• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.551-552
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• 2006

This study was attended to demonstrate synthesis of silver nanoparticles stabilized with polymer and their applicability to printed electronics. Silver nanoparticles were synthesized by reduction of silver nitrate in aqueous solution in the presence of polyvinyl pyrrolidone (PVP) as a stabilizer. The ink used here is composed of 50 wt% Ag NP, 15 wt% humectant and then were printed on polyimide film. Particle deposit morphologies were controlled by varying the ink compositions. Printed silver patterns and dots were cured on a convection oven in air at $300^{\circ}C$ for 60 min. The printed patterns show good shape definition and the resistivity of the printed films is about $5{\mu}{\Omega}{\cdot}cm$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.689-693
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• 2005

Inkjet printing is a non-contact and direct writing associated with a computer. In the industrial field, there have been many efforts to utilize the inkjet printing as a new way of manufacturing, especially for electronic devices. For the application of inkjet printing to electronic field, one of the key factors is exact realization of designed images into printed patterns. In this work, micro patterning for conducting line has been studied using the piezoelectric print head and silver nano ink. Dimensions of printed images have been predicted in terms of print resolution and diameter of a single dot. The predicted and the measured values showed consistent results. Using the results, the design capability for industrial inkjet printing could be achieved.

• Journal of Sensor Science and Technology
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• v.32 no.4
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• pp.252-256
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• 2023

A one-step method for nanoscale patterning of silver ionic ink on a substrate is developed using a microscale, elastic mold deformation. This method yields unique micro/nanoscale metallic structures that differ from those produced using the original molds. The linewidth of these metallic structures is significantly reduced (approximately 10 times) through the sidewall deformation of the original mold cavity on a thin liquid film, as verified by finite element analysis. The process facilitates the fabrication of various, isolated and complex micro/nanoscale metallic structures with negligible residual layers at low cost and high throughput. These structures can be utilized for various applications, including optoelectronics, wearable sensors, and metaverse-related devices. Our approach offers a promising tool for manipulation and fabrication of micro/nanoscale structures of various functional materials.

• Journal of Advanced Technology Convergence
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• v.2 no.4
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• pp.1-6
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• 2023

Research on power inductor surface UV printing equipment using cylindrical magnets can prevent damage to quality consumable materials (making plates, Squeegees) during printing and improve printing quality by applying technology to prevent product from flipping or standing up when fixing the product by making the magnetic formation of cylindrical magnets form up and down. The development of cylindrical magnets that changed the direction of magnetic force will stabilize the fixing method for metal products made by powder compression, increasing the production capacity for small products. Finally, by studying the power inductor surface UV printing device using cylindrical magnets, it can be differentiated from the spray and deeping methods that were being worked on, production will be greatly improved, and as a result, cost reduction and competitive production will be possible.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.105-105
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• 2006

IT 산업 및 반도체 산업이 발전함에 따라 초소형, 고집적화 시스템의 요구에 대응하기 위해서 고해상도 및 고정밀의 패턴 구현에 관한 많은 연구가 진행되고 있다. 이러한 연구는 각종 산업제품의 PCB(Printed Circuit Board) 및 디스플레이 장치인 PDP(Plasma Display Panel), LCD(Liquid Crystal Display) 등에 적용되어 널리 응용되고 있다. 현재 널리 사용되는 인쇄 회로 기판은 마스킹 후 선택적 에칭 방식을 적용하여 금속 배선을 형성하는 방식을 적용하고 있다. 이러한 방식은 설계가 변경될 경우 마스크를 다시 제작해야 하는 번거로움이 있어 설계 변경이 용이하지 않고 더욱 길어진 생산시간의 증가로 인하여 생산성 및 집적도가 떨어지게 된다. 따라서 최근에는 이러한 한계를 극복하기 위한 방안이 여러 가지 측면에서 시도되고 있으며, 그 중에서도 Inkjet Printing 기술에 대한 관심이 증가하고 있다. 본 연구에서는 Inkjet Printing 방식을 적용하여 금속 배선을 형성하고 선폭과 두께의 오차를 줄여 배선의 Tolerance 를 개선할 수 있는 방안을 제안하였다. Inkjet Printing 방식을 이용한 기존의 금속 배선 형성은 고해상도의 DPI(Dot Per Inch)에서 잉크 액적이 뭉치는 Bulge 현상이 발생되어 원하는 형상 및 배선의 폭을 구현하는데 어려움이 있었다. Bulge 현상은 배선의 불균일성을 야기할 뿐만 아니라 근접한 배선의 간섭에도 영향을 미처 금속 배선의 기능을 할 수 없는 단점을 발생시킨다. 따라서 본 연구에서는 이러한 Bulge 현상을 줄이고 배선간의 간섭을 방지하여 원하는 배선을 용이하게 형성할 수 있는 순차적 인쇄 방식을 적용하였다. 본 연구에서는 노즐직경 35um 의 Inkjet Head 와 나노 Ag 입자 잉크를 사용하여 Glass 표면 위에 배선을 형성하고 배선의 폭과 두께를 측정하였다. 또한 순차적 인쇄 방식을 적용하여 700DPI 이상의 고해상도에서 나타날 수 있는 Bulge 현상이 감소하였음을 관찰하였으며 금속 배선의 Tolerance를 10%내외로 유지할 수 있음을 확인하였다.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.3
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• pp.25-30
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• 2015

