Ken,

Your wash system is tracking the resistivity or conductivity of your rinse
water and your filter plant is taking care of such contaminants that are
entering the process.

The question is how much contamination is on the assembly, and has it all been
removed? I doubt that you can accurately maintain the amount of contamination
that is being applied to your assembly both in your process and that of your
PC Fab shop.

It is therefore a good idea to conduct regular ROSE tests to ensure that your
process is always under control. The sampling rate to achieve that is another
subject that should be addressed.

Graham Naisbitt
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[log in to unmask]          Concoat Ltd
Tel: +44(0)1276691100           Alasan House, Albany Park
Fax: +44(0)1276691227           Camberley GU15 2PL UK

-----Original Message-----
From:   TechNet  On Behalf Of Ken Patel
Sent:   Thursday, November 13, 1997 10:26 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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