Hey Lon,

I ran into white residue a while ago.  It may not be what's going on in your
situation - white residue can be so many things and all them defects in
IPC-A-610.  My residue turned out to be tin oxide and lead oxide.

We were activating the RMA flux (Kester 186) in a lengthy preheat stage.
Once the flux ran out of activators the tin-lead did what it was suppose to
- oxide rapidly especially at the elevated temperature.

You'll need to find out what kind of white residue you are getting.  Another
white residue we see in cleaning (immediately after wave flow soldering) is
excess heat sink adhesive.

If it's oxide you could try a deoxidizer.  As you know, oxidation is a
chemical reaction so it will take a chemical reaction to remove it.  Rudy
Sedlak sent me a sample that I hope clears it up. I still need try out as
part of my investigation/DOE.

Hans

~~~~~~~~~~~~~~~~~~~
Hans M. Hinners
Materials (Process & Manufacturing) Engineer
Warner Robins Air Logistics Center
Avionics Production Division
Manufacturing Branch
380 Second Street, Suite 104
Building: 640, Mail Stop: LYPME
Robins AFB, GA 31098-1638
Voice: (912) 926 - 1970 Fax: (912) 926 - 7164
mailto:[log in to unmask]
http://www.robins.af.mil



-----Original Message-----
From: Lon Weffers [mailto:[log in to unmask]]
Sent: Tuesday, April 04, 2000 3:18 AM
To: [log in to unmask]
Subject: [TN] white residue


Hello technetters


We have a small problem concerning white residue on the componentside of
the boards.
After soldering the boards on certain points we detect a small amount of
white residue around the tin-leaded joints of an IC. First we thought it
was flux, bud it seems to be something else. We detect it only around
certain joints of that particullar IC. Is it possible that it has something
to do with the leads of the IC?

Thanks in advance


Lon Weffers
Matas Electronics bv
De Dieze 16
5684PT Best
Http://www.matas.nl

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