Grounding Strategies for Printed Circuit Boards
Design and layout of a printed circuit board (PCB) for electromagnetic compatibility (EMC) is probably the most cost-effective measure possible in the quest for EMC compliance. It is cost-effective because it requires no additional components. It requires just the knowledge of EMC layout methods and experience in applying them.
http://www.ce-mag.com/ce-mag.com/arc...103CE_028.html