• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2006.02a
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• pp.77-85
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• 2006

• Journal of the Microelectronics and Packaging Society
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• v.19 no.3
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• pp.77-82
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• 2012

In this paper, the research of IC embedded PCB process is carried out. For embedding chips into PCB, solder-balls on chips were etched out and ABF(Ajinomoto Build-ip Film), prepreg and Cu foil was laminated on that to fabricate 6 layer build-up board. The chip of which solder ball was removed was successfully interconnected with PCB by laser drilling and Cu plating. However, de-lamination phenomenon occurred between chip surface and ABF during reflow and thermal shock. To solve this problem, de-smear and plasma treatment was applied to PI(polyimide) passivation layer on chip surface to improve the surface roughness. The properties of chip surface(PI) was investigated in terms of AFM(Atomic Force Micrometer), SEM and XPS (X-ray Photoelectron Spectroscopy). As results, nano-size anchor was evenly formed on PI surface when plasma treatment was combined with de-smear(NaOH+KMnO4) process and it improved thermal shock reliability ($260^{\circ}C$-10sec solder floating).

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.4
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• pp.72-77
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• 2008

This paper investgated on fabrication process and tolerance of resistance body with a uniform thickness formed by the process of cavity type on organic substrate for application of embedded resistor. To improve the tolerance of resistance value according to a position of PCB cause by conventional screen printing, we introduced the process of cavity type from organic substrate. A resistor with a desired shape and volume was precisely formed by the process of cavity using a resistor paste and screen printing. This method can increase PCB's productivity by shortening its production time because process conditions of a screen prining device can be set quickly without any affection on its position accuracy.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.2
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• pp.102-107
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• 2007

Environmental contamination becomes a great public concern as our society gets industrialized rapidly. The present study examine the role of chitosan in a effort to intervene the environmental pollutant-induced toxicity. PCB-induced neurotoxicity with respect to the PKC signaling was examined. Since the developing neuron is particularly sensitive to PCB-induced neurotoxicity, we isolated cerebellar granule cells derived from 7-day old SD rats and grew cells in culture for additional 7 days to mimic PND-14 conditions. PCB showed the alteration of PKC signaling pathway. The alteration was structure-dependent. Mono-ortho-substituted congeners at a high dose showed a significant increase of total PKC activity at [$^3H$]PDBu binding assay, indicating that mono-ortho-substituted congeners are more neuroactive than non-ortho-substituted congeners in neuronal cells. PKC isoforms were immunoblotted with respective monoclonal antibodies. PKC-beta II and -epsilon were activated with mono-ortho-substituted congeners exposure. The result suggests that the position with ortho has a higher potential of altering the signaling pathway. Alteration of PKC was blocked with treatment of high molecular weight of chitosan. The study demonstrated that the ortho position in PCBs are important in assessing the structure-activity relationship. The results suggest a potential use of marine bioactive materials as a means of nutritional intervention to prevent the harmful effects of pollutant-derived toxicity.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.4
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• pp.77-82
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• 2022

During etching process of PCB, the electroplated copper line and seed layer copper have different etching rates and it caused the over etching of copper line as well as undercut of lines. In this research, the effects of etchants composition on copper etching characteristics were investigated. The optimum concentration of hydrogen peroxide and sulfuric acid of etchants were obtained using polarization and OCV (open circuit voltage) analysis for both rolled copper and electroplated copper. The inhibiting effects of different inhibitors were investigated using OCV and ZRA (zero resistance ammeter) analysis. The galvanic current between electroplated copper and seed layer copper were measured using ZRA method. Inhibitors for least galvanic current could be chosen based on galvanic coupling in ZRA analysis.

• Fire Science and Engineering
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• v.30 no.6
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• pp.71-77
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• 2016

The electrolyte of the capacitor in mobile phone chargers leaks to the power input terminal resulting in tracking on the PCB board to form a carbonized conductive path. As a result of structural analysis of the cause of the tracking, It occurred when the power input terminal and the PCB board were connected directly using the connector. The larger the amount of electrolyte leaked from the capacitor into the power input terminal, or the lower the height of the partition provided between the plug pins of the power input terminal, the higher the tracking occurrence rate. Accordingly, to lower the occurrence rate of tracking in the charger, it is necessary to provide a partition on the capacitor or increase the height of the partition provided on the power input terminal so that the leaked electrolyte does not flow to the power input terminal. In addition, the tracking occurrence rate will be reduced further if the shape of the PCB board touching ther power connection terminal is changed to ${\Pi}$.

• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.520-528
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• 2007

A practical and efficient disposal of PCBs (polychlorinated biphenyls) in waste transformer oil by a chemical dechlorination process has been reported. The transformer oil containing commercial PCB mixtures (Aroclor 1242, 1254 and 1260) was treated by the required amounts of PEG 600 (polyethylene glycol 600), potassium hydroxide (KOH) and aluminum (Al), along with different reaction temperatures and times. The reaction of PEG with PCBs under basic condition produces arylpolyglycols, the products of nucleophilic aromatic substitution. The relative efficiencies of PCB treatment process were assessed in terms of destruction and removal efficiency (DRE, %). Under the experimental conditions of PEG600/KOH/Al/100 oC/2hr, average DRE of PCBs was approximately 78%, showing completely removal of PCBs containing 7-9 chlorines on two rings of biphenyl which appear later than PCB no. 183 (2,2',3,4,4',5',6-heptaCB) in retention time of GC/ECD. However, when increasing the reaction temperature and time to 150 oC and 240 min, average DRE of PCBs including the most toxic PCBs (PCB no. 77, 105, 118, 123 and 169) in PCB family reached 99.99% or better, with the exception of PCB no. 5 and 8 (2,3-diCB and 2,4'-diCB). In studying the reaction of PEG with PCBs, it confirmed that the process led to less chlorinated PCBs through a stepwise process with the successive elimination of chlorines. The process also permits complete recovery of treated transformer oil through simple segregating procedures.

