Compatibility study of 3D printing and PCB technologies for RF components and circuits

This paper explores the potential of combining additive manufacturing with printed circuit board technology to fabricate radio frequency components and circuits. This combination aims to leverage the design freedom of additive manufacturing to implement very compact, high-quality components, while capitalizing on the established processes and design knowledge associated with printed circuit board manufacturing of radio frequency circuits. The idea behind this technological combination is not just to incorporate 3D-printed parts onto the printed circuit board, as usual, but go a step forward and embed these components as parts of the board itself. By doing so, we aim to improve the compactness, electrical connectivity and mechanical stability of the entire system. As a test component for our study, we chose a helical-microstrip transmission line segment. Due to the 3D nature of this type of transmission line, large values of electrical length can be obtained with short segments, making them very useful in the design of compact radio frequency components. We propose a new procedure for embedding this 3D structure into a printed circuit board substrate while considering electrical connectivity and mechanical stability during the different steps of the process. To demonstrate the functionality of our proposed method in the design of more complex structures, two embedded helical-microstrip transmission line segments are combined to form a compact 2-way Wilkinson power divider/combiner suitable for operation in the radio frequency band of a few hundreds MHz.