Dave, I use split planes fairly often. The placement of the parts on top and bottom become the critical point. You don't want to cause or create a loop in the signal return paths. This may generate "ringing" in critical signals, and increase magnetic cross talk between circuits. I would suggest taking a class or seminar on using split planes and EMC. Sometimes they are a necessary evil. There is one scheduled for Boston October 15-16 and Milwaukee September 17-18. Both are presented by The University of Wisconsin. Hope this helps, John Shaub Sr. Designer Honeywell Inc. ---------- From: [log in to unmask] Sent: Tuesday, July 21, 1998 1:37 PM To: [log in to unmask] Cc: Shaub, John (PA62) Subject: [DC] !!! SPLIT GROUND PLANES !!! I'm looking for information regarding SPLIT GROUND PLANES. Experts on grounding, EMI, EMC are teaching that gaps in ground planes create serious problems. Component manufacturers, however, continue to recommend placing gaps under components (such as A/D's and D/A's). Can anyone: - point me in the direction of theoretical reference material - relate their experiences / practices Thanks, -- Dave Schaefer Phone : (204)631-2298 Senior PWB Designer FAX : (204)631-2475 NORTEL - Broadband Wireless Access email : [log in to unmask] 37 Stevenson Road Winnipeg, MB R3H 0H9 ################################################################ DesignerCouncil E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE DesignerCouncil <your full name> To unsubscribe: SIGNOFF DesignerCouncil ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ DesignerCouncil E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE DesignerCouncil <your full name> To unsubscribe: SIGNOFF DesignerCouncil ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################