Low dielectric epoxy composites cured with synthesized binaphthyl-based active ester

As modern electronic technology rapidly advances, electronic devices are continuously evolving toward higher integration, miniaturization, and faster signal transmission. In order to keep pace with the development of the electronics industry, higher demands are placed on electronic packaging materials, such as maintaining low dielectric constant (Dk) and dielectric loss (Df) across a broad frequency range, as well as possessing excellent dielectric performance stability in complex environments. Epoxy resin is widely used in electronic packaging due to its excellent processing and insulation performances. However, conventional epoxy resin materials often exhibit relatively high Dk and Df, limiting their applicability in next generation high-performance electronics. In this study, a binaphthyl-based active ester (BINAE) was prepared through a one-step esterification reaction between 1,1’-bi-2-naphthol (BINOL) and p-toluoyl chloride. Compared with traditional curing agent such as m-phenylenediamine (MPD) and phthalic anhydride (PA), the use of BINAE significantly improves the dielectric performance of epoxy composites. The BINAE-cured epoxy composites achieve a low Dk (3.07 ~ 3.20) and a low Df of 0.0065 ~ 0.0095 in the frequency range of 100 Hz to 1 MHz. Even at 20 GHz, the BINAE/EP film still exhibits an ultralow Dk of 2.66 and a low Df of 0.0066. Owing to the introduction of binaphthyl ring structure, the composites also exhibit a large water contact angle of 118.5° and a low water absorption rate of 0.31%. Consequently, after absorbing water, the Dk and Df increase by less than 4.5% and 5.3%, respectively. Furthermore, the BINAE-cured epoxy composites also demonstrate excellent dielectric stability across a wide temperature range. Hence, this study provides promising strategy for the development of low-dielectric and moisture-resistant epoxy composites for advanced electronic applications.