Characterization and Design Improvement of a High Bandwidth, High Frequency Flexible Connector for Signal Delivery

System bandwidth requirements have been rapidly increasing, driven by applications such as artificial intelligence and machine learning, high performance computers (HPCs), and wafer-scale systems. This in turn has resulted in the need for additional high bandwidth channels for delivering signals to and from such systems. Commercially available flexible connector technologies often suffer from low shoreline bandwidth and bulky headers, particularly detrimental for connecting to compact assemblies such as Systems-on-Wafers (SoWs) in which assembly to a silicon wafer is necessary, and where issues related to the mismatch in coefficients of thermal expansion (CTE) limit the size of the connector. Here, we present the design development of a high bandwidth, high frequency flexible connector which we call FlexCon. A comparative study between three channel geometries suggests differential microstrips provide the best performance. A study on five different dielectrics shows that a dielectric with loss tangent <0.002 do not provide additional benefits. The experimental RF characteristics of a 20mm length differential microstrip FlexCon with stitched vias are provided, showing that insertion loss is < -7dB up to 40GHz. A fabrication process flow for FlexCon is provided, which enables the implementation of embedded active dies such as signal buffers.