----- Original Message -----
From: "Bob Jones" <[EMAIL PROTECTED]>
To: "Protel EDA Forum" <[EMAIL PROTECTED]>
Sent: Friday, March 15, 2002 11:43 AM
Subject: Re: [PEDA] Limitations on InternalPlane layers


>
> ----- Original Message -----
> From: <[EMAIL PROTECTED]>
> To: "Protel EDA Forum" <[EMAIL PROTECTED]>
> Sent: Friday, March 15, 2002 9:34 AM
> Subject: [PEDA] Limitations on InternalPlane layers
>
> >
> > I'm still on my first PCB under P99SE. I need to add quite a few extra
> routes,
> > but the PCB is really dense. Can I route these on the InternalPlane
> layers?
>
> I've done this on occasion. It's a bit tricky, but if you have no other
> routing options and don't want to add layers it can be done.
>
> > Should I have used Polygon pours on ordinary layers instead?
>
> I've used the internal layer as is.
>
> > If I am allowed to use the plane layers, then how can I tell whether I'm
> going to isolate some
> > connections from others and how can I clean up where the trace ploughing
> would
> > leave nasty slices / lost copper?
>
> When I've done this I've used a midlayer to route the connections that I
> needed. The tricky part is to keep an eye on the internal layer that you
> will be merging these on. You'll want to make sure you don't block off
your
> VCC or GND hits to the plane. In my case I tried to route along the edge
of
> the pcb.
> I only needed to add 3 traces to my internals, so you may have a more
> difficult time. I added (3) 8 mil traces on a mid layer and then copied
them
> and pasted them onto my internal layer were I made them 24 mils to keep a
> clearance between them and the plane. This is anti-area because of the
> positive-negative issues with internals. The internal is negative and the
> mid layer is positive. When the internal becomes positive the 24 mil
traces
> will accommodate the 8 mil traces nicely!
> Then you can make composites, depending on your Cam package to let the
> fabricator know that these will be merged. Maybe an explanation will help
> them also.
> I hope I was able to explain this. It was a lot easier for me when I'm
> looking on screen at my job. If you need to you can call me.
>
> >Also on plane layers can I pull the plane
> > completely away from a particular area?
>
> I've had instances where a pcb is say 12" long and I've removed 6" of the
> plane. I was unsure if this was appropriate but I didn't hear anything
from
> the fabricator. Other companies have asked me to add various islands of
> copper to control the "evenness" of the pcb stackup.
>
> >And finally, if I use a polygon on a
> > normal layer, then how do I create the thermal relief's?
>
> I didn't go with this method, but it should pour them the way you want in
> the setup for polygons. You may need to look into the rules to adjust them
> further.
>
>
> >
> >
> Bob Jones
> Digitized Technologies
> 2 Summit Road
> P.O.Box 7284
> Prospect, CT. 06712-1541
> Tel: 203-758-6312
> Fax: 203-758-3338
> email: [EMAIL PROTECTED]
>           [EMAIL PROTECTED]
>
> Notice:  This message is intended solely for the person to whom it
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>
> > Kiernan Fitzpatrick
> >
> > -------------------------------------------------
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>

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