• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.75-87
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• 2001

Three different kinds of substrate used in this study : bare Cu substrate, Ni-P/Cu substrate with a Ni-P layer thickness of $5\mu\textrm{m},$ and Au/Ni-P/Cu substrate with the Ni-P and Au layers of $0.15\mu\textrm{m}$ and $5\mu\textrm{m}$ thickness respectively. The wettability of various Sn-base solders was affected by the substrate metal finish used, i.e., nickel, gold and copper. On the Au/Ni-F/Cu substrate, Sn-base solders wet better than any of the other substrate metal finishes tested. The interfacial reaction between various substrate and Sn-base solder was investigated at $70^{\circ}C,$ $100^{\circ}C,$ $120^{\circ}C,$ $150^{\circ}C,$ $170^{\circ}C$ and $200^{\circ}C$ for reaction times ranging from 0 day to 60 day. Intermetallic phases was formed along a Sn-base solder/ various substrate interface during solid-state aging. The apparent activation energy for growth of Sn-Ag/Cu, Sn-Ag-Bi/Cu, and Sn-Bi/Cu couples were 65.4, 88.6, and 127.9 Kj/mol, respectively. After isothermal aging, the fracture surface shoved various characteristics depending on aging temperature and time, and the types of BGA pad.

• Journal of Navigation and Port Research
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• v.30 no.2
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• pp.137-143
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• 2006

The optimum grillage design belongs to nonlinear constrained optimization problem. The determination of beam scantlings for the grillage structure is a very crucial matter out of whole structural design process. The performance of optimization methods, based on penalty functions, is highly problem-dependent and many methods require additional tuning of some variables. This additional tuning is the influences of penalty coefficient, which depend strongly on the degree of constraint violation. Moreover, Binary-coded Genetic Algorithm (BGA) meets certain difficulties when dealing with continuous and/or discrete search spaces with large dimensions. With the above reasons, Real-coded Micro-Genetic Algorithm ($R{\mu}GA$) is proposed to find the optimum beam scantlings of the grillage structure without handling any of penalty functions. $R{\mu}GA$ can help in avoiding the premature convergence and search for global solution-spaces, because of its wide spread applicability, global perspective and inherent parallelism. Direct stiffness method is used as a numerical tool for the grillage analysis. In optimization study to find minimum weight, sensitivity study is carried out with varying beam configurations. From the simulation results, it has been concluded that the proposed $R{\mu}GA$ is an effective optimization tool for solving continuous and/or discrete nonlinear real-world optimization problems.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.05a
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• pp.183-188
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• 2002

With the contact pad consisted of $0.5{\mu}{\textrm}{m}$ $Au/5{\mu}{\textrm}{m}$ Ni/Cu layers on a conventional ball grid array(BGA) substrate, metallurgical reaction properties between the pad and In-15(wt.%)Pb-5Ag solder alloy were studied after reflow and solid aging. In as-reflow condition, thin AuIn$_2$or Ni$_{28}$In$_{72}$ intermetallic layer was formed at the solder/pad interface according to reflow time. Dissolution of the Au layer into the molten solder was remarkably limited in comparison with eutectic Sn-37Pb alloy. After solid aging of 300 hrs, thickness of In-Ni layer increased to about $2{\mu}{\textrm}{m}$ in the both as-reflow case. It was observed that In atoms diffuse through the AuIn$_2$phase to react with underlaying Ni layer. The metallurgical reaction properties between In-l5Pb-7Ag alloy and Au/Ni surface finish were analysed to result in suppression of Au-embrittlement in the solder joints.

• Journal of fish pathology
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• v.10 no.2
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• pp.125-135
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• 1997

The possibility of identification of families of antibacterial agent residues in fish tissue was studied by disk assay using three test organisms, Bacillus subtilis BGA, Micrococcus luteus ATCC 9341, and Bacillus cereus var. mycoides ATCC 11778. In the present method, a simple clean-up procedure was performed to obtain the aqueous solution from homogenized flounder muscle sample(10g) in Mcilvaine buffer. Then, aqueous solution was fractionated into A and B to be used in disk assay by choloroform and Sep-Pak $C_{18}$ cartridge column after being defatted in hexane. The chloroform layer of fraction A was used for the analysis of macrolide antibiotics(ML), sulfa drugs(SA), chloramphenicol(CP), and quinolone antibiotics(QN). Adsorbed materials to Sep-Pak $C_{18}$ of fraction B were also employed for the analysis of penicillins(PC), tetracyclines(TC), and nitrofuran derivatives(NF) Minimun-detectable concentrations by the present method were, $0.1{\mu}g$/g for oxytetracycline, tetracycline, doxycycline, spiramycin and ciprofloxacin, $0.025{\mu}g$/g for erythromycin and ampicillin, $1.0{\mu}g$/g for sodium nifurstyrenate and florfenical, $0.25{\mu}g$/g for sulfamonomethoxie and sulfadimethoxine, $2.5{\mu}g$/g for oxolinic acid and flumequine, and $15{\mu}g$/g for piromidic acid, respectively. Three test organisms showed different sensitivity patterns for each family of antibacterial agent. Sensitivity patterns were B. cereus > B. subtilis > M. luteus for TC and NF, M. luteus > B, subtilis > B. cereus for ML and PC, B. cereus = B. subtilis > M. luteus for CP and QN, and B. subtilis > B. cereus＝M. luteus for SA. The present method utilizing these characteristics could be useful as a routine screening test for the determination of family of antibacterial agent residues in fish tissue.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.05a
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• pp.126-129
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• 2002

