Study on 3D Printed Snap-Fit Joints for Assembly of PCB-Integrated Additively Fabricated Air-Filled Waveguide

In this paper, 3D printed snap-fit joints are investigated for assembly of the recently introduced Printed Circuit Board (PCB) integrated air-filled waveguide (AF-WG) to reduce the fabrication cost and assembly effort. Various joint constructions were designed and tested to provide pressure-assisted low-resistance contact between flanges of the metal-coated 3D printed U-shaped waveguide shell and on-PCB ground plane that serves as one of the guide's walls. The above is an alternative to the originally proposed through-hole screw joint that although low resistance requires extra parts and a more complicated assembly. Exemplary separable ball and cantilever snap-fit joints were developed and integrated at different pitches into test vehicles fabricated for the experimental study being a through-patch microstrip to AF-WG transition in back-to-back configuration operating within 9 GHz to 12 GHz bandwidth with long waveguide section in-between. The obtained results show that a ball joint can provide comparable performance in terms of total power loss of the circuit to a screw joint when properly spaced making it superior to use for highly-integrated circuits.