초미세 SAC305 나노입자를 사용한 저온 코팅법으로 제조된 SAC305 코팅 Cu의 솔더 젖음성
Wettability of SAC305-coated Cu Fabricated by Low Temperature Process Using Ultrafine SAC305 Nanoparticles
0
조회
0
다운로드
0
인용
0
참고문헌
키워드
초록
직경 20 nm 미만의 금속 나노입자들이 나타내는 저온 용융특성을 이용한 새로운 패드 피니쉬 공정을 적용하여 Cu 표면을 SAC305로 코팅한 후 wettability의 변화를 평가하였다. SAC305 잉크를 사용한 160oC의 저온 코팅공정 시형성되는 SAC305 코팅층의 두께는 수 나노미터 수준으로 극히 얇았으며, 이 코팅층 밑으로 10~100 nm 두께 수준의Cu6Sn5 및 50~150 nm 두께 수준의 Cu3Sn 금속간화합물층 반응층이 생성되었음을 확인할 수 있었다. 즉, 생성된 금속간화합물층의 두께는 압연동 시편에 비해 전해도금동 시편에서 훨씬 두꺼웠는데, 이는 전해도금동 시편에서 관찰되는 향상된 표면 거칠기 특성에 의해 단위면적 기준으로 보다 많은 수의 SAC305 나노입자들이 접촉된 상태에서 용융되어 반응하기 때문으로 분석되었다. 이후 SAC305 솔더볼을 사용한 젖음각 측정 실험에서 저온 SAC 코팅이 이루어진 Cu 표면은SAC 코팅이 없는 Cu 표면에 비해 눈에 띄게 낮은 젖음각을 나타내어 당 코팅법으로 Cu 표면에 단지 수 나노미터 두께의 SAC305 층을 형성시킨 경우에서도 솔더의 wettability 개선을 유도할 수 있음을 확인할 수 있었다.
Abstract
SAC-coated Cu specimens were fabricated by novel pad finish process using a phenomenon that metal nanoparticles less than 20 nm in diameter melted at a temperature lower than the melting point of bulk metal, and their wettabilities were evaluated. The thickness of SAC305 layer coated at low temperature of 160oC using SAC305 ink was extremely thin as the level of several nanometers. It was analyzed by Auger electron spectroscopy that Cu6Sn5 intermetallic layer with a thickness of 10~100 nm and Cu3Sn intermetallic layer with a thickness of 50~150 nm were sequentially formed under the SAC305 coating layer. The thickness of formed intermetallic layers was thicker in electroplated Cu than rolled Cu, which attributed to improved surface roughness in the electroplated Cu. The improved surface roughness induces the contact, melting, and reaction of a larger number of SAC305 nanoparticles per the unit area of Cu specimen. In the wetting angle test using SAC305 solder balls, the Cu coated with SAC305 through the low temperature process presented evidently low wetting angles than those in non-coated Cu, indicating that only a few nanometer-thick SAC305 coating layer on Cu could also cause the enhancement of wettability.
참고문헌 (15)
- J. Fellman, "A Study of The Lead-Free Hot Air Solder Levelling Process", Circuit World, 31(2), pp.3~ (2005)
- A Pietrikova, "VPS and Reliability of Solder Joint", Proc. 15th International Symposium for Design and Technology of Electronics Packages (SIITME2009), pp.395~ (2009), IEEE
- C. M. Liu, "Reflow Soldering And Isothermal Solid-state Aging of Sn-Ag Eutectic Solder on Au", Ni Surface Finish, 2001, pp.30(9), 1152~
- Y. Tomita, "Cu Bump Interconnections in 20 μm-Pitch at Low Temperature Utilizing Electroless Tin-Plating on 3D Stacked LSI", J. Chem. Eng. Jpn, 36(2), pp.119~ (2003)
- J. F Rohan, "Selective Electroless Nickel Deposition on Copper as A Final Barrier", Bonding Layer Material for Microelectronics Applications, 2002, pp.185(3-4), 289~
- P. Snugovsky, "Electroless Ni", Immersion Au Interconnects: Investigation of Black Pad in Wire Bonds and Solder Joints, 2001, pp.30(9), 1262~
- D. Y. R. Chong, "Drop Impact Reliability Testing for Lead-free And Lead-based Soldered IC Packages", Microelectron. Reliab, 46(7), pp.1160~ (2006)
- 성지윤, "리플로우 횟수가 ENIG", Sn-3.5Ag, 마이크로전자 및 패키징학회지, pp.2009, 16(1)[DOI]
- S. L. Lai, "Size-Dependant Melting Properties of Small Tin Particles: Nanocalorimetric Measurements", Phys. Rev. Lett, 77(1), pp.99~ (1996)
- Y. Gao, "Nanoparticles of SnAgCu Lead-free solder Alloy with An Equivalent Melting Temperature of SnPb Solder Alloy", J. Alloys Compd, 484, pp.777~ (2009)
- C. Zou, "Synthesis and DSC Study on Sn3.5Ag Alloy Nanoparticles Used for Lower Melting Temperature Solder", J. Mater. Sci.: Mater. Electron, 21, pp.868~ (2010)
- Y. H. Jo, "New Synthesis Approach for Low Temperature Bimetallic Nanoparticles: Size and Composition Controlled Sn-Cu Nanoparticles", J. Nanosci. Nanotech, 11, pp.1037~ (2011)
- Y. H. Jo, "Synthesis and Characterization of Low Temperature Sn Nanoparticles for The Fabrication of Highly Conductive Ink", Nanotechnology, 22, pp.225701~ (2011)
- 장남이, "주석 나노 입자의 상온 환원 합성에서 PVP Capping Agent의 분자량에 따른 입도 변화", 마이크로전자 및 패키징학회지, 18(4), pp.27~32 (2011), 한국마이크로전자및패키징학회
- T. Novák, "The Area of Spread Solderability Test Use for Roughness Influence Assessment", Proc. 33rd International Spring Seminar on Electronics Technology (ISSE), pp.160~ (2010), IEEE