• 한국결정성장학회지
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• 제13권2호
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• pp.68-72
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• 2003

본 논문에서는 3차원 마이크로구조물을 위한 새로운 UV-LIGA 공정을 개발하였다. 일반적으로 photoresist는 얇은 두께로 코팅이 되지만, SU-8은 수십 $\mu\textrm{m}$ 이상의 두께를 가질 수 있으며, 높은 형상비를 갖는다. SU-8과 같은 Thick photoresist는 기존의 baking 공정과 같이 급격한 cool down을 할 경우 stress에 의한 crack이 발생한다. 이와 같은 경우 도금을 위한 마이크로구조물이 구현이 되지 않는다. SU-8의 코팅, bake에서의 시간 조절, 그리고 PEB의 시간 조절 및 cool down조절을 통하여 stress에 의한 crack이 발생하지 않도록 3차원 마이크로구조물을 제작 할 수 있도록 하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2000년도 추계학술대회논문집
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• pp.120-123
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• 2000

This paper reports a newly developed sol-gel process to synthesize dense YBCO thick films with BaTiO$_3$additives using electrophoretic deposition and metal alkoxide sol/particle suspension, which we successfully produce dense $YBCO+BaTiO_3$ ceramics at a rather low temperature, compared with the sintering temperature used in conventional methods. The thick films of HTS were prepared by electrophoretic deposition, using pre-sintered powder with barium titanate addition in the form of $BaTi(OR)_6$ solution in suspension for electrophoresis. The conditions for applied voltage and deposition times for electrophoretic deposition of HTS thick films were studied in detail.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.120-123
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• 2000

This paper reports a newly developed sol-gel process to synthesize dense YBCO thick films with $BaTiO_3$ additives using electrophoretic deposition and metal alkoxide sol/particle suspension, which we successfully produce dense $YBCO+BaTiO_3$ ceramics at a rather low temperature, compared with the sintering temperature used in conventional methods. The thick films of HTS were prepared by electrophoretic deposition, using pre-sintered powder with barium titanate addition in the form of $BaTi(OR)_6$ solution in suspension for electrophoresis. The conditions for applied voltage and deposition times for electrophoretic deposition of HTS thick films were studied in detail.

• 마이크로전자및패키징학회지
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• 제21권2호
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• pp.65-70
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• 2014

박형 package-on-package의 상부 패키지에 대하여 PCB 기판, 칩본딩 및 에폭시 몰딩과 같은 공정단계 진행에 따른 warpage 특성을 분석하였다. $100{\mu}m$ 두께의 박형 PCB 기판 자체에서 $136{\sim}214{\mu}m$ 범위의 warpage가 발생하였다. 이와 같은 PCB 기판에 $40{\mu}m$ 두께의 박형 Si 칩을 die attach film을 사용하여 실장한 시편은 PCB 기판의 warpage와 유사한 $89{\sim}194{\mu}m$의 warpage를 나타내었으나, 플립칩 공정으로 Si 칩을 PCB 기판에 실장한 시편은 PCB 기판과 큰 차이를 보이는 $-199{\sim}691{\mu}m$의 warpage를 나타내었다. 에폭시 몰딩한 패키지의 경우에는 DAF 실장한 시편은 $-79{\sim}202{\mu}m$, 플립칩 실장한 시편은 $-117{\sim}159{\mu}m$의 warpage를 나타내었다.

• 한국수소및신에너지학회논문집
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• 제21권5호
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• pp.375-382
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• 2010

A layered perovskite photocatalysts, $SrBi_2Nb_2O_9$ (SBN), was synthesized by the conventional solid-state reaction method and characterized by X-ray diffraction (XRD) and UV-visble spectrophotometry. The results showed that the structure of $SrBi_2Nb_2O_9$ is orthorhombic. Diffuse reflectance spectra for calcined and attrition-milled SBN showed the main absorption edges were less 400 nm, that is ultraviolet region. SBN under micron-sized powder was deposited on the $Al_2O_3$ by room temperature powder spray in vacuum process, so called aerosol deposition (AD), and nano-grained $SrBi_2Nb_2O_9$ photocatalytic thick film was fabricated. AD-deposited SBN thick films were characterized by XRD, scanning electron microscopy (SEM) and UV-visable spectrophotometry, Moreover, it was found that several nano-sized SBN film by AD process can improve the photocatalytic activity under visable reflectance.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1326-1331
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• 2003

