• 한국재료학회지
• /
• 제13권10호
• /
• pp.663-667
• /
• 2003

The effects of paste materials on field emission properties in a carbon nanotube(CNT) cathode were investigated for high-efficient field emission displays. The major components in CNT paste for screen printing were a metallic Ag-paste, a dielectric glass-frit and CNT ink. The emission current from the cathode by an electron tunneling effect increased with an increase in the dielectric material fraction in the CNT paste, which is related to an increase of field enhancement factor in Fowler-Nordheim equation. The surface treatment used, after soft baking of the screen-printed CNT films, greatly affected the decrease in the turn-on field in CNT cathode and the uniformity of emission sites over the entire CNT film area.

• 동력기계공학회지
• /
• 제22권1호
• /
• pp.64-71
• /
• 2018

Currently, functional patterns are formed by screen printing on stretchable films, and they are applied to wearable and stretchable devices. In this study, three types of silver paste were prepared using three polyester binders with different Tg and molecular weights in order to impart elasticity to the conductive pattern itself. Rheological properties and DSC measurements were performed for each silver paste. Then, each silver paste was screen printing and cured by an IR dryer to evaluate adhesive strength, pencil hardness, resistance and surface shape change according to strain. As a result, it was found that the silver paste using a binder with a low Tg and a high molecular weight has the smallest resistance change depending on the strain. Namely, it was found that it is most preferable to use a binder with a low Tg and a high molecular weight as the stretchable electrode.

• 한국전기전자재료학회논문지
• /
• 제22권9호
• /
• pp.724-727
• /
• 2009

We have fabricated (Ba,Sr)TiO3$TiO_3$ thick films doped with various amount of ZnBO dopants (1, 3, and 5 wt%) by screen printing method on the alumina substrates, which were sintered at the temperature below $1200^{\circ}C$. With increasing the amount of ZnBO dopants, the relative dielectric permittivity of ZnBO doped (Ba,Sr)$TiO_3$ was decreased, while loss tangent was increased. 1 wt% ZnBO doped (Ba,Sr)$TiO_3$ thick film has relative dielectric permittivity of 759 at 1 MHz, while 3 and 5 wt% of ZnBO doped (Ba,Sr)$TiO_3$ thick films have 624 and 554, respectively. By introducing ZnBO dopants to the (Ba,Sr)$TiO_3$ thick films, leakage current densities were decreased. The decreased leakage current with increasing ZnBO dopants can be explained by increased density and grain size of thick film on alumina substrate. We believe this decreased leakage current density probably come from the increased grain size and increased density.

• Journal of Information Display
• /
• 제4권3호
• /
• pp.6-11
• /
• 2003

We have fabricated a carbon nanotube field emission display (CNT-FED) panel with a 2-inch diagonal size by using a screen printing method and vacuum in-line sealing technology. The sealing temperature of the panel was around 390$^{\circ}C$ and the vacuum level was obtained with 1.4x$10^{-5}$torr at the sealing. When the field emission properties of a fabricated and sealed CNT-FED panel were characterized and compared with those of the unsealed panel which was located in a test chamber of vacuum level similar with the sealed panel. As a result, the sealed panel showed similar I-V characteristics with unsealed one and uniform light emission with very high brightness at a current density of 243 ${\mu}A/cm^2$, obtained at the electric field of 10 V/${\mu}m$.

• Transactions on Electrical and Electronic Materials
• /
• 제7권3호
• /
• pp.129-133
• /
• 2006

Ferroelectric PZT heterolayered thick films were fabricated by the alkoxide-based sol-gel method. PZT(20/80) and PZT(80/20) paste were made and alternately screen-printed on the alumina substrates. The coating and drying procedure was repeated 4 times to form the heterolayered thick films. The thickness of the PZT heterolayered thick films was approximately $60{\mu}m$. All PZT thick films showed the typical XRD patterns of a polycrystalline rhombohedral structure. And in the PZT thick films sintered at $1100^{\circ}C$, the pyrochlore phase was observed due to the evaporation of PbO. The relative dielectric constant and the dielectric loss of the PZT thick films sintered at $1050^{\circ}C$ were 445.2 and 1.90 % at 1 kHz, respectively. The remanent polarization and coercive field of the PZT thick films sintered at $1050^{\circ}C$ were $14.15{\mu}C/cm^2$ and 19.13 kV/cm, respectively.

• Transactions on Electrical and Electronic Materials
• /
• 제12권1호
• /
• pp.11-15
• /
• 2011

In this study, $ZnGa_2O_4$ phosphors in its application to field emission displays and electroluminescence were synthesized through the precipitation method and $Mn^{2+}$ ions. A green luminescence activator, $Cr^{3+}$ ions, and a red luminescence activator were separately doped into $ZnGa_2O_4$, which was then screen printed to an indium tin oxide substrate. The thick films of the $ZnGa_2O_4$ were deposited with the various thicknesses using nano-sized powder. The best luminescence characteristics were shown at a thickness of 60 ${\mu}m$. Additionally, green-emission $ZnGa_2O_4:Mn^{2+}$ and red-emission $ZnGa_2O_4:Cr^{3+}$ phosphor thick films, which have superior characteristics, were manufactured through the screen-printing method. These results indicate that $ZnGa_2O_4$ phosphors prepared through the precipitation method have wide application as phosphor of the full color emission.

