• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.88.1-88.1
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• 2015

In recent printed electronics technology, Photo-Sintering, a technique for sintering materials using a light source, has attracted attention as an alternative to time-consuming high-temperature thermal processes. The key principle of this technique is the selective heating of a strongly absorbent thin film, while preventing the heating of the transparent substrate by the light source. Many recent studies have used a flash lamp as the light source, and investigated the material-dependent effect of the width or intensity of the pulsed light. However, the flash lamp for sintering is not suitable for industry yet, because of needing too high power to sinter for a large scale. In energy-saving and large-scale sintering, LED technologies would be very useful in the near future. In this work, we investigated a sintering process for silver nanoparticles using UV-LED array. Silver nanoparticles in ink were inkjet-printed on a $1{\times}1cm$ area of a PET film and photo-sintered by 365 nm UV-LED module. A sheet resistance value as low as $72.6m{\Omega}/sq$ (2.3 - 4.5 times that of bulk silver) was obtained from the UV-LED sintering at 300 mW/cm2 for 50 min.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.181-185
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• 1996

Rapid prototyping is becoming an increasingly importnat techniuqe involved in the design cycles of modern industry. The majority of the rapid prototyping systems currently available use photo-reactive resins and waxes as the raw materials. The models produced by these systems often have relatively poor mechanical and physical properties and as such have a limited application to the production of advance prototypes but are excellently suited to the manufacture of engineering prototyes. This work identifies the need to produed near production grade advance prototypes from a variety of metals and a novel prototyping process based on the techniques of selective laser sintering and conventional machining is proposed. The integration of a carbon dioxide laser and a conventional machine tool to create the opto-mechanical by multi-layer sintering and some of the problems involved are also discussed.

• 한국결정성장학회지
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• 제30권5호
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• pp.174-182
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• 2020

최근 잉크젯 프린팅 기술을 이용한 인쇄전자 분야가 차세대 기술로서 각광받고 있으며, 복수의 프린트 헤드(head)로부터 다양한 잉크 형태의 소재를 정밀하게 출력하여 적층할 수 있는 3D 프린팅 기술에 관한 연구가 활발하게 진행되고 있다. 본 연구에서는 잉크젯 3D 프린팅 기술을 이용하여 광경화성 실리카 잉크와 PVP가 첨가된 나노 구리 잉크로 절연층과 전도층의 복합구조체를 제작하였다. 프린팅 구동 조건과 잉크의 유변학적 거동을 최적화하여 정밀한 광경화 실리카 절연층을 적층 제조하였으며, 절연층의 저항은 2.43 × 10¹³ Ω·cm의 값을 나타내었다. 광경화 실리카 절연층 위에는 액적 간격 제어를 통하여 나노 구리 전도층을 프린팅하였다. PVP 첨가 나노 구리 잉크의 소결은 IPL 광소결 공정을 이용하였으며, 어닐링 온도와 인가 전압 변화에 따른 전기적, 기계적 특성을 확인하였다. 100℃ 어닐링 온도와 700 V IPL 광소결 조건에서 PVP가 첨가된 나노 구리 전도층의 저항은 29 μΩ·cm으로 매우 낮으며, 광경화 실리카 절연층과의 접착력은 매우 우수한 것으로 확인하였다.

• 전기학회논문지
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• 제57권5호
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• pp.803-807
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• 2008

A making process of DSC(dye sensitized solar cell) was presented. In general, Photo electrodes of DSC was made by using colloid paste of nano $TiO_2$ and processing of Doctor-blade printing and high temperature sintering for porous structure. These methods lead to cracks on $TiO_2$ surface and ununiform of $TiO_2$ thickness. This phenomenon is one factor that makes low efficiency to cells. After $TiO_2$ printing on TCO glass, a physical vibration was adapted for reducing ununiform of $TiO_2$ thickness. And a thermal treatment at low temperature(under $75^{\circ}C$) was adapted for reducing cracks on $TiO_2$ surface. In this paper, we have designed and manufactured an ultrasonic circuit (100W, frequency and duty variable) and a thermal equipment. Then, we have optimized forcing time, frequency and duty of ultrasonic irradiation and thermal heating for surface treatment of photo-electrode of DSC. In I-V characteristic test of DSC, ultrasonic and thermal treated DSC shows 19% improved its efficiency against monolithic DSC. And it shows stability of light-harvesting from drastically change of light irradiation test.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.293.1-293.1
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• 2016

