Analysis of a PCB-chassis system including different sizes of multiple planes based on SPICE

Abstract

This paper describes the SPICE modeling of multiple plane structures where the inner layers planes have different shapes than the outer layer planes. These structures are often seen in a printed circuit board (PCB), or the space between a PCB and metal chassis. First, a SPICE model is proposed for these structures using 2-dimensional ladder networks and ideal transformers. Next, the model is expanded to structures including vertical connecting conductors, such as vias in a PCB and grounding posts connecting a PCB to a metal chassis. Coupling properties inside a PCB are calculated using the SPICE model and shown to be consistent with experimental data. Furthermore, radiated emissions from a PCB-chassis system are also calculated based on the SPICE and equivalent magnetic current source models. The results are consistent with experimental data to show the changes in radiated EMI due to the locations of grounding posts.