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September 1999

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Subject:
From:
Rudy Sedlak <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Sat, 11 Sep 1999 20:09:07 EDT
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Do not know if passing, or failing, the Bellcore ionic contamination test
(for innerlayers) will affect this kind of problem, but suspect that a board
that passes, will be less likely to fail, given that the ionic contamination
can provide some sort of reduced resistance which can lead to electron
leakage, which can lead to electromigration....?

And, this test is a bear, as certain laminates seem to pick up, and hold,
metal ions (Copper) from the processing solutions (etch, microetch, etc).

We have had some success in passing getting boards past this test by cleaning
them with HEAVILY chelated alkaline cleaners.  This seems to suck the Copper
out of the substrate.  ( My old chemistry prof would be spinning in his grave
if he heard me discuss chelation in those terms, but it actually fits real
well...)

This is an FYI.

Rudy Sedlak
RD Chemical Company
[log in to unmask]

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