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From: | "esvax::mrgate::a1::kenyonwg"@esvax.dnet.dupont.com |
Date: | Mon, 18 Nov 96 18:54:51 EST |
Content-Type: | text/plain |
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From: NAME: WILLIAM G KENYON
FUNC: Chemicals/Electronics
TEL: 302-652-4272 <KENYONWG AT A1 AT ESVAX>
To: NAME: [log in to unmask] <"[log in to unmask]"@ESDS01@MRGATE@ESVAX>
It is my understanding that NaCl is liberated during the coupling
reactions needed to make the high molecular weight laminate
resin. If the boards were stored in a humid environment, or one
that experienced changes in humidity, it is possible that the
residual NaCl could migrate to the surface. The first thing to
do however, might be to calibrate both your ionic tester and that
of the PWB suppliers, with the same NaCl solut to see if the two
instruments are giving the same readings. Then try 0.5 and 2x
the calibration levels as unknowns to see what the response of
the instruments comes out to be. It would be a real bummer to do
a lot of detective work just to find out the instruments were not
giving the same numbers.
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