Ken
There are several aspects to this:
- what chemistry are you using? No clean / RMA / OA? This will
influence your decision to use or not use one.
- what do your existing contracts say?
- how much of a history do you have with your existing chemistry and
cleaning systems? Do you have historical data to back not using an
Ionograph?
In my current position we do use ionic contamination measurement
equipment, per contract. However, at a previous employer (who will
remain nameless to protect the somewhat innocent), the process was
stable, very well known, and the cleaning chemistry was pretty
straightforward (water soluble fluxes), so ionic testing was
discontinued. However, two things were used to compensate for this: the
monitoring on a by shift basis of the conductivity of the DI water, and
a fairly thorough qualification of new processes / components. For
example, when a QFP was introduced with near zero clearance, some
samples were clipped off and the amount of ionic contamination under the
part was measured by the lab.
A pet peeve of mine is people who use ionic testing without using their
brains. Once worked with a supplier who didn't seem to think that
having the measurements within 90% of the spec limit on a regular basis
was a bad thing. It is a good tool if used correctly, so if you do go
with it, do it right.
** Disclaimer: all opinions are my own, not those of my employer, the
government, or of alien abductors...)
regards,
Graham Collins
Process Engineer,
Litton Systems Limited, Atlantic Division
> -----Original Message-----
> From: Ken Patel [SMTP:[log in to unmask]]
> Sent: Thursday, November 13, 1997 6:26 PM
> To: [log in to unmask]
> Subject: [TN] Do we really need ionic contamination measurement
> equipment?
>
> SMT/Wave Process Expert,
>
> If the conductivity of the DI water of wash machine is maintained
> along with
> good maintenance of the wash machine, do we still feel that it is
> always or
> must to have ionic contamination measurement equipment like one of
> that
> Alphametal makes?
>
> I am really interested in pros and cons of having such system from
> need
> point of view rather than sales pitch (to show to prospective
> customers).
>
>
> Re,
> Ken patel
> ______________________________________________________
> Ken Patel Phone: (408) 490-6804
> 575 Cottonwood Dr. Fax: (408) 490-6859
> Milpitas, CA 95035 Beeper: (888) 769-1808
>
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