The truth of the matter is routing traces on planes is poor practice for
several reasons. ( though it can easily be done as suggested in previous
posts). By breaking your plane into several areas you may be creating
ground loops on your planes, lengthening the path that the current wants as
return path. Longer return paths yield higher reactance higher drops=
higher radiated emissions. On low speed boards it is not really a problem.
The problem with using copper pours in combination with signals, another
common practice by designers, is your fab house cringes when they have to
deal with a very uneven distribution of copper on internal layers. A solid
copper on internal layers will also cause bonding material to squish out at
a different rate when the laminates are pressed together from the rest of
the layer, resulting in delamination. So if you have to use this
method, use a hatch, and again some board houses may not like your hatch so
call first then pour.
Mike Reagan
EDSI
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, May 15, 2001 4:25 PM
> To: Protel EDA Forum; Eric Albach
> Subject: Re: [PEDA] Traces on an internal plane
>
>
>
>
>
> > How can I route copper traces on an internal plane? I need to place
> many
> > copper traces on the internal ground plane and have only found normal
> split
> > planes or non-copper traces which would be a very difficult way
> to do it.
>
>
> I have seen it done by using another routing layer and combining the two
> gerbers later. Otherwise Protel don't do that. Of course after
> the problems
> I had fixing the screwed up board (done in PCAD) I inherited from our
> closed California office I don't want to do that either. They blanked off
> some of the analog ground layer to route analog signals and cutoff the
> analog grounds going out the input connector. This didn't show up on the
> DRC because the pins were connected by guard traces so they were hooked to
> analog ground, just not an effective analog ground.
>
> Hope this helps,
>
> Rob LaMoreaux
>
>
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