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April 1998

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From:
Paul Terranova <[log in to unmask]>
Date:
Wed, 1 Apr 1998 09:21:03 -0500
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1.0
X-To:
Michael Weiner <[log in to unmask]>
Reply-To:
"TechNet E-Mail Forum." <[log in to unmask]>, Paul Terranova <[log in to unmask]>
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Mickey,

I've asked this question before (about 9 months ago) with no responses
at that time. I'm not so sure galvanic corrosion would be an issue. My
concern would be intermetallic formation which would lead to higher
resistance. I don't know if this increase would be high enough to be
detected or cause a problem. I was wondering about this because someone
was looking into using a Ni/Au board finish with press fit connectors.
The big issue here was the higher insertion force since solder to solder
provides a nice slippery interface.

Paul Terranova
Analytical and Environmental Test Services Lab
Worldwide Module Components Group

 Digital Equipment Corp
 200 Forest Street
 Mail Stop: MRO3-1/D2
 Marlboro,  MA  01752-3085

'    Phone: (508)467-3109
* Fax: (508)467-6796
* Email: [log in to unmask]


        -----Original Message-----
        From:   Michael Weiner [SMTP:[log in to unmask]]
        Sent:   Wednesday, April 01, 1998 7:36 AM
        To:     [log in to unmask]
        Subject:        [TN] (assy)press-fit connectors

        Dwight,
         May I join in on this issue with another aspect.
         We assemble back planes and daughter boards with press fit type
        connectors for
         years now with very good results.
         As you have  mentioned, we too consult the bible (GR-78-CORE).
          We always specify solder finish for the connector  tails for
use in
        our pwb's,
          which are hasl finished.
          Mating section is gold on both male and female.
          Recently, a distinguished (no names ) connectors manufacturer
has
        announced that
          a particular part no. is available with  gold finish only.
Promising
        us that even though
          there is potential difference between gold and tin (lead):
          "this will not result in a galvanic corrosion"
          The Bellcore does not address this issue of galvanic
intermetal
        compatibility
          with regard to press -fit .
           Is there  any test data to prove that galvanic couples do not
pose
        any problem in
          press fit application for telecom environment.
          BTW the potential difference between gold and solder according
to
        mil-f-14072
          is 0.65 volt.
          Any help will be appreciated.

          Mickey
        --
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                 michael weiner    Tadiran Telecommunications Ltd
                   tel: 972-3-9262937      fax: 972-3-9261803
                      e-mail: [log in to unmask]
                    homepage  http://www.tadirantele.com/
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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