Low-Loss 3-D Multilayer Transmission Lines and Interconnects Fabricated by Additive Manufacturing Technologies

This paper presents low-loss 3-D transmission lines and vertical interconnects fabricated by aerosol jet printing (AJP) which is an additive manufacturing technology. AJP stacks up multiple layers with minimum feature size as small as 20 $\mu \text{m}$ in the $xy$ -direction and 0.7 $\mu \text{m}$ in the z-direction. It also solves the problem of fabricating vias to realize the vertical transition by 3-D printing. The loss of the stripline is measured to be 0.53 dB/mm at 40 GHz. The vertical transition achieves a broadband bandwidth from 0.1 to 40 GHz. The results of this paper demonstrate the feasibility of utilizing 3-D printing for low-cost multilayer system-on-package RF/millimeter-wave front-ends.