Hi,

White residues can also be expected in WS-process. If one have a
no-clean reflow, then wave soldering with WS-flux plus pure water
washing, white residues might be seen around SMT-joints on reflowside
where is vias near the joints. The white residues is a result of
interaction between the no-clean reflowflux, the WS-flux that has came
to reflowside through vias and the water. If you remove one of the
factors, you will not see any white residues. And the residues ARE
conductive. We solved the problem by reducing the amount of the flux on
paste.

Enermet Oy
Jarmo Kiiski
FIN-40420 JYSKÄ
FINLAND
INTERNET: [log in to unmask]
TEL: int. + 358 14 660 100
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> -----Original Message-----
> From: Charles Barker [SMTP:[log in to unmask]]
> Sent: 19. joulukuuta 1997 17.39
> To:   [log in to unmask]
> Subject:      Re: [TN] ASSY:White residue after cleaning
> 
> Charles Barker@I-O INC
> 12/19/97 09:39 AM
> 
> 1. Is the RMA flux one of those that is considered "no clean?"
> 2. Does Axarel 32 contain much alcohol?
> 3. have seen white residue between surface mount leads on parts
> soldered
> with "no clean" RMA (really just low solids) flux AFTER they were
> cleaned
> in an Aquastorm with Armakleen and then put through the Omegameter.
> We
> were told that this was the result of a reaction between trace amounts
> of
> flux remaining and the alcohol in the Ohmegameter.
> 
> We eventually changed to a WS flux and a different chemistry.
> 
> 
> 
> 
> 
> [log in to unmask] on 12/19/97 08:58:00 AM
> 
> Please respond to [log in to unmask]; Please respond to
>       [log in to unmask]
> 
> To:   [log in to unmask]
> cc:    (bcc: Charles Barker/US/I-O INC)
> Subject:  [TN] ASSY:White residue after cleaning
> 
> 
> 
> 
> Has anyone come across a white residue on the circuit side of board
> assemblies after cleaning?  We are using Axarel 32 in a semi-aqueous
> cleaner to remove an RMA flux after the wave solder operation.
> Thanks for your help!
> Larry Davis
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