Here are two papers downloaded from the KEMET website.

We had large ceramic caps cracking a couple of years ago. 1825 packages
and larger. Turned out to be board flexing after assembly. This could apply to
smaller packages but we have not seen it happen.

Dave


(See attached file: FlexCracks.pdf)(See attached file: flexTesting.pdf)




"Mary L. Sugden, C.I.D." <[log in to unmask]> on 08/22/2001 05:22:09 PM

Please respond to "(Designers Council Forum)" <[log in to unmask]>; Please
      respond to [log in to unmask]

To:   [log in to unmask]
cc:    (bcc: Dave Seymour/Raleigh/TEKELEC)
Subject:  [DC] Capacitor Cracking




To:  [log in to unmask]    Attn:   Designer Council Forum

From:   Mary Sugden           At:   [log in to unmask]

Date:   August 20, 2001     Subj:   Capacitor Cracking

Hello PCB Lovers,
One of our colleagues is experiencing a "capacitor cracking"
problem and needs technical reports, articles or any other
type of information you may have on the causes and
preventions.  Some possibilities are;

    Absorbed moisture? He does not know if the caps
    are maintained in humidity proof packaging.

    Absorbed moisture? Boards are washed after first
    soldering then subjected to a second loading &
    soldering.

    Handling Abuse?  The cracking seems to be limited to
    capacitors in specific areas near the board edges
    and tooling holes.

He does not have an assembly flow map so troubleshooting the
problem is difficult.  Our friend needs all the help he can
get.  Please send whatever you can.

As you can imagine, he does not want to post his company's
name and have it broadcasted with this problem.  He says,
"Business is slow enough as it is."  Please send the info
to me and I will pass it on to him.  He will contact you
directly and express his deep appreciation.


Best Regards, Mary

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