• Journal of Welding and Joining
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• 제25권3호
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• pp.57-63
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• 2007

Electrochemical migration characteristics of Pb-free solder alloys are quantitatively correlated with corrosion characteristics in harsh environment conditions. In-situ water drop test and corrosion resistance test for Sn-3.0Ag-0.5Cu solder alloys were carried out in NaBr and NaF solutions to obtain the electrochemical migration lifetime and pitting potential, respectively. Sn-3.0Ag-0.5Cu solder alloy shows similar ionization and electrochemical migration behavior with pure Sn because of Ag and Cu do not migrate due to the formation of resistant intermetallic compounds inside solder itself. Electrochemical migration lifetime in NaBr is longer than in NaF, which seems to be closely related to higher pitting potential in NaBr than NaF solution. Therefore, it was revealed that electrochemical migration lifetime of Sn-3.0Ag-0.5Cu solder alloys showed good correlation to the corrosion resistance, and also the initial ionization step at anode side is believed to be the rate-determining step during electrochemical migration of Pb-free solders in these environments.

• 한국전기전자재료학회논문지
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• 제28권1호
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• pp.7-11
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• 2015

In this study, $Si_3N_4$/SnZnO/AZO/Ag/Ti/ITO multi-layer film were prepared on glass substrate by DC/RF magnetron sputtering method. To prevent interfacial reaction between Ag and ITO layer, Ti buffer layer was inserted. Optical properties and sheet resistance were studied depending on laminating times of each multi-layered film especially in visible ray. The simulation program, EMP (essential macleod program), was adopted and compared with experimental data to expect the experimental result. It was found out that the transmittance of the first stacked $Si_3N_4$/SnZnO/AZO/Ag/Ti/ITO multi-layer film was more than 90%. However, with increasing stacking times, the optical properties of $Si_3N_4$/SnZnO/AZO/Ag/Ti/ITO multi-layer film get worse. Consequently, Ti layer is good for oxidation barrier, but too many uses of this layer may have an adverse effect to optical properties of TCO film.

• 한국생산제조학회지
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• 제18권5호
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• pp.449-454
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• 2009

This paper presents an experimental study on the failure characteristics of SnAgCu lead-free solder balls. To estimate the effect of Ag, three types of SnAgCu balls are first prepared by varying the weight percent of Ag(1.0, 3.0, 4.0 wt%) and then analyzed by reliability tests such as thermal shock, high speed ball shear, and drop tests. Thermal shock test reveals that the higher the weight percent of Ag is, the longer the fatigue lift becomes. To the contrary, high speed ball-shear test and drop test show that the shear strength and the fracture toughness of solder balls are inversely proportional to the weight percent of Ag, respectively, Reasons for these observations will be further investigated In the future work.

• 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).

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1999년도 특별강연 및 추계학술발표대회 개요집
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• pp.251-254
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• 1999

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2005년도 춘계총회 및 학술발표회
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• pp.23-23
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• 2005

• 마이크로전자및패키징학회지
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• 제15권1호
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• pp.33-37
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• 2008

Kirkendall void는 전해도금 Cu/Sn-Ag 솔더 접합부에서 형성되었으며 Cu 도금욕에 함유되는 첨가제에 의존한다. 첨가제로 사용된 SPS의 함량의 증가와 함께 $150^{\circ}C$에서 열처리 후 많은 양의 Kirkendall void가 $Cu/Cu_3Sn$ 계면에 존재하였다. AES 분석은 void 표면에 S가 편석되어 있음을 보여주었다. $Cu/Cu_3Sn$ 계면을 따라 파괴된 시편에서 Cu, Sn, S peak만 검출되었고 AES 깊이 프로파일에서 S는 급격하게 감소하였다. $Cu/Cu_3Sn$ 계면에서 S 편석은 계면에너지를 낮추고 Kirkendall void 핵생성을 위한 에너지장벽을 감소시킨다. 낙하충격시험은 SPS를 사용하여 도금된 Cu의 경우 Kirkendall void가 형성된 $Cu/Cu_3Sn$ 계면에서 파괴가 진행되고 급격하게 신뢰성이 감소됨을 보였다.

• 마이크로전자및패키징학회지
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• 제17권1호
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• pp.81-88
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• 2010

Sn-3.0Ag-0.5Cu 솔더범프의 금속간화합물 성장거동에 미치는 PCB 표면처리의 영향을 알아보기 위해서 PCB 패드 표면에 각각 OSP, immersion Sn, 그리고 ENIG를 처리하였고, 열처리는 $150^{\circ}C$ 조건에서 실험을 실시하였다. 또한, 전류인가시 Sn-3.0Ag-0.5Cu 솔더범프의 접합부 계면반응에 미치는 표면처리의 영향을 알아보기 위해서 $150^{\circ}C$, $4{\times}10^3\;A/cm^2$ 조건에서 electromigration특성을 비교 평가하였다. 열처리시 OSP와 immersion Sn의 금속간화합물 성장거동은 서로 비슷한 경향을 보인 반면, ENIG는 다른 표면처리에 비해 훨씬 느린 성장거동을 보였다. electromigration특성 평가결과 열처리에 비해 금속간화합물의 성장이 가속화되나 표면처리별 경향은 유사하였고, 전자 이동 방향에 따른 음극-양극에서 금속간화합물 형성의 차이를 보이는 극성효과(polarity effect)가 나타나는 것을 알 수 있었다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년 추계학술발표대회 개요집
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• pp.187-189
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• 2006

최근 유연솔더에서 무연솔더로 전환함에 따라서 PCB의 도금이 솔더접합부의 각도에 미치는 영향이 중요하게 되었다. 현재 PCB 도금은 Sn, Au, OSP 등으로 다양하게 진행되고 있다. 그러나 PCB 도금이 솔더접합부의 강도에 미치는 영향에 대한 연구는 아직 미비하다. 따라서 본 연구에서는 PCB 도금(Sn, Au, OSP)이 무연솔더(Sn-3.0Ag-0.5Cu) 접합부의 초기 전단강도에 미치는 영향과 열사이클시험 후 솔더접합부의 전단강도에 미치는 영향에 대해서 연구하였다.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.344-351
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• 2020

AgInCd alloy is widely used as neutron absorber in nuclear reactors. However, the AgInCd control rods may fail during service due to the irradiation swelling. In the present study, a calculational method is proposed to calculate the composition change of the AgInCd absorber. Calculated results show that neutron fluence has significant impact on the chemical compositions. Ag and In contents gradually decrease while Cd and Sn conversely increases from the center to the rim of AgInCd absorber due to the depression of neutron flux. The composition change at the surface is higher almost two times than that at the center. Based on the calculated compositions, six simulated AgInCdSn alloys were prepared and examined. With the increase of Cd and Sn, the simulated AgInCdSn alloys transform from a single fcc phase into the mixed fcc and hcp phases, and finally into the single hcp phase. The atomic volume of the hcp phase is obviously larger than the fcc phase. The fcc-hcp transformation results in considerable volume swelling of the AgInCd absorber. Moreover, the lattice parameters of the fcc and hcp phases gradually increase with Cd and Sn contents, which also can induce small volume swelling.