MXene Nanofluid-Driven Interfacial Synergy for Next-Generation Anisotropic Conductive Films.

Anisotropic conductive films (ACF) are pivotal in enabling high-precision interconnects for next-generation flexible electronics, yet the long-standing trade-off between mechanical robustness and electrical/thermal performance severely limits their application in high-end devices. Here, we present a paradigm-shifting strategy that leverages covalently bonded core-shell structured MXene nanofluid (NF) to achieve multifunctional enhancement in epoxy-based ACF. The innovative MXene NF creates multiscale interfacial synergy through covalent siloxane bridging and physical crack deflection mechanisms, delivering remarkable mechanical improvements: 35% increase in bonding strength (25.22 MPa), enhanced tensile strength (10.87 MPa), and unprecedented elongation at break (199.12%) at 10% loading. Crucially, the MXene NF/ACF preserves directional electrical anisotropy with Z-axis contact resistance of 7.68-7.77 Ω and XY-plane insulation resistance exceeding 106 Ω, alongside superior thermal stability (Td, 5% > 200 °C). Additionally, a proof-of-concept PCB-FPC-FPC (Printed Circuit Board to Flexible Printed Circuit to Flexible Printed Circuit) multilayer interconnection board validates practical applicability. This work establishes MXene NF as a transformative toughening agent, pioneering a universal platform to design mechanically resilient, flexible electronic packaging materials critical for foldable displays and wearable microsensors.