that resolidified debris of melted and evaporated silver nanowires after laser ablation causes the color change of the electrode. Further research is needed to determine a means of mitigating this yellowing phenomenon.

• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.5
• /
• pp.89-96
• /
• 2007

Inkjet printing has become one of the most attractive manufacturing techniques in industry. Especially inkjet printing technology will soon be part of the PCB (Printed Circuit Board) fabrication processes. Traditional printing on PCB includes screen printing and photolithography. These technologies involve high costs, time-consuming procedures and several process steps. However, by inkjet technology manufacturing time and production costs can be reduced, and procedures can be more efficient. PCB manufacturers therefore willingly accept this inkjet technology to the PCB industry, and are quickly shifting from conventional to inkjet printing. To produce the printed circuit board by the inkjet technology, it must be harmonized with conductive nano ink, printing process, system, and inkjet printhead. In this study, micro patterning of conductive line has been investigated using the piezoelectric printhead driven by a bipolar voltage signal is used to dispense 20-40 ${\mu}m$ diameter droplets and silver nano ink which consists of 1 to 50 nm silver particles that are homogeneously suspended in an organic carrier. To fabricate a conductive line used in PCB with high precision, a printed line width was calculated and compared with printing results.

• Journal of the Korean Ceramic Society
• /
• v.56 no.6
• /
• pp.549-557
• /
• 2019

More than two decades of world-wide research efforts have resulted in several classes of potentially important materials. Among them are incipient piezoelectrics, which are especially useful for actuator applications. However, relatively large electric fields are required for activating the large incipient electromechanical strains. So far, many attempts have been made to reduce the required electric field by intentionally inhomogenizing the electric field distribution in the microstructure through core-shell and composite approaches. Here, we show that electric field concentration can be realized simply by adjusting electrode patterns. We have investigated the effect of electrode patterning on the incipient electromechanical strain properties of an exemplarily chosen lead-free relaxor system, revealing that electrode patterning does have a significant role on the strain properties of the given lead-free relaxor system. We believe that this approach would make a new strategy for ones to consider bringing the functional properties of electroceramics beyond their conventional limit.

• Korean Journal of Optics and Photonics
• /
• v.17 no.2
• /
• pp.203-206
• /
• 2006

Femtosecond laser-induced nano-patterning of an Al surface coated on a slide glass is reported in this paper. It was found that the period of the laser-induced nano-patterning was much dependent on the incident laser power and pulse number. Through finely adjusting the laser power and pulse number, uniform nano-patterns could be formed on the Al surface. It is based on the interference of the incident laser beam with some form of a surface scatted electromagnetic wave. It was also found that an Al oxide layer played an important role in forming the nano-patterning on the Al surface.

• Journal of the Korean institute of surface engineering
• /
• v.49 no.1
• /
• pp.20-25
• /
• 2016

Femtosecond laser ablation of ultrathin polymer films on quartz glass using laser pulses of 100 fs and centered at ${\lambda}=400nm$ wavelength has been investigated for nanometer precision thin film patterning. Single-shot ablation craters on films of various thicknesses have been examined by atomic force microscopy, and beam spot diameters and ablation threshold fluences have been determined by square diameter-regression technique. The ablation thresholds of polymer film are about 1.5 times smaller than that of quartz substrate, which results in patterning crater arrays without damaging the substrate. In particular, at a $1/e^2$ laser spot diameter of $0.86{\mu}m$, the smallest craters of 150-nm diameter are fabricated on 15-nm thick film. The ablation thresholds are not influenced by the film thickness, but diameters of the ablated crater are bigger on thicker films than on thinner films. The ablation efficiency is also influenced by the laser beam spot size, following a $w_{0q}{^{-0.45}}$ dependence.