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June 2004

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Subject:
From:
"Douglas O. Pauls" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 24 Jun 2004 14:25:32 -0500
Content-Type:
text/plain
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text/plain (186 lines)
Joe,
So, in summary, you can have water soluble flux residues, RMA flux
residues, and low solids flux residue?  I agree with others that you have a
potentially dangerous mix of fluxes.  And you wish to go from an in-line
cleaner, which has generally better cleaning, to  a batch cleaner, which
gives more variable cleaning?  As to recommendations, try Austin America
Technologies (AAT), which make a pretty good line of cleaners.  I recommend
Kyzen products for cleaning.  Their Aquanox line is pretty good, especially
the new stuff, and should be able to clean all the flux chemistries in your
flux soup.

I must say that the term "vulcanization of flux residues" is a new one to
me.  Vulcanization refers to a polymerization action that occurs in rubbers
and some silicone based adhesives.  Flux residues have neither.  A more
appropriate term would be unreacted flux.  Low residue fluxes must reach a
minimum temperature, called the activation temperature, before all the
carrier solvent is driven off and the residues change chemically to a
benign condition.  That is why the flux manufacturers recommend putting as
little low solids flux on as possible.  Have you considered not cleaning
your low residue flux?

And now Dewey can start thinking of a suitable Trek tie in.  Must be a hot
one down in Phoenix today.......

Doug Pauls




                      "Macko, Joe @
                      IEC" <joe.macko          To:       [log in to unmask]
                      Sent by: TechNet         cc:
                      <[log in to unmask]>        Subject:  Re: [TN] circuit board batch cleaner recommendation


                      06/24/2004 11:33
                      AM
                      Please respond to
                      "TechNet E-Mail
                      Forum."; Please
                      respond to
                      "Macko, Joe @
                      IEC"







Ramon,

Thanks for the feedback.  Our venders are using water soluble type fluxes
which are cleaned at their facility using aqueous in-line cleaners and
verified by random Omegameter and visual tests.  We had not had any
problems
receiving uncleaned boards from our CMs.

joe

-----Original Message-----
From: Dehoyos, Ramon [mailto:[log in to unmask]]
Sent: Thursday, June 24, 2004 9:27 AM
To: [log in to unmask]
Subject: Re: [TN] circuit board batch cleaner recommendation


        Hi Joe:
        The questions is what type of flux is used by your vendor?
        You may be mixing three types of flux, which is not a good idea.
        Regards,
        Ramon

-----Original Message-----
From: David Douthit [mailto:[log in to unmask]]
Sent: Thursday, June 24, 2004 11:58 AM
To: [log in to unmask]
Subject: Re: [TN] circuit board batch cleaner recommendation


Joe,

The use of "No-Clean" for rework is problematic. Unvulcanized flux will go
places where it can not be removed. The best method to deal with this is to
run the boards back through an oven and make sure the entire board reaches
a high enough temperature to vulcanize the remaining flux.

If there is a combination of fluxes on the board you are in serious
trouble.
Do all the RMA rework and clean-up prior to "No-Clean" rework.

Hope this helps.

David A. Douthit
Manager
LoCan LLC

Macko, Joe @ IEC wrote:

>Fellow Technets,
>
>We are looking at switching to a "batch" type cleaner from our WESTEK
>in-line cleaner for circuit boards.  We outsource all of our board
assembly
>so we do not have to worry about cleaning screens, etc..  Our boards are
>densely populated, double sided with multiple BGAs on both sides. We use
>wire form, RMA cored solder for in-house rework and touch up.  Use NC for
>BGA rework.
>
>Looking for some recommendation / comments on what fellow techs are using
to
>successfully clean their boards - make, model, etc....  Their seem to be a
>lot of units out there.  Thanks
>
>joe
>
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