마이크로전자및패키징학회지 (Journal of the Microelectronics and Packaging Society)

  • 제29권3호
  • /
  • Pages.49-53
  • /
  • 2022
  • /
  • 1226-9360(pISSN)
  • /
  • 2287-7525(eISSN)
한국마이크로전자및패키징학회 (The Korean Microelectronics and Packaging Society)
권호 표지
DOI QR코드

DOI QR Code

초박형 유리층 보호를 위한 펜 낙하 시험의 기계적 모델링

Mechanical Modeling of Pen Drop Test for Protection of Ultra-Thin Glass Layer

  • Oh, Eun Sung (Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST)) ;
  • Oh, Seung Jin (Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST)) ;
  • Lee, Sun-Woo (Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST)) ;
  • Jeon, Seung-Min (SK Innovation Co. Ltd.) ;
  • Kim, Taek-Soo (Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST))
  • 투고 : 2022.09.13
  • 심사 : 2022.09.28
  • 발행 : 2022.09.30
PDF 다운로드
⟨ 이전 논문 다음 논문 ⟩

초록

초박형 유리(Ultra-Thin Glass, UTG)는 디스플레이 보호용 커버 윈도우로 폴더블(foldable) 디스플레이에 사용되고 있으며, 향후에는 롤러블(rollable) 디스플레이나 다양한 플렉시블(flexible) 전자기기에 확대 적용될 것으로 예상되고 있다. 폴더블 디스플레이의 경우, 사용자들에 의해 굽힘과 터치 펜에 의해 충격을 받게 되고, 이 외에도 낙하 등 다른 외부충격에 쉽게 노출되어 있다. 초박형 유리는 100 ㎛ 이하로 두께가 얇고 취성하여 여러 외부 충격에 의해 쉽게 균열이나 파단이 발생할 수 있고, 이러한 균열이나 파단은 폴더블 디스플레이에 심각한 신뢰성 문제를 야기한다. 따라서, 본 연구에서는 초박형 유리의 내충격 신뢰성을 평가하는 펜 낙하 실험을 유한 요소 모델로 구성하고, 초박형 유리의 내충격 신뢰성을 향상시키기 위한 기계적 모델링을 진행하였다. 초박형 유리층 상부 혹은 하부에 보강층을 삽입했을 때, 펜 낙하에 의해 초박형 유리층에 작용하는 응력 메커니즘을 분석하였고, 그에 따라 신뢰성 향상을 위한 최적의 구조를 제시하였다. 또한 초박형 유리의 강도에 따른 최대 펜 낙하 높이를 예측할 수 있도록 펜 낙하 높이에 따라 초박형 유리층에 작용하는 최대 주 응력 값을 분석하였다.

Ultra-thin glass (UTG) has been widely used in foldable display as a cover window for the protection of display and has a great potential for rollable display and various flexible electronics. The foldable display is under impact loading by bending and touch pen and exposed to other external impact loads such as drop while people are using it. These external impact loads can cause cracks or fracture to UTG because it is very thin under 100 ㎛ as well as brittle. Cracking and fracture lead to severe reliability problems for foldable smartphone. Thus, this study constructs finite element analysis (FEA) model for the pen drop test which can measure the impact resistance of UTG and conducts mechanical modeling to improve the reliability of UTG under impact loading. When a protective layer is placed to an upper layer or lower layer of UTG layer, stress mechanism which is applied to the UTG layer by pen drop is analyzed and an optimized structure is suggested for reliability improvement of UTG layer. Furthermore, maximum principal stress values applied at the UTG layer are analyzed according to pen drop height to obtain maximum pen drop height based on the strength of UTG.

키워드

과제정보

본 연구는 (주)SK innovation의 위탁 연구 지원을 받아 수행된 연구결과입니다.

