We conformal coat our assembled PCB's with polyurethane coating--typically
there is a solder mask beneath the coating.  Occasionally at the end of the
process (after curing) a board is discovered with a "dewetted" region in
the form of a band.

We know this is caused by the use of a plating/masking tape with a silicone
adhesive  where the silicone has not been cleaned from the board (our
supplier has discontinued use of such tapes).

Does anyone know of a technique for repairing this region which is
cosmetically "pretty good".  Just recoating--by machine or by hand--does
not solve the problem.


                                  Thanks for any tips.

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