Hi Rod,

I'm not aware of any real test a normally-equipped PCB lab can run to
measure or test for the removal of chromates.  However, there are other ways
to measure effectiveness of a chemical clean line that should indicate
fairly well how successful your removal was.

The simplest way is the old standby "water break" test.  Chromate
interference will cause water to "break" and you can assume there may well
be chromates left (of course it could also indicate finger oils or other
contaminates as well).

Another way, and one you're most likely using now, is to closely monitor
weight loss through the line.  I'd imagine you're removing anywhere from 20
to 80 microinches.  Chromates will be removed during normal chemical clean
cycles that maintain a reasonable etch rate.  You may want to use laminate
samples as your coupons in order to get a handle specifically on its etch
rate.

You can also try using a black oxide dip following your chem-clean process
(process only through the oxide pre-dip and oxide bath).  This will point
out resin spots or perhaps areas of excessive chromates.  Odds are that this
method will point more accurately towards resin spots or foil pin holes
rather than chromates.

Good luck

Mark Mazzoli
Eng. Mgr.
Circuit Technologies, Inc.
3622 Clearview Pkwy.
Atlanta, GA 30340
770-458-1700
[log in to unmask]

----- Original Message -----
From: Rod Semen <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, September 21, 1999 2:53 PM
Subject: [TN] Quick, Chromate Test


> Does anybody know of a quick test to see if I am removing chromate
> coating on laminate foil? I know about EDX, but I want to do this in
> our lab.
>
> Thanks,
>
> Rod
>
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