Journal of the Microelectronics and Packaging Society (마이크로전자및패키징학회지)

The Korean Microelectronics and Packaging Society (한국마이크로전자및패키징학회)
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Flexible Durability of Ultra-Thin FPCB

초박형 FPCB의 유연 내구성 연구

  • Jung, Hoon-Sun (Graduate School of NID Fusion Technology, Seoul National University of Science and Technology) ;
  • Eun, Kyoungtae (Graduate School of NID Fusion Technology, Seoul National University of Science and Technology) ;
  • Lee, Eun-Kyung (Graduate School of NID Fusion Technology, Seoul National University of Science and Technology) ;
  • Jung, Ki-Young (Newflex) ;
  • Choi, Sung-Hoon (Newflex) ;
  • Choa, Sung-Hoon (Graduate School of NID Fusion Technology, Seoul National University of Science and Technology)
  • 정훈선 (서울과학기술대학교 NID 융합기술대학원) ;
  • 은경태 (서울과학기술대학교 NID 융합기술대학원) ;
  • 이은경 (서울과학기술대학교 NID 융합기술대학원) ;
  • 정기영 (뉴프렉스) ;
  • 최성훈 (LS 엠트론) ;
  • 좌성훈 (서울과학기술대학교 NID 융합기술대학원)
  • Received : 2014.11.11
  • Accepted : 2014.12.26
  • Published : 2014.12.30
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Abstract

In this study, we developed an ultra-thin flexible printed circuit board(FPCB) using the sputtered flexible copper clad laminate. In order to enhance the adhesion between copper and polyimide substrate, a NiMoNb addition layer was applied. The mechanical durability and flexibility of the ultra-thin FPCB were characterized by stretching, twisting, bending fatigue test, and peel test. The stretching test reveals that the ultra-thin FPCB can be stretched up to 7% without failure. The twisting test shows that the ultra-thin FPCB can withstand an angle of up to $120^{\circ}$. In addition, the bending fatigue test shows that the FPCB can withstand 10,000 bending cycles. Numerical analysis of the stress and strain during stretching indicates the strain and the maximum von Mises stress of the ultra-thin FPCB are comparable to those of the conventional FPCB. Even though the ultra-thin FPCB shows slightly lower durability than the conventional FPCB, the ultra-thin FPCB has enough durability and robustness to apply in industry.

본 연구에서는 스퍼터링 공정으로 제작된 FCCL(flexible copper clad laminate)을 이용하여 초박형 FPCB를 개발하였다. 또한 구리 박막과 폴리이미드 기판의 접착력을 향상시키기 위한 NiMoNb 접착층을 적용하였다. 개발된 초박형 FPCB의 기계적 내구성과 유연성은 인장, 비틀림 및 굽힘 피로 수명시험을 이용하여 검증하였다. 인장 시험 결과 초박형 FPCB는 약 7% 까지 인장이 가능하였으며, 비틀림 각도 $120^{\circ}$ 까지의 내구성과 유연성을 갖고 있음을 알 수 있었다. 또한 초박형 FPCB는 10,000회의 굽힘 피로시험에도 파괴가 발생하지 않았다. 수치해석에 의한 응력 및 변형율의 계산 결과, 인장 시에 초박형 FPCB에 걸리는 최대 응력 및 변형률은 기존 FPCB에 비하여 크게 차이가 나지 않음을 알 수 있었다. 결론적으로 초박형 FPCB의 강건성은 기존 FPCB에 비하여 약간 열세이나, 제품에 적용하기에는 충분한 강건성과 신뢰성을 갖고 있다고 판단된다.

