Dave,

   Can you provide more information on this IPC paper on the above stated
topic.
Is there a contact name and/or phone number.

Victor,

-----Original Message-----
From: Dave Hillman [mailto:[log in to unmask]]
Sent: Thursday, September 11, 2003 11:36 AM
To: [log in to unmask]
Subject: Re: [TN] Zinc Plating Finish(3)


Hi TechNet! Steve - you have fallen into the galvanic series trap! There is
the potential for a galvanic reaction between Zn and Sn but there are
several other factors which need to be considered - the Galvanic Series
chart is only a first order approximation of a possible reaction. Your
cathode-to-anode ration, the type/use of coatings (postcoat, chem film), the
"chemistry" of the use environment, and how "sealed" the electronic assembly
is designed all play a role in the amount and type of corrosive attack on
the Zn plating. There will be a paper at the IPC Fall meeting on the subject
of galvanic compatibility of the new immersion finishes and aluminum which
may be helpful.

Dave Hillman
Rockwell Collins
[log in to unmask]




                      Steve Gregory
                      <[log in to unmask]        To:       [log in to unmask]
                      m>                       cc:
                      Sent by: TechNet         Subject:  Re: [TN] Zinc
Plating Finish
                      <[log in to unmask]>


                      09/11/2003 11:16
                      AM
                      Please respond to
                      "TechNet E-Mail
                      Forum."; Please
                      respond to
                      SteveZeva






Hi Victor!

What will probably happen is that the Zinc will start to corrode because of
the galvanic action between itself and the tin, or tin / lead. Go to:

http://www.ccfast.com/ccfcorrosion.html

There you will see a Galvanic Series chart, and a simple explaination about
Galvanic action. Zinc, and Tin or Tin / Lead isn't all that far apart in the
chart, but far enough that the Zinc will corrode.

-Steve Gregory-


 Fellow TechNetters:

    What are the exposures of having or selecting a ZINC plating finish for
an ELECTRICAL CONTACT such as a solder less
 crimp connector and straight pin connector.   What can occur if these
 finishes are mixed mated with a SnPb or Sn finish surface.

 Victor,



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