Hi Joyce! Yep, zinc plating can produce whiskers but the behavior and
physical structure of those whiskers is quite a bit different than a tin
whisker. Zinc whiskers have been shown to have a preferred growth along the
{1120} crystal plane. Zinc plating can also be rendered "immune" to whisker
growth by an annealing treatment which can be applied to zinc plating used
for nuts/screws/bolts hardware applications. Its a good thing that we can
deal with zinc (unlike tin) plating and its whisker issues, otherwise there
would be lots of "fur coat" problems with all the zinc plated hardware
running around the planet.
Dave
"joyce"
<[log in to unmask] To: "'TechNet E-Mail Forum.'" <[log in to unmask]>, <[log in to unmask]>
om> cc:
Subject: RE: [TN] Zinc Plating Finish
09/11/2003 11:56
AM
Please respond to
joyce.koo
Even galvanic corrosion may (not say is) not be a problem, fretting
corrosion should be a concern.
http://www.amp.com/products/technology/articles/dd68_1.stm
If the force is very high (stress) and on/off is not that often, you may
(not say are) worry about cat whiskers (zinc).... If you are un-lucky,
you may have "fur coat" instead...Dave is going to tell me he filled up
nitrogen, argon in the package... I guess...;-(
jk
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Dave Hillman
>Sent: Thursday, September 11, 2003 12:36 PM
>To: [log in to unmask]
>Subject: Re: [TN] Zinc Plating Finish
>
>
>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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