Keywords

References

  1. E. Menard, R. G. Nuzzo and J. A. Rogers, "Bendable Single Crystal. Silicon Thin Film Transistors Formed by Printing on Plastic Substrates", Appl. Phys. Lett., 86, 093507 (2005). https://doi.org/10.1063/1.1866637
  2. W. Chen, T. L. Alford, T. F. Kuech and S. S. Lau, "High Electron Mobility Transistors on Plastic Flexible Substrates", Appl. Phys. Lett., 98, 203509 (2011). https://doi.org/10.1063/1.3593006
  3. J. S. Eom and S. H. Kim, "Plasma Surface Treatment of Polyimide for Adhesive Cu/80Ni20Cr/PI Flexible Copper Clad Laminate", Thin Solid Films, 516, 4530 (2008). https://doi.org/10.1016/j.tsf.2008.01.022
  4. I.-S. Kang, Y.-S. Koo and J.-H. Lee, "The Effects of Levelers on Electroplating of Thin Copper Foil for FCCL", J. Microelectron. Packag. Soc., 19(2), 67 (2012). https://doi.org/10.6117/kmeps.2012.19.2.067
  5. B. I. Noh, J. W. Yoon and S. B. Jung, "Effect of Laminating Parameters on the Adhesion Property of Flexible Copper Clad Laminate with Adhesive Layer", Int. J. Adhes. Adhes., 30, 30 (2010). https://doi.org/10.1016/j.ijadhadh.2009.07.001
  6. IPC Standard, "IPC-2223B Sectional Design Standard for Flexible Printed Boards" (2008).
  7. ASTM D2176 MIT Folding Endurance Test Method.
  8. B.-I. Noh, J.-W. Yoon and S.-B. Jung, "Effect of Ni-Cr Seed Layer Thickness on the Adhesion Characteristics of Flexible Copper Clad Laminates Fabricated using a Roll-to-Roll Process", Met. Mater. Int., 16, 779 (2010). https://doi.org/10.1007/s12540-010-1013-8
  9. B.-I. Noh, J.-W. Yoon and S.-B. Jung, "Fabrication and Adhesion Strength of Cu/Ni-Cr/polyimide Films for Flexible Printed Circuits", Microelectronic Engineering, 88, 1024 (2011). https://doi.org/10.1016/j.mee.2011.01.071
  10. K.-J. Min, S.-C. Park, J.-J. Lee, K.-H. Lee, G.-H. Lee and Y.-B. Park, "Interfacial Ffracture Eenergy between Electroless Plated Ni Film and Polyimide for Flexible PCB Application", J. Microelectron. Packag. Soc., 14(1), 39 (2007).
  11. S.-H. Bang, K.-K. Kim, H.-Y. Jung, T.-H. Kim, S.-H. Jeon, J.-B. Seol, "Application of NiMoNb Adhesion Layer on Plasma-treated Polyimide Substrate for Flexible Electronic Devices", Thin Solid Films, 558, 405 (2014). https://doi.org/10.1016/j.tsf.2014.02.085
  12. W. C. M. Filho, S. Hameau and M. Brizoux, "Evaluation of Very Low Bending Radius of Flexible Circuits Beyond the Standard Design Rules", 13th. Int. Conference on Thermal, Mechanical and Multiphysics Simulation and Experiments in Micro-Electronics and Micro-Systems, 1 (2012).
  13. S.-I Park, J.-H. Ahn, S. Wang, Y. G. Huang and J. A. Rogers, "Theoretical and Experimental Studies of Bending of Inorganic Electronic Materials on Plastic Substrates", Adv. Funct. Mater., 18, 2673 (2008). https://doi.org/10.1002/adfm.200800306
  14. Z. Suo, E. Y. Ma, H. Gleskova, and S. Wagner, "Mechanics of Rollable and Foldable Film-On-Foil Electronics", Appl. Phys. Lett., 74, 1177 (1999). https://doi.org/10.1063/1.123478
  15. A. Ptchelintsev, "Automated Modeling and Fatigue Analysis of Flexible Printed Circuits", 7th. Int. Conference on Thermal, Mechanical and Multi-physics Simulation and Experiments in Micro-Electronics and Micro-Systems, 1, (2006).

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