A Fluorinated Thermocrosslinkable Organosiloxane: A New Low‐k Material at High Frequency with Low Water Uptake

Abstract In order to obtain low ‐k material with good comprehensive properties, a trifluoromethyl‐containing organosiloxane with thermocrosslinkable vinyl and benzocyclobutene groups is designed and synthesized through the Piers–Rubinsztajn reaction. After treating at high temperature, the organosiloxane changed to form a cross‐linked polysiloxane (called as c‐FSi‐BCB). c‐FSi‐BCB exhibits good dielectric properties with dielectric constant ( D k ) of 2.60 and dielectric loss ( D f ) of 1.49 × 10 −3 at a high frequency of 5 GHz. Importantly, c‐FSi‐BCB maintains such good dielectric properties and exhibits low water uptake of below 0.076%, even after immersing it in boiling water for 96 h. c‐FSi‐BCB also displays good thermostability with a 5% weight loss temperature ( T 5d ) of 453 °C. These data indicate that this fluorinated organosiloxane is suitable as the matrix resin for the fabrication of devices used in 5G communication.