• Title/Summary/Keyword: wetting resistance

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Analysis of the experimental cooling performance of a high-power light-emitting diode package with a modified crevice-type vapor chamber heat pipe

  • Kim, Jong-Soo;Bae, Jae-Young;Kim, Eun-Pil
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.8
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    • pp.801-806
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    • 2015
  • The experimental analysis of a crevice-type vapor chamber heat pipe (CVCHP) is investigated. The heat source of the CVCHP is a high-power light-emitting diode (LED). The CVCHP, which exhibits a bubble pumping effect, is used for heat dissipation in a high-heat-flux system. The working fluid is R-141b, and its charging ratio was set at 60 vol.% of the vapor chamber in a heat pipe. The total thermal conductivity of the falling-liquid-film-type model, which was a modified model, was 24% larger than that of the conventional model in the LED package. Flow visualization results indicated that bubbles grew larger as they combined. These combined bubbles pushed the working fluid to the top, partially wetting the heat-transfer area. The thermal resistance between the vapor chamber and tube in the modified design decreased by approximately 32%. The overall results demonstrated the better heat dissipation upon cooling of the high-power LED package.

Development of MEMS based Piezoelectric Inkjet Print Head and Its Applications

  • Shin, Seung-Joo;Lee, Hwa-Sun;Lee, Tae-Kyung;Kim, Sung-Jin
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2010.05a
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    • pp.20.2-20.2
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    • 2010
  • Recently inkjet printing technology has been developed in the areas of low cost fabrication in environmentally friendly manufacturing processes. Although inkjet printing requires the interdisciplinary researches including development of materials, manufacturing processes and printing equipment and peripherals, manufacturing a printhead is still core of inkjet technology. In this study, a piezoelectric driven DOD (drop on demand) inkjet printhead has been fabricated on three layers of the silicon wafer in MEMS Technology because of its chemical resistance to industrial inks, strong mechanical properties and dimensional accuracy to meet the drop volume uniformity in printed electronics and display industries. The flow passage, filter and nozzles are precisely etched on the layers of the silicon wafers and assembled through silicon fusion bonding without additional adhesives. The piezoelectric is screen-printed on the top the pressure chamber and the nozzle plate surface is treated with non-wetting coating for jetting fluids. Printheads with nozzle number of 16 to 256 have been developed to get the drop volume range from 5 pL to 80 pL in various industrial applications. Currently our printheads are successfully utilized to fabricating color-filters and PI alignment layers in LCD Flat Panel Display and legend marking for PCB in Samsung Electronics.

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An Optimization of the Porous Asphalt Pavement Permeability Function Focusing on the Surface Free Energy of Polymer Fog-Coat Methods

  • Ohmichi Massaru;Yamanokuchi Hiroshi;Maruyama Teruhiko
    • International Journal of Highway Engineering
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    • v.8 no.2 s.28
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    • pp.13-22
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    • 2006
  • Surface fog coating methods to porous pavements with a polymer, that contains MMA as a main ingredient, are being widely used in Japan and called 'Top-Coat Processes'. They have lots of effects such as to prevention of the pavement void choking, improvement of the water permeability of the pavements and so on. The purpose of this research is to show the characterization of the polymer to optimize the functions of the polymer fog-coat methods. This study focused on the difference of 'wetting' by water among polymers used for the fog coatings, and calculation the surface free energy from the water contact angle on each material. At the end, the water permeability test were conducted using porous asphalt mixtures that were coated with several kinds of polymers. The permeability was also measured on the specimens that were forcibly choked by muddy water and the resistance to choking was compared. It is concluded that the reduction of the surface free energy between water and a polymer improves the life of the permeability functions of porous pavements. Improvement of water permeation capacity and void-blocking controlling effects can be quantitatively evaluated using the interfacial tension ($\gamma$sl) with water for the coating material (high-viscosity asphalt and hardening resin binder). Consequently, the smaller the $\gamma$sl of the coating material the higher the water permeation capacity and void-blocking controlling effects of the porous asphalt pavements.

