Engineering Specification
ES-3U5T-1B257-AA
EMC Design Guide for Printed Circuit Boards
Frame 53 of 78
Rev. A
10/01/2002
Printed copies are uncontrolled
4. All two-layer PCBs, where ground plane is not feasible, should utilize a ground grid
system.
The top and bottom side of PCB should look like a ground plane with horizontal
ground tracks on one side, and vertical ground tracks on the other side. Ground grid
traces should be as wide as possible and be placed apart as close as possible. A
ground grid is achieved by connecting vertical and horizontal lines on opposite sides
of PCB with vias. A via is a plated through hole that interconnects two or more PCB
layers. In addition, multi-layer PCBs should use ground grids even if they employ one
or more ground planes. A properly designed ground grid is the next best ground
system (Figure 54)
Figure 54. Ground Grid Technique
5. Install ground vias around the perimeter of the PCB every 0.5 inches or less as shown
in Figure 55. Connect these vias together with 15 mil (0.4 mm) minimum trace
thickness on all layers.
This should help to contain frequencies up to 5 GHz on the PCB board by forming a
"Faraday's cage". Routing of traces outside the ground vias should not
be permitted
except for connections with the 'outside world'.
Figure 55. Creating 'Faraday's Cage'
= via
Vias 0.5" max. apart
connect Gnd planes
together
PCB
Summary :
All two-layer PCBs, where ground plane is not feasible, should utilize a ground grid system. The top and bottom side of PCB should look like a ground plane with horizontal ground tracks on one side, and vertical ground tracks on the other side.
Tags :
pcb,ias,grid,figure,side,pcbs,54,plane,ertical,system,outside,connect,traces