Shielding

Sean Murray (SMURRAY@SLIP.NET)
Tue, 1 Jul 1997 15:26:11 +0100

I'm a little confused on the subject of shielding (guard traces). I'm
currently designing a board for a customer, in which the analog & digital
traces are on seperate layers. Both layers are shielded by their respective
planes (i.e. Digital by Dgnd; Analog by Agnd). My question is; do the
analog traces still need to have guard traces to protect against any noise
that might be coming from other analog traces on that layer? (and likewise
for Digital). The customer has stated that he wants the traces shielded,
but when asked why he could not give me a scientific answer. I was under
the understanding that you only needed to shield the traces if they were
very high speed and were not utilizing proper ground shielding (planes)
techniques.

Any help?

Regards,
Sean Murray
M&M Specialties, Inc.