• 센서학회지
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• 제15권4호
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• pp.245-250
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• 2006

In this paper, glass cap wafer for MEMS device package is fabricated by using sand blaster dry etcher and Its surface is studied. The surface of dry etched glass is analyzed by using SEM, and many glass particles and micro cracks are observed. If these kind of particles were dropped from glass to the surface of device, It would make critical failure to the operation of device. So, several cleaning and etching methods are induced to remove these kinds of dormant failure mode and optimized condition is found out.

• 한국전기전자재료학회논문지
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• 제19권12호
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• pp.1106-1111
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• 2006

To improve warpage, delamination and the chemical reaction between 2 different co-fired materials, the bonding behavior with common glass was studied. As shown in the previous paper, the phenomenon of the infiltration is different with the composition of the glass. In particular, in the case of low temperature melting glass, infiltration is experimented in this study. GA-1 glass is infiltrated among $BaTiO_3$ particles below $800^{\circ}C$ and is made by glass/ceramic composite. Until the laminate is fired under $850^{\circ}C$, provskite phase is observed. Although in the case of GA-12 glass, the temperature of the glass infiltration is lower than it of GA-l glass, the perovskite phase already disappears at $800^{\circ}C$. As a result, GA-1 and GA-12 glasses are infiltrated among particles at low temperature, however, the chemical reactivity of the glass/ceramic and sintering temperature should be considered.

• 대한기계학회논문집B
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• 제30권10호
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• pp.935-941
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• 2006

Many important properties in colloidal systems are usually determined by surface charge $({\zeta}-potential)$ of the contacted solid surface. In this study, ${\zeta}-potential$ of glass ${\mu}-channel$ was evaluated from the electro-osmotic velocity distribution. The electro-osmotic velocity inside a glass f-channel was measured using a micro-PIV velocity field measurement technique. This evaluation method is more simple and easy to approach, compared with the traditional streaming potential technique. The ${\zeta}-potential$ in the glass ${\mu}-channel$ was measured fur two different mole NaCl solutions. The effect of an anion surfactant, sodium dodecyl sulphate (SDS), on the electro-osmotic velocity and f-potential in the glass surface was also studied. In the range of $0{\sim}6mM$, the surfactant SDS was added to NaCl solution in few different mole concentrations. As a result, the addition of SDS increases ${\zeta}-potential$ in the surface of the glass ${\mu}-channel$. The measured $\zeta-potential$ was found to vary from -260 to -70mV. When negatively charged particles were used, the flow direction was opposite compared with that of neutral particles. The ${\zeta}-potential$ has a positive sign for the negative particles.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1331-1334
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• 2004

The research on electromagnetic shielding has been advanced for military applications as well as for commercial products. Utilizing the reflective properties and absorptive properties of shielding material, the replied signal measured at the rear surface or at the signal source can be minimized. The shielding effect was obtained from materials having special absorptive properties or from structural characteristics such as stacking sequence. Recently researchers studied the electromagnetic properties of nano size particles. In this research {glass fiber}/{epoxy}/{nano particle} composites(GFR-Nano composites), was fabricated using various nano particles, and their properties in electromagnetic shielding were compared. For the visual observation of the nano composite materials, SEM(Scanning Electron Microscope) and TEM(Transmission Electron Microscope) were used. For the measurement of electromagnetic shielding, HP8719ES S-parameter Vector Network Analyser System was used on the frequency range of 8 GHz～12GHz. Among the nano particles, carbon black and Multi-Walled Carbon Nano-Tube (MWCNT) revealed outstanding electromagnetic shielding. Although silver nano particles (flake and powder) were expected to have effective electromagnetic shielding due to their excellent electric conductivities, test showed little shielding effect.

• 한국세라믹학회지
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• 제42권6호
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• pp.399-404
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• 2005

Anti-reflection film was coated by using spherical silica nano colloidal particles and fumed silica particles. Silica colloid sol was reserved between two inclined slide glasses by capillary force, and particles were stacked to form a film onto the substrate as the upper glass was sliding. The deposition processes were studied to enhance the wavelength dependency of the light transmittance and to control the effective refractive index of the film. Both of the spherical and fumed silica particles showed an enhancement of $4.0-4.4\%$ in light transmittance by one step coating. The dependence of the transmittance on wavelength was largely improved at the longer wavelength by partial coating of fumed particles on the film of spherical particles. The effective refractive index of the film was controlled by removing latex particles that were co-deposited with silica particles. Using this process the light reflectance from one side of the glass substrate could be reduced from $4.2\%$ to $0.6\%$ although zero reflectance was not achieved due to the agglomeration of the latex particles.

• 대한금속재료학회지
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• 제46권8호
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• pp.516-523
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• 2008

The effect of glass-frit size on microstructural evolution and electrical resistance of conductive silver paste was investigated. Silver paste was prepared by mixing 70 wt% commercial silver powder with $1.6{\mu}m$, 3 wt% Bi based glass-frit and 27 wt% organic vehicle. Two different sizes of glass-frit were obtained by ball-milling of commercial glass-frit ($3{\mu}m$) for 3 and 5 days, which had an average particle size of 1.0 and $0.5{\mu}m$. The smaller glass-frit was melt at low sintered temperature and rapidly spread between the silver particles, which is induced the dense networking among silver particles and strong adhesiveness to $Al_2O_3$ substrate. The silver film with smaller glass-frit sintered at $500^{\circ}C$ showed the small pore size and low porosity resulting in low electrical resistivity of $4{\mu}{\Omega}cm$.

