• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.959-960
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• 2008

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1491-1494
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• 2005

We have studied ink-jet printing method for patterning conductive line on flexible plastic substrates. Synthesized silver nano-particles of ${\sim}$20nm were used for the conductive ink and the printed patterns exhibit a smooth line whose linewidth is below 100 ${\mu}m$. This ink-jet printing technique can be applied to flexible displays and electronics.

• Journal of Welding and Joining
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• v.31 no.3
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• pp.84-88
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• 2013

These days embedded technology may be the most significant development in the electronics industry. The study focused on the development of active device embedding using flexible printed circuit in view of process and materials. The authors fabricated 30um thickness Si chip without any crack, chipping defects with a dicing before grinding process. In order to embed chips into flexible PCB, the chip pads on a chip are connected to bonding pad on flexible PCB using an ACF film. After packaging, all sample were tested by the O/S test and carried out the reliability test. All samples passed environmental reliability test. In the future, this technology will be applied to the wearable electronics and flexible display in the variety of electronics product.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.9
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• pp.879-884
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• 2015

Printed electronics is a technology that produces electronic devices and circuits by printing functional ink on a web, which is a film-like flexible material. This technology is suitable for large-scale and high-speed mass production, and is a next-generation process technology that can fabricate electronic devices from flexible materials. As precise measurement of the positions of the web is required in order to commercialize such a printed electronics process, a measurement system with an optical encoder with a precision of micrometers had been proposed in the preceding research of this study. However, the lateral positions of the web could not be measured in the preceding research as the phenomenon of the entire web being moved in the lateral direction could not be detected. In this study, a measurement system that utilizes the differences in the amount of light reflected from the alignment patterns depending on the web positions in the lateral direction was proposed for measuring the lateral positions of the web. In addition, its reliability was verified and then the effect when measuring printed alignment patterns was analyzed by experiments.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.3
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• pp.233-243
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• 2017

This paper proposes a structure of direct-printed flexible tactile-sensor. These flexible tactile sensors are based on pressure-sensing materials that allow pressure to be measured according to resistance change that in turn results from changes in material size because of compressive force. The sensing material consists of a mixture of multi walled carbon nanotubes (MWCNTs) and TangoPlus, which gives it flexibility and elasticity. The tactile sensors used in this study were designed in the form of array structures composed of many lines so that single pressure points can be measured. To evaluate the performance of the flexible tactile sensor, we used specially designed signal-processing electronics and tactile sensors to experimentally verify the sensors' linearity. To test object grasp, tactile sensors were attached to the surface of the fingers of grippers with three degrees of freedom to measure the pressure changes that occur during object grasp. The results of these experiments indicate that the flexible tactile sensor-based robotic gripper can grasp objects and hold them in a stable manner.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.9
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• pp.894-898
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• 2009

In a post printing section of roll to roll printing systems, scratch problem is the major defects. The functional qualities such as conductivity, mobility could deteriorate because of the scratch defect. In general, the scratch of the printed pattern on the flexible substrate was induced from a contact between rolls and printed pattern in the post printing section. In this paper, for non-contacting transfer of a moving web, a mathematical tension model has been developed considering strain due to air floatation and the proposed mode has been validated by numerical simulation. Additionally, the correlation between floatation height and speed compensation to control the tension and register are investigated. On the basis of the proposed model, a guide line of speed control in R2R printing system is presented to guarantee the non-contact between rolls and R2R printed pattern on the flexible substrate.

• Electronics and Telecommunications Trends
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• v.24 no.6
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• pp.41-51
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• 2009

인쇄전자(printed electronics) 기술은 인쇄(graphic art printing)가 가능한 기능성전자 잉크소재를 이용하여 초저가격의 프린팅 공정을 통해서 다양한 전자소자를 제작하는 기술로서, 차세대 모바일 IT 기기의 제작에 적합한 전자제품을 생산하는 데 적합한 공정 기술로 인식되고 있다. 현재 기술 수준이 일부 요소 부품을 제작하는 수준에 머무르고 있으나, 여러 가지 잉크소재 및 다양한 초미세 인쇄공정 기술의 개발이 진행됨에 따라 향후 다양한 공정 분야에 적용될 것으로 예상되며, 궁긍적으로 전자제품을 생산하는 기존 반도체 공정을 대체하는 공정으로 자리매김을 할 것으로 예상된다. 특히 인쇄공정 기술은 저온에서 공정이 가능한 기능성 잉크소재들의 개발을 통해서 유연한 플라스틱 기판에 전자소자를 제작하는 플렉시블 전자소자(flexible electronics) 기술과 높은 공정 결합성을 지니고 있으며 이들 공정을 결합하여 향후 연속 공정(roll-to-roll)의 구현이 가능할 것으로 예상된다. 본 기고문에서는 이러한 인쇄전자 기술의 개발동향에 대해서 기술하였다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.1
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• pp.63-71
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• 2020

Recently, to improve convenience, flexible electronics are quickly being developed for a number of application areas. Flexible electronic devices comprise characters such as being bendable, stretchable, foldable, and wearable. Effectively manufacturing flexible electronic devices requires high efficiency, low costs, and simple processes for manufacturing technology. Through this study, we enabled the rapid production of multifunctional flexible bending sensors using a simple, low-cost Fused Deposition Modeling (FDM) 3D printer. Furthermore, we demonstrated the possibility of the rapid production of a range of functional flexible bending sensors using a simple, low-cost FDM 3D printer. Accurate and reproducible functional materials made by FDM 3D printers are an effective tool for the fabrication of flexible sensor electronic devices. The 3D-printed flexible bending sensor consisted of polyurethane and a conductive filament. Two patterns of electrodes (straight and Hilbert curve) for the 3D printing flexible sensor were fabricated and analyzed for the characteristics of bending displacement. The experimental results showed that the straight curve electrode sensor sensing ability was superior to the Hilbert curve electrode sensor, and the electrical conductivity of the Hilbert curve electrode sensor is better than the straight curve electrode sensor. The results of this study will be very useful for the fabrication of various 3D-printed flexible sensor devices with multiple degrees of freedom that are not limited by size and shape.

• Prospectives of Industrial Chemistry
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• v.23 no.2
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• pp.1-11
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• 2020

In this report, we summarize recent progress in the development of electrolyte-gated transistors (EGTs) for various printed electronics. EGTs, employing a high capacitance electrolyte as gate dielectric layer in transistors, exhibits increasing of drive current, lowering operation voltage, and new transistor architectures. While the use of electrolytes in electronics goes back to the early days of silicon transistors, the new printable, fast-responsive polymer electrolytes are expanding their range of applications from printable and flexible digital circuits to various neuromorphic devices. This report introduces the structure and operating mechanism of EGT and reviews key developments in electrolyte materials used in printed electronics. Additionally, we will look at various applications with EGTs that are currently underway.

• Journal of Sensor Science and Technology
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• v.29 no.1
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• pp.40-44
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• 2020

An integrated multifunctional sensor, capable of raising an early electric-fire warning, was fabricated. An arc-light, temperature, and humidity sensor was fabricated on a flexible substrate using a printed thin film of indium tin oxide. A polyethylene terephthalate (PET) substrate was used as the flexible substrate. The sensor was fabricated on a PET substrate, and its operating characteristics were tested. The operating performances of the sensor when serving as an arc-light, a temperature, and a humidity sensor were estimated to be 0.6247 Ω/W, 80.6 Ω/K, and -4.08 Ω/RH, respectively. The feasibility of the proposed fire sensor was demonstrated; it costs low and offers multiple functionalities.