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September 2005

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Subject:
From:
Dennis Fritz <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Fri, 16 Sep 2005 10:03:54 EDT
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text/plain
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In a message dated 9/16/2005 9:10:09 AM Eastern Daylight Time,
[log in to unmask] writes:

Yep,  they're buried vias and I think they're filled with resin. If they
weren't  filled they would look darker and the copper plating in the hole would
look a  lot rougher from the grinding & polishing.

I think the hole fill  was a separate operation (there's not enough pre-preg
each side to fill the  hole with resin). All the delam is on one side only,
maybe there was some  contamination of the layer during the filling.

Geoff  Layhe


This seems to be Resin Coated Copper construction.  The  1+4+1 construction
is interesting - the four layer core is pretty standard  (thick), but the added
outer layer dielectric is quite thin. Definitely, there  is not enough resin
to fill the buried vias.  It is hard to see from the  magification here for
sure that there is no glass in the surface dielectric.

Check to be sure this is RCC construction.  The treatment  for RCC adhesion
will be per the vendor's recommendation, and I suspect the  board fab shop
knows there were some shortcuts taken for them to give you the  baking
recommendations.  If they also took shortcuts in pressing the parts  to add the RCC
layers, I doubt any procedure at this point will be sure to give  you good boards
after assembly.

Denny Fritz
MacDermid, Inc

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