Additive Manufacturing for Next Generation Microwave Electronics

Xuanke He, Bijan K. Tehrani, Ryan A. Bahr, Manos Tentzeris
Georgia Institute of Technology
Atlanta, GA

The paper will discuss the integration of 3D printing and inkjet printing fabrication technologies for microwave and millimeter-wave applications. With the recent advancements in 3D and inkjet printing technology, achieving resolution down to 50 um, it is feasible to fabricate electronic components and antennas operating in the millimeter-wave regime. The nature of additive manufacturing allows designers to create custom components and devices for specialized applications and provides an excellent and inexpensive way of prototyping electronic designs. The combination of multiple printable materials enables the vertical integration of conductive, dielectric, and semi-conductive materials which are the fundamental components of passive and active circuit elements such as inductors, capacitors, diodes, and transistors. Also, the on-demand manner of printing can eliminate the use of subtractive fabrication processes, which are necessary for conventional micro-fabrication processes such as photolithography, and drastically reduce the cost and material waste of fabrication.

The utilization of 3D and inkjet printing to fabricate integrated circuits interconnects and antennas is an interesting avenue for research due to the customized nature of certain applications such as automotive radar and 5G wireless solutions. This paper will explore different ways of interfacing with monolithic microwave integrated circuits (MMICs) using additive manufacturing methods including printed vias, ramp interconnects, and wire bonds. With these structures, microwave properties such as matching and losses can be improved due to the ease of printing tailored interfaces that match with each individual device. It will also include demonstration of fully additively-manufactured antennas exhibiting excellent bandwidth and circular polarization, something that is expensive and difficult to achieve with traditional manufacturing methods. Finally, the paper will also introduce future directions for additively-manufactured electronics, including the packaging of high power devices, cooling functionality, and using exotic materials for electromagnetic interference shielding and flexibility.

This paper reviewed some of the state-of-the art designs in high frequency additive manufactured passive devices, IC interconnects, and introduced some new antenna designs that are possible only with additive manufacturing. Future topics of research includes utilizing higher integration with active devices to create smart packaging, improving quality factor and SRF resonance of RF and system integration with 3D printed antennas. Additionally, additive manufacturing tolerance and minimum feature sizes are still behind traditional fabrication methods, however many other areas are being explored, such as two-photon polymerization printing, which can meet or exceed traditional methods of fabrication. These topics will greatly benefit 5G applications in creating the next generation of smart electronics.