Various materials including conductive, dielectric, and semi-conductive materials, constitute suitable candidates for printed electronics. Metal nanoparticles (e.g. Ag, Cu, Ni, Au) are typically used in conductive ink. However, easily oxidized metals, such as Cu, must be processed at low temperatures and as such, photonic sintering has gained significant attention as a new low-temperature processing method. This method is based on the principle of selective heating of a strongly absorbent film, without light-source-induced damage to the transparent substrate. However, Cu nanoparticles used in inks are susceptible to the growth of a native copper-oxide layer on their surface. Copper-oxide-nanoparticle ink subjected to a reduction mechanism has therefore been introduced in an attempt to achieve long-term stability and reliability. In this work, a flash-light sintering process was used for the reduction of an inkjet-printed Cu(II)O thin film to a Cu film. Using a photographic lighting instrument, the intensity of the light (or intense pulse light) was controlled by the charged power (Ws). The resulting changes in the structure, as well as the optical and electrical properties of the light-irradiated Cu(II)O films, were investigated. A Cu thin film was obtained from Cu(II)O via photo-thermal reduction at 2500 Ws. More importantly, at one shot of 3000 Ws, a low sheet resistance value ($0.2527{\Omega}/sq.$) and a high resistivity (${\sim}5.05-6.32{\times}10^{-8}{\Omega}m$), which was ~3.0-3.8 times that of bulk Cu was achieved for the ~200-250-nm-thick film.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.269-271
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• 2009

We investigated on the sintering behaviors and electrical properties of photo-sensitive aluminum (Al) electrode materials in plasma display panels. General characteristics of Al electrodes was totally different to that of conventional Ag materials; resistivity was decreased with the increasing of metal particle sizes and the amount of frit content and there is almost no width difference between developed and fired electrodes layers. Microstructures of fired electrodes revealed that Al electrodes had different mechanism on necking between metal particles and making electrical conducting path. Chemical durability (especially, antialkalinity) and adhesion of Al electrodes must be carefully controlled. Nevertheless there are difficulties of processing Al electrodes, we developed and optimized photo-sensitive Al materials as address electrodes without any changes of existing patterning equipment and sintering conditions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1394-1399
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• 2007

Recently, Study of 3D freeform fabrication method was working in the various applications. For example, in the powder base, it's laminated using a binding method or laser sintering method. However, these methods are not suitable in the office environments because it dust with powder that is bad for health. In this paper, we introduce a method of 3D freeform fabrication using a curing of photo-polymer resin and construct a system has multi printing head. A photo-polymer curing method has simply fabrication process and high strength of manufacturing part. However, this method has a problem on the multi print-head system. Because multi-printing system has a other printing method compare with a single printing system. Therefore, we experiment a single head 3D printing and proposed a 3D printing method using a multi-piezo head.

• 태양에너지
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• 제8권1호
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• pp.49-56
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• 1988

Thermally treated Korean ilmenite was characterized and used for water splitting to obtain hydrogen by photo-catalytic reaction. Experiments on specific surface area, X-ray diffraction and EDS showed that the formation of FeO, $Fe_2O_3$ and $TiO_2$ ilmenite crystal surface increased the specific surface area with maximum value, phase change of $TiO_2$ at $600^{\circ}C$ and hetrogeneity. The hydrogen evolved in caustic soda solution on these ilmenites indicated that there was a maximum yield point at about $600^{\circ}C$. This point was explained with the change of the surface area due to sintering of newly formed FeO, $Fe_2O_3$ and $TiO_2$, as well as crystal phase change of anatase to rutile at $600^{\circ}C$. Produced hydrogen increased also as the concentration of caustic soda, but become constant at the near 1N solution.

• 조명전기설비학회논문지
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• 제24권7호
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• pp.57-63
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• 2010

Photo-capacitor electrodes are attracting great attention because of their high capacitance and potential applications in electronic devices. Carbon capacitor, active carbon capacitor and its combination will be fabricated using a sandwich method as carbonaceous material on each type of storable electrode with $20{\times}15$[mm] cell size. Carbon/active carbon cell was fabricated using sol-gel process with $120[^{\circ}C]$ dry temperature in 2hour and using sintering process with $500[^{\circ}C]$ in 2hour. The effect of sintering temperature on carbon properties was also investigated with an X-ray diffraction technique to get the best sintering temperature. The detail of the fabrication process will be explained. Active carbon as carbonaceous material has a better capacitance in storable electrode with mean thickness $32[{\mu}m]$ and with particle size $1[{\mu}m]$ to $4.5[{\mu}m]$ in $20{\times}15$[mm] sample size of storable electrode.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 추계학술대회 논문집
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• pp.411-414
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• 2009

Photo-capacitor electrodes are attracting great attention because of their high capacitance and potential applications in electronic devices. Carbon capacitor, active carbon capacitor and its combination will be fabricated using simple sandwich capacitor electrode method as carbonaceous material on each type of capacitor electrodes with 20 ${\times}$ 15 mm cell size. Carbon/active carbon cell was fabricated using sol-gel process with 120oC dry temperature in l hour and using sintering process with 500oC in 2 hour. The effect of sintering temperature on carbon properties was also investigated with X-ray diffraction technique to get the best sintering temperature. The detail of fabrication process will be explained. Elemental composition in electrode material can be measured using quantitative spectroscopic as and a cyclic voltammetric technique was used to study the combined effects of electrode material and effect of annealing temperature and also time on the capacitance of thermally treated in capacitor electrode. In this work, characterization impedance technique is used to measurement of capacitance and giving complementary results. Active carbon as carbonaceous material has a better capacitance in charge/discharge process with mean thickness $32{\mu}m$ and with particle size $1{\mu}m$ to $4.5{\mu}m$ in 20 ${\times}$ 15 mm sample size of capacitor electrode.