Dielectric Properties of Low-Loss Polymers for mmW and THz Applications
Sahin, Seckin, Niru K. Nahar, and Kubilay Sertel. “Dielectric properties of low-loss polymers for mmW and THz applications.” Journal of Infrared, Millimeter, and Terahertz Waves 40, no. 5 (2019): 557-573.
We present a systematic characterization of dielectric permittivity of 6 commonly used, low-loss polymers namely polystyrene, parylene, polyimide, SLA resin, SU-8, and SUEX for the 100-GHz to 2-THz bands using transmission mode time domain spectroscopy. The dielectric constant and loss tangent for each polymer was systematically recorded using the commercially available TeraView TPS-3000 system and an analytical multilayered media transmission model is used to extract sample permittivity and loss through curve fitting the measured data. Among the studied polymers, polystyrene exhibits the lowest material loss with a loss tangent less than 0.0069 up to 100 GHz to 2 THz. Also, effects of lithographic processing on permittivity and loss for commonly used epoxy-based photoresists SU-8 and SUEX are documented and compared. We show that the dielectric properties of dry film SUEX is comparable with those of SU-8. As such, SUEX is an easy-to-process alternative to commonly used SU-8 for mmW and THz frequency applications.