• Title/Summary/Keyword: 표면젖음성

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The Study on Micro Soldering Using Low-Residue Flux in $N_2$Atmosphere (질소 분위기에서 저잔사 플럭스를 사용한 마이크로 솔더링에 관한 연구)

  • 최명기;정재필;이창배;서창제;황선효
    • Journal of the Microelectronics and Packaging Society
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    • v.7 no.4
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    • pp.7-15
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    • 2000
  • The purpose of this work is to evaluate the solderahility and characteristics of solder joints. Bridge defect of solder joint was examined in natural atmosphere and $N_2$ condition. Consequently, wettability was excellent for each of Sn-Pb plated Cu specimen, Sn plated Cu specimen, and Cu polished in $N_2$ condition. The wetting time in $N_2$ condition was shorter than that of natural atmosphere condition, showing the decreasing values of about 0.2~0.45 seconds. The max. wetting force under the $N_2$ condition was more increasing that of natural atmosphere condition, showing the increasing values of about 1.8~2.8 N. With the result of wetting balance test, the wetting time ($t_2$) and wetting farce according to increasing amount of $N_2$ from 10 1/min to 30 1/min, the wetting time ($t_2$) was reduced about 0.25 second and wetting force was increased about 2.3 N. In non-cleaning flux, when $N_2$ gas is applied, it is compensated to decrease of wettability. In the case of using the $N_2$ gas, the wettability was improved. The reason for improving wettability is due to preventing the formation of dross. The generation rate of bridge in $N_2$ condition decreased than that of natural atmosphere, and when the specimen had a fine pitch, the rate of bridge defects was considerably decreased in $N_2$ condition, showing the decreasing rate of 25~75%.

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Surface Wetting Effect on Spread-Splash Transition Criterion (표면 젖음성이 스프레드-스플래시 영역 간 천이 조건에 미치는 효과)

  • Ryu, S.U.;Lee, S.Y.
    • Journal of ILASS-Korea
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    • v.12 no.4
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    • pp.198-203
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    • 2007
  • In the present work, surface wetting effect on spread-splash regime and transition criterion of the water and ethanol droplets impacting an unheated dry wall has been experimentally investigated. The droplet was directed on a polished STS plate and a glass slide, and the impinging behavior was visualized and recorded using a CCD camera. Droplet diameter and velocity approaching the wall were measured as well. The critical Sommerfeld number representing the spread-splash boundary for the ethanol droplet impinging on the substrates turned out to be smaller compared to that for the water droplet impinging on the substrates with the surface roughness condition remained unchanged. The shift of the transition boundary is considered to be due to the effect of the surface wettability represented by static contact angle and surface tension of droplet.

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A Study on the Interfacial Properties of Bioabsorbable Fibers/PoIy-L-Lactide Composites using Micromechanical Tests and Surface Wettability Measurement (Micromechanical 시험법과 표면 젖음성 측정을 이용한 생흡수성 섬유 강화 Poly-L-Lactide 복합재료의 계면물성 연구)

  • Park, Joung-Man;Kim, Dae-Sik;Kim, Sung-Ryong
    • Journal of Adhesion and Interface
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    • v.3 no.2
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    • pp.17-29
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    • 2002
  • Interfacial properties and microfailure degradation mechanisms of the bioabsorbable composites for implant materials were investigated using micromechanical technique and measurement of surface wettability. As hydrolysis time increased, the tensile strength, the modulus and the elongation of poly(ester-amide) (PEA) and bioactive glass fibers decreased, whereas those of chitosan fiber almost did not change. Interfacial shear strength (IFSS) between bioactive glass fiber and poly-L-lactide (PLLA) was much higher than PEA or chitosan fiber/PLLA systems using dual matrix composite (DMC) specimen. The decreasing rate of IFSS was the fastest in bioactive glass fiber/PLLA composites whereas that of chitosan fiber/PLLA composites was the slowest. Work of adhesion, $W_a$ between bioactive glass fiber and PLLA was the highest, and the wettability results were consistent with the IFSS. Interfacial properties and microfailure degradation mechanisms can be important factors to control bioabsorbable composite performance.

