While reviewing the EMI mitigation techniques of our engineers, a few of us have been debating the use of ground islands on a multilayer board.
The designs have one layer for Vcc, one for ground and 2 signal layers. The Vcc layer is isolated into various islands. The debate involves the segregation of grounds. The benefit of isolating digital from analog ground is understood. The question is whether I/O ground should be isolated from processor ground. Some schools of thought say keep the ground plane whole for lowest impedance, stitching it to the chassis ground through conductive stand-offs periodically. Some prescribe segregating I/O from processor ground, being careful where to place chassis connection points to prevent ground loops and ground reference corruption. I would be interested in hearing from the forum what your pet approach is and why you believe it works for your situation. Thanks in advance for your comments. Don Umbdenstock Sensormatic Electronics Corporation
