• 한국세라믹학회지
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• 제39권7호
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• pp.693-698
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• 2002

반응소결 탄화규소의 잔류 실리콘 양을 최소화하기 위해 3성분계 탄화규소 분말을 혼합하여 최밀 충전 반음소결 탄화규소를 제조하였다. 기지상의 충전밀도 증가로 인해 반응소결 중 실리콘의 불완전 침윤이 발생하였으며, 이로 인한 잔류 기공은 조대 탄화규소 입자의 표면을 따라 존재함을 확인하였다. 불완전 침윤은 승온 중 분해되지 않고 남은 산화물이 실리콘의 용융 온도 이상에서 분해되어 생긴 고립기공에 의한 것으로 확인되었다. 기지상의 표면에 존재하리라 여겨지는 산화물을 제거하기 위해 침윤전 열처리 및 부식처리를 통해 완전침윤을 달성하였다.

• 한국농공학회논문집
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• 제49권3호
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• pp.51-60
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• 2007

This study was performed to evaluate void ratio, compressive and flexural strengths, and pH properties according to the content ratio of rice husk ash, aggregate size, and neutral treatment time of porous concrete with content of rice husk ash produced as an agricultural by-product. The SEM results for cement mortar with a 5% rice husk ash for the weight of cement formed more C-S-H hydrates due to the $SiO_2$ of rice husk ash. In the XRD test, cement mortar with a 5% rice husk ash for the weight of cement registered a higher peak point of approximately $2{\theta}=20{\sim}25^{\circ}$ compared to cement mortar without rice husk ash. According to the results of the XRD and SEM tests, the $SiO_2$ that was a major chemical element of rice husk ash generated a large amount of calcium hydroxide in the early stage of the hydration process of cement leading to the formation of ettringite. The void ratio of porous concrete with rice husk ash decreased with increasing content ratio of rice husk ash. In addition, the void ratio of porous concrete with rice husk ash decreased compared to porous concrete without rice husk ash. The compressive and flexural strength of porous concrete with a 5% and 10% content ratio of rice husk ash slightly increased compared to concrete without rice husk ash. The pH value of porous concrete rapidly decreased immediately after neutral treatment. Then, it gradually increased and decreased again after 14 days. However, the pH value was nearly the same regardless of neutral treatment time in 28 curing days. Also, for neutral treatment, the pH value of porous concrete showed appropriate pH levels (less than 9.5) in all mixtures for planting at 28 curing days.

• 마이크로전자및패키징학회지
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• 제31권1호
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• pp.35-42
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• 2024

최근 반도체 칩의 소형화 및 고집적화에 따라 미세 피치에 의한 범프 브리지 (bump bridge) 현상이 문제점으로 주목받고 있다. 이에 따라 범프 브리지 현상을 최소화할 수 있는 Cu pillar bump가 미세 피치에 대응하기 위해 반도체 패키지 산업에서 널리 적용되고 있다. 고온의 환경에 노출될 경우, 접합부 계면에 형성되는 금속간화합물(Intermetallic compound, IMC)의 두께가 증가함과 동시에 일부 IMC/Cu 및 IMC 계면 내부에 Kirkendall void가 형성되어 성장하게 된다. IMC의 과도한 성장과 Kirkendall void의 형성 및 성장은 접합부에 대한 기계적 신뢰성을 약화시키기 때문에 이를 제어하는 것이 중요하다. 따라서, 본 연구에서는 CS(Cu+ Sn-1.8Ag Solder) 구조 Cu pillar bump의 등온 시효 처리에 따른 접합부 특성 평가가 수행되었으며 그 결과가 보고되었다.

• 한국재료학회지
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• 제8권10호
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• pp.961-968
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• 1998

상변화형 광디스크의 보호막으로 사용되는 $ZnS-SiO_2$ 유전체막을 RF magnetron 스퍼트링방법에 의하여 제조하는 경우에 기판 바이어스전압의 영향을 조사하기 위하여, 알곤가스 분위기에서 ZnS(80mol%)-$SiO_2$(20mol%)타겟을 사용하여 Si Wafer와 Corning flass 위에 박막을 증착시켰다. 본 실험에서는 여러 실험 변수를 효과적으로 조절하면서 실험의 양을 줄이고 도시의 산포를 동시에 만족시키는 최적조건으로 타겟 RF 출력 200W, 기판 RF 출력 20W, 아르곤 압력 5mTorr과 증착시간 20분을 얻을 수 있었으며, 신뢰구간 95%에서 확인실험을 수행하였다. 증착된 박막의 열적 저항성을 측정하기 위해 $300^{\circ}C$와 $600^{\circ}C$에서 열처리시험을 수행하였고, Spectroscopic Ellipsometry 측정을 통한 광학적 데이터를 바탕으로 Bruggeman EMA(Effective Medium Approximation)방법을 이용하여 기공(void)분률을 측정하였다. 본 연구결과에 의하면 특성치 굴절률에 대하여 기판 바이어스인자와 증착시간 사이에는 서로 교호작용이 강하게 존재함을 확인할 수 있었다. TEM분석과 XRD 분석 결과에 의하면 기판 바이어스를 가한 최적조건에서 증착된 미세조직은 기존의 바이어스를 가하지 않을 조건에서 증착시킨 박막보다 미세한 구조를 가지며, 또한 과도한 바이어스전압은 결정구조의 조대화를 야기시켰다. 그리고 적절한 바이어스전압은 박막의 밀도를 증가시키며, 기공분률을 약 3.7%정도 감소시킴을 확인할 수 있었다.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2004년도 ISMP Pb-free solders and the PCB technologies related to Pb-free solders
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• pp.1-26
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• 2004

