• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.05a
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• pp.85-91
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• 2002

Even though electroless Hi and Sn-Ag-Cu solder are widely used materials in electronic packaging applications, interfacial reactions of the ternary Ni-Cu~Sn system have not been known well because of their complexity. Because the growth of intermetallics at the interface affects reliability of solder joint, the intermetallics in Ni-Cu-Sn system should be identified, and their growth should be investigated. Therefore, in present study, interfacial reactions between electroless Ni UB7f and 95.5Sn-4.0Ag-0.5Cu alloy were investigated focusing on morphology of the IMCs, thermodynamics, and growth kinetics. The IMCs that appear during a reflow and an aging are different each other. In early stage of a reflow, ternary IMC whose composition is Ni$_{22}$Cu$_{29}$Sn$_{49}$ forms firstly. Due to the lack of Cu diffusion, Ni$_{34}$Cu$_{6}$Sn$_{60}$ phase begins growing in a further reflow. Finally, the Ni$_{22}$Cu$_{29}$Sn$_{49}$ IMC grows abnormally and spalls into the molten solder. The transition of the IMCs from Ni$_{22}$Cu$_{29}$Sn$_{49}$ to Ni$_{34}$Cu$_{6}$Sn$_{60}$ was observed at a specific temperature. From the measurement of activation energy of each IMC, growth kinetics was discussed. In contrast to the reflow, three kinds of IMCs (Ni$_{22}$Cu$_{29}$Sn$_{49}$, Ni$_{20}$Cu$_{28}$Au$_{5}$, and Ni$_{34}$Cu$_{6}$Sn$_{60}$) were observed in order during an aging. All of the IMCs were well attached on UBM. Au in the quaternary IMC, which originates from immersion Au plating, prevents abnormal growth and separation of the IMC. Growth of each IMC is very dependent to the aging temperature because of its high activation energy. Besides the IMCs at the interface, plate-like Ag3Sn IMC grows as solder bump size inside solder bump. The abnormally grown Ni$_{22}$Cu$_{29}$Sn$_{49}$ and Ag$_3$Sn IMCs can be origins of brittle failure.failure.

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.1-26
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• 1994

The purpose of this study was to investigate the dissolution components during corrosion of amalgams and to identify surface corrosion products in the modified Fusayama artificial saliva. Four type of amalgam alloys were used: low copper lathe cut amalgam alloy (Cavex 68), low copper spherical amalgam alloy (Caulk Spherical Alloy), high copper admixed amalgam alloy (Dispersalloy) and high copper single composition amalgam alloy (Tytin). Each amalgam alloy and Hg were triturated according to the manufacturer's direction by means of mechanical amalgamator (Capmaster, S.S.White), and then the triturated mass was inserted into the cylindrical metal mold which was 10mm in diameter and 2.0mm in height and condensed with compression of 150kg/$cm^2$ using oil pressor. The specimens were removed from the mold and stored at room temperature for 7 days and cleansed with distiled water for 30 minutes in an ultrasonic cleaner. The specimens were immersed in the modified Fusayama artificial saliva for the periods of 1 month, 3 months and 6 months. The amounts of Hg, Cu, Sn and Zn dissolved from each amalgam specimen immersed in the artificial saliva for the periods of 1 month, 3 months and 6 months were measured using Inductivity Coupled Plasma Atomic Emission Spectrometry (ICPQ-1000, Shimadzu, Japan) and amount of Ag dissolved from amalgam specimen was measured using Atomic Absorption Spectrophotometry (Atomic Absorption/Flame emission spectrophotometer M-670, Shimadzu, Japan). A surface corrosion products of specimens were analysed using Electron Spectroscopy Chemical Analyser (ESCA PHI-558, PERKIN ELMER, U.S.A.). The secondary image and back scattered image of corroded surface of specimens was observed under the SEM, and the corroded surface of specimens was analysed with the EDX. The following results were obtained. 1. The dissolution amount of Cu was the most in high copper admixed amalgam(Dispersalloy) and the least in high copper single composition amalgam(Tytin). 2. Sn and Zn were dissolved during all the experiment periods, and dissolution amounts were decreased as the time elapsed. 3. Initial surface corrosion products were ZnO and SnO. 4. Corrosion of ${\gamma}$ and ${\gamma}_2$ phase in low copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in low copper spherical amalgam(Caulk Sperical Alloy). 5. Corrosion of ${\gamma}$ and $\eta$' phase in high copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in high copper admixed amalgam(Dispersalloy). 6. Sn-Cl was produced in the subsurface of low copper amalgams and high copper admixed amalgam.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2004.02a
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• pp.37-59
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• 2004

