To improve α-Al₂O₃ dispersion and increase the possible interaction between α-Al₂O₃ and a polyamideimide (PAI) matrix, the α-Al₂O₃ surface was modified with different amounts of a silane coupling agent, N-phenyl-(3-aminoproyl)trimethoxy silane (N-APTMS). Surface-modified α-Al₂O₃ was successfully functionalized with N-APTMS through a binary solvent system. To confirm and modify the amount of silane precisely, the OH site density on α-Al₂O was measured through acid-base titration as 1.001, 2.537, and 0.980 OH/nm² for pristine (A-O), ball-milled (A-M), and surface-modified (A-SM-100) α-Al₂O₃, respectively. The surface-modified α-Al₂O₃ was dispersed in N-methyl-2-pyrrolidone (NMP) and the solutions were fully mixed in PAI resin. The A-SM/PAI were coated on Cu plate and thermally cured. The thermal conductivity and dielectric breakdown strength of A-SM/PAI film on Cu plate were greater than those of pristine PAI or pristine hybrid material.

Keywords: Organic-inorganic hybrid material, α-Al2O3, OH site density, Silane coupling agent, Thermal properties