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From: root@kesher.UUCP (Aaron_Schmiedel)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Layered M/B?
Summary: Layered mo' bo'
Message-ID: <221@kesher.UUCP>
Date: 4 Jun 90 15:45:12 GMT
References: <6811@ucrmath.ucr.edu> <838@peyote.cactus.org>
Organization: KESHERnet International - Dallas, Tx
Lines: 20


Actually, layered motherboards have a great propensity AGAINT RFI
than to single or double sided motherboards.  One of the main reasons
is that on most of the multi-layer motherboards one of the layers
(in the case of a simple voltage construct of +5vdc and ground), is
made up of a ground plane, and another is made up of a vcc plane,
which is QUITE effective in eliminating interlayer capacitance and
most effectively RFI.
  
Most of today's PC stuff is usually built on a 4 layer motherboard
in the process described above.  This is in order to help pass the
FCC's "B" rating.
  
Some of the motherboards I worked on in the military had up to 12
layers, but this was only on krypto equipment.
  
Multi-layer boards are superior overall to single or double layer
boards, and do not have any inherent problems (except more expensive
to make and design).