• 마이크로전자및패키징학회지
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• 제8권3호
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• pp.43-47
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• 2001

Sn-3Ag-8Bi-5In 솔더는 중온계 무연솔더의 하나로서 개발되었다. In함유 솔더는 고가이지만, 솔더의 융점은 Sn-Ag-Cu 합금계보다 낮다. 본 연구에서 사용된 Sn-3Ag-8Bi-5In 솔더의 용융범위는 188~$204^{\circ}C$ 사이이다. 본 연구에서는 Sn-3Ag-8Bi-5In 솔더의 무연솔더로서의 적용가능성을 조사하기 위하여 솔더의 젖음특성을 평가하였다. Sn-3Ag-8Bi-5In 솔더의 젖음성을 기존 솔더 및 다른 무연솔더와 비교하기 위하여 Sn-37Pb, Sn-3.5Ag 공정솔더의 젖음특성도 조사하였다. 실험결과 영점시간과 젖음시간은 Sn-3Ag-8Bi-5In솔더의 경우 $240^{\circ}C$에서 각각 1.1, 2.2 초로서 Sn-37Pb 및 Sn-3.5Ag 무연솔더에 비하여 비슷하거나 다소 우수하였다. 또한, Sn-3Ag-8Bi-5In의 평형젖음력은 $240^{\circ}C$에서 5.8 mN으로 Sn-37Pb 솔더보다 낮고 Sn-3.5Ag 솔더보다 높았다.

• Journal of Welding and Joining
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• 제20권4호
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• pp.505-509
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• 2002

Pb is considered to be eliminated from solder, due to its toxicity. However, melting temperatures of most Pb-free solders are known higher than that of Sn37Pb. Therefore, there is a difficulty to apply Pb-free solders to electronic industry. Since Sn3Ag8Bi5In has relatively lower melting range as $188~200^{\circ}C$, on this study. Wettability and soldering characteristics of Sn3Ag8Bi5In solder in BGA were investigated to solve for what kind of problem. Zero cross time, wetting time, and equilibrium force of Sn3Ag8Bi5In solder for Cu and plated Cu such as Sn, Ni, and Au/Ni-plated on Cu were estimated. Plated Sn on Cu showed best wettability for zero cross time, wetting time and equilibrium farce. Shear strength of the reflowed joint with Sn3Ag8Bi5In ball in BGA was investigated. Diameter of the ball was 0.5mm, UBM(under bump metallurgy) was $Au(0.5\mu\textrm{m})Ni(5\mu\textrm{m})/Cu(18\mu\textrm{m})$ and flux was RMA type. For the reflow soldering, the peak reflow temperature was changed in the range of $220~250^{\circ}C$, and conveyor speed was 0.6m/min.. The shear strength of Sn3Ag8Bi5In ball showed similar level as those of Sn37Pb. The soldered balls are aged at $110^{\circ}C$ for 36days and their shear strengths were evaluated. The shear strength of Sn3Ag8Bi5In ball was increased from 480gf to 580gf by aging for 5 days.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2003년도 기술심포지움 논문집
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• pp.128-132
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• 2003

무전해 Ni-P UBM과 3가지 경우의 무연 솔더간의 계면연구를 통해 Bi가 솔더의 합금원소로 들어감에 따라 계면반응에 어떠한 영향을 줄 수 있는 가를 연구했다. 3가지 다른 무연 솔더는 Bi가 각각 $0wt\%,\;4.8wt\%,\;58wt\%$들어간 Sn3.5Ag, Sn3.5Ag4.8Bi, Sn58Bi 이다. reflow를 수행한 후에 세 가지 솔더에서 나타나는 계면에서의 IMC는 $Ni_3Sn_4$로서 어떤 다른 솔더도 Bi를 함유한 IMC가 계면에선 관찰되지 않았다. 다만 SnAgBi 솔더의 경우 특이하게 솔더내에서 침상의 $Ni_3Sn_4$가 reflow후에 관찰되었다. 또한 반응속도의 척도가 되는 Ni-P UBM소모속도를 비교해 보면 reflow후의 SnAg와 SnAgBi의 경우에는 비슷하나 SnBi의 경우에는 알서 두 솔더에 비해 눈에 띠게 느림을 관찰하였다. 이러한 Ni-P UBM의 소모경향을 Bi의 함량, 그에 따른 Sn의 상대적인 함량의 관점에서 고찰하고자 한다.

