• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.5
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• pp.12-18
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• 2008

Ag paste was employed for source and drain electrode of OTFTs and for the data metal lines of OTFT-OLED array on PC(polycarbonate) substrate. We tested two kinds of Ag-pastes such as pastes for 325 mesh and 500 mesh screen mask to examine the pattern ability and electrical performance for OTFTs. The minimum feature size was 60 ${\mu}m$ for 325 mesh screen mask and 40 ${\mu}m$ for 500 mesh screen mask. The conductivity was 60 $m{\Omega}/\square$ for 325 mesh and 133.1 $m{\Omega}/\square$ for 500 mesh. For the OTFT performance the mobility was 0.35 $cm^2/V{\cdot}sec$ and 0.12 $cm^2/V{\cdot}sec$, threshold voltage was -4.7 V and 0.9 V, respectively, and on/off current ratio was ${\sim}10^5$, for both screen masks. We applied the 500 mash Ag paste to OTFT-OLED array because of its good patterning property. The pixel was composed of two OTFTs and one capacitor and one OLED in the area of $2mm{\times}2mm$. The panel successfully worked in active mode operation even though there were a few bad pixels.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.6
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• pp.282-286
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• 2021

Penetration depth and compressive residual stress of laser-carburized TiZrN coating by thickness of carbon paste were investigated in terms of carbon potential. The carbon paste was covered with a thickness of 1.1 mm using screen printing, and applied to a thickness of 0.4 mm using spin coating, and laser carburization was performed under the same conditions. As the thickness of carbon paste increased, the diffraction pattern of the laser-carburized TiZrN coating shifted to a lower angle, indicating solid solution strengthening and lattice distortion. For microstructure analysis using TEM, the defects and carbon concentration of the laser-carburized TiZrN coating increased as the carbon paste was thicker. It indicated that the variation of the carbon potential corresponds to the change in the paste thickness. In XPS depth profile analysis, high concentration of carbon and formation of carbide were observed in laser-carburized TiZrN coating with thick carbon paste. It revealed that the carbon concentration on the surface and carbon potential were changed by the thickness control of carbon paste. The compressive residual stress increased from 3.67 GPa to 4.58 GPa by the variation of carbon concentration.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.130-137
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• 2023

By using XRF (X-ray fluorescence), this study investigates the variation of chemical properties in cement pastes at elevated temperatures. High-temperature conditions were prepared by using an electric furnace, planning a total of 11 target temperatures ranging from room temperature to 1000 ℃. A standard library of geo-quant basic was applied for the analysis of 12 elements in cement paste, including Ca, Si, Al, Fe, S, Mg, Ti, Sr, P, Mn, Zn and K. The results revealed that, as the temperature increased, the proportion of each element in the cement paste also increased. With the exception of a few elements present in extremely low amounts in the cement pastes, the variation in the composition ratio of most elements exhibited a strong correlation with temperature, with an R-squared value exceeding 0.98. In this study, cement pastes exposed to normal and high-temperature environments were compared. The authors established that the reasons for the different results in this comparison can be explained from the same perspective as when comparing raw cement with cement paste. Furthermore, this study discussed the potentially most dominant parameter when investigating the properties of cement paste using XRF.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.240-244
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• 2003

후막 리소그라피 기술은 기판 위에 감광성 페이스트를 도포한 후 자외선과 패턴마스크를 사용하는 광식각(photolithography) 방법을 이용하여 세부 패턴을 형성시키는 기술이다, 이 기술은 후막기술로서는 높은 해상도인 선폭 $30{\mu}m$ 이하의 미세도선을 구현할 수 있어, 후막기술을 이용한 고주파 모듈의 제조에 있어서 새로운 대안으로 주목받고 있다. 본 연구에서는 알루미나 기판 상에 수십 ${\mu}m$ 이하의 마이크로 비아를 가지는 유전체 층을 형성시킬 수 있는 저온소결용 감광성 유전체 페이스트를 개발하였다. 저온소결용 유전체 파우더와 폴리머, 모노머, 광개시제 등의 양을 조절하여 마이크로 비아를 형성할 수 있는 최적 페이스트 조성을 연구하였으며, 노광량 및 현상시간과 같은 공정변수가 마이크로 비아의 해상도에 미치는 영향을 평가하였다. 알루미나 기판에 전면 프린팅 한 후 건조, 노광, 현상, 소성 과정을 거쳐 소결전 $37{\mu}m$, 소결후 $49{\mu}m$의 해상도를 가지는 마이크로 비아를 형성할 수 있었다.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.2
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• pp.107-112
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• 2022

In this study, a silver paste capable of UV curing without using any solvent was developed. The viscosity and viscoelasticity of the silver paste developed as a solvent-free type were measured. And after printing the pattern by screen printing, an electrode coating film was formed by UV curing. Conductivity, pencil hardness, and adhesive force of the formed electrode coating film were evaluated. Finally, the curing characteristics of the electrode coating film were evaluated by TGA and FT-IR. Summarizing these results, in terms of conductivity, adhesion, and curing characteristics, it was found that Paste (4), that is, silver paste obtained by mixing 1.2 ㎛ spherical silver powder and 50 nm silver powder at 72:8% had the best physical properties.

