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September 2003

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Subject:
From:
Brian Ellis <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Mon, 29 Sep 2003 11:45:07 +0300
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Instead of trying the rounds of cleaning products, you may find it much
more profitable to try the rounds of fluxes. In particular, try those
with less rosin (say ~25%, which is still high-solids). Also, you may
care to try RA -- and before you jump down my throat, these often clean
off much more easily than RMA and you can use smaller quantities to get
a similar degree of activation, into the bargain.

I agree that cleaning machine geometry is critical and experience shows
that impingement angles of ~25 - 30° to the board plane gives optimum
cleaning under critical components, provided that shadowing can be
minimised. If cleaning in the Detrex is visually OK, you might give a
post-clean in the batch machine, with just DI water, to "polish" the
boards, but this may not help if there are visible residues.

Brian

Evans, Jack wrote:
> Gentleman (and others):
>
> Our company builds high reliability circuit cards, mostly complying with J-STD Class 3 or NASA 8739.X. As required in most of our standards, we must comply with a contamination test (ROSE) prior to shipment and must achieve a level of <10ug per sq" of Ionic contamination.  The cleaning system that we use is a Detrex in line with Kyzen I3330. This chemistry gives us good contamination results and takes care of most of our RMA cleaning requirements. However, lately we have noticed that we are not getting good results under tight fitting (about 2 mils) SMT components.  This may be due to our machines spray under emersion, which doesn't give us enough impingement to get under these tight fitting  components.  I have a batch cleaner (Unit Design) that might give me better results in this application, but I have never used any chemistry in this machine.  I am down selecting various chemistries to put in this thing and I wonder if any of you have had any experience with them.  Fe
ed!
> back of
> Good results is  important, and I am especially interested in positive results that have been achieved cleaning high solids (36%) RMA in both reflow and wave processes. I am also concerned with any residue that might be left behind in the batch cleaner and later contaminate assemblies that require DI only cleaning. I was burned pretty bad in the past when using Armaclean. I am considering Kyzen  Aquanox and Zestron Vigon A200.  I have tried Envirogold and had problems with damage to solder mask, etching and graying of solder joints, I also wasn't impressed with the bath life that I achieved.  Any comments or suggestions on this???
>
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