I don't know what the latest and greatest is but about 5 years ago I looked
at Shiply's Solderposit.  It is not a true electroless process but an
immersion process.  That is, each atom of deposited metal displaces an atom
of copper.  The copper provides the electrons for the reduction of the
tin/lead metal rather than a reducing agent like formaldehyde in electroless
copper.  In theory, all you have to provide is enough extra copper to be
oxidized and still have enough for the board's requirements.  In truth, it
seemed there was a lot more than a one-for-one removal.  On the positive
side, it deposited more than 0.0002" of solder that was 60-70% tin.
Immersion tin baths are available from several vendors.  Shiply, Enthone and
MacDermid come to mind.  The baths I've had experience with generally would
not deposit much more than 0.0001".  Because immersion baths are constantly
dissolving copper for the replacement reaction, they are self poisoning and
the stannous tin will tend to oxidize in the bath over time.

        -----Original Message-----
        From:   [log in to unmask] [SMTP:[log in to unmask]]
        Sent:   Wednesday, May 06, 1998 3:32 PM
        To:     [log in to unmask]
        Subject:        [TN] Electroless Solder Plating Solution

        From: Dennis J Fall@TFT on 05/06/98 02:31 PM


        To:   [log in to unmask]
        cc:
        Subject:  Electroless Solder Plating Solution

        Can anyone give me some info on an electroless solder
plating/tinning
        solution.  I know that something has to exist.



        Thanks


        --

        Dennis Fall

        Thin Film Technology Corporation

        1980 Commerce Drive

        North Mankato, MN 56003-1702



        Phone: 507-625-8445 x17

        Fax: 507-625-3523

        http:\\www.thin-film.com

        mailto:[log in to unmask]

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