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Keywords:

  • electrically conductive adhesives;
  • flexible electronics;
  • polyurethane;
  • high-conductivity materials

Abstract

Flexible interconnects are one of the key elements in realizing next-generation flexible electronics. While wire bonding interconnection materials are being deployed and discussed widely, adhesives to support flip-chip and surface-mount interconnections are less commonly used and reported. A polyurethane (PU)-based electrically conductive adhesive (ECA) is developed to meet all the requirements of flexible interconnects, including an ultralow bulk resistivity of ≈1.0 × 10−5 Ω cm that is maintained during bending, rolling, and compressing, good adhesion to various flexible substrates, and facile processing. The PU-ECA enables various interconnection techniques in flexible and printed electronics: it can serve as a die-attach material for flip-chip, as vertical interconnect access (VIA)-filling and polymer bump materials for 3D integration, and as a conductive paste for wearable radio-frequency devices.