Constructing a Hydrophobic Composite Surface for Anisotropic Conductive Films with Durable Electronic...

The long-term reliability of epoxy-based anisotropic conductive films (ACFs) is limited by moisture-induced degradation arising from the hydrophilic nature of epoxy matrices. In this work, an intrinsically hydrophobic anisotropic conductive film (H-ACF) is developed by engineering the hydrophobic composite surface through the incorporation of core-shell structured hydrophobic alumina (H-Al₂O₃) nanoparticles into the epoxy surface. The fluorinated polysiloxane shell forms covalent Al-O-Si linkages with the alumina core, creating a durable low-surface-energy composite that simultaneously imparts micro/nanoscale hierarchical roughness and strong interfacial bonding. The optimized H-ACF exhibits exceptional hydrophobicity (water contact angle = 157.06°), high bonding strength (26.12 MPa), and enhanced electrical conductivity. It maintains the hydrophobic performance after 400 abrasion cycles and 20 tape-peeling tests and demonstrates superior stability under hygrothermal aging (85 °C/85% RH), showing only a 59% resistance increase compared with 228% for the pristine ACF. A self-assembled μ-LED array confirms reliable Z-axis conductivity with negligible XY-plane leakage. This intrinsic hydrophobic modification strategy herein overcomes the durability limitations of conventional coatings and commercial ACFs, offering a scalable, roll-to-roll compatible solution toward high-reliability electronic interconnections in demanding hygrothermal environments.