Abstract: The rapid advancement of radar and 5 G communication technologies has created an urgent need for materials that possess both low dielectric constants and superior mechanical strength to ensure efficient signal transmission and minimal loss. Herein, a synergistic effect of multiple regulation strategies from the atomic scales to the molecular scales was proposed to develop Covalent Organic Frameworks (COFs) modified cyanate ester resins (COF-mCE). The strategy has proven highly effective in enhancing both dielectric and mechanical properties. With only 3 wt% COFs, the dielectric constant of COF-mCE is reduced from 3.32 to 2.84 at 1 MHz. Meanwhile, the mechanical performance of COF-mCE composites exhibits substantial improvements, with flexural strength increasing by 42.6 % and tensile strength by 52.1 % compared to pure mCE. The investigation explores that hydrogen bonding and π-π stacking interactions restrain the polarization feature and the mechanical property improvements of the COF-mCE derived from the entanglement effect of COF-polymer chains. Furthermore, the 3D-printed COF-mCE honeycomb structure demonstrates excellent electromagnetic wave transmittance and low reflectance, achieving a transmittance of 94.1 % at 10 GHz with a 60° incidence angle. This multi-scale design strategy offers new insights into the development of low-k dielectric material for next-generation electronic science applications.

Key words: Low-k materials, Chain entanglement, Molecular interaction, 3D print