Signaling enabler in high-speed system design by using hybrid stackup printed circuit board

FR4 is a commonly used material in industry to build printed circuit boards. However signals propagating in this media have significant attenuation when the frequency is going higher and higher. In this paper, hybrid PCB stack-up is studied for signal integrity design, where only specific layers of the board use low loss dielectric while the others are fabricated with traditional FR4 in order to have optimized cost-performance. The investigation focuses on full channel signal integrity analysis based on the proposed hybrid stackup. Simulations for Intel^® Quick Path Interconnect (Intel^® QPI) show noticeable improvement. Such a hybrid stackup is normally less costly than all low loss PCB stackup, thus achieving a good compromising between cost and performance for system design and production.