03/07/2003 17:59:14, Harry Selfridge 
<[EMAIL PROTECTED]> wrote:

>You will find that nesting split planes works just fine.

Er, in my experience, that's not the case. Protel believes that 
_both_ planes are present in the middle, not just the inner one. If 
you punch a power via of the 'sausage' net down, in the 'island' 
section, you'll get a connection to the plane. Boom - plane short :(
(This is most likely to happen if you're feeding various power 
supplies to a BGA - loads of vias and split planes in circles / 
sausages, but vias not necessarily in the 'appropriate' plane - 
sometimes, you need to reach tricky pins with bits of track.)

>  We have done 
>variations on that kind of nesting in several hundred designs
> without problems.  Perhaps the designer's guide was based on 
>some variation of Protel99 before it evolved into 
>Protel99SE+SP6.  If you should find a 
>situation where it doesn't work - please let me know.

I'm definitely seeing it on P99SE,SP6 (and previous versions). It's 
not a bug, it's just the way it works, annoying though it may be. 
However, just overlaying planes is a recipe for disaster, sooner or 
later. I can send you a little sample job to show it, if you need - 
you just have to squint carefully at the colours of the plane entry 
crosses (or the gerbers make it very clear))

Steve





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