Application of Aerosol Jet 3-D Printing With Conductive and Nonconductive Inks for Manufacturing mm-Wave Circuits

In this paper, an application of aerosol jet 3-D printing with conductive and nonconductive inks for the realization of millimeter (mm)-wave circuits well above 30 GHz is presented and investigated. The Optomec 5X aerosol jet 3-D printing system is used together with polyimide (PI) and silver inks to fully-additive manufacture various microstrip circuits. A section of microstrip transmission line with a transition to a via-less conductor-backed coplanar waveguide was designed together with a T-junction and a branch-line coupler. These circuits were designed to operate within the Ka and V frequency bands. The measured thickness of the PI dielectric substrate is
$20.7 \pm 1.35~\mu \text{m}$
, while the silver traces are
$2.6 \pm 1.35 ~\mu \text{m}$
. A section of the transmission line with the developed transitions was measured up to the W-band, exhibiting a total loss of 0.65 dB/mm at 100 GHz. The T-junction power divider yielded a total loss at its center frequency of 34 GHz of 0.55 dB. The 3-dB branch-line coupler yielded a loss at its center frequency at 42 GHz of 1.1 dB. The experimental results demonstrate the application of this approach for fast and high-resolution mm-wave circuit fabrication.