• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.10
• /
• pp.1153-1158
• /
• 2011

Roll-to-roll process is an emerging mass production method for printed and flexible electronics such as touch screen panel, RFID tag, thin film solar cell, and flexible display due to its high throughput. High precision in printing and coating is required to apply functional materials onto substrate. For such reason, every part of the roll-to-roll equipment needs to be precisely fabricated and to retain its precision under regular operation. In this article, the precision of cantilever type idler roller and a novel method to mitigate its deflection under web tension loading are discussed and the method is verified using both the numerical and the experimental works. The proposed method improves the structural rigidity of cantilever type roller whose advantages, such as low capital cost and high web path configurability, are maintained.

• International Journal of Precision Engineering and Manufacturing
• /
• v.3 no.1
• /
• pp.26-32
• /
• 2002

Laser direct patterning of the coated photoresist (PMER-NSG31B) layer was studied to make halftone dots on the gravure printing roll. The selective laser hardening of the photoresist by Ar-ion laser(wavelength: 333.6∼363.8 nm) was controlled by the A/O modulator. The coating thickness in the range of 5∼11㎛ 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 farmed under the laser power of 200∼260mW 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 width of 10㎛ could be obtained. The change of line width was also found after etching, and the minimum line widths of 6㎛ 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.

• Korean Journal of Materials Research
• /
• v.22 no.9
• /
• pp.476-481
• /
• 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 $200^{\circ}C$.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.243-246
• /
• 2008

Roll-printed organic thin-film transistors (OTFTs) were fabricated by gravure or flexography printing using patterned PDMS stamp with various channel lengths, silver pastes, coated polyvinylphenol dielectric, and jetted bis(triisopropyl-silylethynyl) pentacene semiconductor on plastic substrates. The roll-printed OTFT parameters were obtained: fieldeffect mobility of $0.1\;cm^2/Vs$, an on/off current ratio of $10^4$ and a subthreshold slope of 2.53 V/decade.

• Journal of Information Display
• /
• v.12 no.2
• /
• pp.97-99
• /
• 2011

We report flexible, bistable cholesteric displays utilizing polyester (PET) substrates with printed internal black electrodes. The black electrodes consist of carbon ink dispersed in butyl carbitol using a patented roll-to-roll gravure-offset printing. A transparent conducting polymer printed on PET serves as the counter electrode. The electro-optic material is a chiral nematic mixture dispersed in a low-concentration polymer binder. The device can be switched between scattering (black) and reflective (vibrant green) states upon application of an electric pulse. The internal black electrode enhances the contrast of the display and simplifies the roll-to-roll manufacture of flexible displays.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.8
• /
• pp.17-20
• /
• 2008

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.30 no.1
• /
• pp.95-103
• /
• 1998

Many new technologies and developments designed to increase paper machine speeds and improve paper printability have emerged in recent years. These improvements have changed the structure of paper and given winder manufacturers new challenges, especially as the requirements of printing presses have also changed. Ever-increasing roll widths and diameters are needed. Along with faster press speeds and shorter acceleration times, the unwinding of roils in the press room has become a true test of paper strength and roll structure, In the following we will review the special winding features of coated papers and discuss a selection of the winder type to meet a mill's specific needs.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2007.06a
• /
• pp.439-440
• /
• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.119-120
• /
• 2011

• Journal of the Korean Graphic Arts Communication Society
• /
• v.29 no.2
• /
• pp.45-58
• /
• 2011

Gravure off-set printing recently is used in electronics display market. This method has advantages of mass production and high printing speed. It is also fine pattern can be implemented. We have manufactured low-curable conductive Ag pastes for gravure off-set printing. When printing, the pastes be used different silver powder shape because of the printing characteristics. The pastes were prepared with silver powder by silver powder shape and size, epoxy resin, solvent and homogenized on a standard three-roll mill. And the pastes exhibited a shear-thinning flow at viscosity profile. Moreover the adhesive strength and resistivity of silver film had a good characteristics. With the manufactured paste in this study, touch panel had is manufactured and it had $4{\times}10-5{\Omega}.cm$.