• ETRI Journal
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• v.35 no.6
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• pp.1152-1155
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• 2013

A cost-effective and simple solder on pad (SoP) process is proposed for a fine-pitch microbump interconnection. A novel solder bump maker (SBM) material is applied to form a 60-${\mu}m$ pitch SoP. SBM, which is composed of ternary Sn3.0Ag0.5Cu (SAC305) solder powder and a polymer resin, is a paste material used to perform a fine-pitch SoP through a screen printing method. By optimizing the volumetric ratio of the resin, deoxidizing agent, and SAC305 solder powder, the oxide layers on the solder powder and Cu pads are successfully removed during the bumping process without additional treatment or equipment. Test vehicles with a daisy chain pattern are fabricated to develop the fine-pitch SoP process and evaluate the fine-pitch interconnection. The fabricated Si chip has 6,724 bumps with a 45-${\mu}m$ diameter and 60-${\mu}m$ pitch. The chip is flip chip bonded with a Si substrate using an underfill material with fluxing features. Using the fluxing underfill material is advantageous since it eliminates the flux cleaning process and capillary flow process of the underfill. The optimized bonding process is validated through an electrical characterization of the daisy chain pattern. This work is the first report on a successful operation of a fine-pitch SoP and microbump interconnection using a screen printing process.

• Journal of the Korean Ceramic Society
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• v.38 no.6
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• pp.522-530
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• 2001

발굴된 과거 고려청자의 화학성분조성과 물리적 특성에 대한 평가를 하고 미량성분의 청자의 발색에 미치는 영향을 고찰한 결과, 고려 청자 태토는 Fe$_2$O$_3$가 2%, TiO$_2$가 0.8% 함유되어 있었으며, 청자유는 석회.장석유로서 Fe$_2$O$_3$가 1.0~1.2%, TiO$_2$가 0.16% 포함되어 있었다. 비색청자의 경우 미량성분인 MnO$_2$가 P$_2$O$_{5}$의 함량이 0.37%와 0.76%, CuO는 300~500ppm 정도 함유하고 있었다. 반사율 측정 결과 일반적인 청자가 540~570nm의 장파장대에서의 반사율이 급격히 떨어지는데 반하여, 13세기 비색 청자의 것은 적색 파장대에서 10%이상 높았다. CoO는 미량 첨가로도 유약의 청색 파장대 반사율이 높고, 적색 파장대의 반사율이 급격히 떨어지며 청자 발색에 부정적인 영향을 미쳤다. CuO는 0.05%를 첨가했을 경우 적색 파장대에서 반사율 곡선이 높게 나타나고 있어 비색 청자발색에 효과적이었다. 또한 명도를 나타내는 L*값도 CuO가 첨가된 유약이 가장 높았고, 비색청자의 색상은 녹청자에 비해 맑고 깊은 색감을 보였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.53-53
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• 2010

The development of synthetic pathway to produce a highly yield nanoparticles is an important aspect of industrial technology. Herein, we report a simple, rapid approach to synthesize organic-soluble Cu and Ag nanoparticles in colloidal method for the application in a conductive pattern using inkjet printing. The silver nanoparticles have been synthesized in highly concentrated organic phase. The Cu nanoparticles have been synthesized by the reducing of the copper oxide materials using acid molecules in high concentrated organic phase. Their sintering and electric conductivity properties were investigated by melting process between $200^{\circ}C$ and $250^{\circ}C$ for application to printed electronics.

• Journal of the Korean Ceramic Society
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• v.49 no.2
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• pp.151-154
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• 2012

Flower-like and plate-like CuO nanopowder has been successfully synthesized using a facile microwave-assisted synthetic route. The morphology and size of the final products strongly depended on microwave power. The phase, structures and morphologies of the as-prepared products were investigated in detail by BET surface area analysis, X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). In addition, the chemical oxygen demand of polluted lake water was employed for characterization of these new photocatalysts. The results showed correlations between the morphology of CuO micro-crystals and their catalytic properties.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.393.1-393.1
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• 2014

유기물/무기물 나노복합체를 이용하여 제작한 유기비휘발성 메모리 소자는 간단한 공정과 플렉서블기기 응용 가능성 때문에 많은 연구가 진행되고 있다. 유기물/무기물 나노복합체를 사용하여 제작한 비휘발성 메모리 소자의 전기적 성질에 대한 연구는 많이 진행되었으나, Poly (N-vinylcarbazole) (PVK) 박막 내부에 분산된 친환경 CuInS2 (CIS) 나노입자를 이용하여 제작한 유기 쌍안정 소자의 메모리 특성에 대한 연구는 미미한 실정이다. 본 연구에서는 PVK박막층안에 분산된 CIS나노입자를 사용한 메모리 소자를 제작하여 전기적 특성에 대하여 연구하였다. 화학적으로 합성 된 CIS 나노입자를 톨루엔에 용해되어있는 PVK에 넣고 초음파 교반기를 사용하여 두 물질을 고르게 섞었다. 전극이 되는 indium-tin-oxide 가 성장된 유리 기판 위에CIS 나노입자와 PVK가 섞인 용액을 스핀코팅 한 후, 열을 가해 용매를 제거하여 CIS 나노입자가 PVK에 분산되어 있는 나노복합체 박막을 형성하였다. 형성된 나노복합체 박막 위에 상부 전극으로 Al을 열증착하여 비휘발성 메모리 소자를 제작하였다. 제작된 소자의 전류-전압 측정 결과는 메모리 특성을 나타내었으며, CIS 나노입자를 포함하지 않은 소자와의 비교를 통해 CIS나노입자가 비휘발성 메모리 소자에서 메모리 특성을 나타내게 하는 역할을 확인하였다. 전류-시간 측정 결과 소자의 ON/OFF 전류 비율이 시간에 따라 큰 변화 없이 1,000 회 이상 지속적으로 유지함을 관찰함으로써 소자의 전기적 기억 상태 안정성을 확인하였다.

