• 한국표면공학회지
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• 제36권5호
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• pp.373-378
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• 2003

With increasing environmental concerns, application of lead-free solder and fluxless soldering process have been taken attention from the electronic packaging industry. Plasma treatment is one of the soldering methods for the fluxless soldering, and it can prevent environmental pollution cased by flux. On this study fluxless soldering process under $Ar-H_2$plasma using lead free solders such as Sn-3.5 wt%Ag, Sn-3.5 wt%Ag-0.7 wt%Cu and Sn-37%Pb for a reference was investigated. As the plasma reflow has higher soldering temperature than normal air reflow, the effects of UBM(Under Bump Metallization) thickness on the interfacial reaction and bonding strength can be critical. Experimental results showed in case of the thin UBM, Au(20 nm)/Cu(0.3 $\mu\textrm{m}$)/Ni(0.4 $\mu\textrm{m}$)/Al(0.4 $\mu\textrm{m}$), shear strength of the soldered joint was relatively low as 19-27㎫, and it's caused by the crack observed along the bonded interface. The crack was believed to be produced by the exhaustion of the thin UBM-layer due to the excessive reaction with solder under plasma. However, in case of thick UBM, Au(20 nm)/Cu(4 $\mu\textrm{m}$)/Ni(4 $\mu\textrm{m}$)/Al(0.4 $\mu\textrm{m}$), the bonded interface was sound without any crack and shear strength gives 32∼42㎫. Thus, by increasing UBM thickness in this study the shear strength can be improved to 50∼70%. Fluxed reflow soldering under hot air was also carried out for a reference, and the shear strength was 48∼52㎫. Consequently the fluxless soldering with plasma showed around 65∼80% as those of fluxed air reflow, and the possibility of the $Ar-H_2$ plasma reflow was evaluated.

• 마이크로전자및패키징학회지
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• 제24권2호
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• pp.69-74
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• 2017

인쇄전자소자 금속 배선의 고온 신뢰성 평가를 위해 스크린 프린팅 기법으로 도포된 Ag 박막과 폴리이미드 기판 사이의 계면접착력을 $200^{\circ}C$ 후속 열처리 시간에 따라 $180^{\circ}$ 필 테스트를 통해 평가하였고, 박리 계면 미세구조를 분석하였다. 후속 열처리 전 필 강도는 약 16.7 gf/mm 이었고, 열처리 24 시간 후 필 강도는 29.4 gf/mm까지 증가하였는데, 이는 초기 열처리에 의해 접합계면에서 Ag-O-C 화학 결합의 증가와 바인더의 organic bridges 효과가 주 원인인 것으로 판단된다. 한편, 열처리 시간이 48, 100, 250, 500 시간으로 더욱 증가함에 따라 필 강도는 각각 22.3, 3.6, 0.6, 0.1 gf/mm으로 급격히 감소하는 거동을 보였다. 이는 $200^{\circ}C$의 고온에서 장시간 노출되었을 때 Cu/Ag 계면 산화막 형성이 주 원인인 것으로 판단된다.

• 한국광학회지
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• 제17권4호
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• pp.354-358
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• 2006

적층으로 구성되는 초소형 전자렌즈의 실리콘 렌즈와 절연체인 파이렉스는 접합과 정렬을 동시에 수행하여야 한다. 이를 위한 방법으로 회절을 이용한 정렬과 레이저 접합을 이용하였으며, source 렌즈와 Einzel 렌즈의 정렬오차는 가장 큰 개구를 기준으로 최대 $\pm$4% 이내에서 이루어졌다. 정렬 조건과 레이저 접합 조건을 제시하였으며, 접합을 견고히 하기 위한 양극 접합 방식을 기술하였다. 전류영상화를 통해 선폭이 9 $\mu$m인 Cu grid를 시험한 결과 완성된 전자렌즈는 감속모드보다 가속모드에서 분해능이 좋았으며, 작은 개구를 가진 렌즈의 정밀한 정렬과 조합으로 높은 분해능을 믿을 수 있었다.

