• Proceedings of the KWS Conference
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• 2007.11a
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• pp.211-214
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• 2007

Sn-0.3Ag-0.7Cu 조성의 젖음 특성과 반응 특성을 Sn-1.0Ag-0.5Cu 및 Sn-3.0Ag-0.5Cu 합금의 결과와 비교, 분석하였다. 또한 Sn-0.3Ag-0.7Cu 조성의 용융 및 응고 특성을 DSC로 측정하고, 인장시험을 통한 stress-strain curve를 관찰하였다. 아울러 할로겐 함유량이 많은 플럭스를 사용하여 Sn-0.3Ag-0.7Cu 조성의 젖음 특성을 향상 시킬 수 있는지를 조사하였으며, Sn-0.3Ag-0.7Cu 조성에 미량의 In을 첨가하여 젖음 특성의 개선 정도를 분석하였다. 그 결과 할로겐 함유량이 높은 플럭스를 사용한 경우보다 미량의 In을 첨가한 경우에서 wettability의 향상을 보다 효과적으로 유도할 수 있음을 관찰할 수 있었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.2
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• pp.94-98
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• 2017

In the past few years, Sn-3.0Ag-0.5Cu (weight%) solder composition has been a representative material to electronic industries as a replacement of Pb-base solder alloy. Therefore, extensive studies on process and/or reliability related with the composition have been reported. However, recent rapid rise in Ag price has demanded solder compositions of low Ag content. In this study, Sn-3.0Ag-0.5Cu solder bar sample was fabricated by melting of Sn, Ag and Cu metal powders. Crystal structure and element concentration were analyzed by XRD, optical microscope, FE-SEM and EDS. The Sn-3.0Ag-0.5Cu solder sample was composed of ${\beta}$-Sn, ${\varepsilon}-Ag_3Sn$ and ${\eta}-Cu_6Sn_5$ phases.

• Journal of Welding and Joining
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• v.25 no.2
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• pp.82-88
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• 2007

Sn-3.0Ag-0.5Cu lead fee solder was generally utilized in electronics assemblies. But it is insufficient to research about activation energy(Q) that is applying to evaluate the solder joint reliability of environmental friendly electronics assemblies. Therefore this study investigated Q values which are needed to IMC formation and growth of Sn-3.0Ag-0.5Cu/Cu and Sn-40pb/Cu solder joints during aging treatment. We bonded Sn-3.0Ag-0.5Cu and Sn-40Pb solders on FR-4 PCB with Cu pad$(t=80{\mu}m)$. After reflow soldering, to observe the IMC formation and growth of the solder joints, test specimens were aged at 70, 150 and $170^{\circ}C$ for 1, 2, 5, 20, 60, 240, 960, 15840, 28800 and 43200 min, respectively. SEM and EDS were utilized to analysis the IMCS. From these results, we measured the total IMC$(Cu_6Sn_5+Cu_3Sn)$ thickness of Sn-3.0Ag-0.5Cu/Cu and Sn-40Pb/Cu interface, and then obtained Q values for the IMC$(Cu_6Sn_5,\;Cu_3Sn)$ growth of the solder joints.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.235-237
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• 2007

In this paper, fabrication of Sn-3.0Ag-0.5Cu solder bumping having accurate composition and behavior of intermetallic compounds(IMCs) growth at interface between Sn-Ag-Cu bumps and Cu substrate were studied. The ternary alloy of the Sn-3.0Ag-0.5Cu solder was made by two binary(Sn-Cu, Sn-Ag) electroplating on Cu pad. For the manufacturing of the micro-bumps, photo-lithography and reflow process were carried out. After reflow process, the micro-bumps were aged at $150^{\circ}C$ during 1 hr to 500 hrs to observe behavior of IMCs growth at interface. As a different of Cu contents(0.5 or 2wt%) at Sn-Cu layer, behavior of IMCs was estimated. The interface were observed by FE-SEM and TEM for estimating of their each IMCs volume ratio and crystallographic-structure, respectively. From the results, it was found that the thickness of $Cu_3Sn$ layer formed at Sn-2.0Cu was thinner than the thickness of that layer be formed Sn-0.5Cu. After aging treatment $Cu_3Sn$ was formed at Sn-0.5Cu layer far thinner.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.4 s.33
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• pp.43-48
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• 2004

