• Journal of the Microelectronics and Packaging Society
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• v.18 no.3
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• pp.53-57
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• 2011

In the modern packaging technologies highly condensed metal interconnects are typically formed by highcost processes. These methods inevitably require the precise controls of mutually dependant process parameters, which usually cause the difficulty of the change in the layout design for interconnects of chip to-chip, or chip-to-substrate. In order to overcome these problems, the unique concept and methodology of self-assembly even in micro-meter scale were developed. In this report we focus on the factors which influenced the self-formed bumps by analyzing the phenomenon experimentally. In case of RMA flux, homogenous pattern was obtained in both plain surface and cross-section surface observation. By using RA flux, the phenomena were accelerated although the self-formtion results was inhomogenous. With ussage of moderate RA flux, reaction rate of the self-formation was accelerated with homogeneous pattern.

• YAKHAK HOEJI
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• v.20 no.3
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• pp.130-137
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• 1976

Specific association phenomena of riboflayin-2',3',4',5',- tetraacetate and salicylic acid derivatives, such as salicylic acid, aspirin and salicylamide have been measured by infrared and fluorescence spectroscopy. Salicylic acid and riboflavin tetraacetate oxyl group of the former. Asprin and riboflavin tetraacetate form the 1:1 cyclic hydrogen bonded dimer by the same mode. Salicylamide froms the 1:1 cyclic hydrogen bonded dimer with riboflavin tetraacetate by using its amide group and carbonyl group. Salicylic acid derivatives are effective quenchers of the fluorescence of riboflavin tetraacetate. It is appeared that salifylamide is the strongest quencher among them. The quenching effect is attributed to the formation of association dimer.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.89-96
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• 2000

This paper describes the characteristic of die finishing to obtain smooth surface using electro-chemical grinding after cutting process. Electro-chemical grinding is possible under lower load and tool wear comparing with those in the mechanical grinding. Conventionally, if the metal bonding material of the grinding wheel is directly t contacted with workpiece, the current is circulated without electrolytic phenomena. Sometimes, electrical discharge is occurred between tool and workpiece. To cope with this problem, the metal-resin bonded pellet was used in this study. This pellet is composed of optimal volume of metal and resin powders and its characteristics are changable with the each volume of powders. Finally, high efficient die finishing is realized using metal resin bonded pellet in electro-chemical grinding.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.575-580
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• 2002

The most recent, like any other field we have requested that the concrete would increase more a performance. So, in this research we are intended to study on the property of Photocatalytic Concrete which is one of the High Performance Concrete. The fundamental phenomena of the Photocatalytic Concrete were observed by the NOx Analyzer, Bonding strength, SEM, Flow and Surface hardness(Pencil tester). As a result of this study, the Photocatalytic Concrete used Photocatalytic powder, admixture and other materials can obtain its properties, also photocatalytic efficiency(NOx reduction). Also, we have convinced of the Photocatalytic Concrete possibility and put on a spurt to improve its properties added a various experiment.

• Journal of Welding and Joining
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• v.16 no.5
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• pp.100-107
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• 1998

This paper describes fluxless soldering of reflow soldering process using solder foil instead of solder pastes. There is an increasing demand for the reliable solder connection in the recent high density microelectronic components technologies. And also, it is problem fracture of an Ozone layer due to freon as which is used to removal of remained flux on the substrate. This paper discussed joining phenomena, boudability and joining processes of microelectronics devices, such as between outer lead of VLSI package and copper pad on a substrate without flux. The shear strength of joints is 8 to 13 N using Sn/Pb (63/37 wt.%) solder foil with optimum joining conditions, meanwhile, in case of using Sn/In (52/48 wt.%) solder foil, it is possible to bond with low heating temperature of 550 K, and accomplish to high bonding strength of 25N in condition heating temperature of 650K. Finally, this paper experimentally shows fluxless soldering using solder foil, and accomplishes key technology of microsoldering processes.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.4 s.112
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• pp.26-31
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• 2005