• 한국의류산업학회지
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• 제9권1호
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• pp.119-123
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• 2007

Dyeing properties of soybean fabrics on gromwell colorants were studied for the effect of dyeing conditions, such as colorants concentration, temperature, time and pH on the dye uptake and effect of mordants on color change, dye uptake and various colorfastness. Antimicrobial activity of soybean fabrics dyed and sim-mordanted with gromwell colorants was examined by shake flask method. Gromwell colorants showed considerably affinity to soybean fabric and its isotherm adsorption curve was Freundlich type. Therefore, it is considered that hydrogen bonding and Van der Waals force were involved in the adsorption of gromwell colorants to soybean fabric. Soybean fabrics showed R color on Al, Cu and Sn mordant, RP color on Cr and Fe mordant, but soybean fabrics showed low dye uptake depending on mordanting treatment. Light colorfastness was increased for Cr and Fe mordants. Staphylococcus aureus reduction rates were above 90% for Cr and Cu mordanted soybean fabrics, and the others were poor. Klebsiella pneumoniae reduction rates soybean fabrics did not show reduction rate hardly.

• 한국염색가공학회지
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• 제19권4호
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• pp.10-17
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• 2007

Chitosan(CS) and cellulose acetate(CA) composite films were prepared using formic acid as a cosolvent by casting, solvent evaporating and neutralization method. This study examines if the blending method, which uses formic acid as a cosolvent is efficient in improving the mechanical properties of CS film, especially wet strength and elongation. Formic acid is an effective cosolvent for the blend of CS and CA. Under wet condition, tensile strength and elongation of the composite films were obviously higher than those of the films made from pure CS. FTIR, DSC, and X-ray diffraction showed that the composite films exhibit a high level of compatibility and that strong interaction between the CS and CA was caused by intermolecular hydrogen bonding. The affinity series of composite film to transition metal ions are Cu(II) > Cd(II) > Cr(III). The adsorption of Cu((II) ion was shown to be highly pH sensitive.

• 한국재료학회지
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• 제17권2호
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• pp.91-95
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• 2007

Electromigration characteristics of Sn-3.5Ag flip chip solder bump were analyzed using flip chip packages which consisted of Si chip substrate and electroplated Cu under bump metallurgy. Electromigration test temperatures and current densities peformed were $140{\sim}175^{\circ}C\;and\;6{\sim}9{\times}10^4A/cm^2$ respectively. Mean time to failure of solder bump decreased as the temperature and current density increased. The activation energy and current density exponent were found to be 1.63 eV and 4.6, respectively. The activation energy and current density exponent have very high value because of high Joule heating. Evolution of Cu-Sn intermetallic compound was also investigated with respect to current density conditions.

• 한국물환경학회지
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• 제27권4호
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• pp.486-490
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• 2011

As(V) adsorption on aluminum oxide powder which was recycled from industrial wastes containing aluminum hydroxide was evaluated. Aluminum oxide powder in this study was prepared by calcinating aluminum hydroxide wastes at$550^{\circ}C$. Spectroscopic analysis indicated that the aluminum hydroxide wastes were changed to aluminum oxide by calcination. Arsenic adsorption isotherm was conducted with variation of ionic strength and multiple-ion systems using Ca(II) and Cu(II). As(V) removal showed typical anionic adsorption characteristics that the removal efficiency decreased with increasing pH in single As(V) system as well as in binary and ternary system. More than 80% of As(V) at an initial concentration of $5{\times}10^{-5}$ M was removed from aluminum oxide powder in As(V) single system. The effect of ionic strength on As(V) adsorption was negligible, which indicated the strong bonding between aluminum oxide powder and As(V). The removal efficiency of As(V) was higher in a binary system with Cu(II) than in a binary system with Ca(II).

