Inkjet and 3D Printing Technology for Fundamental Millimeter-Wave Wireless Packaging

This article outlines the design, processing, and implementation of inkjet and 3D printing technologies for the development of fully printed, highly integrated millimeter-wave (mm-wave) wireless packages. The materials, tools, and processes of each technology are outlined and justified for their respective purposes. Inkjet-printed 3D interconnects directly interfacing a packaging substrate with an integrated circuit (IC) die are presented using printed dielectric ramps and coplanar waveguide transmission lines exhibiting low loss (.6–.8 dB/mm at 40 GHz). Stereolithography 3D printing is presented for the encapsulation of IC dice, enabling the application-specific integration of on-package structures, including dielectric lenses and frequency selective surface–based wireless filters. Finally, inkjet and 3D printing technology are combined to present sloped mm-wave interconnects through an encapsulant, or through mold vias, achieving a slope of up to 65° and low loss (.5–.6 dB/mm at 60 GHz). The combination of these additive techniques is highlighted for the development of scalable, application-specific wireless packages.