Fluorinated intrinsic low-k materials at high frequency with good dielectric performance and excellent hydrophobicity

Through the Grubbs reaction, two fluorinated precursors (M1 and M2) with the thermo-crosslinkable benzocyclobutene (BCB) groups and an unconjugated double bond have been successfully synthesized. The thermally cured products of the precursors exhibit low Dk and Df at a frequency of 10 GHz, as well as excellent hydrophobicity even being immersed in boiling water for 72 h. Among the cured resins, cured M1 exhibits the best comprehensive performance, including a Dk of 2.41, a Df of 1.02 × 10−3, and water uptake (Wa) of 0.013%. For comparison, a control precursor M3 without the unconjugated double bond in the molecular backbones has been also prepared, displaying that the unconjugated double bond has a positive effect on the dielectric and mechanical properties of the resins. Further investigation indicates that cured M1 displays low density than cured M3. This contribution has given an insight to design the intrinsic low-k materials, as well as provided a facile way for the preparation of the materials.