The purpose of this study was to confirm paper strengthening properties with recently commercialized polyvinylamine. Because of its high cationic charge density, polyvinylamine has been investigated as a size retention and surface coating aids. In this study, we tried to confirm polyvinylamine as wet-end additives to improve dry and wet strength using LBKP and BCTMP pulps. As a result, we found improvement of dry and wet tensile properties of polyvinylamine with BCTMP were much better than LBKP condition. This phenomena could be explained that ionic bonding of cationic charge of polyvinylamine with abundant anionic substances of BCTMP was a very important factor to improve dry and wet strength of paper.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.2
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• pp.149-157
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• 2003

The purpose of this paper is to quantitatively investigate aging state of epoxy coating on containment structure at nuclear power plant. In order to evaluate an physical bonding of the epoxy coating, adhesion test was performed on a degraded epoxy coating on concrete specimens fabricated by accelerated aging experiment. In addition, impedance data by ultrasonic test were measured to compare with adhesion data. From almost 50 % of the specimens, aging phenomena of epoxy coating such as pin hole, blistering was discovered. To improve reliability on quality degradation of epoxy, co-relation between two kinds of different data was analyzed. By tracing co-related these data, it was possible to figure out physical state of as-built epoxy coating. The possibility to develop new methodology of time - dependent aging state on epoxy coating was found and discussed.

• Carbon letters
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• v.1 no.2
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• pp.87-90
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• 2000

Porous carbon from charcoal filled polypropylene composites were prepared and their mechanical properties were evaluated. In preparing the composites, crosslinking agent (sodium benzonate) were used in order to improve the bonding force between matrix and fillers. In this study, the effects of charcoal powder and sodium benzonate concentration on the mechanical properties and interface phenomena on the composites were evaluated. The mechanical properties of composites increased progressively with the decrease of filler loading. In the case of addition of the crosslinking agent into the composite, the mechanical properties were increased and showed maximum value at the 3 wt% concentration of sodium benzonate. According to the result of the TGA, the weight loss of composite according to crosslinking agent was not observed and initial thermal degradation temperature of composite reinforced charcoal was located at $390^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.32 no.5
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• pp.601-607
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• 1995

The bond strength between the low-firing-substrate and Cu conductor depended on the softening point and the amount of frit added to the metal paste. The addition of 3 wt% frit (softening point: 68$0^{\circ}C$) to the metal paste resulted in the improvement of bond strength, which was approximately 3 times higher (3kg/$\textrm{mm}^2$) than that of non frit condition. It was also found that fracture surface shifted to the ceramic substrate in the interface region. These phenomena were attributed to the frit migration into the metal-ceramic interface. It was thought that the migration of glass frit occurred extensively when the softening point of glass firt was 68$0^{\circ}C$. The sheet resistance of Cu conductor remained constant by the addition of 4 wt% frit regardless of softening point of frit. For all samples with more than 4 wt% frit, the sheet resistance increased abruptly.

• Bulletin of the Korean Chemical Society
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• v.14 no.6
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• pp.704-708
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• 1993

The intramolecular charge transfer (ICT) phenomena of the photoexcited 2-biphenylcarboxylic acid (2BPCA) and 4-biphenylcarboxylic acid (4BPCA) have been investigated in some surfactant micellar solutions. The ICT emission of 4BPCA and 2BPCA in aqueous solution at sufficiently low pH (1-3) has been observed to be markedly quenched and blue-shifted upon addition of a cationic surfactant, cetyltrimethylammonium chloride (CTAC) in contrast to little change in anionic sodium dodecyl sulfate (SDS) and neutral Brij 35. An anionic emission band has been observed to be enhanced at expense of the ICT emission as a function of the concentration of CTAC. These results with the micellar effects on the fluorescence decay kinetics of 4BPCA suggest that formation of the ICT state of the excited acids is inhibited by CTAC-induced proton transfer as well as the decrease in the polarity and/or hydrogen-bonding ability of the micellar microenvironment entrapping the acids.