Interconnecting Mechanically Different Components Using Magnetically Aligned Anisotropic Conductive Epoxy for Flexible and Stretchable Electronics Integration

The use of magnetically aligned anisotropic conductive epoxy (MA-ACE) as a versatile interconnection technology for flexible and stretchable electronics is explored. The MA-ACE leverages magnetically induced self-assembly of vertically conductive columns within a polymer matrix. Additionally, it offers low curing temperatures and pressure-less assembly while providing strong adhesion to a wide range of materials. Moreover, it integrates well with traditional surface mount technology (SMT) lines. The MA-ACE was used to interconnect microelectronic components with different mechanical properties: (1) printed polymerized liquid metal networks (Poly-LMNs) to surface-mount devices (SMDs), electronic textiles (E-textiles), and copper-clad laminates; (2) E-textiles to SMDs; (3) E-textiles to other E-textiles; and (4) screen-printed flexible silver to SMDs at variable pitch sizes on either polyethylene terephthalate (PET) or polyimide (PI) substrates. The performance of the MA-ACE interconnects was assessed under mechanical stress conditions, including tensile tests, shear tests, fatigue cycling, and exposure to various temperature and humidity conditions. The MA-ACE was found to be highly compliant, successfully bonding different materials while maintaining electrical continuity and mechanical reliability. The results showed that the MA-ACE exhibited a high yield of 86-100%, strong adhesion to all surfaces, low contact resistance (~50-150 mΩ per connection), and high x-y isolation (>10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> Ω). While the MA-ACE was mechanically robust under stress across all interconnection configurations, other components, including E-textiles, Poly-LMNs, and printed flexible silver traces, demonstrated failures such as leakage and delamination.