This article presents that the affecting factors to solderability and initial reliability. It was discussed that effect of the solder ball hardness and composition on the reliability of solder joints. In this study, lead free solder alloys with compositions of Sn-Cu, Sn-Ag, Sn-Ag-Cu, Sn-Ag-Cu-Bi were applied to the $\muBGA$ packages. As a result of experiments, the high degree of hardness with the displacement of 0.22mm was obtained Sn-2.0Ag-0.7Cu-3.0Bi. The shear strength of lead free solder was higher than of Sn-37Pb solder, and it was increased about 150% in Sn-2.0Ag-0.7Cu-3.0Bi.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.431-432
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• 2012

In the era of 20 nm scaled semiconductor volume manufacturing, Microelectronics Manufacturing Engineering Education is presented in this paper. The purpose of microelectronic engineering education is to educate engineers to work in the semiconductor industry; it is therefore should be considered even before than technology development. Three Microelectronics Manufacturing Engineering related courses are introduced, and how undergraduate students acquired hands-on experience on Microelectronics fabrication and manufacturing. Conventionally employed wire bonding was recognized as not only an additional parasitic source in high-frequency mobile applications due to the increased inductance caused from the wiring loop, but also a huddle for minimizing IC packaging footprint. To alleviate the concerns, chip bumping technologies such as flip chip bumping and pillar bumping have been suggested as promising chip assembly methods to provide high-density interconnects and lower signal propagation delay [1,2]. Aluminum as metal interconnecting material over the decades in integrated circuits (ICs) manufacturing has been rapidly replaced with copper in majority IC products. A single copper metal layer with various test patterns of lines and vias and $400{\mu}m$ by $400{\mu}m$ interconnected pads are formed. Mask M1 allows metal interconnection patterns on 4" wafers with AZ1512 positive tone photoresist, and Cu/TiN/Ti layers are wet etched in two steps. We employed WPR, a thick patternable negative photoresist, manufactured by JSR Corp., which is specifically developed as dielectric material for multi- chip packaging (MCP) and package-on-package (PoP). Spin-coating at 1,000 rpm, i-line UV exposure, and 1 hour curing at $110^{\circ}C$ allows about $25{\mu}m$ thick passivation layer before performing wafer level soldering. Conventional Si3N4 passivation between Cu and WPR layer using plasma CVD can be an optional. To practice the board level flip chip assembly, individual students draw their own fan-outs of 40 rectangle pads using Eagle CAD, a free PCB artwork EDA. Individuals then transfer the test circuitry on a blank CCFL board followed by Cu etching and solder mask processes. Negative dry film resist (DFR), Accimage$^{(R)}$, manufactured by Kolon Industries, Inc., was used for solder resist for ball grid array (BGA). We demonstrated how Microelectronics Manufacturing Engineering education has been performed by presenting brief intermediate by-product from undergraduate and graduate students. Microelectronics Manufacturing Engineering, once again, is to educating engineers to actively work in the area of semiconductor manufacturing. Through one semester senior level hands-on laboratory course, participating students will have clearer understanding on microelectronics manufacturing and realized the importance of manufacturing yield in practice.

• Journal of Environmental Impact Assessment
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• v.27 no.6
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• pp.674-684
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• 2018

The purpose of this study is to construct ecological pond using LID technique in order to create naturally comfortable community space in urban idle space. The specification of the ecological pond is $110m^2$ of surface area, $0.45{\pm}0.02m$ of average depth, and bed material is composed of gravel (diameter ${\leq}60mm$), sand (diameter ${\leq}2mm$) and bentonite. Rainfall and water depth monitoring were conducted to determine the annual characteristics of inflow of the water for the ecological pond, result of total rainfall was 1,287 mm and showed a seasonal imbalance that accounted for 71.3% (918 mm) during July to August, but the annual mean water depth was kept constant at $0.45{\pm}0.02m$ due to the secondary water source. Annual trends of basic water quality showed a significant changes according to the season, such as water temperature ($5.2{\sim}28.8^{\circ}C$), DO (5.0 ~ 13.8 mg/L), EC ($113{\sim}265{\mu}S/cm$). BOD, COD, TN, and TP in physicochemical water quality tended to increase after October, but the ion parameters such as $NH_3$ and $PO_4{^{3-}}$ were generally low. Phytoplankton indicators Chl-a and BGA (blue green algae) showed a sharp increase from July to August, and green algae (Selenastrum bibraianum, Pediastrum boryanum etc.) and filamentous blue green algae (Phormidium sp.) emerged as a dominant species. The ion parameters ($F^-$, $Na^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$) were strongly correlated with the $Cl^-$ as a conservative substance (R=0.70~0.97, p<0.05). Water quality was influenced by the ambient environment such as seasonal changes or rainfall, and it was closely related to fluctuation of the inflow of the water. In the future, it is necessary to consider ecological connections by referring to the characteristics surveyed in this study in order to effectively manage the water quality and biodiversity of the ecological pond in idle space.