On the other hand, we have been using press-fit into Immersion
gold/Electroless Nickel, with press-fit connectors for 3 years with no
problems.
        The press-fit connectors are Nickel/Gold plated and the gold on
gold provides the lubricant.
        Most gold plated press-fit connector pins are underplated with
nickel also.
        The trick is to control the hole size to give a good press fit,
without distorting the fiberglass
in back of the hole.
        It does work!  And works well.
        [log in to unmask]

        -----Original Message-----
        From:   Paul Gould [SMTP:[log in to unmask]]
        Sent:   Monday, October 06, 1997 10:16 AM
        To:     [log in to unmask]
        Subject:        Re: [TECHNET] Press Fit and Ni/Au Surface Finish

        Gus Morvillo wrote:-
        >I am looking into E Ni/ I Au surface finishes, and have heard
of a concern
        >about press fit connectors and barrel cracking. Has anyone
experienced this
        >problem?
        >Would there be a retention force issue, with one removal and
re-insert?
        Hi Gus,

        E Ni/I Au is not recommended for press fit for two reasons.
        Firstly, solder acts as a lubricant to pin insertion and forms a
gas
        tight seal which is why it is recommended for press fit.
        Secondly, Electroless Nickel is brittle and fractures which
could result
        in stray metal causing subsequent connector shorts. Also, there
is no
        gas tight seal formed which could lead to future corrosion.

        We produce many multi-layer backplane pcb's for global companies
and
        they still specify tin-lead, either Reflowed or HASL. I have not
seen
        any other alternatives mentioned or been asked to come up with
one.

        Best Regards
        Paul Gould
        [log in to unmask]
        Teknacron Circuits Ltd
        Isle of Wight,UK

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