A Novel Transmission Line Structure for High-Speed High-Density Copper Interconnects

Abstract

This paper introduces a novel transmission line structure that can be employed in high-speed high-density copper interconnects, including both cables and connectors. The proposed structure uses a unique combination of dielectric materials with high and low permittivity values to decouple metal shields from adjacent signal pairs. In addition, the proposed structure employs an absorbing material to suppress any crosstalk resonances that may arise due to signal discontinuities in such highly dense environments. The optimum electrical properties of such an absorbing material in the proposed structure were determined using a simulation-based investigation. This paper also presents measured electrical properties of stereolithography resins suitable for rapid prototyping of high-speed interconnects. The effects of increasing the height of a connector on signal crosstalk and introducing any absorbing materials on signal loss are also discussed. Finally, this paper presents test boards and corresponding prototypes that were modeled and measured to validate the proposed transmission line structure for frequencies up to 40 GHz.