Additively manufactured flexible on-package phased array antennas for 5G/mmWave wearable and conformal digital twin and massive MIMO applications

This paper thoroughly investigates material characterization, reliability evaluation, fabrication, and assembly processes of additively manufactured flexible packaging and reconfigurable on-package antenna arrays for next-generation 5G/mmWave wearable and conformal applications. The objective is to bridge the technology gap in current Flexible Hybrid Electronics (FHE) designs at mmWave frequencies and address the challenges of establishing future design standards for additively manufactured flexible packages and System-on-Package (SoP) integrated modules. Multiple 3D printed flexible materials have been characterized for their electrical and mechanical properties over the 5G/mmW frequency band (26–40 GHz), and the inkjet printed interconnects on 3D printed Polypropylene (PP) substrates demonstrated excellent electrical and mechanical performance during a 10,000-time cyclic bending test over typical wearable flexible radii down to 1 inch. A proof-of-concept flexible on-package phased array with an integrated microfluidic cooling channel on 3D printed substrates was fabricated and measured, demonstrating ± 37^∘ beam steering capability with efficient cooling. The proposed reconfigurable design and low-temperature fabrication approach using additive manufacturing can be widely applied to next-generation highly-complex on-demand FHE, flexible multi-chip-module integration, and on-package phased-array modules for 5G/mmWave wearable and conformal smart skin, digital twin and massive MIMO applications.