• Journal of Conservation Science
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• v.28 no.4
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• pp.403-410
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• 2012

The brine treatment applied during the fabrication of forged high tin bronze objects is considered effective at the removal of surface oxide layers developed at elevated temperatures. There is not much information, however, available for the understanding of its exact effect and purpose. This work performed laboratory experiments to characterize the effect brine treatments produce on the surface of bronze objects during fabrication. Specimens were first made in the bronze shop of the Yongin folk village under varying conditions of brine treatments, and the results obtained were then used in the following laboratory experiments where the effect of brine treatments were investigated in terms of brine concentrations, alloy compositions and thermo-mechanical treatments. The results show that oxide layers generated at high temperature are easily removed by the brine treatment. It was found that the element, chlorine, played a key role in the removal of such oxide layers as opposed to the other constituent of the brine, sodium, makes no notable contribution. In bronze alloys containing 22% tin, this brine effect is obtained regardless of the application of forging as long as the brine concentration is over 0.5% based on weight. In alloys containing lead, however, no brine effect is observed due to the molten lead that emerges from inside the hot bronze specimen and forms a thin layer on its surface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.549-554
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• 2003

The purpose of this paper is to investigate the solder properties by the change of P mass percentage. Tension test, wetting balance test, spread test, and analysis of intermetallic compound after isothermal aging of Sn-2.5Ag-0.7Cu-0.005P, Sn-2.5Ag-0.7Cu-0.01P, Sn-2.5Ag-0.7Cu-0.02P, Sn-0.7Cu-0.005P were performed. Adding P in the solder alloys resulted in improvement of tensile strength, reduction of intermetallic compound growth, reduction of oxidization in fusible solders under wave soldering. After comparing solder alloy containing P with tin-lead eutectic solder alloy, P contained solders alloys showed much better solder properties than eutectic solder alloy. Furthermore, this solder alloy presented remarkable properties than any other lead-free solder alloy.

• Journal of Welding and Joining
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• v.16 no.4
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• pp.117-124
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• 1998

During the reflow process in SMT, the molten solder has been observed to move upward and solidify along the gullwing lead, which is called the wicking phenomenon. In this paper, possible causes of the wicking are investigated, and its effects on the solder joint profile are quantitatively estimated by introducing the wicking constant. The free energy reduction by intermetallic formation between the copper and tin seems to be the major source of wicking action. The joint profiles of the gullwing lead are calculated using the previous finite element formulation incorporated with the wicking constant. The calculated results show reasonably good agreements with the experimental data when the wicking effects are considered.

• Resources Recycling
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• v.24 no.2
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• pp.62-68
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• 2015

The high pure tin production was conducted from crude-tin containing waste solder by electro-refining process. The electro-refining process maintained at 0.2V produced tin with purity of 99.98%, whereas a little increase of voltage to 0.3 V resulted tin purity of 99.92%. The high pure tin of 3N in the present process was produced by fixing the voltage at 0.3V. Considering the high pure tin production, the current density was maintained within $100-120A/m^2$ with current efficiency of 94%. Addition of sulfuric acid of 20 ~ 25 g/L to the electrolyte solution was performed in order to keep Pb (lead) concentration below 100 mg/L in the final tin product. The anode slime generated during electro refining process was analyzed by X-ray diffraction (XRD) study to understand the phases of impurities in it. It detected the presence of Cu and Ag in the slime as in the form of $Cu_6Sn_5$, $Ag_3Sn$, whereas Pb occurred as $PbSO_4$ compound.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.3 s.32
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• pp.1-7
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• 2004

Tin plating on component finishes may grow whiskers under certain conditions, which may cause failures in electronics equipment. To protect the environment, 'lead-free' among component finishes is being promoted worldwide. This paper presents the evaluation results of whiskers on two kinds of lead-free plating materials at the plating temperature and under the reliability test. The rising plating temperature caused increasing the size of plating grain and shorting the growth of whisker. The whisker was grown under the temperature cycling the bent type in matt Sn plating and striated type in malt Sn-Bi. The whisker growth in Sn-Bi plating was shorter than that in Sn plating. In FeNi42 leadframe, the $7.0{\~}10.0{\mu}m$ diameter and the $25.0{\~}45.0{\mu}m$ long whisker was grown under 300 cycles. In the 300 cycles of Cu leadframe, only the nodule(nuclear state) grew on the surface, and in the 600 cycles, a $3.0{\~}4.0{\mu}m$ short whisker grew. After 600 cycles, the ${\~}0.34{\mu}m$ thin $Ni_3Sn_4$ formed on the Sn-plated FeNi42. However, we observed the amount of $0.76{\~}1.14{\mu}m$ thick $Cu_6Sn_5$ and ${\~}0.27{\mu}m$ thin $Cu_3Sn$ intermetallics were observed between the Sn and Cu interfaces. Therefore, the main growth factor of a whisker is the intermetallic compound in the Cu leadframe, and the coefficient of thermal expansion mismatch in FeNi42.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.05a
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• pp.104-108
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• 2002

