Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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Solder Bump Deposition Using a Laser Beam

레이저빔을 이용한 솔더범프 적층 공정

  • Choi, Won-Suk (Dept. of Nano IT Fusion Program, Seoul National University of Science and Technology, Graduate School of NID Fusion Technology) ;
  • Kim, Jea-Woon (Dept. of Mechanical Design, Seoul National University of Science and Technology, Graduate School of Industry) ;
  • Kim, Jong-Hyeong (School of Mechanical Design & Automation Engineering, Seoul National University of Science and Technology) ;
  • Kim, Joo-Han (Dept. of Mechanical Engineering, Seoul National University of Science and Technology)
  • 최원석 (서울과학기술대학교 NID 융합기술 대학원 Nano IT 융합프로그램) ;
  • 김재운 (서울과학기술대학교 산업대학원 기계설계학과) ;
  • 김종형 (서울과학기술대학교 기계설계자동화공학부) ;
  • 김주한 (서울과학기술대학교 기계공학과)
  • Received : 2011.06.29
  • Accepted : 2011.11.17
  • Published : 2012.01.01
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Abstract

LIFT (laser-induced forward transfer) is an advanced laser processing method used for selectively transferring micron-sized objects. In our study, this process was applied in order to deposit solder balls in microsystem packaging processes for electronics. Locally melted solder paste could be transferred to a rigid substrate using laser pulses. A thin glass plate with a solder cream layer was used as a donor film, and an IR laser pulse (wavelength = 1070 nm) was used to transfer a micron-sized solder ball to the receptor. Mass balance and energy balance were applied to analyze the shape and temperature profiles of the solder paste drops. The transferred solder bumps had measured diameters of 30-40 ${\mu}m$ and thicknesses of 50 ${\mu}m$ in our experiment. The limits and applications of this method are also presented.

LIFT(Laser-Induced-Forward-Transfer) 공정은 선택적으로 마이크로 크기의 물질을 이동시키는데 사용할 수 있는 레이저 공정이다. 본 연구에서 이 공정은 전자부품의 마이크로 시스템 패키징을 위한 솔더볼의 적층을 위해 적용되었다. 레이저 펄스에 의해 국부적으로 녹은 솔더 페이스트는 단단한 기저부분에 이동적층되었다. 솔더 크림층을 지닌 박판유리플레이트가 도우너 필름으로 사용되었고 1070nm 파장의 IR 레이저 펄스를 조사하여 리셉터에 마이크로 솔더를 이동적층하였다. 물질 및 에너지 평형 방정식 등이 솔더 페이스 드롭의 모양과 온도 분포를 분석하기 위해 적용되었다. 실제 실험에서 얻어진 이동적층된 솔더 범프는 30~40 ${\mu}m$ 의 직경과 50 ${\mu}m$ 의 두께를 가진 것으로 측정되었다. 본 공정의 한계 및 적용에 대해서도 논의한다.

Keywords

Acknowledgement

Supported by : 서울과학기술대학교

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