Journal of the Microelectronics and Packaging Society (마이크로전자및패키징학회지)

The Korean Microelectronics and Packaging Society (한국마이크로전자및패키징학회)
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Time-Dependent Warpage Analysis for PCB Considering Viscoelastic Properties of Prepreg

Prepreg의 점탄성 특성을 고려한 PCB의 Time-Dependent Warpage 분석

  • Chanhee Yang (Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST)) ;
  • Chang-Yeon Gu (Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST)) ;
  • Min Sang Ju (Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST)) ;
  • Junmo Kim (Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST)) ;
  • Dong Min Jang (Samsung Electronics Co. Ltd.) ;
  • Jae Seok Jang (Samsung Electronics Co. Ltd.) ;
  • Jin Woo Jang (Samsung Electronics Co. Ltd.) ;
  • Jung Kyu Kim (Samsung Electronics Co. Ltd.) ;
  • Taek-Soo Kim (Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST))
  • 양찬희 (KAIST 기계공학과) ;
  • 구창연 (KAIST 기계공학과) ;
  • 주민상 (KAIST 기계공학과) ;
  • 김준모 (KAIST 기계공학과) ;
  • 장동민 (삼성전자) ;
  • 장재석 (삼성전자) ;
  • 장진우 (삼성전자) ;
  • 김정규 (삼성전자) ;
  • 김택수 (KAIST 기계공학과)
  • Received : 2024.06.07
  • Accepted : 2024.06.26
  • Published : 2024.06.30
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Abstract

In this study, the time-dependent warpage behavior caused by the viscoelastic properties of prepreg in a printed circuit board (PCB) was analyzed by finite element method (FEM). The accurate viscoelastic properties of the prepreg were measured by stress relaxation test, which were then incorporated into constructed warpage analysis model. When the PCB was subjected to repeated thermal cycles, the warpage of the PCB was restored to its initial state when only the elastic properties of the prepreg were considered, but when the viscoelastic properties were also considered, the warpage was not restored and permanent warpage change occurred. The warpage analysis for three different types of prepreg was conducted to compare their mechanical reliability, and the results showed that materials with elastic properties dominating over viscoelastic properties experienced less warpage, resulting in better mechanical reliability.

본 연구에서는 인쇄 회로 기판(printed circuit board; PCB) 내 prepreg의 점탄성 특성에 따라 발생하는 time-dependent warpage 거동 양상을 유한요소해석 시뮬레이션을 통해 분석하였다. 응력 완화 시험(stress relaxation test)을 통해 prepreg의 정확한 점탄성 물성을 측정하였으며, 이를 시뮬레이션에 반영하여 warpage 분석을 진행하였다. PCB에 반복적인 열 사이클이 가해지는 상황에서 prepreg의 탄성 특성만을 반영한 경우에는 PCB의 warpage가 초기 상태로 원복되었지만, prepreg의 점탄성 특성까지 반영하였을 때는 그 warpage가 원복되지 못하고 영구적인 warpage 변화가 발생함을 확인하였다. 각기 다른 3개 종류의 prepreg 원자재에 대한 warpage 해석을 진행하여 그 기계적 신뢰성을 비교 분석하였으며, 그 결과 탄성 특성이 점탄성 특성보다 우세한 재료일수록 warpage가 더욱 적게 발생하여 기계적 신뢰성이 우수하였다.

Keywords

Acknowledgement

This research was supported by a Semiconductor Industry Collaborative Project between Korea Advanced Institute of Science and Technology and Samsung Electronics Co. Ltd. (No. IO230411-05865-01).

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