• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.883-884
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.577-578
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• 2008

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.266-266
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• 2010

실리콘 나노잉크를 이용한 프린팅 공정을 적용하여 결정질 실리콘 박막을 제조하였으며, 다양한 공정조건에 따른 박막의 특성을 연구하였다. 기존의 실리콘 박막형 제조 기술은 고가의 진공프로세스이므로, 비진공 프린팅 공정의 대체를 통하여 박막 태양전지의 제조원가를 획기적으로 절감할 수 있다. 실리콘 나노입자는 저온 플라즈마를 사용하여 합성하였으며, 스핀코팅 (spin coating), 드롭핑 (dropping), 딥핑 (dipping) 등의 프린팅 공정을 이용하여 단결정 실리콘 웨이퍼 위에 박막을 형성하였다. 사용된 실리콘 나노입자는 10 ~ 50 nm 의 크기와 단결정 구조를 갖는다. 이러한 실리콘 나노입자는 Propylene Glycol 용매에 분산시켜 하부기판에 프린팅 하였다. 이렇게 증착된 나노입자들은 $600{\sim}1000^{\circ}C$의 온도와 다양한 분위기에서 열처리되어 고밀도화 되었다. 제조된 실리콘 박막의 물성 분석은 SEM, EDX, 그리고 X-ray 회절 측정을 통하여 수행되었다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.25.2-25.2
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• 2007

• Journal of the Microelectronics and Packaging Society
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• v.17 no.3
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• pp.43-49
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• 2010

Direct printing technology is an attractive metallization method, which has become immerging as "Green technology" to the conventional photolithography, on account of low cost, simple process and environment-friendliness. In order to commercialize the printed electronics in industry, it is essential to evaluate the electrical properties of conductive circuits using direct printing technology. In this contribution, we focused on the electrical characteristics of inkjet-printed circuits. A Cu nanoink was inkjet-printed onto a Bisaleimide triazine(BT) substrate with parallel transmission line(PTL) and coplanar waveguide(CPW) type, then was sintered at $250^{\circ}C$ for 30 min. We calculated the resistivity of printed circuits through direct current resistance by the measurement of I-V curve: the resistivity was approximately 0.558 ${\mu}{\Omega}{\cdot}cm$ which is about 3.3 times that of bulk Cu. Cascade's probe system in the frequency range from 0 to 30 GHz were employed to measure the Scattering parameter(S-parameter) with or without a gap between the substrate and the probe station chuck. The result of measured S-parameter showed that all printed circuits had over 5 dB of return loss in the entire frequency range. In the curve of insertion loss, $S_{21}$, showed that the PTL type circuits had better transmission of radio frequency (RF) than CPW type.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.377-377
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• 2016

Under nanosecond-pulsed laser irradiation, light-absorbing thin films have been used for photoacoustic transmitters for ultrasound generation. Especially, nanostructured absorbers are attractive due to high optical absorption and efficient thermoacoustic energy conversion: for example, 2-dimensional (2-D) gold nanostructure array, synthetic gold nanoparticles, carbon nanotubes (CNTs), and reduced graphene oxides. Among them, CNT has been used to fabricate a composite film with polydimethylsiloxane (PDMS) that exhibits excellent photoacoustic conversion performance for high-frequency, high-amplitude ultrasound generation. Previously, CNT-PDMS nanocomposite films were made by using a high-temperature chemical vapor deposition (HTCVD) process for CNT growth. However, this approach is not suitable to fabricate large-area CNT films (>several cm2). This is because a chamber dimension of HTCVD is limited and also the process often causes nonuniform CNT growth when the film area increases. As an alternative approach, a solution-based process can be used to overcome these issues. We develop PDMS composite transmitters, based on the solution process, using several nanostructured light-absorbers such as CNTs, nanoink powders, and imprinted regular arrays of gold nanostructure. We compare fabrication processes of each composite transmitters and photoacoustic output performance.

• Korean Journal of Materials Research
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• v.26 no.4
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• pp.216-221
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• 2016

A sintering process for copper based films using a rapid thermal process with infrared lamps is proposed to improve the electrical properties. Compared with films produced by conventional thermal sintering, the microstructure of the copper based films contained fewer internal and interfacial pores and larger grains after the rapid thermal process. This high-density microstructure is due to the high heating rate, which causes the abrupt decomposition of the organic shell at higher temperatures than is the case for the low heating rate; the high heating rate also induces densification of the copper based films. In order to confirm the effect of the rapid thermal process on copper nanoink, copper based films were prepared under varying of conditions such as the sintering temperature, time, and heating rate. As a result, the resistivity of the copper based films showed no significant changes at high temperature ($300^{\circ}C$) according to the sintering conditions. On the other hand, at low temperatures, the resistivity of the copper based films depended on the heating rate of the rapid thermal process.

• Particle and aerosol research
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• v.8 no.1
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• pp.37-43
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• 2012

In this study, we designed a 'spark in liquid' system. The spark discharge between two electrodes were used to generate particles by using sufficient temperature to evaporate a part of electrodes. The power supply system provides a continuous spark discharge by discharging of the capacitor to ionize the electrodes in liquid. The DC spark discharge system operates with 1-10 kV voltage. Processed copper and graphite rods were used to both electrodes with 1-3 mm diameter. There are several variables which can control the particle size and concentration such as gap distance between electrodes, applied voltage, operating liquid temperature, electrode type and liquid type. So we controlled these variables to confirm the change of particle size distribution and concentration of particles contained in liquid as wt%. 'spark in liquid' system is expected to apply nanoink by control of concentration with analysis of characteristics.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.1
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• pp.33-39
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• 2010

Printing technologies have been indicated as alternative methods for patterning conductive, semi-conductive or insulative materials on account of their low-cost, large-area patternability and pattern flexibility. For application of the printing technologies in manufacture of semiconductor or display modules, ink or paste composed of nanoparticles, solvent and additives are basically needed. Here, we report recent advances in eco-friendly nano-ink technology for semiconductor and display technology. Then, we will introduce an eco-friendly ink formation technology developed in our group with an example of manufacturing $SiO_2$ nanopowders and inks. We tried to manufacture ultrafine $SiO_2$ nanoparticles by applying a low-temperature synthetic method, and then attempted to fabricate the printed $SiO_2$ film onto the glass substrate to see whether the $SiO_2$ nanoparticles are feasible for the printing or not. Finally, the electrical characteristics of the films were measured to investigate the effect of the manufacturing parameters.