Mark,

Do these spots look "crystalline" in nature? I ask this because, while I
have never seen it as dark, sometimes the active component of an OSP can
crystallize out of solution and deposit as a crystal structure. I recall the
spots actually looked white. Under a 10X power on  a scope you could examine
the spot more closely, if you haven't already. You could try to clean the
spot with a swab of rubbing alcohol. If the spot cleans easily, it could
indicate that the material is organic in nature. Possibly an ionic residue
reacting in some way?

Good luck,

Mike

        -----Original Message-----
        From:   Mark Weckworth [SMTP:[log in to unmask]]
        Sent:   Wednesday, March 22, 2000 7:52 AM
        To:     [log in to unmask]
        Subject:        [TN] Spots on Cu surfaces after OSP coating

        Back in '97, a message was posted asking about dark spots on OSP
surfaces.  The
        message described it as looking like the "fungus" you would see on
an old
        orange.  These spots seem localized and are found on the BGA pads
and annular
        rings.  I would like to know if anyone has any more insight as to
what it may
        be, what causes it, and how to prevent it.  Aside form that single
message and
        single response back in '97, nothing else appears in the archives.

        Any information would be greatly appreciated.

        Thanks in advance,

        Mark W

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