Send a panel to someone like CSL (Hi Doug) to find out what the
contamination actually is, and if the rosin was removed without removing
the activators.

The residue could be detergents/antifoaming agents/saponifiers...from thier
cleaner that dragged into the last rinse or weren't rinsed off. The
supplier's DI bed could have died. Technet could probably fill volumes on
other sources.

The bottom line is, find out what the "contamination" is, and then there is
a solution to the problem. P.S. if the panels are properly specified, the
supplier should pay for any testing, including replacing panels sent out
for testing.
-------------
Original Text
From: C=US/A=INTERNET/DDA=ID/TechNet(a)IPC.ORG, on 5/20/98 10:26 PM:
Hello Technet,

A supplier made us some board-assemblies with a ionic contamination at
least twice as high as the IPC and MIL-specifications allow. This is
probably due to residues from RMA solder paste. The boards are washed after
wave soldering with water/detergent, but there is no intermediate cleaning
after the reflow soldering. It takes a couple of days before the reflow
soldered boards are wave soldered, so the paste-flux is not very cleanable
anymore.I've heard so often that bad cleaning of RMA is much worse than
good cleaning or no cleaning. I'm not sure, but this is what I think is the
cause of the problem..

The question : will this ionic contamination, concentrated around the
topside-smd's, really result in early failures ? The boards are built in
hermetically sealed boxes, but will be used in a wide variety of
temperatures. There are no fine-pitch devices on the boards. Any advice or
comments are welcome.

Andy

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