An effective strategy for the preparation of intrinsic low-k and ultralow-loss dielectric polysiloxanes at high frequency by introducing trifluoromethyl groups into the polymers

Abstract

Two new trifluoromethyl-containing organosiloxanes with cross-linkable styrene groups have been facilely synthesized by the Piers–Rubinsztajn reaction. The homopolymerization of these organosiloxanes at high temperature gives polysiloxanes, one of which exhibits a dielectric constant (D_k) below 2.53 with an ultralow dielectric loss (D_f) of 1.66 × 10⁻³ at a high frequency of 5 GHz. In contrast, a control non-fluorinated polysiloxane sample with methoxy groups exhibits higher D_k of 2.78 and D_f of 2.07 × 10⁻². Moreover, the trifluoromethyl-containing polysiloxanes show no obvious change in D_k and D_f even after immersing them in boiling water for 96 h. This result is attributed to the low water uptake of the polymers (near to 0.1%). These data indicate that this work provides a facile and effective way for the preparation of intrinsic low-k and low-loss materials used in the microelectronics industry. Based on the good properties, these fluorinated polysiloxanes are suitable as matrix or encapsulation resins for the fabrication of devices used in high-frequency communication.