Robison Michael R CNIN wrote:

> hello,
>
> we're duplicating some legacy boards.  in order to avoid flight testing i
> hand-routed the traces to match the old artwork.  i believe that i just
> came close to making a SERIOUS mistake.  i used the pcb wizard to
> generate the board but then hand-editted the various notches in it.  the
> keepout was in the way and i was going to hand rout everything so i
> deleted it.
>
> there is a power and ground plane on this board and there are machined
> metal card guides that get mounted to the board.  does this sound ugly?
> i'm thinking (i know that's rare  ;-) that by deleting the keepoutlayer i've
> let the planes come right out to the edge of the board.   is this correct?
> if so, i've created a potential short between power and ground when the
> card guides are attached to the board.

I don't think the keepout prevents the internal power planes from existing
under the keepout.  (I think it will prevent an outer signal layer pour in that

area.)  What you need to do is place rectangular fills all around the edges
of the board to hold the power planes out of that area.  This is what I've
been doing for years.

> 2.  after simply drawing the keepoutlayer back in, i am not seeing the
> dark green power plane void outside the keepoutlayer.  does this mean
> that i still have the power plane running right to the board edge?

Yes, I believe so.

>
> 3.  without a keepoutlayer do the planes extend right to the board edge?
>
> 4.  how do i recess the power and ground planes back in a few mils on
> this board?

See above.

> 5.  can i visibly see the planes recessed back from the card edge in protel
> or do i need to generate gerbers and use camtastic to do that?

Not really.  You will see your fills, if you have them in ful mode, or just the

outline of them if fills are in draft mode.

My technique is this :

1.  Generate Gerbers

2.  Create "new" blank PCB

3.  gang import (not exact term, but close) the gerbers onto this new
PCB (do NOT make my mistake of importing getbers on TOP of existing
PCB file!)

4.  Shft/S to go to single layer mode

5.  Now, you can go through the board, layer by layer with the + and - keys,
and hit shift/S if you lose track of where you are spatially in the board.
You can even use the report/measure function to measure pad sizes and
clearances in the power or other inner layers to verify that your padstack
settings are working right.

Note that having the real PCB file open at the same time sets the gerber
apertures so the gerber import works right.  If you don't do this, the
apertures may be set from the last board viewed, and a gerber import
will make a picture that looks very wrong.

Jon

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