In the case of Ni/Au finished pad on the package side, the solder joint of SnAgCu system can bring brittle fracture under impact load such as drop test. Therefore, it's difficult to prevent the brittle fracture of lead-free solder, by controlling Cu content. The failure locus existing on the interface between $(Ni,Cu)_3Sn_4\;and\;(Cu,Ni)_6Sn_5$ IMC layers must be changed to other site in order to avoid brittle fracture due to impact load. It was not found any clear evidence that there were two IMC layers exist. But it was strongly assumed these were two layers which have different Cu-Ni composition. From the above analysis it was assumed that Cu atom in the solder alloy or substrate seemed to affect IMC composition and cause to IMC brittle fracture.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.496-499
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• 2000

In order to investigate the effect of Ge addition to the Cu Matrix on the microstructure and the critical current density, four kinds of internal tin processed Nb$_3$Sn strands with pure Cu and Cu 0.2, 0.4, 0.6 wt％ Ge alloy were drawn to 0.8 mm diameter. The microstructure and critical current of internal tin processed Nb$_3$Sn wires that were heat treated at temperatures ranging from 68$0^{\circ}C$ to 74$0^{\circ}C$ for 240 h were investigated. The Ge addition to the matrix did not make workability worse. A Ge rich layer in the Cu-Ge matrix suppressed the growth of the Nb$_3$Sn layer and promoted grain coarsening. The greater the Ge content in the matrix, the lower the net Jc result after Nb$_3$Sn reaction heat treatment. There was no significant variation in Jc observed with heat treatment temperature ranging from 68$0^{\circ}C$ to 74$0^{\circ}C$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.469-470
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• 2012

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2006.04a
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• pp.70-71
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• 2006

• 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.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.1
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• pp.137-143
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• 2008

Thermal fatigue life prediction for solder joints becomes the most critical issue in present microelectronic packaging industry. And lead-free solder is quickly becoming a reality in electronic manufacturing fields. This trend requires life prediction models for new solder alloy systems. This paper describes the life prediction models for SnAgCu and SnPb solder joints, based upon non-linear finite element analysis (FEA). In case of analyses of the SnAgCu solder joints, two kinds of shapes are used. As a result, it is found that the SnAgCu solder has longer fatigue life than the SnPb solder in temperature cycling analyses.

• Journal of Conservation Science
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• v.1 no.1 s.1
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• pp.27-39
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• 1992

Metallurgical studies of the bronze artifacts excavated from Miruksa Temple were performed by chemical analysis and metallographic observation. Alloy systems of the bronze artifacts were classified into two groups of Cu-Sn and Cu-Sn-Pb, according to the items. The contents of impurities such as Sb, As, Ni and Fe in bronze artifacts are within the limiting range of the mod ern standard bronze castings. Chemical compositions of the kitchen utensils such as bronze vessels and dishes in the Unified Silla dynasty, are in the follow ing range, Cu : 74.8-79.4% and Sn : 18.6-21.1%. Chemical composition of the Buddha-image in Koryo dynasty are 820Cu-7.0Sn-10.3Pb, showing increased Pb content and decreased Sn content. The results of chemical analysis suggest that the chemical compositions were good controlled. Any casting defects such as voids and shrinkage holes are not found microscopically, indicating high casting skill. Zinc atoms are not contained in the all bronze artifacts of Miruksa Temple site. This is the common facts founded in the east asian bronze artifacts of Korea, China and Japan. It is comparable with the European bronze of Cu-Sn-Pb-Zn system, after the Middle Age.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.246-249
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• 2000

The effects of Zr on the mechanical workability and tensile strength of Cu-Ni-Mn-Sn-Al alloys have been investigated and the following results were obtained. The mechanical workability of Cu-Ni-Mn-Sn-Al alloys are increased with addition of Zr. And the surface cracks of specimen were not produced in Zr added Alloys. Especially in condition of hot-worked beyond the 90% working ratio, Zr contained specimen showed intra-granule crack propagation but Zr-free specimen showed inter-granule mode. The tensile strength have maximum value in 0.05% Zr contained alloy. The aging mechanism of Cu-Ni-Mn-Sn-Al alloys were varied by Zr addition.