The water is measured at two different points in that machine. Once
before it is sprayed onto the boards ( about 18 megs ) and the second time
at the sump, which is water that has been sprayed on the boards. Water at
the sump will have a very hard time to be much more than a Meg because it is
regaining ions from the air and the chamber walls. You may double check it
with Austin America Technology, but it is my understanding that when the
resistivity reaches 0.8 megs at the sump, the boards are clean. Also you may
run a rinse only cycle while the machine is empty and find out what your
machine is capable of reaching with no load.
Regards,
Ramon
> -----Original Message-----
> From: Wilson Jason [SMTP:[log in to unmask]]
> Sent: Wednesday, April 16, 2003 6:34 AM
> To: [log in to unmask]
> Subject: Re: [TN] Cleaning Question - Rinse water resistivity?
>
> Hi,
>
> We do use DI water in the rinse.
>
> We use AAT Corp Emulsonator 9700. It has the feature of monitoring the
> rinse cycle's resistivity, and comparing that to a predetermined value.
> When the resistivity reaches the predetermined value the rinse stops (if
> the time has expired).
>
> Thus I am not sure what to enter for the predetermined rinse restivity
> value. Does anyone have a similar machine? We use an RMA type flux.
>
> Thanks in advance for any help,
> Jason
>
>
> >>> [log in to unmask] 04/15/03 04:31PM >>>
> Jason,
> I would recommend that you use deionized water in your cleaning for
> the
> same reason that soft water is better for cleaning clothes. DI water
> is a
> hungrier solvent. I would recommend using 2 megohm-cm resistivity
> water
> (0.5 uS/cm conductivity) as a minimum. When you get below 2 megohm,
> you
> get in RO purity water, better than tap water, but not as good a
> cleaner.
> I also recommend 140-150F for temperature.
>
> A 10 minute rinse is about normal.
>
> Doug Pauls
> Rockwell Collins
>
>
>
>
> Jason Wilson
> <wilson.jason@NORTHROP To:
> [log in to unmask]
> GRUMMAN.CA> cc:
> Sent by: TechNet Subject: [TN]
> Cleaning Question - Rinse water resistivity?
> <[log in to unmask]>
>
>
> 04/15/2003 01:39 PM
> Please respond to
> "TechNet E-Mail
> Forum."; Please
> respond to Jason
> Wilson
>
>
>
>
>
>
> Hi Everyone,
>
> I am a new member to the list and I have a question on cleaning.
> Thanks in
> advance for any help you can provide. It is much appreciated.
>
> What should the value be for rinse water resistivity? The cleaner we
> have
> is a AAT Corp Emulsonator 9700.
>
> We use an RMA flux (both in wave solder, and in solder paste). The
> solvent
> we use is EC7R.
>
> Also, we currently rinse for 10 min (+ time to reach resistivity).
> Does
> this seem low? We are having trouble with board cleanliness.
>
> Once again, thanks for any help provided.
>
> Jason
>
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