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

The Korean Society of Mechanical Engineers (대한기계학회)
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Characterization for Viscoelasticity of Glass Fiber Reinforced Epoxy Composite and Application to Thermal Warpage Analysis in Printed Circuit Board

유리섬유강화 복합재의 점탄성 특성 규명 및 인쇄회로기판 열변형해석에의 적용

  • Song, Woo-Jin (Industrial Liaison Innovation Center, Pusan Nat'l Univ.) ;
  • Ku, Tae-Wan (Industrial Liaison Innovation Center, Pusan Nat'l Univ.) ;
  • Kang, Beom-Soo (Dept. of Aerospace Engineering, Pusan Nat'l Univ.) ;
  • Kim, Jeong (Dept. of Aerospace Engineering, Pusan Nat'l Univ.)
  • 송우진 (부산대학교 부품소재산학협력연구소) ;
  • 구태완 (부산대학교 부품소재산학협력연구소) ;
  • 강범수 (부산대학교 항공우주공학과) ;
  • 김정 (부산대학교 항공우주공학과)
  • Published : 2010.02.01
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Abstract

The reliability problems of flip chip packages subjected to temperature change during the packaging process mainly occur due to mismatches in the coefficients of thermal expansion as well as features with time-dependent material properties. Resin molding compounds like glass fiber reinforced epoxy composites used as the dielectric layer in printed circuit boards (PCB) strongly exhibit viscoelastic behavior, which causes their Young's moduli to not only be temperature-dependent but also time-dependent. In this study, the stress relaxation and creep tests were used to characterize the viscoelastic properties of the glass fiber reinforced epoxy composite. Using the viscoelastic properties, finite element analysis (FEA) was employed to simulate thermal loading in the pre-baking process and predict thermal warpage. Furthermore, the effect of viscoelastic features for the major polymeric material on the dielectric layer in the PCB (the glass fiber reinforced epoxy composite) was investigated using FEA.

전자기기부품에 적용되는 회로기판의 패키지 공정상에서 가해지는 온도변화에 따른 신뢰성 평가시 발생되는 문제들은, 주로 회로기판을 구성하고 있는 기본 재료들의 열팽창 계수 차이 및 시간의존성 물성에 의해 영향을 받는다. 특히, 인쇄회로기판 내부 회로층 사이에서 절연 역할을 수행하는 유리섬유강화 복합재료와 같은 수지몰딩 고분자 재료는 온도에 따른 물성변화 뿐만 아니라, 변형 및 하중이 가해지는 시간에 대한 물성변화도 고려해야 하는 점탄성 성질을 나타낸다. 본 논문에서는 인쇄회로기판에 사용되는 주요 고분자 재료인 유리섬유강화 복합재의 시간 및 온도에 따른 점탄성 특성을 규명하기 위하여, 단축인장 모드의 응력완화 시험과 크리프 시험을 각각 수행하였다. 또한, 고분자 재료 점탄성 물성의 영향성을 파악하기 위하여, 유한요소해석을 이용한 인쇄회로기판의 예비가열 공정 상에서 가해지는 온도변화에 따른 열변형을 평가하였다. 이러한 해석결과를 바탕으로, 인쇄회로기판과 같이 고분자재료를 사용하는 전자회로 구조물의 수치해석 기반의 열변형 예측시 점탄성 물성의 고려 필요성을 검증하였다.

Keywords

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