Design and fabrication of a 3D-printed phase shifter using thermal-pressed Ag electrodes

Abstract Digital light processing (DLP), a high-resolution 3D printing technique known for its smooth surface finish and fast printing speed, has recently been explored for fabricating patterned dielectric substrates for phase shifters in antenna systems. However, integrating metal inks to produce conductive circuits often results in poor conductivity due to porosity and incomplete sintering, requiring precise control of sintering temperature and process. In this study, a phase shifter was fabricated using DLP-based 3D printing with a photocurable resin. Recessed circuit patterns formed within the dielectric substrate and filled with Ag nanoparticle (NP) ink via a squeegee technique. A low-temperature thermal-pressing method applied to enhance electrode conductivity without exceeding the polymer substrate thermal limitations. Microstructural analyses under varying pressing conditions revealed improved interparticle connectivity and densification of the Ag NP network, significantly reducing resistivity. The fabricated phase shifter exhibited 6.8 dB insertion loss and a full 360° phase tuning range at the target frequency of 3.1 GHz under bias voltage control, closely matching RF simulation results. The results of this study suggest that the combination of DLP 3D printing and thermal pressing offers a promising avenue for developing and manufacturing miniature, high-performance RF devices and components, such as phase shifters with complex circuit structures, transmission lines, filters, antennas and arrays essential for 5 G, satellite communications, and other emerging wireless systems.