Hi Tom, Our biggest problem was maintaining trace impedances and printed wiring board thickness during layout. We would start out with the best of intentions, but as things were being routed, compromises of trace widths and layer thicknesses to meet other board restrictions and to work around components. Invariable, they would come back to ask, can the trace width change or the layers decrease/increase, and what would be the impact on trace impedances? To make a long story short, I had to create a spreadsheet that would calculate the trace impedances and automatically update the values if layer thicknesses changed and trace widths changed. Even though there may be great pwb stackup programs out there, we were not going to spend the money. In the end, the pwb vendor provided the impedances based on our layout, and that told us how close we were using our spreadsheet impedance model. As a side benefit, using the spreadsheet documented the changes or we could do a lot of "what-if's" in minutes.
Hopes this helps. Richard Georgerian Compliance Engineer Carrier Access Corporation 5395 Pearl Parkway Boulder, CO 80301 USA Tele: 303-218-5748 Fax: 303-218-5503 mailto:[email protected] -----Original Message----- From: [email protected] [ mailto:[email protected]] Sent: Friday, April 25, 2003 7:21 AM To: [email protected] Subject: Check list for PCB Layout Hi everybody, I would like to create a check list in order to help designers and PCB routers of my company to improve their design / EMI and SI. Where can I find documentations (PDF, links...) with basics PCB rules regarding EMI and SI ?? Witch kind of tests can I set up to verify radiations only with two close field probes ? Is there some referencies (standards, norms...) for close fields levels ? Can I measure them?? Thanks. Thomas K. Genius Institute ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ************************************************************************* This e-mail transmission, and any documents, files, or previous e-mail messages attached to it may contain information that is confidential or legally privileged. If you are not the intended recipient, or a person responsible for delivering it to the intended recipient, you are hereby notified that you must not read this transmission and that any disclosure, copying, printing, distribution, or use of any of the information contained in or attached to this transmission is strictly prohibited. If you have received this transmission in error, please immediately notify the sender by telephone or return e-mail and delete the original transmission and its attachments without reading or saving them in any manner. Thank you. *************************************************************************