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Novel Convenient Method to Determine Wettability and Dispersibility of Dairy Powders

  • Lee, Jeae;Chai, Changhoon;Park, Dong June;Lim, Kwangsei;Imm, Jee-Young
    • Food Science of Animal Resources
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    • v.34 no.6
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    • pp.852-857
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    • 2014
  • This study was carried out to develop a simple, convenient, and reproducible testing device to determine wettability and dispersibility of dairy powders. The testing device consists of a sieve ($150{\mu}m$) attached to a sample chamber, sensors mounted on a supporting body and a main control unit containing a display panel. The sensors detect the difference in electrical resistance between air and water. A timer is automatically triggered by the sensor when the bottom of sample-loaded chamber contacts water in the petri dish. Wettability and dispersibility of commercial skim milk powders (SMPs) produced at different heating strengths (low-, medium-, and high-heat SMP) are compared using the new testing device. Wettability of the SMPs were correlated with particle size and are found to increase in the order of medium-, low-, and high-heat SMP regardless of the amount of sample tested. Dispersibility of SMPs showed the same trend and high heat-SMP which has the smallest particle size resulted in the lowest dispersibility. Unlike existing methods, the new testing device can determine both wettability and dispersibility of powders and successfully detected differences among the samples.

Study on Self-Organized Ru Dots Using ALD and Low Temperature Rapid Thermal Annealing Process (ALD와 저온 RTA를 이용한 자가정렬 Ru 응집체의 제조와 물성)

  • Park, Jongseung;Noh, Yunyoung;Song, Ohsung
    • Korean Journal of Metals and Materials
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    • v.50 no.8
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    • pp.557-562
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    • 2012
  • Self-organized ruthenium (Ru) dots were fabricated by $400^{\circ}C$ RTA (rapid thermal annealing) and ALD (atomic layer deposition). The dots were produced under the $400^{\circ}C$ RTA conditions for 10, 30 and 60 seconds on all Si(100)/200 nm-SiO2, glass, and glass/fluorine-doped tin oxide (FTO) substrates. Electrical sheet resistance, and surface microstructure were examined using a 4-point probe and FE-SEM (field emission scanning electron microscopy). Ru dots were observed when a 30 nm-Ru layer on a Si(100)/200 nm-SiO2 substrate was annealed for 10, 30 and 60 seconds, whereas the dots were only observed on a glass substrate when a 50 nm-Ru layer was annealed on glass. For a glass/FTO substrate, RTA <30 seconds was needed for 30 nm Ru thick films. Those dots can increase the effective surface area for silicon and glass substrates by up to 5-44%, and by 300% for the FTO substrate with a < $20^{\circ}$ wetting angle.

Prediction of Wetting and Interfacial Property of CNT Reinforced Epoxy on CF Tow Using Electrical Resistance Method (전기저항 평가법을 이용한 CNT 함유 에폭시의 탄소섬유내 젖음성 및 계면특성 예측 연구)

  • Kwon, Dong-Jun;Choi, Jin-Yeong;Shin, Pyeong-Su;Lee, Hyung-Ik;Lee, Min-Gyeong;Park, Jong-Kyoo;Park, Joung-Man
    • Composites Research
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    • v.28 no.4
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    • pp.232-238
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    • 2015
  • As a new method to predict the degree of dispersion in carbon nanocomposites, the electrical resistance (ER) method has been evaluated. After CNT epoxy resin was dropped on CF tow, the change in electrical resistance of carbon fiber tow was measured to evaluate dispersion condition in CNT epoxy resin. Good dispersion of CNTs in carbon nanocomposite exhibited low change in ER due to wetted resin penetrated on CF tow. However, because CNT network was formed among CFs, non-uniform dispersion occurred due to nanoparticle filtering effect by CF tow. The change in ER for poor dispersion exhibited large ER signal change. The change in ER was used for the dispersion evaluation of CNT epoxy resin. Correlation between interlaminar shear strength (ILSS) and dispersion condition by ER method was established. Good CNT dispersion in nanocomposites led to good interfacial properties of fiberreinforced nanocomposites.

