Contactless BGA Interconnection of Gap Waveguide MLW Slot Array Antenna for E-Band Automotive Radar Applications

Paper in proceeding, 2025

This paper presents a novel Multi-Layer Waveguide (MLW) antenna-to-Launcher-In-Package (LiP) integration concept for E-band automotive radar, utilizing solder balls as an electromagnetic bandgap (EBG) structure implemented directly on the PCB. Although solder balls are commonly used for electrical interconnections, in this approach, they are strategically designed to create a stopband at a specific frequency, mitigating field leakage at the antenna-PCB interface in the presence of an air gap. Unlike previous designs that require a spacer - an additional metal component with pins - this method enables direct antenna placement on the PCB, offering a potentially more cost-effective solution. To validate the concept, simulation results of the EBG unit cell are presented, demonstrating its stopband characteristics. Additionally, a prototype PCB was fabricated and assembled with solder balls, and its performance was evaluated experimentally using a back-to-back (B2B) adapter plate. The measured results closely align with simulations, confirming the effectiveness of solder balls in enhancing integration and proving their suitability for future LiP-based antenna contactless interconnections.