Thick 3D Printed RF Components: Transmission Lines and Bandpass Filters

In this paper, thick 3D printed plastic structures with metal coatings are used in the design of RF components. Two designs are considered, ridged and trenched high sidewall structures. Circuits investigated includes a coplanar waveguide, a combline filter, and a parallel coupled microstrip bandpass filter. To realize the proposed circuits, a commercial 3D Polyjet printing tool was utilized. For metallization, sputter deposition (seed layer) and electroplating (up to 5 µm) of copper was used. A damascene-like process was utilized to pattern the metal layer. Both simulation and measured results are presented, and the results match closely. The results of this paper show that 3D printing can be utilized to design and readily fabricate high aspect ratio RF structures.