After we had our layer mixup issue about 20 months ago (some might remember
some posts generated about it), one of the suggestions given was the copper
pattern on the edge, as well as the window.
We tried the copper edge pattern idea, but as Robert said below, board
houses don't like it.  The board house we used for the next build took it
upon themselves to route the copper about 10mil away from the edge, because
they don't like exposed copper visible on the edge, and when we asked where
our pattern was, they told us they refused to build it that way.  So much
for the copper edge pattern.  The window works but only for a limited number
of layers, and space can be an issue with a really dense board layout, but
that is probably our most common method, since most of our boards are 4
layers.
For the most part, our changes became that we revamped our layer naming
method, to make it much less ambiguous and likely for the board house to
switch layers.  While this doesn't provide a check method, there is less
finger pointing if something goes wrong...  We haven't had any more issues
since. {knock on wood}

Genny.

-----Original Message-----
From: Robert Tarzwell [mailto:[log in to unmask]]
Sent: July 11, 2003 6:51 AM
To: [log in to unmask]
Subject: Re: [TN] Board Stackup fabrication errors


As  ex owner of a board shop yes we made errors , and some times they got
out of the shop, its real easy to mix a layer up in the lamination stackup,
there can literly be hundreds of sheets of prepreg, spacers, packopads,
packothane and layers.  but no excuse, it just happens. the best idea is to
open a window as one person said its easy to see each layer, however at
anything above 6 layers it can get difficult. as a board manufacture I dont
like to see copper along a edge but the idea works , and is probably the
easiest for the assenmbler or user. robert tarzwell   megadawn.com

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