Hi Cathy,
The assumption that ionic species will be entrapped may be erroneous. It's
difficult (but not impossible) to determine 'non-destructively', in that the
residue would have to be removed which could be classed as destructive, with
a suitable solvent then the ionic species extracted and analysed. You'd then
have to be very careful hat he processing didn't convert non-ionic species
to ionic species.
The residue may or may not contain ions, however if it did (likely) then the
key to whether you'll get ionic contamination or not is mainly down to
whether the organic residue permits moisture/humidity/water ingress. Any
ready passage of water into the residue would generally permit dissolution
of the ionic species entrapped there-in and that would be problematic for
you as the ions would potentially be released.
I apologies for all the 'ifs & buts' but (sic) the presence of ions and
their subsequent release from a no-clean residue depends on so much e.g.,
initial ionics in the flux, initial covalents in the flux, dissociation
temperature of the covalent species, reflow temperature, % reaction of the
active chemical components with the metal oxides, % evaporation or
sublimation of the active chemical components, rosin or resin type and
polarity et al....
Best regards,
Andrew Hoggan
BBA Associates Ltd
www.bba-associates.com
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Cathy Killen
Sent: 31 July 2001 09:17
To: [log in to unmask]
Subject: [TN] Encapsulated Ions
Apologies for 'Iconic' instead of ionic. I wish it was because of the
mountain dew.
I have another question:
How do you carry out a non-destructive test in a no-clean process. Ions are
encapsulated as part of the process, surely methods used in the standards
will release the ions and then fail the test?
Cathy Killen
Training Instructor
[log in to unmask] <mailto:[log in to unmask]>
An Oasis of Training Excellence
* 028 38314305
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