• Journal of Conservation Science
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• v.25 no.2
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• pp.207-217
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• 2009

After replicating 10 bronze types such as Gyemija, Gyeongjaja, Eulhaeja, etc. before the Imjin war, we studied the change of microstructure from each casting process, method, and alloy ratio by Gyechukja replicated from "Donggukyeojiseungnam". We selected the average of compositions of Eulhaeja in the National Museum of Korea as the standard(Cu 86.7%, Sn: 9.7%, Pb: 2.3%) of bronze types, so we decided on the alloy's composition of Cu 87%, Sn 15%, Pb 8% added to 5% Sn and Pb contents because of evaporating the Sn and the Pb. Before replicating major metal types, we made master-alloy first, melting it again, and then replicated metal types. The composition of the 1'st replicated Gyechukja showed the range of Cu 85.81~87.63%, Sn 9.27~10.51%, Pb 3.05~3.19%. The 2'nd replicated Gyechukja made using the branch metal left after casting the 1st replica. The 2nd replicated Gyechukja showed the composition range of Cu 87.21~88.09%, Sn 9.06~9.36%, Pb 2.80~3.05%. This result decreases a little contents of Sn and Pb as compared with metal types of the 1st replica. However, it's almost the same as the Eulhaeja's average composition ratio in the National Museum of Korea. As a result of observing the microstructure of restored Gyechukja, it showed the dendrite structure of the typical casting structure and the segregation of Pb. There is no big difference of microstructure between the 1st and the 2nd restored metal types, even though the 2nd restored types partially decreases the eutectoid region in comparison with the 1st types. The systematic and scientific restoration experiment of metal types using Joseon period will be showed the casting method and alloy ratio, and this will be of great help to the study of restoration metal types in the future.

• Journal of the Microelectronics and Packaging Society
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• v.6 no.3
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• pp.45-50
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• 1999

Copper has been widely used for the electronic parts, and especially spot welded one for the leads of condenser or resistor. However, copper is generally hard to be spot welded because of its low electrical resistivity. For this experiment, Sn-37%Pb solder which has relatively higher resistivity was coated on the Cu-sheet to improve the spot weldability of copper. As the experimental variables welding pressure was varied from 100 to 200kgf, welding time from 20 to 50ms, and welding current from 100 to 2500A. Experimental results showed that the solder coated Cu-sheet can be spot welded under the conditions of 400~2200A welding current, 100~200kgf pressure and 20-50ms welding time. The tensile shear strength of the spot welded joint increased with welding current up to the critical current, and after the critical value decreased with current.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.206-207
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• 2005

Display 소재로서 유전체나 격벽재 실링재로 사용되고 있는 frit는 PbO를 주성분으로 갖는 유리가 사용되고 있다. PbO 성분이 함유된(50$\sim$85%) 구성소재는 최근 RoHS 나 WEEE 등의 환경규제 실행에 직면해 있으며, 대체재료의 개발을 위한 많은 연구가 진행되고 있다 PbO 성분을 대체할 성분으로는 $Bi_2O_3$ 계, BaO-ZnO 계, $P_2O_5$ 계 등의 성분이 주요성분으로 이루어져 있으며, PbO 성분을 함유한 유리의 저융점, 저유전율, 고 투과율, 내산성, 내전압, 팽창계수 matching 등의 특성들에 부합되는 재료를 개발하기 위해 많은 노력을 기울이고 있다. 본 연구에서는 SnO-$P_2O_5$ 계 유리 조성을 선택하여 $R_2O_3$의 치환 및 용융분위기의 조절에 따른 저융점 유리로서의 특성과 효과에 대하여 고찰하였다.

• Korean Journal of Materials Research
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• v.4 no.3
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• pp.334-338
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• 1994

This report details the microscopic aspects of grain boundary cracking in Pb-Sn eutecticduring displacement-controlled mechanical tests performed over a range of low frequency ($10^{-3}-10^{-5}$/s)and moderate strain range (0.2 - 1 %) where is the most technologically relevant to solder jointssubjected to thermal cycling. It is shown that intergranular cracking begins with the appearance ofcrack-like features (CLF's), which can be seen due in part because they are associated with grainboundary sliding, and is able to be described by certain stages of isolated crack growth. In the initialstages CLF's are not ture cracks but instead what I shall call "proto-cracks" where grain boundarysliding begins to damage the gram boundary at the surface. At some point during the initiation stagesonce proto-cracks become ture cracks, they develop into isolated cracks and the growth of isolatedcracks is eventually accomplished by coalescence, resulting in 5 stages of cracking.ing in 5 stages of cracking.

• Journal of the Korean institute of surface engineering
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• v.27 no.5
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• pp.292-302
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• 1994

Alloy deposits of 80Sn-20Pb, electroplated on Cu-based leadframe alloy from an organic sulfonate bath were aged at $150^{\circ}C$ to form intermetallic phases between substrate and deposit, and effects of the deposit morphology, influenced by deposition conditions, on the fracture resistance of the 80Sn-20Pb deposit aged at $150^{\circ}C$ were examined. The growth rate of intermetallic compound layer on aging depended on the microstructure of deposit ; it was fastest in deposit formed using pulse current in bath without grain refining additive, but slowest in deposit formed using dc current in bath containing grain refining additive in spite of similar structure with equivalent grain size. The grain refining additive incorporated in electrodeposit appears to inhibit diffusion of atoms on aging, resulting in slow growth of intermetallic layer in the thickness direction but substantial growth in the lateral one. Density of surface cracks that were occurring when samples were subjected to the $90^{\circ}$-bending test increased with increasing the thickness of intermatallic layer on aging. For the same aged samples, the surface crack density of the sample electrodeposited from a bath containing the grain refining additive was the least due to the inhibiting effect of the additive incorporated into the deposit during electrolysis on atomic diffusion.

