• 마이크로전자및패키징학회지
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• 제11권1호
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• pp.77-85
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• 2004

플라즈마 리플로우 솔더링에서 솔더볼의 접합성을 향상시키기 위해 UBM(Under Bump Metallization)을 Ar-10vol%$H_2$플라즈마로 클리닝하는 방법을 연구하였다. UBM층은 Si 웨이퍼 위에 Au(두께; 20 nm)/ Cu(4 $\mu\textrm{m}$)/ Ni(4 $\mu\textrm{m}$)/ Al(0.4 $\mu\textrm{m}$)을 웨이퍼 측으로 차례대로 증착하였다. 무연 솔더로는Sn-3.5wt%Ag, Sn-3.5wt%Ag-0.7wt%Cu를 사용하였고 Sn-37wt%Pb를 비교 솔더로 사용하였다. 지름이500 $\mu\textrm{m}$인 솔더 볼을 플라즈마 클리닝 처리를 한 UBM과 처리하지 않은 UBM위에 놓고, Ar-10%$H_2$플라즈마 분위기에서 플럭스 리스 솔더링하였다. 이 결과는 플럭스를 사용하여 대기 중에서 열풍 리플로우한 결과와 비교하였다. 실험 결과, 플라즈마 클리닝 후 플라즈마 리플로우한 솔더의 퍼짐율이 클리닝 하지 않은 플라즈마 솔더링보다 20-40%정도 더 높았다. 플라즈마 클리닝 후 플라즈마 리플로우한 솔더 볼의 전단 강도는 약58-65MPa로, 플라즈마 클리닝 하지 않은 플라즈마 리플로우보다 60-80%정도 높았으며, 플럭스를 사용한 열풍 리플로우보다는 15-35%정도 높았다. 따라서 Ar-10%$H_2$가스를 사용하여 UBM에 플라즈마 클리닝하는 공정은 플라즈마 리플로우 솔더 볼의 접합강도를 향상시키는데 상당한 효과가 있는 것으로 확인되었다.

• 보존과학연구
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• 통권10호
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• pp.1-40
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• 1989

Between 1976 and 1984 approximately 26.7 tons of Chinese coins were recovered from a shipwreck which was found at the seabed of the Shin an area in the south-western coast of the Korean peninsula. Elements, Cu, Pb, Sn, Fe, Sb, As, Zn, Ag, Ni, Co and Mn, of 54 pieces of the coins were determined by Inductively Coupled Plasma Atomic Emission Spectroscopy(ICP-AIS). The result shows that Ch, Pb, and Sn were found to be major elements roughly the coins with the ratio of 7 : 2 : 1, respectively. Trace elements were classified into 3 levels according to the avarage concentration : Fe,As and Sb(0.1-0.5%), Ag, Mi, Co and Zn(100-1000ppm) and Mn(10ppm). Some systematic tendencies are observed in the composition change with a function of their minting ages .The Wuzhu coins(오수전) from the Eastern Han dynasty(A.D.25-219 )are much more abundant in Cu than the coins of Tang dynasty(A.D.618-907) and later periods. Major element compositions of the Kai -tong Vuan-Bao(개통원보) coins from the Tang dynasty, were remarkably variable. In general, however, the Tang dynasty coins were much more abundant in Cu than the Song dynasty(A.S.S60-1279) coins. The amount of major elements Cu and Sn decreases while that of Pb in creasesby passage of age from the Bei Song dynasty(A.D.960-1127) to later Nam Song dynasty (A.D.1127-1279 ). It means that the quality of coins mere degraded. The amounts of trace elemends(Fe, As, Co, Hn) increases with the above age. High amounts of trace elements are supposed to be a reflection of immaturity of minting techniques or use of impurity-rich raw materials. The Jin dynasty(A.D.1125-1234) coins are found to be rich in Sn and thus contain Pb as the third component. It is quite different from the coins of the Song dynasty. The Zhi-dai Tong-Bao(지대통보) coins of the Yuan dynasty from A.0.1310 are much more abundant in Cu and Sn than those of the Nam Song dynasty .

• 자원리싸이클링
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• 제31권3호
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• pp.61-72
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• 2022

