• 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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• 제19권5호
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• pp.534-539
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• 2001

The formation mechanism of microconstituents in brazed joints of duplex stainless steel and Cr-Cu alloy which is an essential process of rocket engine manufacturing was investigated using Cu base insert metal. $SUS329J_3L$ and C18200 were used for base metal and AMS 4764 was used for insert metal. The brazing was carried out under various conditions. There were various phases in the joints, because of reaction between liquid insert metal and base metals. Since liquid insert metal reacts with duplex stainless steel, liquid Cu from insert metal infiltrated into the $\alpha/\beta$ interface of duplex stainless steel. Through the process of Cu infiltration, isolated stainless steel pieces come into the liquid insert metal. Since liquid insert metal reacts with Cr-Cu alloy. Cr precipitates from C18200 come into the liquid insert metal. With increment of bonding temperature and holding time, amounts and sizes of phases increased. but Cr-Mn compounds decreased at 1303k for 1.2ks and Mn-rich phases disappeared Fe-Cr compounds formed.

• 마이크로전자및패키징학회지
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• 제26권4호
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• pp.1-6
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• 2019

Recently, as electric vehicles and hybrid vehicles are widely used, the use of rechargeable batteries is increasing. Electric and hybrid cars are made up of hundreds to thousands of electric cells depending on the car model. And the assembly process of the cells and modules requires a variety of bonding process. Meanwhile, in order to connect several cells in series, Cu used as a cathode and Al of an anode must be bonded. In this paper, the characteristics of Al and Cu metals, laser types, characteristics and principles of welding lasers for welding of Cu and Al electrodes are introduced.

• 한국표면공학회지
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• 제27권1호
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• pp.29-35
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• 1994

The effects of coating of 3$\mu\textrm{m}$ thickness on the mechanical property of alumina after heat treatment at 100$0^{\circ}C$ for 30minutes under $10^{-6}$torr vacuum was quantified in terms of modulus of rupture(MOR) using Weibull plot. While the copper coating did not change MOR of alumina due to the nonwetting behavior of Cu on $Al_2O_3$, the reactive titanium metal coating caused a noticeable 29% reduction in averaged MOr strength. This was related with the combined effects of microcracks in coating formed during heat treatment and good bonding character between Ti and $Al_2O_3$. The effect of cosputtering of Ti and Cu, bilayer coatings of Cu/Ti and Ti/Cu were also investigated. It was found that Ti, cosputtered, Cu/ti and Ti/Cu coatings reduced MOR strength of alumina in the order listed. This was correlated with the amount of Ti at coating/alumina inter-face associated with a coated layer or segregation of Ti during heat treatment.

• 마이크로전자및패키징학회지
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• 제29권2호
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• pp.73-79
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• 2022

본 연구에서는 최근 저온접합 소재로 각광받고 있는 Ga과 대표적인 전극 물질인 Cu와의 반응연구를 실시하여 저온 솔더링 적용시 필요한 정보들을 확인하고자 하였다. 80-200℃ 온도범위에서 Ga과 Cu/Au 기판을 반응시켜 계면반응 및 금속간화합물(IMC) 성장을 관찰하고 분석하였다. 반응계면에서 성장하는 주요한 IMC는 CuGa₂ 상이었으며 그 상부에는 작은 입자크기를 가지는 AuGa₂ IMC 그리고 하부에는 얇은 띠 형상의 Cu₉Ga₄ IMC가 형성되었다. CuGa₂ 입자들은 scallop 형상을 보이며 Cu₆Sn₅ 성장의 경우와 비슷하게 반응시간이 증가함에 따라서 큰 형상변화없이 입자 크기가 증가하였다. CuGa₂ 성장기구를 분석한 결과 120-200℃ 온도범위에서 시간지수는 약 3.0으로 산출되었고, 활성화에너지는 17.7 kJ/mol로 측정되었다.

• Journal of Welding and Joining
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• 제15권5호
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• pp.56-63
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• 1997

In The study, the bonding of WC-9%Co to SUJ2 steel using Ag-Cu-Zn-Cd insert metal has performed to investigate the bonding properties by heat-treatment. Bonding was brazed for 5-30min at 95$0^{\circ}C$, performed solution treatment for 5 min at 85$0^{\circ}C$ and sustained subsequently oil quenching. To investigate the effect of heat-treatment, tempering was executed at $600^{\circ}C$ for 30 min after oil quenching. Mechnical properties and chemical compositions on the brazed bonding interface were investigated by means of microstructural observation, 4-point bending test and EDS and XRD measurements. The results obtained were as follows. 1) The bonding strength of WC-9%Co/SUJ2 joints by Ag-Cu-Zn-Cd insert metal obtained about 78, 117 and 72MPa after brazing for 5, 20 and 30 min at 95$0^{\circ}C$. And the highest bonding strength obtained about 131MPa after brazing for10 min at 95$0^{\circ}C$ 2) Higher bonding strength of 288MPa was obtained in the joint that brazed for 10 min at 95$0^{\circ}C$, and carried out tempering for 30 min at $600^{\circ}C$ subsequently. 3) Fracture of joint brazed by Ag-Cu-Zn-Cd insert metal for 5, 10, 20 and 30 min created WC-9%Co/SUJ2 interface. The joint that brazed for 10 min at 95$0^{\circ}C$ and then tempered for 30 min at $600^{\circ}C$ was fractured at the site of WC-9%Co.