Electromigration of Sn-3.5Ag-0.5Cu solder bumps was investigated with current densities of $3{\~}4{\times}10^4 A/cm^2$ at temperatures of $130{\~}160^{\circ}C$ using flip chip specimens which consisted of upper Si chip and lower Si substrate. Electromigration failure of the Sn-3.5Ag-0.5Cu solder bump occurred with complete consumption of Cu UBM and void formation at cathode side of the solder bump. The activation energies for electromigration of the Sn-3.5Ag-0.5Cu solder bump were measured as 0.61 eV at current density of $3{\times}10^4 A/cm^2$, 0.63 eV at $3.5{\times}10^4 A/cm^2$, and 0.77 eV at $4{\times}10^4 A/cm^2$, respectively.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.4
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• pp.51-57
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• 2008

In this paper, wetting and interfacial reaction properties for low Ag containing Sn-Ag-Cu Pb-free solder alloy, i.e., Sn-0.3Ag-0.7Cu were investigated and compared with those of Sn-1.0Ag-0.5Cu and Sn-3.0Ag-0.5Cu. Melting behavior and stress-strain curves of some Sn-xAg-xCu alloys were also measured using a differential scanning calorimeter(DSC) and a tensile test machine, respectively. In order to enhance insufficient wetting properties of Sn-0.3Ag-0.7Cu alloy, the improvement of wetting properties were analyzed by applying fluxes containing higher content of halide or indium adding of 0.2wt.% into the solder alloy. It was concluded that the small addition of indium is more effective for the improvement of wettability in low temperature range of $230{\sim}240^{\circ}C$ than applying flux containing higher content of halide.

• Korean Journal of Materials Research
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• v.15 no.9
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• pp.598-603
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• 2005

To develope new lead-free solders with the melting temperature close to that of Sn-37Pb$(183^{\circ}C)$, Sn-0.7Cu-5Pb-1Ga, Sn-0.7Cu-5Pb-1Ag, Sn-0.7Cu-5Pb-5Bi-1Ag, and Sn-0.7Cu-SBi-1Ag alloys were composed by adding low-netting elements such as Ga, Bi, Pb, and Ag to Sn-0.7Cu. Then the melting temperatures, microstructures, wettability, and adhesion properties of these alloys were evaluated. DSC analysis showed that the melting temperature of Sn-0.7Cu-SPb-1Ga was $211^{\circ}C$, and those of other alloys was in the range of $192\~200^{\circ}C$. Microstructures of these alloys after heat-treatment at $150^{\circ}C$ for 24 hrs were basically composed of coarsely- grown $\beta-Sn$ grains, and $Cu_6Sn_5$ and $Ag_3Sn$ intermetallic precipitates. Sn-0.7Cu-5Pb-1Ga and Sn-0.7Cu-5Pb-5Bi-1Ag showed excellent wettability, while Sn-0.7Cu-5Bi-1Ag and Sn-0.7Cu-5Pb-5Bi-1Ag revealed good adhesion strength with the Cu substrates. Among 4 alloys, Sn-0.7Cu-5Pb-5Bi-1Ag with the lowest melting temperature $(192^{\circ}C)$ and relatively excellent wettability and adhesion strength was suggested to be the best candidate solder to replace Sn-37Pb.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.18-18
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• 2007