Thick PZT films are required for the cases of micro actuators and sensors with high driving force, high breakdown voltage and high sensitivity, and so on. In this work, thick PZT films were fabricated by Sol-Gel multi-coating method. Total 8 types of samples using thick PZT films with thicknesses, about $1{\mu}m$ and $2{\mu}m$, and Pt top electrodes shapes for measuring transverse piezoelectric coefficient ($e_{31,f}$) were fabricated using MEMS processes. They were characterized by fabricated e31,f measurement system before and after poling. $e_{31,f}$ values of samples after poling were higher than before poling. Those of $2{\mu}m$ thick PZT films were also higher than $1{\mu}m$ thick PZT films. And those with long electrodes as top electrodes were also higher than shorter.

• 마이크로전자및패키징학회지
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• 제18권4호
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• pp.63-70
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• 2011

Anorthite forming glass frits in amounts up to 25 vol% of the silver powder were added to improve the adhesion between the conductor pattern formed by thick film photoimageable process and the low temperature co-fired ceramics (LTCC) substrate. The sheet resistance of the conductor pattern was raised from 0.13 ${\Omega}/{\square}$ to 2.25 ${\Omega}/{\square}$ as the volume percentage of glass frit increased up to 25 vol%. The adhesion strength was improved with this glass frit increase, but it decreased when the glass content exceeded 20 vol% which are possibly attributed to the liquid pool effect and the reduced fracture toughness in the interface between conductor and LTCC layer. The shrinkage of the width of the conductor pattern decreased with the addition of glass contents.

• Journal of Welding and Joining
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• 제12권4호
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• pp.110-116
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• 1994

This paper has been researched bondability of electronics devices, such as lead frame and the thick film of Ag/Pd on an alumina substrate by different heat sources. To obtain the bonds with high quality, it is very important to consist of different materials. Therefore, this paper clarifies not only heat mechanism of micro parallel gap resistance bonding method and pulse heat tip bonding method but also investigates selection of heat sources with micro-electronic materials for bonding. Finally, it is realized fluxless bonding process with filler metal such as plating layers.

• 한국재료학회지
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• 제12권4호
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• pp.304-307
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• 2002

A zinc oxide (ZnO) single crystal was used as a substrate in the hydride vapor-phase epitaxy (HVPE) growth of GaN and the structural and optical properties of GaN layer were characterized by x- ray diffraction, transmission electron microscopy, secondary ion mass spectrometry, and photoluminescence (PL) analysis. Despite a good lattice match and an identical structure, ZnO is not an appropriate substrate for application of HVPE growth of GaN. Thick film could not be grown. The substrate reacted with process gases and Ga, being unstable at high temperatures. The crystallinity of ZnO substrate deteriorated seriously with growth time, and a thin alloy layer formed at the growth interface due to the reaction between ZnO and GaN. The PL from a GaN layer demonstrated the impurity contamination during growth possibly due to the out-diffusion from the substrate.

• E2M - 전기 전자와 첨단 소재
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• 제8권2호
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• pp.184-189
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• 1995

The electrical property of ultra thin PVA films(several hundreds .angs.-several .mu.m in thickness) formed by sphere bulb blowing technique, has been studied. The electrical conductivity of relatively thick films(>several thousands .angs.) has been very high and enhanced by the exposure either to high humidity of air or $NH_3$, which can be explained in terms of the role of ionic transport. The use of PVA films as NH$_{3}$ sensor is also proposed. In ultra thin PVA films less than 1500.angs., two conducting states ; high conducting and low conducting states, are observed. The nonlinear current-voltage characteristics in the low conducting state and the switching between these two states are also confirmed. These properties are discussed in terms of electronic conduction processes. The breakdown strength of the ultra thin PVA film is found to be very high(-30MV/cm), supporting the electron avalanche process in a thick polymer films.