• Applied Chemistry for Engineering
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• v.35 no.3
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• pp.209-213
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• 2024

To improve the adhesion properties between the conductive paste and PET film, the PET film was chemically treated using acids and bases and physically treated through corona discharge. A paste using ethylcellulose, which is used in actual industrial manufacturing and silane-treated CNF, as a binder was manufactured and coated on PET film to compare the adhesive properties. The specimen coated with a paste containing silane-treated CNF as a binder on a corona discharge-treated PET film showed the highest level of adhesion, 5B. On the other hand, it was confirmed that when PET film was chemically treated with acid/base, there was no improvement in adhesive properties.

• 전자공학회논문지 IE
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• v.44 no.2
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• pp.26-31
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• 2007

A surface treatment was performed after the screen printing of a carbon nanotube paste for obtaining the carbon nanotube field emission array(CNT FEA) on the soda-lime glass substrate. In this experiment, Ar ion bombardment was applied as an effective surface treatment method. After making a cathode electrode on the glass substrate, photo sensitive CNT paste was screen-printed, and then back-side was exposure by uv light. Then, the exposed CNT paste was selectively remained by development. After post-baking, the remained CNT paste was bombarded by accelerated Ar ions for removing some binders and exposing only CNTs. As results, the field emission characteristics were strongly depended on the accelerating energy. At 100 eV, the emission was highest and as the acceleration energy increases more then 100 eV, the emission decreased. This was due to the removal of CNT itself as well as binders.

• Korean Journal of Food Science and Technology
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• v.22 no.4
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• pp.415-420
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• 1990

To prevent red pepper from post harvest decay and to reduce the labor and drying expenses, the red pepper paste was directly prepared from fresh red pepper. The characteristics of red pepper paste and processing properties were investigated, and the effect of salt and heat on product quality during processing and storage were studied. After the processed red pepper paste was stored at room temperature, $5^{\circ}C\;and\;-3^{\circ}C$ without light for 6 months, kimchi was prepared with the stored red pepper paste to evaluate any quality change. The weight and pH of pericarp were 73.2% of total and 5.0, respectively. Addition of 10% salt to the paste decreased the pH of paste, reducing the sterilization time down to 10 min against growth of Clostridium botulinum. Thermal diffusivity of paste after pasteurization was $1.190{\times}10cm^{-7}/sec$, which was lower than control, probably due to air in pouch. The red pepper paste with 10% salt added, followed by sterilization for 10 min, could be preserved for over 6 months at $5^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.626-631
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• 1993

The effects of mugwort on some physicochemical properties of rice flour, on the viscosity of rice flour pastes (2 and 4%), on the hardness and the freeze-thaw stability of rice flour gels (20 and 40%), and on the degree of gelatinization (DG) of pastes and gels were investigated. By addition of mugwort, water holding capacity, swelling power, and solubility of rice flour were increased. The rice flour pastes became thicker by addition of mugwort, but viscosities of both the rice flour pastes and the rice flour-mugwort pastes, without noticeable difference between them, were decreased during storage at $25^{\circ}C\;and\;4^{\circ}C$ for 7 days. The rice flour gels became firmer by addition of mugwort and hardnesses of both the rice flour gels and the rice flour-mugwort gels were increased during storage, especially at $4^{\circ}C$. DGs, measured by glucoamylase digestion, of pastes and gels were decreased slightly during storage. Freeze-thaw stability of gels was not affected by addition of mugwort.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.82-82
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• 2010

표면실장 공법을 통해 CSP 패키지를 보드에 실장 하는데 있어 무연솔더 접합부의 신뢰성에 영향을 미치는 인자 중 가장 중요한 것은 접합부에 형성되는 IMC (Intermetallic compound, 금속간화합물)인 것으로 알려져 있다. 접합부의 칩 부분에는 솔더와 칩의 UBM (Under bump metalization)이 접합하여 IMC가 형성되나, 보드 부분에는 솔더와 보드의 UBM 뿐만 아니라 그 사이에 솔더 페이스트가 함께 접합되어 IMC가 형성된다. 본 연구에서는 패키지의 신뢰성 연구를 위해 솔더 페이스트의 유무 및 두께에 따른 무연 솔더 접합부의 미세조직의 변화를 분석하였다. 본 실험에서는 Sn-3.0(Wt.%)Ag-0.5Cu 조성과 본 연구진에 의해 개발된 Sn-Ag-Cu-In 조성의 직경 $450{\mu}m$ 솔더 볼을 사용하였으며, 솔더 페이스트는 상용 Sn-3.0Ag-0.5Cu (ALPHA OM-325)를 사용하였다. 칩은 ENIG (Electroless nickel immersion gold) finish pad가 형성된 CSP (Chip scale package)를, 보드는 OSP (Organic solderability preservative)/Cu finish pad가 형성된 것을 사용하였다. 실험 방법은 보드를 솔더 페이스트 없이 플라즈마 처리 한 것, 솔더 페이스트를 $30{\mu}m$ 두께로 인쇄한 것, $120{\mu}m$의 두께로 인쇄한 것, 이렇게 3가지 조건으로 준비한 후, 솔더 볼이 bumping된 칩을 mounting하여, $242^{\circ}C$의 peak 온도 조건의 oven(1809UL, Heller)에서 reflow를 실시하여 패키지를 형성하였다. 이후 시편은 정밀 연마한 후, OM(Optical Microscopic)과 SEM(scanning electron microscope) 및 EDS(energy dispersive spectroscope)를 사용하여 솔더 접합부 IMC의 미세조직을 관찰, 분석하였다.