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March 2004

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Subject:
Re: White residue
From:
"Douglas O. Pauls" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 19 Mar 2004 08:11:10 -0600
Content-Type:
text/plain
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text/plain (55 lines) 
I will add one item to Mike's post.  White residues are sometimes the
interaction between the flux residue and moisture, either from an aqueous
cleaning process or more often from the air itself.  Heating the residue
can drive off the moisture, making the residue clear again, but the white
can return after 3-4 days at ambient humidity conditions.  Faster if it is
more humid.

Doug Pauls
Rockwell Collins




                      Mike Fenner
                      <[log in to unmask]        To:       [log in to unmask]
                      om>                      cc:
                      Sent by: TechNet         Subject:  Re: [TN] White residue
                      <[log in to unmask]>


                      03/19/2004 03:10
                      AM
                      Please respond to
                      mfenner







Very neat Bill thanks.
May I suggest a refinement, or at least a flag, to test 3 the heat gun?
If the residues are partially removed rosin or resin, which can also
have a white or off white appearance, the heat gun will melt it to a
translucent or clear appearance. Visually this would be similar to the
powder disappearing. So the refinement would be to either know the
generic flux type in use, or carry out an additional inspection, or pick
at the area to see if the resides flake off.

Regards

Mike Fenner
Indium Corporation

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