I agree with Brian's assessment. It appears in the pictures that the
white mongue does not appear on the solder joints, only on the solder
mask in this case. Therefore I am led to believe that it is some type of
a reaction with the solder mask.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
Sent: Tuesday, August 16, 2005 2:43 AM
To: [log in to unmask]
Subject: Re: [TN] White residues at wave soldering

Impossible to say without a full rundown of all your materials and
processes. However, if this happens with only one flux, I would suggest
you start looking at an incompatibility between some component in the
flux and the solder mask. What you ***may*** be seeing is the surface of
the mask being very slightly attacked, exposing fillers which would
normally be invisible.

Brian

Peter Lee wrote:
> 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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