• Transactions of the Korean Society of Mechanical Engineers A
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• 제36권2호
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• pp.173-178
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• 2012

Currently, active research is being performed on printing of electronic devices such as RFID devices, flexible displays, solar cells, and e-paper. This technique has several advantages over existing technologies such as lithography and etching. In particular, RFID devices, flexible displays, solar cells, and e-paper require flexibility and a mass production system. Thus, attention is being focused on the roll-to-roll process. High quality should be guaranteed in the roll-to-roll printed electronics systems, and good thickness and roughness qualities must be ensured. Experimental design was applied to this problem to analyze the main effects and interaction effects of various factors. Matching technology between the nip roll characteristics and the quality of the print pattern in roll-to-roll printed electronics systems was proposed to improve the printing quality.

• Journal of the Korean Society for Precision Engineering
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• 제28권10호
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• pp.1123-1130
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• 2011

The pattern shape engraved on the gravure printing roll is one of the most important factors influencing ink transfer. This study focuses on the relations between dot geometry engraved on gravure printing roll and the ink transfer during the gravure printing process. The influence of dot width on printed patterns will be demonstrated. Results reveal that as the width of a dot on the printing roll increases, the ink transfer rate also increases. But over a certain size of width, surface uniformity began to recede. Therefore, proper dot geometry on the printing roll should be decided to guarantee good printing quality according to printing conditions and expected performance of the electronic devices.

• Journal of the Korean Society for Precision Engineering
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• 제31권11호
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• pp.987-992
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• 2014

Register control of roll-to-roll printing system for printed electronics requires accurate measurement of register errors. The register marks used for the recognition of patterns position between layers have inherently defects due to low printability of register marks themselves, which brings out inaccurate register accuracy and consequently low performance of printed electronics devices. In this study, the compensation methods for the unrecognized or missing register data are proposed to improve the recognition and consequently the control performance of register accuracy in roll-to-roll printing equipment. The compensation methods using the prior data and the linear interpolation are proposed and compared with the case without compensation for the simulation as well as experiment. Only the linear interpolation method could successfully compensate the missing data and consequently improve the register control performance. We should apply the compensation process of the register errors to improve the register control accuracy in the roll-to-roll printing equipment.

• Journal of the Microelectronics and Packaging Society
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• 제28권4호
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• pp.47-50
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• 2021

Nanoimprint lithography (NIL) has revolutionized the fabrications of electronics, photonics, optical and biological devices. Among all the NIL processes, roll-to-roll nanoimprinting is regarded best for having the attributes of low cost, continuous, simple, and energy-efficient process for nanoscale device fabrication. However, large-area printing is limited by the master mold deformation. In this study, a finite element model (FEM) has been constructed to assess the deformation of the roll mold adhesively wrapped on the carbon fiber reinforced material (CFRP) base roll. This study also optimizes the deformations in the metallic roll mold with respect to nip-forces applied in the printing process of nano-fabrication on large scale. The numerical simulations were also conducted to evaluate the deflection in roll mold assembly due to gravity. The results have shown decreasing trend of the deformation with decreasing nip-force. Also, pressure uniformity of about 40% has been optimized by using the current numerical model along with an acceptable deflection value in the vertical axis due to gravity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.281-282
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• 2006

Tension control performance is very important in high-speed printing machine. One of the major factors that effect to tension control performance is the process of roll changing. Even if the turret arm moves during roll changing process and the span length of the unwinding system varies, it is customary to neglect it in motion and tension control and to consider it as a disturbance. In this paper, its effect is modeled nonlinearly and compared with linear model, and an effect of an infeeder dancer is analyzed under the condition with no unwinder dancer. We verify the performance of the proposed method via simulation in the high-speed printing machine.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.593-594
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.967-968
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.251-252
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.465-466
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• 2011

• Journal of the Korean Society for Precision Engineering
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• 제26권10호
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• pp.65-73
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• 2009

For mass production of printed electronics in roll-to-roll fashion, precision tension control is important to reduce register errors. Register error should be minimized within several to tens of microns for many electronic devices to be manufactured through printing technology. In order to achieve this goal, tension disturbance must be attenuated before printing process within a certain range. In this paper, a certain tension range which allows maintaining register error within 10 micron was defined with specific operating conditions. A LQG controller was proposed instead of the conventional PI controller for precision tension control using a multivariable feedback. A guideline to determine design parameters for calculating LQ gain was proposed. The proposed LQG controller was compared to both PI controller and LQ regulator with white noise by numerical simulations. Results showed that the proposed LQG controller was effective for attenuating tension disturbance with white noise.