Prediction of Cohesive Sediment Transport and Flow Resistance Around Artificial Structures of the Beolgyo Stream Estuary

  • Cho, Young-Jun;Hwang, Sung-Su;Park, Il-Heum;Choi, Yo-Han;Lee, Sang-Ho;Lee, Yeon-Gyu;Kim, Jong-Gyu;Shin, Hyun-Chool
    • Fisheries and Aquatic Sciences
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    • v.13 no.2
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    • pp.167-181
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    • 2010
  • To predict changes in the marine environment of the Beolgyo Stream Estuary in Jeonnam Province, South Korea, where cohesive tidal flats cover a broad area and a large bridge is under construction, this study conducted numerical simulations involving tidal flow and cohesive sediment transport. A wetting and drying (WAD) technique for tidal flats from the Princeton Ocean Model (POM) was applied to a large-scale-grid hydrodynamic module capable of evaluating the flow resistance of structures. Derivation of the eddy viscosity coefficient for wakes created by structures was accomplished through the explicit use of shear velocity and Chezy's average velocity. Furthermore, various field observations, including of tide, tidal flow, suspended sediment concentrations, bottom sediments, and water depth, were performed to verify the model and obtain input data for it. In particular, geologic parameters related to the evaluation of settling velocity and critical shear stresses for erosion and deposition were observed, and numerical tests for the representation of suspended sediment concentrations were performed to determine proper values for the empirical coefficients in the sediment transport module. According to the simulation results, the velocity variation was particularly prominent around the piers in the tidal channel. Erosion occurred mainly along the tidal channels near the piers, where bridge structures reduced the flow cross section, creating strong flow. In contrast, in the rear area of the structure, where the flow was relatively weak due to the formation of eddies, deposition and moderated erosion were predicted. In estuaries and coastal waters, changes in the flow environment caused by artificial structures can produce changes in the sedimentary environment, which in turn can affect the local marine ecosystem. The numerical model proposed in this study will enable systematic prediction of changes to flow and sedimentary environments caused by the construction of artificial structures.

New Generation of Lead Free Paste Development

  • Albrecht Hans Juergen;Trodler K. G.
    • Proceedings of the International Microelectronics And Packaging Society Conference
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    • 2004.09a
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    • pp.233-241
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    • 2004
  • A new alloy definition will be presented concerning increasing demands for the board level reliability of miniaturized interconnections. The damage mechanism for LFBGA components on different board finishes is not quite understood. Further demands from mobile phones are the drop test, characterizing interface performance of different package constructions in relation to decreased pad constructions and therefore interfaces. The paper discusses the characterization of interfaces based on SnPb, SnPbXYZ, SnAgCu and SnAgCuInNd ball materials and SnAgCuInNd as solder paste, the stability after accelerated tests and the description of modified interfaces strictly related to the assembly conditions, dissolution behavior of finishes on board side and the influence of intermetallic formation. The type of intermetallic as well as the quantity of intermetallics are observed, primaliry the hardness, E modules describing the ability of strain/stress compensation. First results of board level reliability are presented after TCT-40/+150. Improvement steps from the ball formulation will be discussed in conjunction to the implementation of lead free materials In order to optimize ball materials for area array devices accelareted aging conditions like TCTs were used to analyze the board level reliability of different ball materials for BGA, LFBGA, CSP, Flip Chip. The paper outlines lead-free ball analysis in comparison to conventional solder balls for BGA and chip size packages. The important points of interest are the description of processability related to existing ball attach procedures, requirements of interconnection properties and the knowledge gained the board level reliability. Both are the primary acceptance criteria for implementation. Knowledge about melting characteristic, surface tension depend on temperature and organic vehicles, wetting behavior, electrical conductivity, thermal conductivity, specific heat, mechanical strength, creep and relaxation properties, interactions to preferred finishes (minor impurities), intermetallic growth, content of IMC, brittleness depend on solved elements/IMC, fatigue resistance, damage mechanism, affinity against oxygen, reduction potential, decontamination efforts, endo-/exothermic reactions, diffusion properties related to finishes or bare materials, isothermal fatigue, thermo-cyclic fatigue, corrosion properties, lifetime prediction based on board level results, compatibility with rework/repair solders, rework temperatures of modified solders (Impurities, change in the melting point or range), compatibility to components and laminates.

