In this article, we report the development of a new method for 3D printing of dielectrics. An aerosol jet printer was used to deposit overlapping layers of photopolymer material under ultraviolet (UV) floodlight in the assembly of ramping microstructures in situ without the need for supporting structures. Printing is conducted using an in-house photodielectric ink, the development of which is presented with an emphasis on dielectric and mechanical bulk material characterization. Low dielectric loss at the X-band and structural strength are demonstrated, followed by print characterization wherein the driving mechanisms of the new method are explored, tied to print conditions, and related to specific material properties. Finally, a complex structure in the form of a 3D flower is printed to demonstrate the controlled and repeatable performance of the proposed technique.

Direct write printing is restricted by the lack of dielectric materials that can be printed with high resolution and offer dissipation factors at radio frequency (RF) within the range of commercial RF laminates. Herein, we outline the development of dielectric materials with dielectric loss below 0.006 in X and Ku frequency bands (8.2−18 GHz), the range required for radio frequency and microwave applications. The described materials were designed for printability and processability, specifically a prolonged viscosity below 1000 cps and a robust cure procedure, which requires minimal heat treatment. In the first stage of this work, nonpolar ring-opening metathesis polymerization (ROMP) is demonstrated at room temperature in an open-air environment with a low-viscosity monomer, 5-vinyl-2-norbornene, using the second-generation Grubbs catalyst (G-II). Differential scanning calorimetry (DSC) was used to study how the catalyst activity is increased with heating at various stages in the reaction, which is then used as a strategy to cure the material after printing. The resulting cured poly(5-vinyl-2-norbornene) material is then characterized for dielectric and mechanical performance before and after a secondary heat treatment, which mimics processing procedures to incorporate subsequent printed conductor layers for multilayer applications. After the secondary heat treatment, the material exhibits a 55.0% reduction in the coefficient of thermal expansion (CTE), an increase in glass-transition temperature (T g ) from 32.4 to 46.1 °C, and an increased 25 °C storage modulus from 428 to 1031 MPa while demonstrating a minimal change in dielectric loss. Lastly, samples of the developed dielectric material are printed with silver overtop to demonstrate how the material can be effectively incorporated into fully printed, multilayer RF applications.

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This paper presents the use of Additive Manufacturing (AM) in packaging applications. Specifically, the design, fabrication, and test of an AM packaged receiver phased array front-end will be shown. As part of this work, an LNA and phase shifter bare die will be directly integrated on board with the antenna array. The bare die integration is conducted through attaching the die to a pocket milled into the dielectric of a copper laminate. Filet bridges between the chip and board are then applied using a photocurable dielectric ink, and aerosol-jet silver conductors are printed overtop. Rigorous modeling of the phase shifter and LNA die are conducted and compared to measured data. The two-element array will be printed alone with spacing and amplitude/phase excitation for broadside radiation and the measured results for the antenna will be compared with simulated results from Ansys HFSS modeling tool. Finally, the fully integrated system will be assembled on a single substrate and tested