• Toxicological Research
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• v.22 no.1
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• pp.23-30
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• 2006

Among poly aromatic hydrocarbons, dioxin and PCBs are the most controversial environmental pollutants in our modern life. These pollutants are known as human carcinogens, and liver is the most sensitive target in animal cancer models. Specific aims of the study were focused on the mechanism of carcinogenesis in hepatocytes and the structure-activity relation among these diverse environmental chemicals. Because key mechanisms of dioxin-induced carcinogenesis in human epithelial cell model are the alteration of signal transduction pathway and PKC isoforms, the alteration of the signal transduction pathways and other factors associated with carcinogenesis were studied. Rat hepatocytes cultured under the sandwich protocols were exposed with the various concentration of dioxins and PCBs, and signal transduction pathway, protein kinase C isoforms, oxidant stress, and apoptotic nuclei were evaluated. Since it is important to understand the structure-activity relation among these chemicals to properly assess the carcinogenic potentials, the study analyzed the parameters associated with carcinogenic processes, based on their structural characteristics. In addition, signal transduction pathways and PKC isoforms involved in inhibition of UV-induced apoptosis were also analyzed to elaborate the tumor promotion mechanism of these chemicals. Induction of apoptosis by UV irradiation was optimal at $60\;J/m^2$ in primary hepatocyte in culture. Compared to non coplanar PCBs such as PCB 114 and PCB 153, coplanar PCBs such as PCB 77 and PCB126 showed a stronger inhibition of apoptosis induced by UV irradiation. Production of reactive oxygen species (ROS) was more stimulated by non-coplanar PCBs than coplanar PCBs with the most potent induction of ROS by chlorinated non-coplanar PCB. As compared to the level of induction by PCB126, non-coplanar PCB153 showed a higher increase of intracellular concentrations. Besides the alteration of intracellular calcium concentration, translocation of PKC from cytosolic fraction to membrane fraction was clearly observed upon the exposure of non-coplanar PCB. Taken together, the present study demonstrated that there is a potent structure-activity relationship among PCB congeners and the mechanism of PAH-induced carcinogenesis is structure-specific. The study suggested that more diverse pathways of PAH-induced carcinogenesis should be taken into account beyond the boundary of Ah receptor dogma to assess the health impact of PAH with more accuracy.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.77-77
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• 2010

본 연구에서는 Sn-3.0Ag-0.5Cu (SAC305) 무연솔더의 최적 인쇄성을 위한 PCB 및 마스크설계, 스크린프린팅 공정변수의 최적값을 실험계획법을 통해 평가하였다. 사용된 칩은 가로 0.4mm 세로 0.2mm의 0402 MLCC칩이며, 사용된 시험보드는 OSP 표면처리된 PCB이었다. 인쇄성을 판단하기 위한 공정인자는 금속마스크 두께, 마스크홀 크기, 패드크기 및 모양, 인쇄각도, 인쇄속도, 판분리속도이었다. ANOVA분석을 통해 주인자를 파악하였으며, 인쇄성에 영향을 미치는 주인자는 마스크두께와 인쇄각도임이 확인되었다. 그 후 중심 합성법을 이용하여 인쇄성 최적 조건을 확인하였다. 결과로 나타난 등고선/표면도를 통해, 마스크두께가 작을 때에는 인쇄각도가 작아야 높은 인쇄성을 갖으며, 또한 마스크 두께가 클 경우에는 인쇄각도가 커야 높은 인쇄성을 가짐을 알 수 있었다. 추가실험을 통해서 인쇄성 표면도의 정확도를 확인하였으며, 실험값은 표면도에서 표시된 인쇄성값과 비슷함을 알 수 있었다. 또한, 인쇄성이 낮은 영역과 높은 영역에서 접합강도값을 측정하였으며, 인쇄성이 좋은 영역에서 접합강도도 높음을 알 수 있었다.

• Analytical Science and Technology
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• v.16 no.4
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• pp.325-332
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• 2003

To analyze co-planar PCBs in food, the isotopic dilution method by high resolution gas chromatography/high resolution mass spectrometry was applied. Among 209 PCB congeners, 12 congeners (#77, #81, #126, #169, #105, #114, #118, #123, #156, #157, #167 and #189) were chosen as target compounds that were toxic congeners re-assessed by WHO in 1998. Milk and milk products including cheese and butter were collected as food samples. Samples were homogenized, spiked with the known amount of the standard mixture and extracted. After extraction, extracts were cleaned up by sulfuric acid impregnated silica gel, purified on silica gel and alumina column chromatography and then analyzed by HRGC/HRMS. As results, the overall recoveries were ranged from 83% to 106% and the limit of detection was about 0.1 pg/g at signal/noise>3. Levels of targets in the selected food samples were 0.001~0.107 pgWHO-TEQ/g.