• Journal of Welding and Joining
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• 제23권3호
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• pp.61-67
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• 2005

Since lead (Pb)-free solders for electronics have higher melting points than that of eutectic Sn-Pb solder, they need higher soldering temperatures. In order to decrease the soldering temperature we tried to coat Sn-Bi layer on $Sn-3.5\%Ag$ solder by electroplating, which applies the mechanism of transient liquid phase bonding to soldering. During heating Bi will diffuse into the $Sn-3.5\%Ag$ solder and this results in decreasing soldering temperature. As bonding samples, the 1608 capacitor electroplated with Sn, and PCB, its surface was finished with electroless-plated Ni/Au, were selected. The $Sn-95.7\%Bi$ coated Sn-3.5Ag was supplied as a solder between the capacitor and PCB land. The samples were reflowed at $220^{\circ}C$, which was lower than that of normal reflow temperature, $240\~250^{\circ}C$, for the Pb-free. As experimental result, the joint of $Sn-95.7\%Bi$ coated Sn-3.5Ag showed high shear strength. In the as-reflowed state, the shear strength of the coated solder showed 58.8N, whereas those of commercial ones were 37.2N (Sn-37Pb), 31.4N (Sn-3Ag-0.5Cu), and 40.2N (Sn-8Zn-3Bi). After thermal shock of 1000 cycles between $-40^{\circ}C$ and $+125^{\circ}C$, shear strength of the coated solder showed 56.8N, whereas the previous commercial solders were in the range of 32.3N and 45.1N. As the microstructures, in the solder $Ag_3Sn$ intermetallic compound (IMC), and along the bonded interface $Ni_3Sn_4$ IMC were observed.

• Journal of Welding and Joining
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• 제20권2호
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• pp.77-81
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• 2002

Many kinds of Pb-free solder have been investigated because of the environmental concerns. Sn-Ag-Cu system is well blown as most competitive Pb-free solder. However, since Sn-Ag-Cu system has relatively high melting point compared to Sn-Pb eutectic, it may a limitation, the some application. In this study, Bi and In contained solder of $Sn_3Ag_8Bi_5In$ which has relatively lower melting point, $188~204^{\circ}C$, was investigated. $Sn_3Ag_8Bi_5In$ solder ball of $500\mu\textrm{m}$ diameter was set on the Ni/Cu/Cr-UBM and reflow soldered in the range of $220~240^{\circ}C$ for 5~15s. The maximum shear strength of the solder ball was around 170mN by reflowing at $240^{\circ}C$ for 10s. Intermetallic compound formed on the UBM of Si-wafer was analysed by SEM(scanning electron microscope) and XRD(X-ray diffractometer).

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.481-486
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• 2002

We have investigated the effects of plating materials for Cu lead (Sn-lOPb, AwPdJNi, Sn-3.5Ag, Sn-3Bi and Sn-0.7Cu) on properties of QFP joints using a Sn-8Zn-3Bi solder. The results were compared with the joints using Sn-3. 5Ag-0. 7Cu and Sn-37Pb solders. As a result, the joints with the Sn-3.5Ag, Sn-3Bi and Sn-0.7Cu plated Cu lead had the reliability comparable to those of the Sn-3.5Ag-0.7Cu and Sn-37Pb soldered joints with respect to the joint strength after the high temperature holding tests at 348K to 423k. In particular, the joint with the Sn-3.5Ag plated Cu lead had the best reliability. This is caused by the low growth rate of a Cu-Sn interfacial reaction layer that degrades the joint strength of the soldered joints. Consequently, the Sn-3.5Ag plating was found to be most feasible plating for the Sn-8Zn-3Bi soldered joint.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2001년도 추계학술발표대회 개요집
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• pp.168-170
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• 2001

• Journal of Mechanical Science and Technology
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• 제16권7호
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• pp.919-926
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• 2002

