PCB to Chassis Grounding Graphic Architectures for Minimizing Rediated Emissions

A properly designed and installed metal chassis reduces radiated fields from Printed Circuit Boards (PCBs). The chassis provides short terminations for electric fields, and field cancellations for magnetic fields. It drains the common mode noise current from PCBs and reduced coupling into the radiators such as traces, inductors, component inductors and attached cables. The size of the chassis, separation distance from the PCB, the location and the number of interconnections from PCBs, and dielectric media between the chassis and PCB are some important parameters to be considered in a chassis design. In this paper the radiated emission level variations for different separation distances and number of interconnections to the chassis are investigated. This paper discusses daisy chain, tree, star, collinear, star-daisy chain and mesh interconnection architectures for stacked multiple PCBs that use a single chassis. The radiated emissions measured from highly integrated PCBs for daisy chain, tree, and star architectures are presented and the results discussed.