Pontus Oldberg wrote:
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"Try to avoid 90 degree bends on your tracks. Using two 45 deg bends (or a radius) reduces EMI."

This is a much debated issue, but it seems that is just isn't true! There's a very good article by Douglas Brooks on this subject, called: "90 Degree Corners: The Final Turn"
I would recommend everyone involved in the design of PCB's for digital circuits to read Brooks' other articles as well, they're enlightening: http://www.ultracad.com/articles.htm


"There's very little gain (if any) in having the track run in 30 mils and then reducing it to 13 mil. Keep you tracks even. This will make it esier when you need to change the layout."

Not only that, but the change in width also causes a step change in the characteristic impedance of the trace. If the trace carries a a signal with fast edges, this may very well have an effect on EMI.


Regards,
Rob.