In this study, the numerical prediction of the thermal fatigue lie? of a $\mu$BGA (Micro Ball Grid Array) solder joint was focused. Numerical method was performed using the three-dimensional finite element analysis for various solder alloys such as Sn-37%Pb, Sn-3.5%Ag, Sn-3.5%Ag-0.7%Cu and Sn-3.5%Ag-3%In-0.5%Bi during a given thermal cycling. Strain values obtained by the result of mechanical fatigue tests for solder alloys, were used to predict the solder joint fatigue life using the Coffin-Manson equation. The numerical results showed that Sn-3.5%Ag with the 50-degree ball shape geometry had the longest thermal fatigue life in low cycle fatigue. A practical correlation for the prediction of the thermal fatigue life was also suggested by using the dimensionless variable γ. Additionally Sn-3.5Ag-0.75Cu and Sn-2.0Ag-0.5Cu-2.0Bi were applied to 6$\times$8$\mu$BGA obtained from the 63Sn-37Pb Solder. This 6$\times$8$\mu$BGA were tested at different aging conditions at 130$\^{C}$, 150$\^{C}$, 170$\^{C}$ for 300, 600 and 900 hours. Thickness of the intermetallic compound layer was measured thor each condition and the activation energy thor their growth was computed. The fracture surfaces were analyzed using SEM (Scanning Electron Microscope) with EDS ( Energy Dispersive Spectroscopy).

• 마이크로전자및패키징학회지
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• 제8권3호
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• pp.37-42
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• 2001

지금 까지 전자패키지 접합에 사용되어온 Sn/37Pb 솔더는 낮은 용융온도와 우수한 물리적 특성, 그리고 저렴한 가격 등으로 널리 사용되었다. 그러나 납의 독성으로 인한 환경문제와 인체 유해성이 문제화되면서 이를 대체할 무연솔더의 요구가 시급한 실정이다. 또한 제품의 소형화에 따른 접합부의 미세화로 인한 접합부신뢰성이 요구되고 있다. 본 연구에서는 현재 Sn/37Pb 솔더를 사용하여 제품에 사용되고 있는 48 $\mu$BGA 패키지를 사용하여 Sn/Ag 계열 의 두 무연솔더인 Sn/3.5Ag/0.75Cu와 Sn/2.0Ag/0.5Cu/2.0Bi를 접합하여 장기신뢰성을 시효처리를 통하여 제시하였다. 시효처리는 $130^{\circ}C$, $150^{\circ}C$, $170^{\circ}C$ 온도에서 각각 300, 600, 900 시간동안 하였으며, 시효처리에 따른 전단강도와 각 솔더의 활성화에너지를 구하여 Sn/37Pb 솔더와 비교하였다. 두 무연솔더의 시효강도는 Sn/37Pb 솔더 보다 우수하였으며, 시효처리에 따라 형성된 솔더내부의 금속간화합물의 형상으로부터 균열의 성장과 형성에 대하여 논하였다. 이런 실험결과들로부터 두 무연솔더의 장기신뢰성 측면에서 대체가능성을 제시하였다.

• 대한화학회지
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• 제15권2호
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• pp.49-54
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• 1971

It is shown that the impurities of Cu(II), Pb(II), Zn(II) and Ag(I) in Bismuth metal and the components of Pb(II), Zn(II) and Sn(IV) in Bismuth alloy are separated into their components from each other by elutions through $3.14cm^2{\times}10cm$ cation exchange resin, $Dowex\;50w\;{\times}\;8$ (100~200 mesh), column with the mixed solutions of HAc and NaAc as the eluents. The elution curve of Fe(III) has a long tailing and is not separated quantitatively from Bi(III). The eluents used for this separation are as follows; 1M HAc + 0.1M NaAc (pH 3.36) for Fe(III) and Bi (III). 0.3M HAc + 0.3M NaAc (pH 4.70) for Cu(II), Pb(II) and Zn(II). 0.5M HAc + 0.5M NaAc (pH4.70) for Ag(I) and Sn(IV). The analysis of cations eluted are carried out by spectrophotometry and EDTA titrimetry. Their recoveries are more than 99%.