The question has been asked of whether you can remove corrosion and still
have a reliable assembly.  The answer is, yes you can, provided you put
enough effort into it.  We make stuff that has to last 20-30 years in the
field, and we are not that much different from many military depots in that
respect.  We also service our own equipment, and warrantee it after
repairs.  I know the Naval depots have done it for years.

You must do the following:

1.  Satisfy yourself first that the visual effect is indeed corrosion.
2.  Remove the contaminant that caused the corrosion in the first place.
3.  Remove the corrosion itself by some oblation or abrasive method, down
to the base metal.
4.  Verify that the previous step did not reduce the circuit trace/path
below minimums.
5.  Repassivate the surfaces involved.
6.  Clean the area and verify cleanliness.
7.  Seal the area (e.g. new conformal coat).
8.  Until such a process is well understood, put the unit through extended
burn in testing to verify proper function.

For throw away electronics, this may be much more hassle than it is worth.
But, for legacy systems that are not manufactured anymore, it is a viable
path.

As with most manufacturing, you can do it, provided you know what you are
doing and have the data to back you up.

Doug Pauls
Rockwell Collins

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