Hi Ed.  I just finished a lengthy test regarding this very thing.  If you'd
care to contact me offline I'd be happy to share my data with you.

Mark Mazzoli
Engineering Manager
Circuit Technologies
3622 Clearview Parkway
Atlanta, GA 30340
770-458-1700
[log in to unmask]

----- Original Message -----
From: Louis, Edwin @ CSE <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, July 20, 1999 1:50 PM
Subject: [TN] Blind Vias


> We have an 18 layer PWB with blind vias that have their bottom between
> layer 8 and 9. We have experienced laminate separation between layers 8
> and 9 and separation at the copper plating knee betwwe the vendors
> copper and the plated copper. It reminds me
> resin smear between the board's external copper and the plated copper.
> It is hard to tell if the separation is due to a crack from thermal
> stress or whether it is due to smear.
>
>         The available specifications due not seem to address this effect
> Does any one know whether this copper separation is deleterious or
> whether it is acceptable. There is one opinion that this is acceptable
> because it resulted from fabrication of a board outer layer.
>         There is another view that the resulting separation ends up in
> the internal part of the board after lamination and is thus a separation
>         in an internal layer. Does any one have an answer to these
> questions?
>
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