• 마이크로전자및패키징학회지
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• 제17권1호
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• pp.69-73
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• 2010

Through-silicon-via (TSV)를 포함하고 있는 3차원 적층 반도체 패키지에서 구조적 변수에 따른 열응력의 변화를 살펴보기 위하여 유한요소해석을 수행하였다. 이를 통하여 TSV를 포함하고 있는 3차원 적층 반도체 패키지에서 웨이퍼 간 접합부의 지름, TSV 지름, TSV 높이, pitch 변화에 따른 열응력의 변화를 예측하였다. 최대 von Mises 응력은 TSV의 가장 위 부분과 Cu 접합부, Si, underfill 계면에서 나타났다. TSV 지름이 증가할 때, TSV의 가장 위 부분에서의 von Mises 응력은 증가하였다. Cu 접합부 지름이 증가할 때, Si과 Si 사이의 Cu 접합부가 Si, underfill과 만나는 부분에서 von Mises 응력이 증가하였다. Pitch가 증가할 때에도, Si과 Si 사이의 Cu 접합부가 Si, underfill과 만나는 부분에서 von Mises 응력이 증가하였다. 한편, TSV 높이는 von Mises 응력에 크게 영향을 미치지 못하였다. 따라서 TSV 지름이 작을수록, 그리고 pitch가 작을수록 기계적 신뢰성은 향상되는 것으로 판단된다.

• 마이크로전자및패키징학회지
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• 제14권4호
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• pp.63-69
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• 2007

Cu 비아를 이용한 MEMS 센서의 스택 패키지용 interconnection 공정을 연구하였다. Ag 페이스트 막을 유리기판에 형성하고 관통 비아 홀이 형성된 Si 기판을 접착시켜 Ag 페이스트 막을 Cu 비아 형성용 전기도금 씨앗층으로 사용하였다. Ag 전기도금 씨앗층에 직류전류 모드로 $20mA/cm^2$와 $30mA/cm^2$의 전류밀도를 인가하여 Cu 비아 filling을 함으로써 직경 $200{\mu}m$, 깊이 $350{\mu}m$인 도금결함이 없는 Cu 비아를 형성하는 것이 가능하였다. Cu 비아가 형성된 Si 기판에 Ti/Cu/Ti metallization 및 배선라인 형성공정, Au 패드 도금공정, Sn 솔더범프 전기도금 및 리플로우 공정을 순차적으로 진행함으로써 Cu 비아를 이용한 MEMS 센서의 스택 패키지용 interconnection 공정을 이룰 수 있었다.

• 한국재료학회지
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• 제17권3호
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• pp.152-159
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• 2007

When the electronics are tested with thermal shock for Pb-free solder joint reliability, there are temperature conditions with use environment but number of cycles for test don't clearly exist. To obtain the long term reliability data, electronic companies have spent the cost and times. Therefore this studies show the test method and number of thermal shock cycles for evaluating the solder joint reliability of electronic components and also research bonding strength variation with formation and growth of intermetallic compounds (IMC). SMD (surface mount device) 3216 chip resistor and 44 pin QFP (quad flat package) was utilized for experiments and each components were soldered with Sn-40Pb and Sn-3.0 Ag-0.5 Cu solder on the FR-4 PCB(printed circuit board) using by reflow soldering process. To reliability evaluation, thermal shock test was conducted between $-40^{\circ}C\;and\;+125^{\circ}C$ for 2,000 cycles, 10 minute dwell time, respectively. Also we analyzed the IMCs of solder joint using by SEM and EDX. To compare with bonding strength, resistor and QFP were tested shear strength and $45^{\circ}$ lead pull strength, respectively. From these results, optimized number of cycles was proposed with variation of bonding strength under thermal shock.

• 대한기계학회논문집
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• 제12권4호
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• pp.755-759
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• 1988

Laminated Composites, SS41-Cu-SS41 plates are made by brazing bonding and hot bonding process. Fatigue repeated plane bending tests are carried out and the fracture behavior of Laminated composites, SS41-Cu-SS41 plates are compared with that of homogeneous steel, SS41plates. The following results are obtained; (1) The fatigue life of the brazing bonding plates is higher than those of SS41 plates and hot bonding plates under high stress. (2) The relations between the fatigue crack growth rate, da/dN and stress intensity factor are, da/dN=4.7*10$^{-10}$ $K^{3.20}$, for SS41 da/dN=7.8*10$^{-9}$ $K^{2.43}$, for CAH da/dN=3.6*10$^{-9}$ $K^{2.54}$, for CAB da/dN=1.58*10$^{-9}$ $K^{2.94}$ , for PAH da/dN=1.23*10$^{-9}$ $K^{2.69}$, for PAB