Nano-Al ₂ O ₃ surface modification and thermal-dielectric properties of epoxy composites

With the rapid development of microelectronics, high-performance epoxy packaging materials are in great demand. Herein, nano-Al ₂ O ₃ (20  and 200 nm) was surface-modified by KH560 and incorporated into epoxy resin (EP) to fabricate Al ₂ O ₃ /EP composites. The effects of filler size, surface modification and loading on microstructure, thermal conductivity, dielectric constant, thermal stability and mechanical properties were systematically investigated. KH560 modification does not change the crystal structure of Al ₂ O ₃ but improves filler dispersion and filler-matrix interfacial compatibility. Modified composites exhibit reduced dielectric constant relative to neat EP, while comprehensive insulation evaluation is beyond the scope of this work. Thermal conductivity increases with filler content; the composite with 80 wt% modified 20 nm Al ₂ O ₃ achieves a thermal conductivity of 0.4962 W·m ⁻¹ ·K ⁻¹ (43% higher than its unmodified counterpart). Benefiting from optimized interfacial interaction, modified composites possess higher initial decomposition temperature and improved mechanical properties. The 60 wt% modified 20 nm Al ₂ O ₃ composite shows optimal mechanical performance with impact strength of 20.98 kJ·m ⁻² and flexural strength of 109.19 MPa. This work provides a feasible strategy for developing multifunctional epoxy composites for microelectronic packaging.