Cracked ceramic Capacitors:

A bloody nitghtmare to say the least.

It was mentioned that centering the jaws with
less pressure could infact prevent cracking.  True.
But there is more.  Pick and place machines
could be blamed for nothing.  We have found solder
balls under the caps.  This causes pressure on the
cap and when the solder solidifies, it causes a
slight twisting or pressure and crack.  Borad flexure
can hurt the component as well.   It all plays in the damage.
Also, I might add, handling assemblies post
soldering is a big problem.   If you twist a board
the ceramic does not give and considering the size
of the cap and nowhere to move-crack.  I have a
tough time selling this to our assemblers-"Oh, we handle
product carefully".  I can't convince them that it does
not take much flexture.   A component in the right area when
a mechanical stress is applied is like the Andrea fault
line in California-somebodies house is going!

One last thing, ceramic capacitor manufacturers can
analysze the component and identify the crack for either
a mechanical stress fracture or thermal fracture, not to forget
a plain old electrical overstress.  Those are great to look at.
Once you know what to look for you'll be an expert.
But, always a butt,  one must remove the capacitor very carefully,
do not to use heat.  I cut the cap off with an exacto knife.
It works for me!

Good luck, but don't feel alone.  We have all been(still) there.
%&&&&&&&&&&&&&&&&&&&&&&&&&&&%
      Don F. Fumia
      [log in to unmask]
   Schneider Automation
      No. Andover MA
   978-975-9344   FAX x9714
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