• Journal of the Korean Ceramic Society
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• v.43 no.9 s.292
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• pp.544-551
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• 2006

The sealing technique between a glass tube and a copper heat pipe in an evacuated tube solar collector is studied. In this study two different sealing techniques, such as flame method and furnace firing, are examined. After the sealing of a copper to a glass, the oxidation state of the copper and its bonding morphology were examined by SEM and XRD. Its oxidation was retarded by coating of borate solution on the copper, and $Cu_2O(cuprite)$ turned into CuO(tenorite) with increase in a firing temperature and firing time. Porous structure was found in the oxide layer when CuO formed. The best sealing morphology was observed when the thickness of the oxidation layer was less than $20{\mu}m$. The sealing technique performed in a furnace was promising and the satisfactory result was obtained when the sample was fired at $950^{\circ}C$ for 5 min under $N_2$ atmosphere. Annealing procedure is recommended to remove the stress left at the bonding zone.

• Korean Journal of Crystallography
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• v.13 no.1
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• pp.31-35
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• 2002

The possibility of producing the pigments from potash feldspar was studied by adopting the mechanical alloying technique under various gas environments. The experiments were carried out by varying grinding time with the addition of copper metal and titanium oxide in N₂, O₂, He, CO₂, H₂and air atmospheres. The mixture of the potash feldspar concentrate and copper and titanium dioxide are finely ground by a planetary ball mill, and then the composite powders were calcined at 1200℃ for 20 minutes. As a result, the calcined feldspar with 1 wt% of Cu has shown various colors like green in air, black in O₂, dark green in CO₂, brown in H₂, purple in He, and pale green in N₂ atmospheres, respectively.

• Journal of the Korean institute of surface engineering
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• v.49 no.3
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• pp.252-259
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• 2016

In order to form an aluminum-doped zinc oxide (AZO) transparent electrode film on a polyethylene terephthalate (PET) substrate used for a flexible display substrate, the AZO transparent electrode was produced at low temperature without substrate heating. Even though the produced electrode showed characteristic optical transmittance of 90 % (at 550 nm) and sheet resistance within $100{\Omega}/sq$, cracks occurred 10 minutes after loading applied 2 mm radius of curvature, and the sheet resistance increased linearly. An insertion layer of ZrCu was formed between the AZO film and the PET substrate to suppress the generation of cracks on the AZO film. It was verified that the crack was not generated 30 minutes after the loading of 2 mm radius of curvature, and no increase in sheet resistance was recorded. There was also not cracks in the dynamic bending test of 4 mm radius, but surface resistance was slightly increased. As a result, the ZrCu insertion film improved the interfacial adhesion between the substrate and AZO film layer without increasing sheet resistance and decreasing transmittance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.262-263
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• 2007

Effect of co-doping on optical and electrical properties of $SnO_2$ based thin films were studied. $SnO_2$ ceramic targets with up to 50mol% $CuSb_2O_6$ were prepared by sintering mixed-oxide compact in the temperature range of $1100^{\circ}C{\sim}1300^{\circ}C$ in air. Thin films were then deposited onto glass substrates by pulsed laser deposition where substrate temperature was maintained in the range of $500{\sim}650^{\circ}C$ with oxygen pressure of 3m~7.5mTorr and energy density of $1Jcm^{-2}$. It was found that with the increase amount of dopant, the electrical properties of thin films tended to improve with the smallest resistivity value obtained at about 8mol% doping, further increase, however, usually impaired the optical transmission in the visible range.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.12 no.1
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• pp.35-43
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• 1999

Microstructures and dielectric properties of (Sr$\_$1-x/Ca$\_$x/) TiO$_3$-0.006Nb$_2$O$\_$5/ (0.05$\leq$x$\leq$0.2) boundary layer ceramics were investigated. The samples fired in a reducing atmosphere(N$_2$) were painted on the surface with CuO paste for the subsequent grain boundary diffusion, and then annealed at 1100$^{\circ}C$ for 2 hrs. The metal oxide of CuO infiltrated by thermal diffusion from surface of sample presents continuously in not grain but only grain boundary, and makes up thin boundary phase. The SEM photo, and EDAX revealed that CuO was penetrated rapidly into the bulk along the grain boundaries during the annealing. The average grain sizes is continuously increased as the content of substitutional Ca is increased from 5[mol%] to 15[mol%], but the average grain size of the sample with content of 20[mol%] Ca is slightly decreased. In the samples with content of 10∼15[mol%] Ca, excellent dielectric properties were obtained as follows; dielectric constant <25000, dielectric loss <0.3[%], and capacitance change rate as a function of temperature <${\pm}$10[%], respectively. All samples in this study exhibited dielectric relaxation with frequency as a functior of the temperature.