• Composites Research
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• 제29권5호
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• pp.262-268
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• 2016

본 연구에서는 피치계 탄소섬유기반 탄소종이에 바인더 피치와 PAN계 미분쇄 탄소섬유를 첨가하여 저온탄화를 통해 재함침된 탄소종이를 제작하였으며, 미분쇄 탄소섬유의 첨가가 탄소종이의 기계적 및 전기적 특성과 열전도도에 미치는 영향을 알아보았다. 실험 결과, 인장강도는 미분쇄 탄소섬유 함량 10 wt.%부터 20 wt.%까지 첨가하였을 때 크게 증가하였다. 또한, 미분쇄 탄소섬유 함량이 증가함에 따라 계면접촉저항은 감소하였으며, 전기전도도 및 열전도도는 증가하였다. 이러한 결과는 미분쇄된 탄소섬유의 첨가가 탄소종이의 밀도를 증가시킴에 따라 전기적 및 열적 전달 경로가 형성되었기 때문이라고 판단된다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.19.2-19.2
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• 2010

Printed electronics using printing process has broadened in all respects such as electrics (lighting, batteries, solar cells etc) as well as electronics (OLED, LCD, E-paper, transistor etc). Copper is considered to be a promising alternative to silver for printed electronics, due to very high conductivity at a low price. However, Copper is easily oxidized, and its oxide is non-conductive. This is the highest hurdle for making copper inks, since the heat and humidity that occurs during ink making and printing simply accelerates the oxidation process. A variety of chemical treatments including organic capping agents and metallic coating have been used to slow this oxidation. We have established synthetic conditions of copper nanoparticles (CuNPs) which are resistant to oxidation and average diameter of 20 to 50nm. Specific resistivity should be less than $4\;{\mu}{\Omega}{\cdot}cm$ when sintered at lower temperature than $250^{\circ}C$ to be able to apply to conductive patterns of FPCBs using ink-jet printing. Through this study, the parameters to control average diameter of CuNPs were found to be the introduction of additive agent, the feeding rate of reducing agent, and reaction temperature. The CuNPs with various average diameters (58, 40, 26, 20nm) could be synthesized by controlling these parameters. The dispersed solution of CuNPs with an average size of 20 nm was made with nonpolar solvent containing 3 wt% of binder, and then coated onto glass substrate. After sintering the coated substrates at $250^{\circ}C$ for 30 minutes in nitrogen atmosphere, metallic copper film resulted in a specific resistivity of $4.2\;{\mu}{\Omega}{\cdot}cm$.

• 한국표면공학회지
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• 제38권5호
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• pp.188-192
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• 2005

Indium zinc oxide (IZO) thin films were deposited on glass substrate by dc magnetron sputtering. The effects of oxygen flow rate and deposition temperature on electrical and optical properties of the films were investigated. With addition of small amount of oxygen gas, the characteristic properties of amorphous IZO films were improved and the specific resistivity was about $4.8{\times}10^{-4}\Omega{\cdot}cm$. Change of structural properties according to the deposition temperature was observed with XRD, SEM, and AFM. Films deposited above $300^{\circ}C$ were found to be polycrystalline. Surface roughness of the films was increased due to the formation of grains on the surface. Electrical conductivity became deteriorated for polycrystalline IZO films. Consequently, high quality IZO films could be prepared by do sputtering with $O_{2}/Ar{\simeq}0.03$ and deposition temperature in range of $150\~200^{\circ}C$; a specific resistivity of $3.4{\times}10^{-4}{\Omega}{\cdot}cm$, an optical transmission over $90\%$ at wavelength of 550 nm, and a rms value of surface roughness about $3{\AA}$.

• 한국분말재료학회지
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• 제18권5호
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• pp.437-442
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• 2011

The present study focused on the synthesis of Bi-Te-Se-based powder by an oxide-reduction process, and analysis of the thermoelectric properties of the synthesized powder. The phase structure, chemical composition, and morphology of the synthesized powder were analyzed by XRD, EPMA and SEM. The synthesized powder was sintered by spark plasma sintering. The thermoelectric properties of the sintered body were evaluated by measuring its Seebeck coefficient, electrical resistivity, and thermal conductivity. $Bi_2Te_{2.7}Se_{0.3}$ powder was synthesized from a mixture of $Bi_2O_3$, $TeO_2$, and $SeO_2$ powders by mechanical milling, calcination, and reduction. The sintered body of the synthesized powder exhibited n-type thermoelectric characteristics. The thermoelectric properties of the sintered bodies depend on the reduction temperature. The Seebeck coefficient and electrical resistivity of the sintered body were increased with increasing reduction temperature. The sintered body of the $Bi_2Te_{2.7}Se_{0.3}$ powder synthesized at $360^{\circ}C$ showed about 0.5 of the figure of merit (ZT) at room temperature.

• 한국표면공학회지
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• 제49권6호
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• pp.530-538
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• 2016

There is a close relationship between the performance and the heat generation of the electronic device. Heat generation causes a significant degradation of the durability and/or efficiency of the device. It is necessary to have an effective method to release the generated heat. Based on demands of the printed circuit board (PCB) manufacturing, it is necessary to develop a robust and reliable plating technique for substrates with high thermal conductivity, such as alumina ($Al_2O_3$), aluminium nitride (AlN), and silicon nitride ($Si_3N_4$). In this study, the plating of metal layers on an insulating silicon nitride ($Si_3N_4$) ceramic substrate was developed. We formed a Pd-$TiO_2$ adhesion layer and used APTES(3-Aminopropyltriethoxysilane) to form OH groups on the surface and adhere the metal layer on the insulating $Si_3N_4$ substrate. We used an electroless Ni plating without sensitization/activation process, as Pd particles were nucleated on the $TiO_2$ layer. The electrical resistivity of Ni and Cu layers is $7.27{\times}10^{-5}$ and $1.32{\times}10^{-6}ohm-cm$ by 4 point prober, respectively. The adhesion strength is 2.506 N by scratch test.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.839-842
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• 2000

