Steve, I looked at the picture before I read all your comments and knew
that it was going to be a plating issue at the termination of the
components.   Then I read the rest of your e-mail and sure enough that is
what it was.   I think you sould go with your instincts here because if it
is a lot related problem and all the parts were plated in the same barrel
then do not think the other parts are going to be ok..   Plating in a
barrel is pretty consistant and if you have a problem with one then you
will have it with all.   The only issue you may have is they may not have
been plated all in the same barrel depending on lot  and barrel size.   I
have found that if you have a wetting problem with soldering then do not
use the parts.   You may be masking the problem by hand soldering and
problems will show up in the future.



                      Steve Gregory
                      <[log in to unmask]        To:       [log in to unmask]
                      M>                       cc:
                      Sent by: TechNet         Subject:  [TN] Capacitor Dewetting...
                      <TechNet@listserv
                      .ipc.org>


                      07/29/03 12:03 PM
                      Please respond to
                      "TechNet E-Mail
                      Forum."; Please
                      respond to
                      SteveZeva






Hi All!

I hope your day is going better than mine...

Starting from the beginning. We have a board here that has SMT capacitors
on the bottom of the board that we wave solder, I also use Kester 2331ZX
flux which is pretty aggressive.

We've been building them a while without problems. Then I get flagged down
one day last week by one of our touch-up operators who tells me that shes
seeing a lot of dewetting on certain capacitors, and sometimes she can't
get the solder to wet at all to the terminations, so she has to change the
cap with another one from the reel.

Go to:  http://www.stevezeva.homestead.com   and look at capacitor
dewetting.

We're seeing this problem in varying degrees on close to half of this
particular capacitor. I sent the picture that's on my page with another one
to the manufacturer.
They asked me to give them the lot code that was on the reel that the
capacitors came from, and could I send at least 200 pieces for analysis.

The response came back via email that this definitely was a lot related
issue, and in short, the parts did not receive proper nickel coverage
during the plating process. I was told that they were working to figure out
the best way to issue us a RMA so we could return the parts we have in
house, and also have the inventory from that lot returned by the
distributor we bought them from.

I replied to their email asking if there were any reliabilty issues with
the caps on boards we've already built, even if they show good wetting, but
I haven't received a reply yet. I've also called only to get voicemail.

Should I suspect the caps that are already installed on assemblies, even if
they look fine? My gut feeling tells me that I shouldn't trust these
caps...am I paranoid?

Thanks everyone...

-Steve Gregory-
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