Studies on the Terahertz Shielding Performance Enhancement and Dielectric Properties of Silane Coupling Agent Modified Epoxy Resin Films

ABSTRACT The proliferation of terahertz (THz) communication and sensing technologies is critically dependent on the availability of compatible electromagnetic interference (EMI) shielding materials. As a cornerstone polymer for electronic packaging, epoxy resin (EP) offers a promising platform, yet its intrinsic shielding effectiveness requires significant enhancement. Herein, a facile chemical modification strategy is presented to improve the baseline performance of epoxy by covalently incorporating silane coupling agents into the network. A systematic investigation of four conventional silanes established clear structure–property relationships, revealing γ‐aminopropyltriethoxysilane (KH550) as the most effective modifier. At an optimal loading of 15%, the KH550‐modified epoxy composite achieved an average EMI shielding effectiveness (SE) of 13.68 dB, a 28% improvement over the pristine amine‐cured matrix. Terahertz time‐domain spectroscopy (THz‐TDS) combined with Debye relaxation modeling indicated that the enhanced shielding originates from an increased dielectric constant, driven by a higher density of polar moieties that intensifies dipolar polarization without altering the fundamental relaxation mechanism. Critically, this electromagnetic enhancement was achieved synergistically with improved mechanical robustness, evidenced by a tensile strength of 3.168 MPa for the EP‐15KH550 sample. Direct silane modification is thus demonstrated to be a robust and predictable route for developing high‐performance epoxy‐based composites for THz shielding in next‐generation electronic systems.