We experienced the same problem a while back. Did all the
investigations, bought a new 'pizza cutter' panel separator (about $5K).
Still had the problem. The caps were too close to edge - ANY flex and we
would get a 45 degree crack inside the end metal cap. Kemet worked with
us and we had the bad ones sliced and could see the cracks. We were
using v-groove separators.

Since then, we have convinced the customer to re-spin the board, move
the caps away from the edges as much as possible, went to a router &
mouse bite separator. We still saw it once in a while, but the
percentages dropped drastically.  There is good literature about cracked
capacitors at the Kemet web site:

http://www.kemet.com/


However - even Kemet (and other cap manufacturers) say right in there
papers ' After all these suggestions are implemented, you still may
experience cracked capacitors - we don't know why either'............

On a third go-around, we changed this cap for a different size and also
moved it again further inward - no problems now.

Tom Parkinson
WinTronics, Inc.
Sharon, PA


Nicolas Ortiz wrote:
>
> I have a question for all you technetters. We are experiencing cracking on
> certain 1812 ceramic capacitor. The cap cracks on the joint between the
> ceramic and the end termination. We already checked our process, following
> the vendor's recommendation, and still have between 1-2% cracked just after
> the second pass oven. The component is placed in the first pass of a double
> sided reflow (no wave solder). Does anybody experienced a situation like
> this?
>
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