Development of Stretchable Low-Dielectric Film Using Hydrophobic PDMS with Porous Silica and Surfactant

A stretchable low-dielectric film was developed using hydrophobic polydimethylsiloxane (PDMS) with porous silica and surfactant. The surface property changes due to the presence or absence of the surfactant were confirmed through contact angle hysteresis and 3D microscopy. The dielectric properties were observed according to the content of porous silica, and the film with a 25% content ratio showed the lowest dielectric constant. Compared to pure PDMS film, the dielectric constant decreased from 2.75 to 2.53, approximately an 8% reduction, and the dielectric loss decreased from 0.045 to 0.025, approximately a 44% reduction. With the improvement in dielectric properties, the S-parameter characteristics showed that the S11 value improved from-13.7 dB to-22.06 dB, approximately a 61% improvement, and the S21 value improved from-3.89 dB to-2.69 dB, approximately a 31% improvement. The stretchability of PDMS with excellent dielectric properties was up to 80%, and the tensile strain rate of the low-dielectric PDMS fabricated as a transmission line was up to 60%. In the repeated tensile test to verify durability, resistance measurement was possible even after 130 repetitions at a tensile strain rate of 15%.