주요성분이 Sn(93.0 %)-Ag(3.26 %)-Cu(0.89 %)로 구성되는 SAC 폐무연솔더로부터 주석과 은을 회수하기 위한 전기화학적인 방법을 연구하였다. 폐무연솔더의 건식용해, 주조를 통해 제조한 작업전극을 사용하여 분극거동 조사와 정전류 전해용해를 실시하였다. 분극시험 시 활성화영역의 산화전류피크는 전해액의 황산 농도가 높아질수록 감소하였으며, 1 molL^-1 황산농도가 전해용해를 위해 가장 적절한 것으로 나타났다. 정전류 용해 시 전극표면의 부동태층인 양극슬라임이 두꺼워짐에 따라 전극전위가 지속적으로 높아졌으며, 10 mAcm^-2에서 25시간동안 지속적인 전해용해가 가능한 반면 50 mAcm^-2에서는 2.5 시간 이후부터 전극전위가 급상승하여 전해용해반응이 중단되었다. 정전류 전해용해 시 은은 양극슬라임에 농축되었으며, 전해액내 염소이온의 농도가 0.3 molL^-1인 경우 농축율이 미첨가 조건보다 12.7% 높은 94.3%를 나타내었다. 또한 염소이온의 첨가에 의해 전해액내 주석이온의 안정성을 높이고 주석의 전착전류효율을 향상시킬 수 있었다.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 추계기술심포지움논문집
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• pp.105-108
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• 2002

환경에 관한 관심이 증대되면서 Sn37Pb 솔더를 대체하기 위한 새로운 무연솔더의 개발이 진행되고 있다1). 또한 연구의 초점이 되고 있는 것이 플럭스의 사용에 관한 것이다. 플럭스는 솔더의 산화막을 제거하는데 필수적이지만, 플럭스 세정제의 독성 문제로 무플럭스 솔더링에 대한 관심이 크게 증대되고 있다2),3). 무플럭스 솔더링의 방법에는 여러 가지가 있으며, 그 중 한가지가 플라즈마를 이용한 방법이다4). 본 연구에서는 솔더표면의 이물질과 산화막을 제거하기 위한 플라즈마 처리가 접합 후, 접합부에 미치는 영향에 대해서 알아보았다. 기판은 Evaporator를 이용하여 Au/Cu/Ni/Al UBM을 증착한 Si-wafer를 사용하였다. 사용된 솔더는 Sn37Pb, Sn3.5Ag와 Sn3.5Ag0.7Cu 솔더볼이며, 열중 및 적외선 겸용 리플로 머신과 Ar＋H$_2$를 이용한 플라즈마 에쳐를 사용하여 범프를 형성하였다. 플라즈마 처리가 계면의 미세조직과 기계적 강도에 끼치는 영향을 알아보기 위하여 플라즈마 처리된 시편과 리플로 한 후의 시편을 비교 분석하였다. 전단시험기로 계면의 강도를 측정하였으며, 주사전자현미경으로 범프의 표면과 계면 및 전단파면을 관찰하고 이에 대하여 고찰하였다. 산화막제거를 위한 플라즈마 처리가 저음점인 솔더의 미세조직을 기존의 솔더링 접합부와는 다르게 변화시킴으로써 솔더부의 전체적인 특성에 영향을 끼치는 것을 알 수 있었다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년도 춘계 학술대회 개요집
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• pp.206-208
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• 2006

The reliability of BGA (ball grid array) package with OSP (organic surface preservative) surface finish under thermal cycle was investigated by using SEM (scanning electron microscopy), EDS(energy dispersive spectroscopy), image tool and ball shear test. The IMCs (intermetallic compounds) were increased with increasing number of thermal cycles. However, the shear strengths of solder ball were decreased with increasing number of thermal cycles. The order of solders which had the highest shear strength as follow: Sn-3.5wt%Ag-0.7wt%Cu, Sn-0.7wt%Cu, Sn-37wt%Pb.

• 한국균학회지
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• 제14권3호
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• pp.209-214
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• 1986

버섯중의 trehalase를 연구하기 위하여 각 버섯의 활성을 측정한 후 가장 활성이 좋은 양송이의 trehalase를 $(NH_4)_2SO_4$로 분획하여 조(粗) trehalase의 성질을 조사해 본 결과는 다음과 같다. 1. 조(粗) trehalase는 pH $5.0{\sim}7.0$, $50^{\circ}C$에서 최적 작용조건을 나타내었다. 2. 조(粗) trehalase는 pH $5.0{\sim}7.0$, $50^{\circ}C$이하에서 안정하였다. 3. 조(粗) trehalase의 활성은 490.2mg%이하의 효소농도 및 $2.6{\times}10^{-3}$이하의 기질 농도 범위 내에서 비례적으로 증가하였다. 4. 기질(trehalose) 농도에 대한 Km 값은 0.76 mM이였다. 5. 금속이온에 대한 조(粗) trehalase 활성은 $Sn^{2+}$, $Ca^{2+}$, $Zn^{2+}$, $Hg^{2+}$, $Cd^{2+}$, $Cu^{2+}$, $Mn^{2+}$, $Al^{3+}$, $Fe^{3+}$에 의하여 현저한 저해효과를 나타낸 반면에 $Ag^{+}$, $Ba^{2+}$, $Mg^{2+}$에 의해서는 활성이 증가하였다.

