초음파를 이용한 Sn-3.5Ag 플립칩접합부의 신뢰성 평가- Si웨이퍼와 Sn-3.5Ag 솔더의 접합 계면 특성 연구
Flip chip solder joint reliability of Sn-3.5Ag solder using ultrasonic bonding- Study of the interface between Si-wafer and Sn-3.5Ag solder
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초록
Si-웨이퍼와 FR-4 기판을 상온에서 초음파 접합한 후, 접합부의 신뢰성을 평가하였다. Si-웨이퍼 상의 UBM(Under Bump Metallization)은 위에서부터 Cu/ Ni/ Al을 각각 0.4㎛, 0.4㎛, 0.3㎛의 두께로 전자빔으로 증착하였다. FR-4 기판위의 패드는 위에서부터 Au/ Ni/ Cu를 각각 0.05㎛, 5㎛, 18㎛의 두께로 전해 도금하여 형성하였다. 접합용 솔더로는 Sn-3.5wt%Ag을 두께 100㎛으로 압연하여 사용하였다. 시편의 초음파 접합을 위하여 초음파 접합 시간을 0.5초에서 3.0초까지 0.5초 단위로 증가 시키면서 상온에서 접합하였으며, 이 때 출력은 1,400W로 하였다. 실험 결과, 상온 초음파 접합법에 의해 신뢰성 있는‘Si-웨이퍼/솔더/FR-4 기판’ 접합부를 얻을 수 있었다. 접합부의 전단 강도는 접합 시간에 따라 증가하여 접합 시간 2.5초에서 65N으로 가장 높게 측정되었다. 이 후 접합 시간 3.0초에서는 전단 강도가 34N으로 감소하였는데, 이는 초음파 접합시간이 과도해지면서 Si-웨이퍼와 솔더 사이의 계면을 따라 균열이 발생되었기 때문으로 판단된다. 초음파 접합에 의해 Si-웨이퍼와 솔더 사이에서 생성된 금속간 화합물은 ((Cu,Ni)6Sn5)으로 확인되었다.
Abstract
Ultrasonic soldering of Si-wafer to FR-4 PCB at ambient temperature was investigated. The UBM of Si-substrate was Cu/ Ni/ Al from top to bottom with thickness of 0.4m, 0.4m, and 0.3m respectively. The pad on FR-4 PCB comprised of Au/ Ni/ Cu from top to bottom with thickness of 0.05 m, 5m, and 18m respectively. Sn-3.5wt%Ag foil rolled to 100m was used for solder. The ultrasonic soldering time was varied from 0.5 s to 3.0 s and the ultrasonic power was 1,400 W. The experimental results show that a reliable bond by ultrasonic soldering at ambient temperature was obtained. The shear strength increased with soldering time up to a maximum of 65 N at 2.5 s. The strength decreased to 34 N at 3.0 s because cracks were generated along the intermetallic compound between Si-wafer and Sn-3.5wt%Ag solder. The Intermetallic compound produced by ultrasonic soldering between the Si-wafer and the solder was (Cu, Ni)Sn.
참고문헌 (18)
- "Tensile properties of Sn-Ag based lead-free solders and strain rate sensitivity", a366, pp.50~55 (2004)
- "Cu bump interconnections in 20m pitch utilizing electroless tin-cap on 3D stacked LSI", pp.107~114 (2001)
- "Thermosonic bonding of high-power semiconductor devices for integration with planar microstrip circuitry", pp.390~393 (1998)
- "Longitudinal Ultrasonic Bonding of Strip-type Au Bumps", 22, pp.258~264 (2004)
- "Modeling and Experimetal Studies on Thermosonic Flip-Chip Bonding", 18, pp.728~733 (1995)
- "A New Look at Flux-Free Ultrasonic Soldering", pp.41~45 (2000)
- "Studies of thermaosonic bonding for flip chip assembly", 42, pp.31~37 (1995)
- "Modeling and Experimetal Studies on Thermosonic Flip-Chip Bonding", 18, pp.728~733 (1995)
- "The Handbook of Machine Soldering-SMT and TH, 3rd edn", pp.306~ (1996), John Wiley & Sons
- "The reaction between electroless Ni-Cu-P deposit and 63Sn-37Pb flip chip solder bumps during reflow", 29, pp.1007~1014 (2000)
- "Gold ball bonding on copper substrates at ambient temperatures", 4(1), pp.16~19 (2004)
- "Fluxless Sn-3.5mass%Ag Solder Bump Flip Chip Bonding by Ultrasonic Wave", 43(6), pp.1336~1340 (2002)
- "Thermodynamic aspect of the wire-bonding process", 15(1), pp.23~31 (1998)
- "Metallurgical Reaction of the Sn-3.5Ag Solder and Sn-37Pb Solder with Ni", Cu Under-Bump Metallization in a Flip-Chip Package, 2003, pp.32(12), 1509~1514
- "Interfacial reactions between lead-free solders and common base materials", 49(1), pp.1~60 (2005)
- "Prediction of primary intermetallic compound formation during interfacial reaction between Sn-based solder and Ni substrate", 46, pp.777~781 (2002)
- "Integrated temperature microsensors for characterization and optimization of thermosonic ball bonding process", 23, pp.393~398 (2000)
- "Integrated temperature microsensors for characterization and optimization of thermosonic ball bonding process", 23, pp.393~398 (2000)