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June 2010

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Subject:
From:
John Parsons <[log in to unmask]>
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Date:
Tue, 1 Jun 2010 09:07:03 -0700
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We have an old copy of an Excel stack-up model from Isola.  It says that for
a 1080 pre-preg with 65% resin that you need about 80% copper on two
adjacent 1oz copper layers to ensure sufficient resin fill.  While the model
provides only a guide I would certainly be concerned about the scenario that
you are describing and would not recommend it to any of our customers.

Good luck,

John Parsons

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Frank Kimmey
Sent: Tuesday, June 01, 2010 8:46 AM
To: [log in to unmask]
Subject: Re: [TN] Single-ply construction

Dan,
From a Designer's view I can see serious issues here.
Firstly there will be a huge risk of delam due to poor fill at traces (you
will need to fill 2.4 mill minimum at trace and pad locations)
Then there is the issue of dielectric isolation between layers (only about 2
mils with one layer 1080)
Then probably some capacitive issues due to proximity of copper to signal
(SI problems)
I would suggest some further discussion with your customer and possibly
listing for them your concerns, then build what they ask for and try not to
say "I told you so"
Or tell them you cannot guarantee the construction and no-bid to save them
the bad lesson they are risking
Good luck,
FNK

Frank N Kimmey CID+
Manager - PCB Design
Powerwave Technologies Inc
Mobile - 916-670-0645

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dan Skweres
Sent: Tuesday, June 01, 2010 8:20 AM
To: [log in to unmask]
Subject: [TN] Single-ply construction

We have a customer insisting that we use a single ply of FR406 1080 between
two copper layers each 1 oz. copper. One layer is a plane and the other a
signal. We're quite concerned that there will be issues with fill. We don't
recommend single-ply construction especially against two 1 oz. copper
layers. Any thoughts, comments and/or concerns would be appreciated.
Thanks!
Dan S.


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