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Effect of Surfactant and Anti-foaming Agent on the Properties of Silicone Rubber Impression Material (계면활성제와 소포제가 실리콘 고무인상재의 물성에 미치는 영향)

  • Kim, Kyoung-Nam;Cho, Lee-Ra;Oh, Young-Il;Kang, Seung-Kyung;Chung, Kyung-Ho
    • Elastomers and Composites
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    • v.36 no.2
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    • pp.102-110
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    • 2001
  • The three types of surfactants such as nonylphenoxy poly(ethylene) ethanol homologues, caster oil poly(ethylene) ethanol homologues, and sodium perfluoroalkyl carboxylates are used to improve the wettability of rubber impression material. Among the surfactants, the usage of sodium perfluoroalkyl carboxylates containing fluoro group resulted in the lowest surface energy of impression material and the result gave the positive effect on the wettability of rubber impression material to teeth. Also, the anti-foaming agents were used to reduce or remove the hydrogen gas generating on the impression material by reaction. In the case of rubber impression material containing sodium perfluoroalkyl carboxylate as a surfactant, it was found that the tear strength of rubber impression material increased over 3 N/mm with the addition of anti-forming agent. Therefore, the anti-foaming agent could contribute to the mechanical property of rubber impression material without the change of surface property.

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Effects of Sulfonation Ratio in Petroleum Sulfonate Synthesis on Interfacial Properties and on Fluidity Properties of Cement Mortar (Petroleum Sulfonate의 합성에 있어서 황산화율이 계면활성 특성 및 시멘트 몰타르의 유동성에 미치는 영향)

  • Kim, Young-Ho
    • Korean Chemical Engineering Research
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    • v.48 no.4
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    • pp.444-449
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    • 2010
  • In this study, the petroleum sulfonate(PS) was synthesized from pyolyzed fuel oil by sulfonation reaction with sulfuric acid. The PS synthesized had surfactant behaviors relating to the interfacial properties such as surface tension, surface adsorption, and wetting, etc. These interfacial properties were affected by the sulfonation ratio in the synthesis. As the sulfonation ratio increased, the surface tension of the PS aqueous solution decreased. However, when the ratio was too high, the surface tension was increased due to the extremely higher value of hydrophilicity of PS. At the optimum sulfonation ratio, the PS had a good wettability on the cement particles and a good fluidity of the cement mortar with a high adsorption.

Experimental Study of Pool Boiling for Enhancing the Boiling Heat Transfer by Hydrophobic Dots on Silicon Surface (실리콘 표면 위에 소수성 점을 이용한 비등 열전달 증진에 관한 실험적 연구)

  • Jo, Hang-Jin;Kim, Hyung-Mo;Ahn, Ho-Seon;Kang, Soon-Ho;Kim, Joon-Won;Shin, Jeong-Seob;Kim, Moo-Hwan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.6
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    • pp.655-663
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    • 2010
  • Wettability is important to enhance not only CHF but also nucleate boiling heat transfer, as shown by the results of different kinds of boiling experiments. In this regard, an excellent boiling performance (a high CHF and heat transfer performance) could be achieved in the case of pool boiling by some favorable surface modifications that can satisfy the optimized wettability condition. To determine the optimized boiling condition, we design special heaters to examine how two materials, which have different wettabilities (e.g., hydrophilic and hydrophobic materials), affect the boiling phenomena. The special heaters have hydrophobic dots on a hydrophilic surface. The contact angle of the hydrophobic surface is $120^{\circ}$ to water at the room temperature. The contact angle of the hydrophilic surface is $60^{\circ}$ at same conditions. Experiments involving micro hydrophobic dots and two types of milli hydrophobic dots are performed, and the results are compared with a reference surface.

Effects of Steel Composition on Heat Resistance and Coatability of Hot-dip Aluminized Sheet Steel (용융 Al 도금강판의 내열성과 밀착성에 미치는 강성분 영향)

  • Bae, Dae-Cheol
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2007.04a
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    • pp.40-41
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    • 2007
  • 용융 Al 도금강판의 내열성, 도금성 향상을 위한 실험실적 변수 영향을 고찰하였다. 내열성 향상을 위한 강 성분 변경시험 결과와 용융 도금성(젖음성 : Wettability) 향상을 위한 표면 농화물 등의 관찰 결과를 Fe-SEM, Glossmeter, 광학현미경, GDS 기기 등을 이용하여 측정하였다. 아울러, 용융 Al도금이 가능한 각 원소의 영향을 고찰함으로써 현재 $400^{\circ}C$ 전후에서 변색 없이 사용가능한 수준을 약 $80-100^{\circ}C$ 상승시킴으로써 Alcosta 제품 사용범위 확대에 기여한다.

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