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New Generation of Lead Free Solder Spheres 'Landal - Seal'

  • Walter H.;Trodler K. G.
    • Proceedings of the International Microelectronics And Packaging Society Conference
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    • 2004.09a
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    • pp.211-219
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    • 2004
  • A new alloy definition will be presented concerning increasing demands for the board level reliability of miniaturized interconnections. The damage mechanism for LFBGA components on different board finishes is not quite understood. Further demands from mobile phones are the drop test, characterizing interface performance of different package constructions in relation to decreased pad constructions and therefore interfaces. The paper discusses the characterization of interfaces based on SnPb, SnPbXYZ, SnAgCu and SnAgCuInNd ball materials and SnAgCuInNd as solder paste, the stability after accelerated tests and the description of modified interfaces stric시y related to the assembly conditions, dissolution behavior of finishes on board side and the influence of intermetallic formation. The type of intermetallic as well as the quantity of intermetallics are observed, primaliry the hardness, E modules describing the ability of strain/stress compensation. First results of board level reliability are presented after TCT-40/+150. Improvement steps from the ball formulation will be discussed in conjunction to the implementation of lead free materials. In order to optimize ball materials for area array devices accelareted aging conditions like TCTs were used to analyze the board level reliability of different ball materials for BGA, LFBGA, CSP, Flip Chip. The paper outlines lead-free ball analysis in comparison to conventional solder balls for BGA and chip size packages. The important points of interest are the description of processability related to existing ball attach procedures, requirements of interconnection properties and the knowledge gained the board level reliability. Both are the primary acceptance criteria for implementation. Knowledge about melting characteristic, surface tension depend on temperature and organic vehicles, wetting behavior, electrical conductivity, thermal conductivity, specific heat, mechanical strength, creep and relaxation properties, interactions to preferred finishes (minor impurities), intermetallic growth, content of IMC, brittleness depend on solved elements/IMC, fatigue resistance, damage mechanism, affinity against oxygen, reduction potential, decontamination efforts, endo-/exothermic reactions, diffusion properties related to finishes or bare materials, isothermal fatigue, thermo-cyclic fatigue, corrosion properties, lifetime prediction based on board level results, compatibility with rework/repair solders, rework temperatures of modified solders (Impurities, change in the melting point or range), compatibility to components and laminates.

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A STUDY ON THE EFFECT OF UV LIGHT ABSORBER ON THE COLOR CHANCE OF MAXILLOFACIAL SILICONE (자외선 차단제가 악안면 실리콘의 색변화에 미치는 영향에 관한 연구)

  • Song, Yun-Seok;Lim, Ju-Hwan;Cho, In-Ho
    • The Journal of Korean Academy of Prosthodontics
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    • v.37 no.3
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    • pp.343-357
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    • 1999
  • The color change of maxillofacial silicone has been attributed to certain environmental factors such as exposure to the UV component of natural sunlight, wetting and drying of the elastomer and surface abrasion resulting from the application and removal of cosmetics. The purpose of this study was to evaluate the color change of maxillofacial silicone (Silastic MDX4-4210) according to type of pigment (cadmium yellow, titanium white, cosmetic red), and UV absorber application method after 200, 400, and 600 hours of 350nm UV light irradiation. The results were as follows. 1. According to type of pigments, after 200 hours cosmetic red showed significantly larger color change than cadmium yellow and titanium white, and after 400 and 600 hours color change significantly decreased in the order of cosmetic red, cadmium yellow, and titanium white (p<0.05). 2. In the cadmium yellow group, after 200 hours, the non-treatment group showed significantly larger color change, but after 400 and 600 hours, color change significantly decreased in the order of non-treatment, surface application and mixed group (p<0.05). 3. In the titanium white group, there was no significant color change difference between the three groups after 200 and 400 hours, but after 600 hours, the mixed group showed significantly smalt or color change than the non-treatment and surface application groups (p<0.05). 4. In the cosmetic red group, there was significant decrease in color change in the order of non-treatment, surface application and mixed group (p<0.05). From the results above, the effect of UV light absorber differed according to the type of pigment, but mixing UV light absorber with maxillofacial silicone is thought to give superior resistance against UV light irradiation in the long run.

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