D-Band Transition from eWLB to Polymer Microwave Fiber: Design, Fabrication, and Characterization

Abstract

This thesis investigates the design, fabrication, and characterization of coupling solutions between embedded Wafer-Level Ball Grid Array (eWLB) packages and Polymer Microwave Fibers (PMFs) for sub-terahertz communication, specifically targeting the 130–150 GHz portion of the D-band frequency range (110–170 GHz). PMFs offer significantly lower attenuation compared to free-space propagation, and better link efficiency and reach compared to copper solutions, as well as being more robust and cheaper compared to optical based solutions for short-range, high-data-rate applications. However, the current coupling solution—using an in-package Vivaldi antenna—suffers from high transition losses. To address this, a dielectric coupling structure is proposed, designed to enhance electromagnetic field confinement and better match the modal profile of the PMF. The coupling system, including a back-to-back simulation setup, is modeled and optimized using the full-wave electromagnetic simulation tool High Frequency Structure Simulator (HFSS). The physical structure is fabricated using 3D printing in Acrylonitrile Butadiene Styrene (ABS), and its performance is verified through Vector Network Analyzer (VNA) measurements. The measured results of the designed coupler show a coupling improvement over the 130-140 GHz frequency range of between 0.5-2.2 dB, compared to the previous solution. A maximum measured improvement of 2.2 dB is observed at 134 GHz. The designed coupler not only improves the coupling, but also gives a compact solution to hold the PMF in front of the eWLB package, and offers easy mounting on the Printed Circuit Board (PCB).