You did not say if this was treated water. If not look at the water supply.
DI or RO water should not have this problem unless you are running too fast
through the wash. Our water here in OK. Has alumn added as a clarifying agent
which does show up as white residue

-----Original Message-----
From: Peter Lee [mailto:[log in to unmask]] 
Sent: Monday, 15 August 2005 11:20 PM
To: [log in to unmask]
Subject: [TN] White residues at wave soldering

Technet,

I have a question on white residues formation at wave soldering. We have
recently run experiments to test the performance of various halide-free
water soluble fluxes (ORH0 under JSTD-004). The flux was applied through a
spray fluxer and all PCAs were immediately washed after wave soldering in
in-line cleaner, with DI water only.

Surprisingly, we've identified several PCAs built with flux A from one
vendor exhibiting white residues at various T/H leads on the boards. See
images below.

http://members.shaw.ca/ppwlee1/Images/White_residues1.JPG
http://members.shaw.ca/ppwlee1/Images/White_residues2.JPG

What could be the cause and forming mechanism of the residues? What causes
it to become (sometimes) insoluble in water? In general what approach can be
taken to minimize or prevent formation of white residues?


Rgds,
Peter

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