참고문헌

  1. E. G. Jeong, J. H. Kwon, K. S. Kang, S. Y. Jeong, and K. C. Choi, "A review of highly reliable flexible encapsulation technologies towards rollable and foldable OLEDs", J. Inf. Disp., 21(1), 19-32 (2020). https://doi.org/10.1080/15980316.2019.1688694
  2. M. H. Ha, J. K. Choi, B. M. Park, and K. Y. Han, "Highly flexible cover window using ultra-thin glass for foldable displays", J. Mech. Sci. Technol., 35(2), 661-668 (2021). https://doi.org/10.1007/s12206-021-0126-y
  3. S. J. Oh, B. S. Ma, C. Yang, M. Song, and T. S. Kim, "Mechanical Property Evaluation of Dielectric Thin Films for Flexible Displays using Organic Nano-Support-Layer", J. Microelectron. Packag. Soc., 28(3), 33-38 (2021).
  4. J. Wu, C. Yin, J. Zhou, H. Li, Y. Liu, Y. Shen, S. Garner, Y. Fu, and H. Duan, "Ultrathin glass-based flexible, transparent, and ultrasensitive surface acoustic wave humidity sensor with ZnO nanowires and graphene quantum dots", ACS Appl. Mater. Interfaces., 12(35), 39817-39825 (2020). https://doi.org/10.1021/acsami.0c09962
  5. D. Kim, S. S. Shin, S. M. Lee, J. S. Cho, J. H. Yun, H. S. Lee, and J. H. Park, "Flexible and semi-transparent ultra-thin CIGSe solar cells prepared on ultra-thin glass substrate: a key to flexible bifacial photovoltaic applications", Adv. Funct. Mater., 30(36), 2001775 (2020). https://doi.org/10.1002/adfm.202001775
  6. G. Macrelli, A. K. Varshneya, and J. C. Mauro, "Ultra-thin glass as a substrate for flexible photonics", Opt. Mater., 106, 109994 (2020). https://doi.org/10.1016/j.optmat.2020.109994
  7. S. J. Oh, B. S. Ma, H. J. Kim, C. Yang, and T. S. Kim, "Measurement of Mechanical Properties of Thin Film Materials for Flexible Displays", J. Microelectron. Packag. Soc., 27(3), 77- 81 (2020).
  8. A. C. Teloeken, D. A. Lamb, T. O. Dunlop, and S. J. C. Irvine, "Effect of bending test on the performance of CdTe solar cells on flexible ultra-thin glass produced by MOCVD", Sol. Energy Mater. Sol. Cells, 211, 110552 (2020). https://doi.org/10.1016/j.solmat.2020.110552
  9. M. S. Bae, C. Park, D. Shin, S. M. Lee, and I. Yun, "Effects of mechanical stresses on the reliability of low-temperature polycrystalline silicon thin film transistors for foldable displays", Solid-State Electron., 133, 1-5 (2017). https://doi.org/10.1016/j.sse.2017.04.003
  10. M. G. Kim, Y. M. Kim, and S. Y. Han, "Mechanical Reliability Prediction of Foldable Displays Using Subcritical Crack Growth in Siloxane-Based Cover Window by TwoPoint Bending Test", Int. J. Precis. Eng. Manuf., 1-13 (2022).
  11. S. M. Lee, C. Park, and I. Yun, "Crack-guided effect on dynamic mechanical stress for foldable low temperature polycrystalline silicon thin film transistors", Microelectron. Reliab., 64, 84-87 (2016). https://doi.org/10.1016/j.microrel.2016.07.056
  12. S. Bouzid, A. Nyoungue, Z. Azari, N. Bouaouadja, and G. Pluvinage, "Fracture criterion for glass under impact loading", Int. J. Impact Eng., 25(9), 831-845 (2001). https://doi.org/10.1016/S0734-743X(01)00023-9
  13. B. S. Ma, W. Jo, W. Kim, and T. S. Kim, "Mechanical Modeling of Rollable OLED Display Apparatus Considering Spring Component", J. Microelectron. Packag. Soc., 27(2), 19-26 (2020).
  14. H. S. Kim, B. K. Ha, B. Y. Yoo, H. S. Jeong, and S. H. Park, "Numerical prediction of dynamic fracture strength of edgemounted non-symmetric tempered glass panels under steel ball drop impact", J. Mater. Res. Technol., 17, 270-281 (2022). https://doi.org/10.1016/j.jmrt.2021.12.134
  15. H. C. Cheng, K. H. Li, C. Y. Shih, and W. H. Chen, "Characterization of the Flexural Strength and Fatigue Life of Ultrathin Glass After Dicing", IEEE Trans. Compon. Packag. Manuf. Technol., 8(12), 2213-2221 (2018). https://doi.org/10.1109/TCPMT.2018.2859256
  16. W. Kim, I. Lee, D. Y. Kim, Y. Y. Yu, H. Y. Jung, S. Kwon, W. S. Park, amd T. S. Kim, "Controlled multiple neutral planes by low elastic modulus adhesive for flexible organic photovoltaics", Nanotechnology, 28(19), 194002 (2017). https://doi.org/10.1088/1361-6528/aa6a44
  17. T. I. Lee, W. Jo, W. Kim, J. H. Kim, K. W. Paik, and T. S. Kim, "Direct visualization of cross-sectional strain distribution in flexible devices", ACS Appl. Mater. Interfaces., 11(14), 13416-13422 (2019). https://doi.org/10.1021/acsami.9b01480
  18. M. H. Ha, J. K. Choi, B. M. Park, and K. Y. Han, "Highly flexible cover window using ultra-thin glass for foldable displays", J. Mech. Sci. Technol., 35(2), 661-668 (2021). https://doi.org/10.1007/s12206-021-0126-y