This paper was investigated the lead free solder characteristics by P mass percentage chang e. Tension test, wetting balance test, spread test, and analysis of intermetallic compound after isothermal aging of Sn-2.5Ag-0.7Cu-0.005P, Sn-2.5Ag-0.7Cu-0.01P, Sn-2.5Ag-0.7Cu-0.02P, Sn-0.7Cu-0.005P were performed for estimation. By adding P on the solder alloys, it was showe d improvement of tensile strength, reduction of intermetallic compound growth and reduction of oxidization of fusible solder under wave soldering processes. After comparing solder alloy containing P with tin lead eutectic solder alloy, p containing solder alloys showed much better solderability than eutectic solder alloys.

• Conservation Science in Museum
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• v.19
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• pp.69-82
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• 2018

The gilt-bronze standing Buddha and bronze standing Buddha statues excavated from Yeongguksa Temple in Yeongdong, currently held in the collection of the Cheongju National Museum, underwent conservation treatment after scientific study. Materials analysis showed that the gilt-bronze statue was made with a ternary alloy of copper, tin, and lead, while the bronze statue is of a binary alloy of copper and tin. The analysis also revealed that the bronze statue contains gold, and it is therefore recommended to change its description to gilt-bronze standing Buddha. The gilt-bronze statue appears to have been made with lead produced in Korea. The material observed on the surface that is presumed to have been used as an adhesive for the gold coloring is thought to be lacquer. For conservation treatment, the statues were minimally cleaned using physical and chemical methods and were treated through consolidation and protective coating.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.1
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• pp.17-24
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• 2012

Recently, flip chip interconnection has been increasingly used in microelectronic assemblies. The common Flip chip interconnection is formed by reflow of the solder bumps. Lead-Tin solders and Tin-based solders are most widely used for the solder bump materials. However, the flip chip interconnection using these solder materials cannot be applied to temperature-sensitive components since solder reflow is performed at relatively high temperature. Therefore the development of low temperature bonding technologies is required in these applications. A few bonding techniques at low temperature of $150^{\circ}C$ or below have been reported. They include the reflow soldering using low melting point solder bumps, the transient liquid phase bonding by inter-diffusion between two solders, and the bonding using low temperature curable adhesive. This paper reviews various low temperature bonding methods.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.148-149
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• 2007

현재 전자부품 시장은 RoHS 규정으로 인하여 lead free화가 진행되고 있으며 많은 주목을 받고 있다. 본 논문에서는 반도체 패키지 및 부품표면일장에서 사용 되는 무전해 주석 도금과정 중 산 탈지 후 막의 표면 거칠기 정도가 도금 후의 표면 거칠기 정도에 미치는 영향을 평가 한다. 실험의 효율성을 높이기 위해 통계적인 실험계획법을 사용하였으며 실험의 횟수를 줄이고 표면 거칠기 정도는 이미지 프로세싱을 통하여 분석하였으며 통계적인 모델링을 통해 micro etch가 도금 표면의 거칠기에 주는 영향을 분석하였다.

• Journal of Welding and Joining
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• v.29 no.1
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• pp.41-45
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• 2011

SnAgCu lead-free solder alloy is considered as the best alternative to eutectic tin-lead solder. However, the detailed material properties of SnAgCu solder are not available in public. Hence, this paper presents an estimation of mechanical properties of SnAgCu lead-free solder. In particular, the weight percent of Ag was varied as 1.0wt%, 2.5wt%, 3.0wt%, and 4.5wt% in order to estimate the effect of Ag in the Sn-xAg-0.5Cu ternary alloy system. For this purpose, four types of SnAgCu bars were first molded by casting and then standard specimens were cut out of molded bars. Micro-Vickers hardness, tensile tests were finally performed to estimate the variations in mechanical properties according to the weight percent of Ag. Test results reveal that the higher the weight percent of Ag is, the higher the hardness, yield strength, and ultimate tensile strength become. More material properties will be further investigated in the future work.