Tutorial III:

Recent Advances in PCB Material Characterization

Speakers: Jayaprakash Balachandran and Ching-Chao Huang

Abstract - Heterogeneous computing is accelerating signaling change from NRZ to PAM4 and leading-edge systems implement IO rates that exceed 112Gbps. To properly design these systems, it is of utmost importance to characterize such PCB material property as dielectric constant (DK), dissipation factor (DF) and surface roughness. This tutorial discusses several conventional methods and proposes a new method for better simulation vs. measurement correlation. The proposed method extracts S parameters of 4-port differential traces by impedance-corrected de-embedding and then matches all IL, RL, NEXT, FEXT and TDR/TDT by a 2D solver. The created models can be used for what-if analysis with width/spacing/thickness variation. In addition, these derived model parameters can be used in 3D EM solvers to simulate such complex structures as vias and BGA breakouts. Little attention was given to FEXT in the past. This tutorial shows that both magnitude and phase of FEXT have significant impact on the extracted DK values. Additional findings to be discussed include how the geometric model, return loss and skew affect the extracted material property. Finally, it is shown that an automated PCB extraction framework can be deployed in large-scale manufacturing for quality control and to aid material selection during the system design stage.

Jayaprakash Balachandran (JP) is with Unified Compute Server (UCS) Group at Cisco Systems Inc. JP has over 16 years of experience in high-speed design and has a PhD from KUL/IMEC Belgium. He has many peer reviewed publications and leading PoC workstream in OCP/ODSA.

Ching-Chao Huang, president of AtaiTec Corporation, has more than 30 years of high-speed design and SI software development experience. He was advisory engineer at IBM, R&D manager at TMA, SI manager at Rambus, and Sr. VP at Optimal. Dr. Huang is an IEEE senior member and he pioneered In-Situ De-embedding (ISD) for causal and accurate de-embedding. He received his BSEE from National Taiwan University and MSEE and PhD from Ohio State University.