Eric,

We saw this problem years ago with our prep of the surface prior to
soldermask.  What is your pre-mask prep?

Anne Ledger
EMDS, Inc.

> -----Original Message-----
> From: Eric Masters [SMTP:[log in to unmask]]
> Sent: Friday, October 01, 1999 3:06 AM
> To:   [log in to unmask]
> Subject:      [TN] Internal shorts
>
> I'm having a rather perplexing problem with shorts on inner layers.
> The
> short is very small, and occurs mainly on fine line jobs (5/5 mils and
> less).
>  It also occurs primarily on layers with one ounce copper, although
> I've seen
> it on half ounce.
>
> The short is very very small; in fact, it is rarely seen at AOI.
> Usually, it
> is discovered at final electrical test.  Failure analysis exhibits a
> very
> fine sliver of copper that appears to have broken loose from a trace;
> it
> remains attached at one end and flips across the adjacent circuit.
>
> Cross sections and SEM's of both developed resist and etched layers
> show a
> near vertical sidewall.  Has anyone seen this phenomenon?  Any
> suggestions?
>
> Eric
>
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