• 한국표면공학회지
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• 제36권5호
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• pp.373-378
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• 2003

With increasing environmental concerns, application of lead-free solder and fluxless soldering process have been taken attention from the electronic packaging industry. Plasma treatment is one of the soldering methods for the fluxless soldering, and it can prevent environmental pollution cased by flux. On this study fluxless soldering process under $Ar-H_2$plasma using lead free solders such as Sn-3.5 wt%Ag, Sn-3.5 wt%Ag-0.7 wt%Cu and Sn-37%Pb for a reference was investigated. As the plasma reflow has higher soldering temperature than normal air reflow, the effects of UBM(Under Bump Metallization) thickness on the interfacial reaction and bonding strength can be critical. Experimental results showed in case of the thin UBM, Au(20 nm)/Cu(0.3 $\mu\textrm{m}$)/Ni(0.4 $\mu\textrm{m}$)/Al(0.4 $\mu\textrm{m}$), shear strength of the soldered joint was relatively low as 19-27㎫, and it's caused by the crack observed along the bonded interface. The crack was believed to be produced by the exhaustion of the thin UBM-layer due to the excessive reaction with solder under plasma. However, in case of thick UBM, Au(20 nm)/Cu(4 $\mu\textrm{m}$)/Ni(4 $\mu\textrm{m}$)/Al(0.4 $\mu\textrm{m}$), the bonded interface was sound without any crack and shear strength gives 32∼42㎫. Thus, by increasing UBM thickness in this study the shear strength can be improved to 50∼70%. Fluxed reflow soldering under hot air was also carried out for a reference, and the shear strength was 48∼52㎫. Consequently the fluxless soldering with plasma showed around 65∼80% as those of fluxed air reflow, and the possibility of the $Ar-H_2$ plasma reflow was evaluated.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2003년도 기술심포지움 논문집
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• pp.84-87
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• 2003

Since Pb-free solder alloys have been used extensively in microelectronic packaging industry, the interaction between UBM (Under Bump Metallurgy) and solder is a critical issue because IMC (Intermetallic Compound) at the interface is critical for the adhesion of mechanical and the electrical contact for flip chip bonding. IMC growth must be fast during the reflow process to form stable IMC. Too fast IMC growth, however, is undesirable because it causes the dewetting of UBM and the unstable mechanical stability of thick IMC. UP to now. Ni and Cu are the most popular UBMs because electroplating is lower cost process than thin film deposition in vacuum for Al/Ni(V)/Cu or phased Cr-Cu. The consumption rate and the growth rate of IMC on Ni are lower than those of Cu. In contrast, the wetting of solder bumps on Cu is better than Ni. In addition, the residual stress of Cu is lower than that of Ni. Therefore, the alloy of Cu and Ni could be used as optimum UBM with both advantages of Ni and Cu. In this paper, the interfacial reactions of Sn-3.5Ag-0.7Cu solder on Ni-xCu alloy UBMs were investigated. The UBMs of Ni-Cu alloy were made on Si wafer. Thin Cr film and Cu film were used as adhesion layer and electroplating seed layer, respectively. And then, the solderable layer, Ni-Cu alloy, was deposited on the seed layer by electroplating. The UBM consumption rate and intermetallic growth on Ni-Cu alloy were studied as a function of time and Cu contents. And the IMCs between solder and UBM were analyzed with SEM, EDS, and TEM.

• Journal of Welding and Joining
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• 제23권5호
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• pp.49-54
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• 2005

The effective charge number and the critical current density of electromigration in eutetic SnPb and Pb Free $(SnAg_{3.8}Cu_{0.7)$ flip chip solder bumps are studied. The effective charge number of electromigration in eutectic SnPb solder is obtained as 34 and the critical current density is $j=0.169{\times}({\delta}_{\sigma}/{\delta}_x})\;A/cm^2,\;where\;({\delta}_{\sigma}/{\delta}_x})$ is the electromigration-induced compressive stress gradient along the length of the line. While the effect of electromigration in Pb free solder is much smaller than that in eutectic SnPb, the product of diffusivity and effective charge number $DZ^{\ast}$ has been assumed as $6.62{\times}10^{-11}$. The critical length for electromigration are also discussed.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2005년도 학술발표대회 논문집
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• pp.385-392
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• 2005

The restriction of the use of hazardous substances in electrical and electronic equipment legislation mandates the substitution of lead and other hazardous substances in electronics products by July 2006. Due to this legislative pressure, the electronics industry is moving to adoption of lead free solders. In this paper, we investigated a flux to restrict generating electrochemical migration in lead-free solder. The lead-free solders used in this study were Sn-0.7Cu-0.01P and Sn-3.0Ag-0.5Cu. To measure the resistance of electrochemical migration, the dew-cycle test and water drop test were adopted. As the result, now flux having high durable of electrochemical migration was developed.