• Korean Journal of Materials Research
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• v.22 no.9
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• pp.476-481
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• 2012

Among the various roll-to-roll printing technologies such as gravure, gravure-offset, and reverse offset printing, reverse offset printing has the advantage of fine patterning, with less than 5 ${\mu}m$ line width. However, it involves complex processes, consisting of 1) the coating process, 2) the off process, 3) the patterning process, and 4) the set process of the ink. Each process demands various ink properties, including viscosity, surface tension, stickiness, and adhesion with substrate or clich$\acute{e}$; these properties are critical factors for the printing quality of fine patterning. In this study, Ag nano ink was developed for reverse offset printing and the effect of polyvinylpyrrolidone(PVP), used as a capping agent of Ag nano particles, on the printing quality was investigated. Ag nano particles with a diameter of ~60 nm were synthesized using the conventional polyol synthesis process. Ethanol and ethylene glycol monopropyl ether(EGPE) were used together as the main solvent in order to control the drying and absorption of the solvents during the printing process. The rheological behavior, especially ink adhesion and stickiness, was controlled with washing processes that have an effect on the offset process and that played a critical role in the fine patterning. The electrical and thermal behaviors were analyzed according to the content of PVP in the Ag ink. Finally, an Ag mesh pattern with a line width of 10 ${\mu}m$ was printed using reverse offset printing; this printing showed an electrical resistivity of 36 ${\mu}{\Omega}{\cdot}cm$ after sintering at $200^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.203-203
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• 2012

The SWCNTs network are formed on various plastic substrates such as poly(ethylene terephthalate) (PET), polyimide (PI) and soda lime glass using roll-to-roll printing and spray process. Selective patterning of carbon nanotubes film on transparent substrates was performed using a femtosecond laser. This process has many advantages because it is performed without chemicals and is easily applied to large-area patterning. It could also control the transparency and conductivity of CNT film by selective removal of CNTs. Furthermore, selective cutting of carbon nanotube using a femtosecond laser does not cause any phase change in the CNTs, as usually shown in focused ion beam irradiation of the CNTs. The patterned SWCNT films on transparent substrate can be used electrode layer for touch panels of flexible or flat panel display instead indium tin oxide (ITO) film.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1472-1475
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• 2009

The microfluidics channel were fabricated using thermal roll-imprinting process on plastic substrates. As rollimprinting surface is heated directly at $100^{\circ}C$ and printing process proceed 380/400 kgf pressure, we fabricated microfluidic patterns separated line of $40.04{\mu}m$, serpentine line of $113.89{\mu}m$ and depth of imprint pattern is $15.35{\mu}m$, it means to get fine pattern has more than 70% imprint rate in designed mask.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.12
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• pp.1017-1023
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• 2007

This study is intended to analyze the effect of thin ink-film thickness around rotating printing roll on the printing quality in the gravure printing process which is used for making electronics circuit like a RFID tag with a conductive ink. The present work numerically estimates the film thickness around rotating roller partially immersed in ink for which the volume of fluid (VOF) method was adopted to figure out the film formation process around rotating roller. Parameter studies were performed to compare the effect of ink properties (viscosity, surface tension), operating condition (roller rotating speed, initial immersed angle) on the film thickness. The result indicates that the film thickness has a strong dependency on the rotating speed, while the surface tension has negligible effect.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1381-1387
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• 2007

Up to now, various continuous-processing systems are used in many industrial applications such as textile machines, paper-making machines, printing machines, and so on. In these applications, the tension forced on the products in the control volume can be changed according to the velocity difference between the feeding roll and the delivery roll. Specially, the tension variation generated by the velocity difference, or the inertial effect can decreases the quality of the products in the textile process. In this paper, the tension control problem in a circular knitting machine system is treated to cope with these problems. Firstly, the tension relationship in the winding mechanism of general continuous-processing systems is modeled. Next, to effectively drive the feeding and delivery rolls in the circular knitting machine system, a new tension control method is presented by considering the inertia compensation and the velocity difference between the feeding roll and the delivery roll. Through the experimental works, it is shown that the proposed tension control method can be used to improve the performance of tension control in the control volume of the given circular knitting machine system.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.76.1-76
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• 2001

Up to now, various continuous-processing systems are used in the various industrial applications such as textile machines, iron-manufacturing plants, paper-making machines, printing machines, and so on. In these applications, the tension forced on the products in the control volume can be changed according to the velocity difference between the feeding roll and the delivery roll. Specially, the tension variation generated by the velocity difference, or the inertial effect can decreases the quality of the products in the textile process. In this paper, the tension control problem in a circular knitting machine system is treated to cope these problems. Firstly, the tension relationship in the winding mechanism of general continuous-processing ...

• Journal of the Korean Society for Precision Engineering
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• v.17 no.11
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• pp.191-198
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• 2000

Laser direct patterning of the coated photoresist (PMER-NSG31B) layer was studied to make halftone dots on gravure printing roll. The selective laser hardening of photoresist by Ar-ion laser(wavelength: 333.6~363.8nm) was controlled by the A/O modulator. The coating thickness in the range of 5~11$\mu m$ could be obtained by using the up-down directional moving device along the vertically located roll. The width, thickness and hardness of the hardened lines formed under the laser power of 200~260㎽ and irradiation time of 4.4~6.6 $\mu$sec/point were investigated after developing. The hardened width increased as the coating thickness increased. Though the hardened thickness was changed due to the effect of the developing solution, the hardened layer showed good resistance to the scratching of 2H pencil. Also, the hardened minimum line widths of 10$\mu m$ could be obtained. The change of line width was also found after etching, and the minimum line widths of 6$\mu m$ could be obtained. The hardened lines showed the good resistance to the etching solution. Finally, the experimental data could be applied to make gravure halftone dots using the developed imaging process, successfully.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2279-2284
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• 2007

This study is intended to analyze the effect of thin ink-film thickness around rotating printing roll on the printing quality in the gravure printing process which is used for making electronics circuit like a RFID tag with a conductive ink. The present work numerically estimates the film thickness around rotating roller partially immersed in ink, for which the volume of fluid (VOF) method was adopted to figure out the film formation process around rotating roller. Parameter studies were performed to compare the effect of ink viscosity, surface tension, roller rotating speed, immersed angle on the film thickness. The result indicates that the film thickness has a strong dependency on the fluid viscosity, while the surface tension has negligible effect.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.111-115
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• 2015

To produce patterns with high resolution in gravure printing, it is important to increase ink transfer ratio. The ink which has higher affinity with substrate can be transferred more from the roll to the substrate due to the good wettability between ink and substrate. However, it is difficult to evaluate the affinity between the substrate and the ink which is viscoelastic in nature. In this study, we suggest a practical method to evaluate the interfacial interaction between the ink and various substrates.

• Laser Solutions
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• v.17 no.4
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• pp.20-23
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• 2014

In printed electronics, printing rolls are used to transfer electronic ink onto a flexible substrate. Generally printing rolls are patterned in microscale by the indirect laser method. Since based on the wet etch process, the indirect method is neither environment-friendly nor suitable for making a printing roll with patterns narrower than $20{\mu}m$. In this paper, we have directly engraved micro-patterns into a Zn-coated metal specimens using a picosecond laser in order both to engrave $10{\mu}m$-wide patterns and to improve the pattern profile. Experiments showed that it is possible to engrave $10{\mu}m$-wide patterns with an a rectangular-shaped profile which is necessary for the dimensionally accurate printing.