• Applied Biological Chemistry
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• 제28권2호
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• pp.68-75
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• 1985

이화학적(理化學的) 특성(特性)이 다른 본양토(本良土), 강서토(江西土) 및 교래토(橋來土)에 대하여 카드뮴, 아연(亞鉛) 및 구리의 흡착현상(吸着現象)을 비교(比較)하였고, 본양토(本良土)에 퇴비(堆肥)와 Humic acid를 각각(各各) 처리(處理)하여 이들의 흡착(吸着)에 미치는 영향(影響)을 검토(檢討)하였다. 카드뮴, 아연(亞鉛) 및 구리의 흡대흡착량(吸大吸着量)은 ph, 유기물함량(有機物含量) 및 양(陽)이온 치환용량(置換容量)이 가장 낮은 본양토(本良土)에서 가장 낮았으며, 강서토(江西土)에 비(比)하여 유기물함량(有機物含量)과 양(陽)이온 치환용량(置換容量)이 높고 pH가 낮은 화산회토(火山灰土)인 교래토(橋來土)에서 최대흡착량(最大吸着量)은 오히려 낮았다. 카드뮴 아연(亞鉛) 및 구리의 최대흡착량(最大吸着量)은 본양토(本良土)에서 각각 양(陽)이온 치환용량(置換容量)의 23%, 23%, 27%, 강서토(江西土)에서 각각 28%, 31%, 58%, 교래토(橋來土)에서 각각 11%, 11%, 14%이였으며 결합(結合)에너지상수(常數)는 강서토(江西土)>본양토(本良土)>교래토(橋來土) 순서(順序)이었다. 3% 및 7% 퇴비(堆肥)를 처리(處理)한 본양토(本良土)에서 중금속(重金屬)의 최대흡착량(最大吸着量)은 처리전(處理前) 토양(土壤)에 비(比)해 카드뮴이 100%, 210%, 아연(亞鉛)이 90%, 230%, 그리고 구리는 130%, 290% 증가(增加)하였으며, 결합(結合)에너지 상수(常數)도 증가(增加)하였다. Humic acid 처리 시(處理 時) 카드뮴과 구리의 최대흡착량(最大吸着量) 및 결합(結合)에너지 상수(常數)는 변하지 않았으며, 아연(亞鉛)의 최대흡착량(最大吸着量)은 변하지 않았으나 결합(結合)에너지 상수(常數)는 약간 증가(增加)하였다.

• 한국산학기술학회논문지
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• 제9권1호
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• pp.9-15
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• 2008

모꾸메가네는 나무결 모양을 낼 수 있는 고부가가치가 가능한 장신구 소재이며 서로 다른 금속을 가공하기 위해 융점이 다른 두 가지 이상 금속을 적층하여 붙인 잉곳 제작이 필수적이다. 기존의 모꾸메가네용 잉곳은 숯을 이용한 환원성 분위기에서 경험에 근거한 육안 판별로 만들어져서 접합의 신뢰성과 후속 가공 도중 층간 분리가 일어나는 분제가 있었다. $900^{\circ}C$에서 2.5kg의 압력을 가하면서 진공 열처리로를 이용하여 90% 이상 접합율이 가능한 조건을 확인하였다. 계면에서의 계면 확산계수가 통상의 벌크 확산계수보다 100배 향상되는 것을 확인하였고 이종 접합시에 계면 확산계수를 확인하여 $700^{\circ}C$의 저온에서 10분동안 진공열처리, 90% 이상 접합율을 가진 모꾸메가네용 잉곳을 성공적으로 제조하였다. 제조된 잉곳으로 핸드폰 외장용 모꾸메가네 시작품을 성공적으로 제조할 수 있었다.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2005년도 수소연료전지공동심포지움 2005논문집
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• pp.383-390
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• 2005

Effect of applying a DC voltage on the interfacial reaction at the metal to zirconia interface was investigated utilizing an oxygen ionic conductivity of partially stabilized zirconia. The joining of copper rod and zirconia tube was carried out in Ar gas atmosphere at $1000^{\circ}C$. There are two type of the joining. The one is the reaction bond consisting of copper and zirconia was dominated by surface reaction with a undetectable very thin layer. It was found that copper elements were diffused to zirconia side, but that Zr ions were not diffused to copper side. These results mean application of a DC voltage to migrate oxygen to the copper-zirconia interface can oxidize metal at the copper-zirconia interface and the bonding reaction between zirconia and copper oxide may occur. The other is the reaction bonding was dominated by interdiffusion with a very thick interface layer. This result mean application of a DC voltage can reduce zirconia at the interface. The bonding reaction is to be an alloying between Zr and Cu.