Microstrip resonators on polyethylene terephthalate substrates realized by direct-write technology

Printed Electronics (PE) technology has obtained considerable attention due to the simplification of the manufacturing process that can be fully additive. In addition, PE offers possibility to use low-cost, low-temperature substrates, such as polyethylene terephthalate (PET) foil, which could serve as an alternative to conventional high-frequency substrates, like Rogers. In this study, digital printing technology direct write, or so-called dispensing is used to print microstrip Rectangular-shaped resonators (RSRs) on a flexible PET foil and a semi-flexible Rogers 4003 substrate. Resonators are printed by a contact dispenser Nordson EFD Pro Plus 4L/A from a conductive silver-based DuPont PE 874 paste. The selected straight and bent RSRs have deep resonance frequencies at 2.50, and 1.90 GHz, with an amplitude of about -50 and -60 dB, respectively. The mentioned resonators are simulated and printed; then the results are compared with a good match. Resonators on Rogers shows a good match between simulation and realization. On a PET substrate, a 6% shift of transmission zero location is observed. To better understand some probable challenges during the manufacturing of high-frequency resonators, the structure of printed layers is characterized, and the manufacturing process itself is completely analyzed.