Jason,

Are you wave soldering in a nitrogen blanket? Sometimes this may help
improve top side coverage.
What type of wave are you employing? Dual, turbulent, etc. Also, how is the
flux applied? Foam, spray, other?
My experience has shown that foam fluxing is better than spray because the
flux wets the holes better.
Also, have you monitored the thickness of the OSP on the copper? Follow the
instructions to determine OSP film thickness to see if it is in spec. A very
thick OSP film will make it difficult for the flux to cut through, thus
impeding solder flow up.

Good luck

        -----Original Message-----
        From:   Jason Smith [SMTP:[log in to unmask]]
        Sent:   Thursday, December 16, 1999 6:50 AM
        To:     [log in to unmask]
        Subject:        Re: [TN] OSP and wave soldering

        I am having problems with wave soldering OSP boards.  After the
boards have seen
        a heat cycle (reflow), they are impossible to get hole fill on
topside without
        first cleaning the boards to remove either oxidation or hardened
OSP.  I don't
        know which one I have because I haven't had them analyzed yet.  The
flux used to
        wave solder the boards is a very weak customer dictated rosin no
clean flux.
        The OSP is Cu106A.  I am not familiar with OSPs.  They won't do HASL
either.
        Any insight?  Suggestions?  Assistance?

        As it stands now, the process is to flux with high solids water
soluble/heat to
        clean the board-->wash off flux-->immediately wave solder with rosin
containing
        no clean.  This is not a production process........

        Jason Smith
        Process Materials Engineer
        Lexmark Electronics

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