지난 수년 동안 Sn-3.0Ag-0.5Cu 합금은 전자산업의 표준 무연솔더 조성으로 전자제품의 제작에 사용되어져 왔으며, 그 신뢰성도 충분히 검증되어 대표적인 무연 솔더 조성으로의 입지를 굳혀왔다. 그러나 전자제품의 mobile화에 따른 내충격 신뢰성에 대한 요구와 최근의 급격한 Ag 가격의 상승은 Ag 함량의 축소에 의한 원가절감을 요청하게 되었으며, 이에 따라 소량의 Ag를 함유하는 솔더 조성 개발에 대한 연구가 산업 현장을 중심으로 절실히 요청되고 있다. Sn-Ag-Cu의 3원계 함긍에서 Ag는 합금의 융점을 낮추고, 강도와 같은 합금의 기계적 특성을 증가시키는 한편, 모재에 대한 합금의 젖음성을 향상시키는데 필수적인 원소로 인식되고 있다. 따라서 Sn-Ag-Cu의 3원계 함금에서 Ag의 함량을 감소시키게 되면, 합금액 액상선 온도와 고상선 온도가 벌어져 pasty range(또는 mush zone)가 증가하게 되고, wettability도 감소하게 되어 솔더 합금으로서의 요구 특성을 많이 상실하게 된다. 또한 Ag 함량을 감소시키게 되면 합금의 elongation이 향상되면서 내 impact 수명이 향상되는 효과를 볼 수 있으나, 합금의 creep 특성 및 기계적인 강도는 감소하면서 열싸이클링 수명은 감소하는 경향을 나타내게 된다. 따라서 솔더 합금의 내 impact 수명과 열싸이클링 수명을 동시에 만족시키지 위해서는 Ag 함량을 최적화하기 위한 고려가 필요하며, 합금원소에 대한 연구가 요청된다고 하겠다. 한편 Ag의 함량을 3wt.% 이상으로 첨가할 경우에도 비교적 느린 응고 속도에서는 조대한 판상의 $Ag_3Sn$ 상을 형성하는 경향이 있어 외관 물량을 야기 시킬 가능성이 매우 커지는 현상도 보고되고 있다. 따라서 Ag의 첨가량을 최적화 하면서 솔더 재료로서의 특성을 계속적으로 유지하기 위해서는 제 4 원소의 함유가 필수적이라고 할 수 있다. 본 연구에서는 Sn-Ag-Cu계에 첨부하는 제 4원소로서 In을 선택하였다. 비록 In은 Ag보다 고가이기 때문에 산업적인 적용을 위한 솔더 합금 원소로는 거의 각광받지 못했으나, 본 연구의 결과로는 In은 매우 소량 첨가할 경우에도 Sn-Ag-Cu계 합금, 특히 소량의 Ag를 함유하는 Sn-Ag-Cu계 합금의 wettabilty와 기계적 특성 향상에 매우 효과적임을 알 수 있었다. 결론적으로 본 연구를 통해 구현된 Sn-Ag-Cu-In계 최적 솔더 조성의 경우 Sn-3.0Ag-0.5Cu의 표준 조성에 비하여 약 18%의 원자재 가격 절감을 도모할 수 있을 것으로 예상되는 한편. Sn-3.0Ag-0.5Cu에 유사하거나 우수한 wettability 특성을 나타내었고. Sn-1.0Ag-0.5Cu 또는 Sn-l.2Ag-0.5Cu-0.05Ni 조성보다는 월등히 우수한 wettability 특성을 나타내었다. 더구나 Sn-Ag-Cu-In계 최적 솔더 조성은 합금의 강도 저하는 최소화 시키면서 합금의 elongation은 극적으로 향상시켜 합금의 toughness 값이 매우 우수한 특성을 가짐을 알 수 있었다. 이렇게 우수한 toughness 값은 솔더 조인트의 대표적 신뢰성 요구 특성인 열싸이클링 수명과 내 impact 수명을 동시에 향상시킬 수 있을 것으로 예상된다. 요컨대 본 연구를 통해 구현된 Sn-Ag-Cu-In계 솔더 조성은 최적 솔더 조성에서 요구되는 4가지 인자, 즉, 저렴한 원재료 가격, 우수한 wettability 특성, 합금 자체의 높은 toughness, 안정하고 낮은 성장 속도의 계면 반응층 생성을 모두 만족시키는 특징을 가짐으로서 기존 무연솔더 조성의 새로운 대안으로 자리 잡을 것으로 기대된다.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.3
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• pp.31-36
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• 2012

In this study, the complex vibration reliability of Sn-3.5Ag and Sn-0.7Cu having a high melting temperature was investigated. For manufacturing of BGA test samples, Sn-3.5Ag and Sn-0.7Cu balls were joined on BGA chips finished by ENIG and the chips were mounted on PCB finished OSP by using reflow process. For measuring of resistance change during complex vibration test, daisy chain was formed in the test board. From the results of resistance change and shear strength change, the reliability of two solder balls was compared and evaluated. During complex vibration for 120 hours, Sn-0.7Cu solder was more stable than Sn-3.5Ag solder in complex vibration test.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.218-220
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• 2006

Sn-3.0Ag-0.5Cu solder is widely used as micro-joining materials of flip chip package(FCP) because of the fact that it causes less dissolution and has good thermal fatigue property. However, compared with ternary electroplating in the manufacturing process, binary electroplating is still used in industrial field because of easy to make plating solution and composition control. The objective of this research is to fabricate Sn-3.0Ag-0.5Cu solder bumping having accurate composition. The ternary Sn-3.0Ag-0.5Cu solder bumping could be made on a Cu pad by sequent binary electroplating of Sn-Cu and Sn-Ag. Composition of the solder was estimated by EDS and ICP-OES. The thickness of the bump was measured using SEM and the microstructure of intermetallic-compounds(IMCs) was observed by SEM and EDS. From the results, contents of Ag and CU found to be at $2.7{\pm}0.3wt%\;and\;0.4{\pm}0.1wt%$, respectively.