SAC-coated Cu specimens were fabricated by novel pad finish process using a phenomenon that metal nanoparticles less than 20 nm in diameter melted at a temperature lower than the melting point of bulk metal, and their wettabilities were evaluated. The thickness of SAC305 layer coated at low temperature of $160^{\circ}C$ using SAC305 ink was extremely thin as the level of several nanometers. It was analyzed by Auger electron spectroscopy that $Cu_6Sn_5$ intermetallic layer with a thickness of 10~100 nm and $Cu_3Sn$ intermetallic layer with a thickness of 50~150 nm were sequentially formed under the SAC305 coating layer. The thickness of formed intermetallic layers was thicker in electroplated Cu than rolled Cu, which attributed to improved surface roughness in the electroplated Cu. The improved surface roughness induces the contact, melting, and reaction of a larger number of SAC305 nanoparticles per the unit area of Cu specimen. In the wetting angle test using SAC305 solder balls, the Cu coated with SAC305 through the low temperature process presented evidently low wetting angles than those in non-coated Cu, indicating that only a few nanometer-thick SAC305 coating layer on Cu could also cause the enhancement of wettability.

• Korean Journal of Materials Research
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• v.27 no.3
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• pp.149-154
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• 2017

Transparent conducting oxides (TCOs) were fabricated using solution-based ITO (Sn-doped $In_2O_3$) nanoinks with nanorods at an annealing temperature of $200^{\circ}C$. In order to optimize their transparent conducting performance, ITO nanoinks were composed of ITO nanoparticles alone and the weight ratios of the nanorods to nanoparticles in the ITO nanoinks were adjusted to 0.1, 0.2, and 0.5. As a result, compared to the other TCOs, the ITO TCOs formed by the ITO nanoinks with weight ratio of 0.1 were found to exhibit outstanding transparent conducting performance in terms of sheet resistance (${\sim}102.3{\Omega}/square$) and optical transmittance (~80.2 %) at 550 nm; these excellent properties are due to the enhanced Hall mobility induced by the interconnection of the composite nanorods with the (440) planes of the short lattice distance in the TCOs, in which the presence of the nanorods can serve as a conducting pathway for electrons. Therefore, this resulting material can be proposed as a potential candidate for solution-based TCOs for use in optoelectronic devices requiring large-scale and low-cost processes.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.1
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• pp.18-23
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• 2022

Electrohydrodynamic jet (e-jet) printing, a type of direct contactless microfabrication technology, is a versatile fabrication process that enables a wide range of micro/nanopattern arrays by applying a strong electric field between the nozzle and the substrate. In general, the morphology and the thickness of polymers/quantum dot micropatterns show a systematic dependence on the diameter of the nozzle and the ink composition with a fully automated printing machine. The purpose of this report is to provide typical examples of e-jet printed micropatterns of polymers/quantum dots to explain the effect of each process variable on the result of experiments. Here, we demonstrate several operating conditions that allow high-resolution printing of layers of polymers/quantum dots with a precise control over thickness and submicron lateral resolution.

• Journal of Powder Materials
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• v.20 no.2
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• pp.120-124
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• 2013

This study is carried out to develop the new process for the fabrication of ultra-fine electrodes on the flexible substrates using superhydrophobic effect. A facile method was developed to form the ultra-fine trenches on the flexible substrates treated by plasma etching and to print the fine metal electrodes using conductive nano-ink. Various plasma etching conditions were investigated for the hydrophobic surface treatment of flexible polyimide (PI) films. The micro-trench on the hydrophobic PI film fabricated under optimized conditions was obtained by mechanical scratching, which gave the hydrophilic property only to the trench area. Finally, the patterning by selective deposition of ink materials was performed using the conductive silver nano-ink. The interface between the conductive nanoparticles and the flexible substrates were characterized by scanning electron microscope. The increase of the sintering temperature and metal concentration of ink caused the reduction of electrical resistance. The sintering temperature lower than $200^{\circ}C$ resulted in good interfacial bonding between Ag electrode and PI film substrate.

• Journal of the Korean Ceramic Society
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• v.46 no.1
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• pp.41-46
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• 2009

The rheological properties of highly concentrated Ag nano sol depending on particle size were studied. The Ag nano sol was prepared by reducing the Ag ion in aqueous solution. The size of Ag nano particle was controlled by two steps of nucleation and growth, and the thickness of adsorption layer was varied by molecular weight of polyelectrolytes. The polyelectrolytes acted as not only ionic complex agent in ionic state and but also dispersant after formation of Ag nano sol. The effective volume was controlled by combination of varying the molecular weight of polyelectrolytes and the size Ag nano sol. The particle size and the viscosity of nano sol were characterized by particle size analyzer, HR-TEM and cone & plate viscometer. It was found that the 10 nm and 40 nm-sized Ag nano sols were prepared by controlling the nucleation and growth steps, respectively. Finally, we could prepare highly concentrated Ag nano sol over 50 wt%.