Journal of the Microelectronics and Packaging Society (마이크로전자및패키징학회지)

The Korean Microelectronics and Packaging Society (한국마이크로전자및패키징학회)
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Room-temperature Bonding and Mechanical Characterization of Polymer Substrates using Microwave Heating of Carbon Nanotubes

CNT 마이크로파 가열을 이용한 고분자 기판의 상온 접합 및 기계적 특성평가

  • Sohn, Minjeong (Micro-Joining Center, Joining R&D Group, Korea Institute of Industrial Technology) ;
  • Kim, Min-Su (Micro-Joining Center, Joining R&D Group, Korea Institute of Industrial Technology) ;
  • Ju, Byeong-Kwon (Display and Nanosystem Laboratory, School of Electrical Engineering, Korea University) ;
  • Lee, Tae-Ik (Micro-Joining Center, Joining R&D Group, Korea Institute of Industrial Technology)
  • 손민정 (한국생산기술연구원 부품기능연구부문 마이크로조이닝센터) ;
  • 김민수 (한국생산기술연구원 부품기능연구부문 마이크로조이닝센터) ;
  • 주병권 (고려대학교 전기전자공학부 디스플레이 및 나노시스템 연구실) ;
  • 이태익 (한국생산기술연구원 부품기능연구부문 마이크로조이닝센터)
  • Received : 2021.06.10
  • Accepted : 2021.06.28
  • Published : 2021.06.30
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Abstract

The mechanical reliability of flexible devices has become a major concern on their commercialization, where the importance of reliable bonding is highlighted. In terms of component materials' properties, it is important to consider thermal damage of polymer substrates that occupy large area of the flexible device. Therefore, room temperature bonding process is highly advantageous for implementing flexible device assemblies with mechanical reliability. Conventional epoxy resins for the bonding still require curing at high temperatures. Even after the curing procedure, the bonding joint loses flexibility and exhibits poor fatigue durability. To solve this problems, low-temperature and adhesive-free bonding are required. In this work, we develop a room temperature bonding process for polymer substrates using carbon nanotube heated by microwave irradiations. After depositing multiple-wall carbon nanotubes (MWNTs) on PET polymer substrates, they are heated locally with by microwave while the entire bonding specimen maintains room temperature and the heating induces mechanical entanglement of CNT-PET. The room temperature bonding was conducted for a PET/CNT/PET specimen at 600 watt of microwave power for 10 seconds. Thickness of the CNT bonding joint was very thin that it obtains flexibility as well. In order to evaluate the mechanical reliability of the joint specimen, we performed lap shear test, three-point bending test, and dynamic bending test, and confirmed excellent joint strength, flexibility, and bending durability from each test.

최근 플렉시블 기기의 상용화를 위하여 기계적 신뢰성 연구가 활발히 진행되고 있으며 이를 고려하여 신뢰성 높은 다양한 접합부의 구현이 중요하다. 기기의 많은 부피를 차지하는 고분자 기판 또는 필름을 접합할 때에는 재료의 약한 내열성으로 접합공정 중 열 손상이 발생할 수 있으므로 신뢰성을 확보를 위해 상온 접합공정이 필요하다는 제약이 있다. 기존의 기판 접합을 위해 사용되는 에폭시 또한 고온 경화가 요구되는 경우가 많고, 특히 경화 접합 후 에폭시는 접합부 유연성 및 피로 내구성에서 한계를 보인다. 이를 해결하기 위하여 접착제 사용이 없는 저온 접합 공정의 개발이 필요한 상황이다. 본 연구에서는 마이크로파에 의한 탄소나노튜브 가열을 이용한 고분자 기판의 저온 접합공정을 개발하였다. PET 고분자 기판에 다중벽 탄소나노튜브 (MWNT)를 박막 코팅한 뒤 이를 마이크로파로 국부 가열함으로써 접합 기판 전체는 저온을 유지하며 CNT-PET 기계적 얽힘을 유도하는 방식이다. PET/CNT/PET 접합시편에 600 Watt 출력의 마이크로파를 10초간 조사함으로써 유연기판 접합에 성공하였고 매우 얇은 CNT 접합부를 구현하였다. 접합 시편의 기계적 신뢰성을 평가하기 위해 중첩 전단 강도 시험, 삼점 굽힘 시험, 반복 굽힘 시험을 수행하였으며 각 시험으로부터 우수한 접합강도, 유연성, 굽힘 내구성이 확인되었다.

Keywords

Acknowledgement

본 논문은 한국생산기술연구원 기관주요사업 "제품생산 유연성 확보를 위한 뿌리공정기술 개발(KITECH EO-21-0008)"의 지원으로 수행한 연구입니다.

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