The implementation of Pb-free solder technology is making good progress in electronic industry. Further understanding on fundamental issues on Pb-free solders/processes is required to reduce reliability risk factors of Pb-free solder joints. Several reliability issues including thermal fatigue, impact reliability, IMC growth, spalling, void formation are reviewed for Pb-free solder joints. Several applications of Pb-free technology are discussed, such as Pb-free, CBGA, CuCGA, flip chips, and wafer bumping by IMS.

• Korean Membrane Journal
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• 제9권1호
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• pp.27-33
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• 2007

PVDF membrane formation via TIPS was performed for PVDF/DBP and PVDF/DMP systems. PVDF/DBP system showed solid-liquid phase separation behavior, while PVDF/DMP system has liquid-liquid phase separation characteristic as well as solid-liquid phase separation characteristic. PVDF contents and cooling conditions had great influence on structure, and the effects of each parameter were examined. Spherulitic structure was obtained due to the dominant PVDF crystallization. Diluent rejected to the outside of spherulite occupied the surface of the PVDF spherulites to result in the microporous spherulite formation and micro-void between spherulites. PVDF/DMP system had competitive solid-liquid and liquid-liquid phase separation depending on the cooling path.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 춘계학술대회 논문집
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• pp.84-89
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• 1996

The nucleation and growth of microporosities was observed during the course of annealing treatment of sputter-deposited AgInSbTe thin films. There was a close correlation between the density of microporosity and the sputtering gas pressure in annealed thin films. The void density for a given composition decreased with sputtering gas pressure. It was shown from the present study that the number of porosities decreased while the average porosity size increased as the annealing temperature and holding time increased. The mechanism of porosity formation in the sputter-deposited AgInSbTe thin flus containing Ar-impurity trapped from the Ar-plasma is discussed in the present article.

• 한국분말재료학회지
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• 제24권3호
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• pp.235-241
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• 2017

Titanium alloys have high specific strength, excellent corrosion and wear resistance, as well as high heat-resistant strength compared to conventional steel materials. As intermetallic compounds based on Ti, TiAl alloys are becoming increasingly popular in the aerospace field because these alloys have low density and high creep properties. In spite of those advantages, the low ductility at room temperature and difficult machining performance of TiAl and $Ti_3Al$ materials has limited their potential applications. Titanium powder can be used in such cases for weight and cost reduction. Herein, pre-forms of Ti-Al-xMn powder alloys are fabricated by compression forming. In this process, Ti powder is added to Al and Mn powders and compressed, and the resulting mixture is subjected to various sintering temperature and holding times. The density of the powder-sintered specimens is measured and evaluated by correlation with phase formation, Mn addition, Kirkendall void, etc. Strong Al-Mn reactions can restrain Kirkendall void formation in Ti-Al-xMn powder alloys and result in increased density of the powder alloys. The effect of Al-Mn reactions and microstructural changes as well as Mn addition on the high-temperature compression properties are also analyzed for the Ti-Al-xMn powder alloys.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.281-292
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• 2008

Prefabricated Board Drains (PBDs) recently become more widely used than conventional sand drains in improving soft ground because the PBD is more time and cost effective. The performance of PBDs is affected by disturbance in the adjacent soil formation during inserting mandrels, the intrusion of fine particles into filter fabric, and necking of the drain by excessive lateral pressure especially occurring in very deep clay formation such as the Busan New Port site. In this study, the PBD with double-core is introduced, which seems to overcome the shortcomings of usual single-core PBDs. An in-situ test program was established in the Busan New Port site, in which a set of the double-core PBDs and the single-core PBDs was installed to compare the efficiency of each of the drains. The discharge capacity of the double-core and the single-core PBDs was compared for various confining pressures in the modified Delft test and the chamber test. A series of CRS consolidation tests was performed in order to obtain profiles of void ratio-effective stress and void ratio-permeability relationships in the Busan New Port site that are used as input date in performing a numerical program ILLICON. The numerically simulated settlements of ground surface in the test site are in good agreement with those of in-situ measurements. In addition, the performance of the double-core and single-core PBDs has been experimentally and numerically compared in this paper.

• Current Photovoltaic Research
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• 제4권4호
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• pp.145-149
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• 2016

Characteristic of aluminum-silicon alloy paste which is applied on the rear side of PERC cell was investigated. The paste was made by aluminum-silicon alloy with eutectic composition to avoid the formation of void which is responsible for the degradation of the open-circuit voltage. Also, the glass frit component of the paste was changed to improve the adhesion of aluminum-silicon paste. We observed the formation of void and local back surface field between aluminum electrode and silicon base by SEM. The light IV, quantum efficiency and reflectance of the solar cells were characterized and compared for each paste.