• 대한기계학회논문집B
• /
• 제41권5호
• /
• pp.365-372
• /
• 2017

결정질 실리콘 태양전지의 전면전극은 수광면적을 극대화하면서도 전기적 저항을 최소화하기 위하여 미세하면서도 높은 종횡비로 형성되어야 한다. 기존의 전면전극 형성공정은 스크린 인쇄가 이용되었으나, 스크린 제판 개구부의 선폭보다 인쇄된 전극의 선폭이 1.3~2.2 배 넓게 형성되는 문제 때문에 $40{\mu}m$ 급 미만의 미세전극을 형성하기 위해서는 스크린 제판의 개구부는 $30{\mu}m$ 이하여야 한다. 그러나, 개구부가 미세화될수록 인쇄압력의 증가, 실버 페이스트 전이 불량률 상승 및 메쉬 마크로 인한 전극의 전기적 저항 상승과 같은 문제들이 발생한다. 본 연구에서는 스크린 인쇄를 대체하기 위한 차세대 인쇄방식으로서 스크류 펌프방식의 디스펜싱 인쇄를 소개하고, 기존 인쇄방식과 차별화되는 점들에 대해 논의하도록 한다.

• Transactions on Electrical and Electronic Materials
• /
• 제8권6호
• /
• pp.241-245
• /
• 2007

[ $(Ba_{0.9-x}Sr_xCa_{0.10})TiO_3$ ] (x=0.33, 0.36) powders were prepared by sol-gel method. $(Ba,Sr,Ca)TiO_3$(BSCT) thick films, undoped and doped with $MnCO_3$ and $Yb_2O_3(0.1{\sim}0.7mol%)$, were fabricated by the screen printing method on the alumina substrate. The coating and drying procedure was repeated 6-times. The Pt bottom electrode was screen printing method on the alumina substrate. These BSCT thick films were annealed at $1420^{\circ}C$ for 2 hr in atmosphere. The upper electrodes were fabricated by screen printing the Ag paste and then firing at $590^{\circ}C$ for 10 min. And then the structured and dielectric properties as a function of the doping amount of $Yb_2O_3$ were studied. As a result of the TG-DTA, exothermic peak was observed at around $670^{\circ}C$ due to the formation of the polycrystalline perovskite phase. All BSCT thick films showed XRD patterns of typical cubic peroveskite structure. The average thickness of BSCT thick films was about $70^{\mu}m$. The curie temperature and the dielectric constant decreased with increasing $Yb_2O_3$ doped content and the relative dielectric constant of the specimen, doped with 0.5 mol% $Yb_2O_3$ at BSCT(54/36/10), showed a best value of 5018 at curie temperature.

• Smart Structures and Systems
• /
• 제22권2호
• /
• pp.161-166
• /
• 2018

In the last decade, there has been an exponential increase of scientific interest in smart additive manufacturing (AM) technology. Among the different AM techniques, one of the most commonly applied processes is digital light processing (DLP). DLP uses a digital projector screen to flash an ultraviolet light which cures photopolymer resins. The resin is cured to form a solid to produce parts with precise high dimensional accuracy. During the curing process, there are several process parameters that need to be optimized. Among these, the exposure time affects the quality of the 3D printed specimen such as mechanical strength and dimensional accuracy. This study examines optimal exposure times and their impact on printed part. It was found that there is optimal exposure time for printed part to have appropriate mechanical strength and accurate dimensions. The gel fraction and TGA test results confirmed that the improvement of mechanical properties with the increasing UV exposure time was due to the increase of crosslinked network formation with UV exposure time in acrylic resins. In addition, gel fraction and thermogravimetric analysis were employed to microscopically investigate how this process parameter impacts mechanical performance.

• 한국세라믹학회지
• /
• 제41권6호
• /
• pp.456-463
• /
• 2004

음극지지형 SOFC의 성능을 향상시키기 위해 단전지 제조공정을 개선하고 그 출력특성을 평가하였다. 액상응결 공정(Liquid Condensation Process : LCP)과 일축가압성형공정을 통하여 NiO/YSZ 복합체 음극기판을 제조하고 위에 YSZ 전해질을 스크린 인쇄한 후 140$0^{\circ}C$에서 3시간동안 동시소결하여 음극/전해질 기판을 제조하였다. 또한 LSM/YSZ 양극층은 임피던스 분석을 통해 분극저항이 최소가 되는 조성 및 열처리 조건을 선택하여 스크린 인쇄법을 이용해 구성하였고 이러한 적층공정을 거쳐 최종적으로 5${\times}$5와 l0${\times}$10 $\textrm{cm}^2$ 크기의 단전지를 제조하였다. 제조된 단전지의 출력특성을 측정한 결과 5${\times}$5와 10${\times}$10 단전지는 80$0^{\circ}C$에서 약 0.45W/$\textrm{cm}^2$ 와 0.22 W/$\textrm{cm}^2$의 최대출력밀도를 각각 나타내어 선행연구에서 기존공정으로 제조된 단전지에 비해 2배 이상 향상된 좋은 성능을 나타내었다.