Hi Somtawin!

There are many different things that cause white residues. I clean no-clean
flux residues using Kyzen Aquanox mixed with DI water in a batch cleaner, and
in my case when I was getting white residues it was because the air knife cycle
between the the wash and rinse cycle was drying the Kyzen mixture on the
assembly before it could be rinsed off. As soon as I shortened the air knife
cycle, the residues went away.

Where you can read some good stuff about cleaning and residues is at Daan's
web page. Go to: http://www.smtinfo.net/Db/_Cleaning.html

You'll find all kinds of information there, and a few articles written by our
own 'Mt Dew" guru Doug Pauls about cleaning and residues.

Here's a couple of other *.PDF's that talk specifically about white residues:

http://www.krepro.no/vask_rens/z-news-2003-januar-eu.pdf
http://www.csma.ltd.uk/application_notes/elec.mount.pdf

-Steve Gregory-


> Has anyone ever seen white contaminate ( like a crystal) on assembly
> boards , between IC lead? I found white residue on  some board after
> reflow . I try to clean by used IPA, flux removal solvent and also DI
> water. But could not remove it. I also found that after we used the
> solvent to clean, the white residue increase more.
>
> Our process used no clean . What is this residue?  What type of solvent
> that should be use to clean flux residue when we have to rework or
> Dedug?
>
>
>
> Thanks & Regards,
>
>
>
> Somtawin Pornpottanamas
>
> Material Engineer
>
> Kimball Electronics (Thailand)
>
> Tel. 038-401566  ext. 211
>
> Fax. 038-495029
>


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