The mechanical and electrical properties of the hot-pressed and annealed $\beta$-SiC-ZrB$_2$ electroconductive ceramic composites were investigated as function of the liquid forming additives of $Al_2$O$_3$+Y$_2$O$_3$. Phase analysis of composites by XRD revelled $\alpha$ -SiC(6H), ZrB$_2$, and YAG(Al$_{5}$ Y$_3$O$_{12}$ ). Owing to crack deflection, crack bridging, phase transition and YAG of fracture toughness mechanism, the fracture toughness showed the highest value of 6.3MPa.m$^{1}$2/ for composites added with 24wt% $Al_2$O$_3$+Y$_2$O$_3$additives at room temperature. The resistance temperature coefficient respectively showed the value of 2.46$\times$10$^{-3}$ , 2.47$\times$10$^{-3}$ , 2.52$\times$ 10$^{-3}$ $^{\circ}C$ for composite added with 16, 20, 24wt% A1$_2$O$_3$+Y$_2$O$_3$additives. The electircal resistivity of the composites was all positive temperature coefficient resistance(PTCR) in the temperature range of $25^{\circ}C$ to 90$0^{\circ}C$.

• 대한금속재료학회지
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• 제48권6호
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• pp.565-569
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• 2010

We report on the characteristics of indium-oxide-doped ZnO (IZO) ohmic contact to p-GaN. The IZO ohmic contact layer was deposited on p-GaN by a Roll-to-Roll (RTR) sputter method. IZO contact film with a thickness of 360, 230 and 100 nm yielded an ohmic contact resistance of $4.70{\times}10^{-4}$, $5.95{\times}10^{-2}$, $4.85{\times}10^{-1}\;{\Omega}cm^{2}$ on p-GaN when annealed at $600{^{\circ}C}$ for 1 min under a nitrogen ambient, respectively. While the transmittance of IZO film with a thickness of 360 nm slightly increased in the wavelength range of 380-800 nm after annealing, the transmittance rapidly increased up to 80% after annealing at $600{^{\circ}C}$ in the wavelength range of 380~430 nm because the crystallization of IZO film and created Ga vacancies near the p-GaN surface region were affected by the annealing. These results indicate that ohmic contact resistance and transmittance of the IZO films improved.

• Composites Research
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• 제31권6호
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• pp.412-420
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• 2018

본 연구에서는 면상발열체 특성을 향상시키기 위해 피치계 탄소종이에 전도성 탄소필러로 석유계 코크스, 카본블랙, 흑연을 페놀수지와 함께 함침시켰으며, 탄소종이에 함침된 탄소필러가 물리화학적 성질에 미치는 영향을 전기적, 열적 특성 분석을 통해 고찰하였다. 그 결과, 면저항과 계면접촉저항이 선형적으로 감소하였으며, 탄소필러의 함량이 증가함으로써 전기전도도와 열전도도가 향상하였다. 또한, 탄소종이에 1~5 V 전압을 인가하였을 경우 탄소종이의 면상발열 특성을 관찰하였을 때 5 V 전압에서 최대 $125.01^{\circ}C$로 발열 특성을 나타내었다. 이러한 결과는 탄소섬유 사이에 존재하는 미세공극이 채워짐으로써, 전기적 네트워크가 형성되어 전기적 및 열적 특성이 향상되었기 때문이다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권5호
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• pp.39-48
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• 2021

Analysis of the change in water content and distribution was conducted according to the supply of recirculation water to a landfill. An excavation sample analysis showed that the recirculation water injection zone had water content 8.8% point higher than that of the non-injection zone, after 8 months of operation. And due to the influence of recirculation water supply by vertical wells in injection zones, the water content increases along with depth more clearly than non-injection zone. According to an electrical specific-resistivity survey after 13 months of operation, the water content got higher towards the bottom of the landfill. The water transmission coefficient is 8.72×10^-4 cm/sec for injection zones and 3.36×10^-5 cm/sec for the intermediate cover layer; analysis shows that the intermediate cover layer may affect the penetration velocity of water supplied by the horizontal injection tube. For the scientific design and operation of re-injection facilities, it was deemed necessary to follow-up research on the residence time and behavior of re-injection water considering the ratio of recirculation water supply in horizontal and vertical tubes, and pitcher coefficient of intermediate and waste layers.

• 대한금속재료학회지
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• 제50권8호
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• pp.613-618
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• 2012

We report on electrical and mechanical properties of silicon nitride ($SiN_x$) films deposited by a plasma enhanced chemical vapor deposition (PECVD) method at $200^{\circ}C$ from $SiH_4$ highly diluted in $N_2$. The films were also prepared from $SiH_4$ diluted in He for comparison. The $N_2$ dilution was also effective in improving adhesion of the $SiN_x$ films, fascilitating construction of thin film transistors (TFTs). Metal-insulator-semiconductor (MIS) and Metal-insulator-Metal (MIM) structures were used for capacitance-voltage (C-V) and current-voltage (I-V) measurements, respectively. The resistivity and breakdown field strength of the $SiN_x$ films from $N_2$-diluted $SiH_4$ were estimated to be $1{\times}10^{13}{\Omega}{\cdot}cm$, 7.4 MV/cm, respectively. The MIS device showed a hysteresis window and a flat band voltage shift of 3 V and 0.5 V, respectively. The TFTs fabricated by using these films showed a field-effect mobility of $0.16cm^2/Vs$, a threshold voltage of 3 V, a subthreshold slope of 1.2 V/dec, and an on/off ratio of > $10^6$.