• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.372-373
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• 2006

Modern business trends call for miniaturization of electronic systems. One of the major impedances in this miniaturization is the conductive and inductive components in chips and circuit boards. Direct Write Technology can write these soft magnetic materials, thus allowing for further miniaturization of inductor devices. Another obstacle in electronics fabrication is the size limitations of thick screen-printing and the material limitations in ink jet printing. Direct Write Technologies address both of these limitations by providing feature sizes less than 20 microns with a wide range of materials possibilities. A discussion of the application of these nano-particulate materials by Direct Write Technologies will be presented.

• Current Photovoltaic Research
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• v.2 no.4
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• pp.173-176
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• 2014

We have investigated the seed layer formation of front side contact using the inkjet printing process. Conductive silver ink was printed on textured Si wafers with 80 nm thick $SiN_x$ anti reflection coating (ARC) layers and thickened by light induced plating (LIP). The inkjet printable sliver inks were specifically formulated for inkjet printing on these substrates. Also, a novel method to prepare nano-sized glass frits by the sol-gel process with particle sizes around 5 nm is presented. Furthermore, dispersion stability of the formulated ink was measured using a Turbiscan. By implementing these glass frits, it was found that a continuous and uniform seed layer with a line width of $40{\mu}m$ could be formed by a inkjet printing process. We also investigated the contact resistance between the front contact and emitter using the transfer length model (TLM). On an emitter with the sheet resistance of $60{\Omega}/sq$, a specific contact resistance (${\rho}_c$) below $10m{\Omega}{\cdot}cm^2$ could be achieved at a peak firing temperature around $700^{\circ}C$. In addition, the correlation between the contact resistance and interface microstructures were studied using scanning electron microscopy (SEM). We found that the added glass particles act as a very effective fire through agent, and Ag crystallites are formed along the interface glass layer.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.4
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• pp.342-347
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• 2008

Bridge circuit was developed such that the pressure wave in the inkjet can be measured. In order to test the circuit, the microfab single ejector was used. For the experiment, the head was filled with nano silver ink (20wt%). In order to generate waveform voltage for jetting signal, the Agilent 33120 was used in order to generate arbitrary waveform. For the driver, PZD 350 from TREK was used in order to amplify the waveform. Experimental results show that the designed circuit can effectively detect the pressure wave in the inkjet head.

• Journal of the Optical Society of Korea
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• v.14 no.3
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• pp.282-285
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• 2010

We printed a one-dimensional array of metallic wires and a two-dimensional array of metallic split ring resonators on a photo-paper by using a high-dots-per-inch resolution printer and an ink with silver nano-particles. The printed sample sizes are $1.0{\times}1.0cm^2$. The transmission measured by a terahertz time domain spectroscopy system shows that the arrays of wires and split ring resonators could act as polarizers and band-stop filters, respectively, in a terahertz frequency region.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.5
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• pp.454-462
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• 2023

Flash lamp annealing (FLA) of metal nanoparticle (NP) ink has provided powerful strategies to fabricate high-performance electrodes on a flexible substrate because of its rapid processing capability (in milliseconds), low-temperature process, and compatibility with to roll-to-roll process. However, metal NPs [e.g., gold (Au), silver (Ag), copper (Cu), etc.] have limitations such as difficulty in synthesizing fine metal NPs (diameter less than 10 nm), high price, and degradation during ink storage and FLA processing. In this regard, organometallic ink has been proposed as a material that can replace metal NPs due to their low-cost (usually 1/100 times cheaper than metal nano inks), low-temperature processability, and high material stability. Despite these advantages, the fabrication of flexible electrodes through FLA treatment of organometallic compounds has not been extensively researched. In this paper, we experimentally guide how to determine the optimal conditions for forming electrodes on flexible substrates by considering material parameters, and flashlight processing parameters (energy density, pulse duration, etc) to minimize the difficulties that may arise during the FLA of organometallic ink.

• Journal of the Korean Vacuum Society
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• v.22 no.3
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• pp.156-161
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• 2013

We fabricated transparent conductive electrodes with silver (Ag) nanofibers by electrospinning process. Ag nanofibers have high aspect ratio and fused junctions which result in low sheet resistance. Electrospinning is a fast and efficient process to fabricate continuous one-dimensional (1D) nanofibers. Ag/polymer ink were prepared in polymer matrix solution by a sol-gel method. Then, Ag/polymer nanofibers precursors are heated at $200{\sim}500^{\circ}C$ in air for 2 h to eliminate partially the polymers. The topographical features of the Ag nanofibers were characterized by FE-SEM, and the electrical property was analyzed through I-V measurement system. Finally, optical property was measured using UV/VIS spectroscopy. The transparent conductive electrodes with Ag nanofibers exhibited a sheet resistance (Rs) of $250{\Omega}/sq$ at a transparency (T) of 83%. Transparent conductive films, contain the Ag nanofibers as conductive materials, have good electrical, optical, and mechanical properties. Therefore, it is expected to be useful for the application of flexible display in the future.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.1
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• pp.12-16
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• 2011

In this study, we fabricated the flexible pentacene TFTs with the polymer gate dielectric and contact printing method by using the silver nano particle ink as a source/drain material on plastic substrate. In this experiment, to lower the cross-linking temperature of the PVP gate dielectric, UV-Ozone treatment has been used and the process temperature is lowered to $90^{\circ}C$ and the surface is optimized by various treatment to improve device characteristics. We tried various surface treatments; $O_2$ Plasma, hexamethyl-disilazane (HMDS) and octadecyltrichlorosilane (OTS) treatment methods of gate dielectric/semiconductor interface, which reduces trap states such as -OH group and grain boundary in order to improve the OTFTs properties. The optimized OTFT shows the device performance with field effect mobility, on/off current ratio, and the sub-threshold slope were extracted as $0.63cm^2 V^{-1}s^{-1}$, $1.7{\times}10^{-6}$, and of 0.75 V/decade, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.1
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• pp.47-53
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• 2015

In this paper, a novel fluid controlled phase tunable line using inkjet printed microfluidic composite right/left-handed(CRLH) transmission line(TL) is proposed. A CRLH-TL prototype has been inkjet-printed on a paper substrate using silver nano particle ink. In addition, a laser-etched microfluidic channel in poly methyl methacrylate(PMMA) has been integrated with the CRLH TL using inkjet-printed SU-8 as a bonding material. The proposed TL provides excellent phase-tuning capability that is dependent on the different fluidic materials used. As the fluid is changed, the proposed TL can have negative-phase, zero-phase, and positive-phase characteristics at 900 MHz and reflection coefficient is maintained to below -10 dB. The performance of the proposed TL is successfully validated using simulation and measurement results.

• Journal of the Korean Vacuum Society
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• v.20 no.2
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• pp.146-154
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• 2011

The adhesive-tape of a liquid leak film sensor including the alarm system is developed. The sensing film is composed of three layers such as base film layer, conductive line layer, and protection film layer. The thickness of film is 300~500 um, the width is 3.55 cm, and the unit length is 200 m. On the conductive line layer, three conducting lines and one resistive line are formulated by the electronic printing method with a conducting ink of silver-nano size. When a liquid leaks for the electricity to be conducted between the conductive line and the resistive line, the position of leakage is monitored by measuring the voltage varied according to the change of resistance between two lines. The error range of sensing position of 200 m film sensor is ${\pm}1m$.