• Journal of the Korean Physical Society
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• v.73 no.9
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• pp.1370-1376
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• 2018

The electronic structures, magnetic properties and half-metallicity in $Zr_2RuZ$ (Z = Ga, In, Tl, Ge, Sn, and Pb) alloys with $AlCu_2Mn-$ and $CuHg_2Ti$-type structures were investigated using first-principles density functional theory (DFT) calculations. The calculations showed that $Zr_2RuIn$, $Zr_2RuTl$, $Zr_2RuSn$, and $Zr_2RuPb$ compounds with $CuHg_2Ti$-type structures were half-metallic ferromagnets with half-metallic band gaps of 0.18, 0.24, 0.22, and 0.27 eV, respectively. The half-metallicity originated from d-d and covalent hybridizations between the transition metals Zr and Ru. The total magnetic moments of the $Zr_2RuZ$ (Z = In, Tl, Sn, and Pb) compounds with $CuHg_2Ti$-type structures were integer values of $1{\mu}B$ and $2{\mu}B$, which is in agreement with Slater-Pauling rule ($M_{tot}=Z_{tot}-18$). Among these compounds, $Zr_2RuIn$ and $Zr_2RuTl$ were half-metals over relatively wide regions of the lattice constants, indicating that these two new Heusler alloys are ideal candidates for use in spintronic devices.

• Journal of Welding and Joining
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• v.20 no.6
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• pp.59-59
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• 2002

Sn-Ag-Cu solder is known as most competitive in many kinds of Pb-free solders. In this study, effects of solderability with plated layers such as Cu, Cu/Sn, Cu/Ni and Cu/Ni/Au were investigated. Sn-3.5Ag-0.7Cu solder balls were reflowed in commercial reflow machine (peak temp. : 250℃ and conveyer speed : 0.6m/min). In wetting test, immersion speed was 5mm/sec., immersion time 5sec., immersion depth 4mm and temperature of solder bath was 250℃. Wettability of Sn-3.5Ag-0.7Cu on Cu, Cu/Sn (5㎛), Cu/Ni (5㎛), and Cu/Ni/Au (5㎛/500Å) layers was investigated. Cu/Ni/Au layer had the best wettability as zero cross time and equilibrium force, and the measured values were 0.93 sec and 7mN, respectively. Surface tension of Sn-3.5Ag-0.7Cu solder turmed out to be 0.52N/m. The thickness of IMC is reduced in the order of Cu, Cu/Sn, Cu/Mi and Cu/Ni/Au coated layer. Shear strength of Cu/Ni, Cu/Sn and Cu was around 560gf but Cu/Ni/Au was 370gf.

• Journal of Welding and Joining
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• v.20 no.6
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• pp.783-788
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• 2002

Sn-Ag-Cu solder is known as most competitive in many kinds of Pb-free solders. In this study, effects of solderability with plated layers such as Cu, Cu/Sn, Cu/Ni and Cu/Ni/Au were investigated. Sn-3.5Ag-0.7Cu solder balls were reflowed in commercial reflow machine (peak temp.:$250^{\circ}C$and conveyer speed:0.6m/min). In wetting test, immersion speed was 5mm/sec., immersion time 5sec., immersion depth 4mm and temperature of solder bath was $250^{\circ}C$. Wettability of Sn-3.5Ag-0.7Cu on Cu, Cu/Sn ($5\mu\textrm{m}$), Cu/Ni ($5\mu\textrm{m}$), and Cu/Ni/Au ($5\mu\textrm{m}/500{\AA}$) layers was investigated. Cu/Ni/Au layer had the best wettability as zero cross time and equilibrium force, and the measured values were 0.93 sec and 7mN, respectively. Surface tension of Sn-3.5Ag-0.7Cu solder turmed out to be 0.52N/m. The thickness of IMC is reduced in the order of Cu, Cu/Sn, Cu/Mi and Cu/Ni/Au coated layer. Shear strength of Cu/Ni, Cu/Sn and Cu was around 560gf but Cu/Ni/Au was 370gf.

• Journal of the Korean institute of surface engineering
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• v.24 no.2
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• pp.88-95
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• 1991

The tin-lead alloy was electrodeposited in the low range of peak current density in order to investigate the change of composition and microstructure of them. The Pb content of alloy deposits, which was decreased with increasing average current density, was relatively lower than that of D.C. plated alloy deposit. The preferred orientation of alloy deposit was changed with increasing peak current density and the surface morphology of alloy deposits was closely related to the preferred orientation of them.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.202-204
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• 2006

The reliability of insert mounted components has been considered as their life time was getting increased. The spread of crack and the growth of IMC(intermetallic compound) were observed by SEM(scanning electron microscope) and EDS(energy dispersive spectroscope). The cracks in Sn-37wt%Pb under thermal shock test were found earlier than other solders(Sn-3.0wt%Ag-0.5wt%Cu and Sn-0.7wt%Cu-0.01wt%P). The IMC thickness was increased with increasing number of thermal shock cycles in the following order : Sn-0.7Cu-0.01P; Sn-3.0Ag-0.5Cu; Sn-37Pb