• 한국재료학회지
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• 제18권5호
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• pp.283-288
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• 2008

The effect of sintering aids and glass-frit on the densification and resistivity of silver paste was investigated in an effort to enhance the sintered density and electrical conductivity of the silver electrode. To prepare Pb-free silver paste for use at low sintering temperatures, two commercial silver powders ($0.8\;{\mu}m$ and $1.6\;{\mu}m$ in size) and 5wt.% lab-synthesized nanoparticles (30-50 nm in size) as a sintering aids were mixed with 3 wt.% or 6 wt.% of glass frit ($Bi_2O_3$-based) using a solvent and three roll mills. Thick films from the silver paste were prepared by means of screen printing on an alumina substrate followed by sintering at $450^{\circ}C$ to $550^{\circ}C$ for 15 min. Silver thick films from the paste with bimodal particles showed a high packing density, high densification during sintering and low resistivity compared to films created using monomodal particles. Silver nanoparticles as a sintering aid enhanced the densification of commercial silver powder at a low sintering temperature and induced low resistivity in the silver thick film. The glass frit also enhanced the densification of the films through liquid phase sintering; however, the optimum content of glass frit is necessary to ensure that a dense microstructure and low resistivity are obtained, as excessive glass-frit can provoke low conductivity due to the interconnection of the glass phase with the high resistivity between the silver particles.

• 접착 및 계면
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• 제11권3호
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• pp.112-119
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• 2010

PMMA와 PBA core 제조 시 개시제는 APS를, 유화제 SDBS의 농도를 0.01에서 0.03 wt% 일 때 전환율이 95.8과 92.3%로 가장 우수하였으며, core-shell 복합입자의 제조 시에는 SDBS의 농도 0.02 wt% 일 때 PMMA/PBA core-shell 복합입자는 전환율이 90.0%, PBA/PMMA core-shell 복합입자는 89.0%가 되었다. FT-IR 분석과 GPC에 의한 평균분자량 측정을 통해 core와 shell 단량체들이 중합되어 있음을 확인하고, 복합입자의 형태는 상온에서의 필름형성정도와 TEM 분석으로 확인하였다. DSC에 의해 유리전이온도를 측정함으로써 일반 공중합체와는 달리 2개의 유리전이온도가 존재하여 core-shell 복합입자가 형성되었음을 알 수 있고, 각각의 core-shell 복합입자의 인장강도와 신율의 측정을 통해 고기능성 접착바인더로서의 사용가능성을 확인하였다.

• 한국어류학회지
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• 제34권2호
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• pp.127-132
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• 2022

현재 하천 하류의 대부분이 보에 막혀 있어 회유성 어종의 이동 및 상류와의 연결을 위한 어도가 필요하다. 따라서 어류의 자유로운 이동에 도움이 될 어도는 생태적 교각으로서 매우 중요하다. 현재 가동되고 있는 실뱀장어 전용어도는 바닥에 솔이 심어져 있으며, 솔 이외에 바닥 재질이 실뱀장어의 소상에 미치는 영향을 알아보기 위해 금강하굿둑에 설치한 모형어도를 이용한 소상 실험을 진행했다. 모형어도는 길이 1.2 m, 넓이 0.3 m, 높이 0.1 m로, 어도 바닥에 각기 다른 입자의 3가지 자갈을 붙여 제작하였다. 첫 번째 어도는 입자가 5 mm인 자갈을 사용하였고, 두 번째 어도는 입자가 2 mm인 자갈을 이용하여 제작하였다. 세 번째 어도는 입자가 1 mm 이하인 모래시멘트를 굳혀 제작하였다. 모든 실험은 1시간씩 5회 반복하여 진행하였다. 실험 결과, 각도가 낮을수록 더 많은 실뱀장어가 소상하였고, 자갈의 입자는 작을수록 실뱀장어가 더 많이 소상하였으나, 시멘트로 만든 어도는 실뱀장어가 거의 소상하지 못했다. 자갈을 굳혀 만든 모형어도는 솔 간격 어도에 비해 유량 및 유속이 적어 실뱀장어가 더욱 많이 소상하였으며, 차후 다양한 바닥 재질 및 변수를 적용한 실험을 통해 어도를 개선하면 더 많은 실뱀장어가 소상할 수 있을 것으로 판단된다.

• 한국재료학회지
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• 제5권8호
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• pp.929-935
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• 1995

구동 IC를 유리기판 위의 Al패드 전극에 연결하는 LCD(Liquid Crystal Display) 모듈을 실장하는 Chip On Glass (COG) 기술을 개발하기 위하여 기존에 잘 알려진 기술 가운데 실제로 적용 가능성이 가장 유망한 이방성 도전 접착제 (ACA, Anisotropic Conductive Adhesives)를 사용한 공정에 대하여 조사하였다. ACA 공정은 본딩 부분에 ACA 수지를 균일하게 분포시키는 공정과 자외선을 조사하여 수지를 경화하여 칩을 실장하는 공정의 2단계로 진행하였다. 칩에 가해준 하중은 2-15kg이었고 칩의 예열 온도는 12$0^{\circ}C$이었다. 이방성 도전체는 Au 또는 Ni이 표면 피막 재료로 사용된 것을 사웅하였으며 전도성 입자의 갯수가 500, 1000, 2000, 4000개/$\textrm{mm}^2$이며 크기가 5, 7, 12$\mu\textrm{m}$이었다. ACA 처리의 결과 입자 크기가 5$\mu\textrm{m}$이고 입자 밀도는 4000개/$\textrm{mm}^2$일 경우가 대단히 낮은 접촉 저항 및 가장 안정된 본딩 특성을 나타냈었다.