Yes, what Tom is saying is completely correct!  The problem occurs when 
your design places the ceramic capacitors to close to the edge or to colse 
to the V-cut used a the break away.  If you make a special fixture you 
still need to avoid clamping down directly on the SMT component parts and 
so you still have to bendo or flex the board during the separtation of the 
various pannelized boards or when breaking away the breackaways after SMT 
and PTH assembly is complete.  So you must set your design rules to place 
these capacitors further inboard from the edges than you would like.  
Once you have done this the problem will go away, at least where my boards 
are concerned!

Best
Doug Mills


From:	IN%"[log in to unmask]" 18-DEC-1995 09:57:55.14
To:	IN%"[log in to unmask]"
CC:	
Subj:	Cracking Capacitors

Another source for information regarding cracked capacitors is through the
Surface Mount Technology Association Academy.  I attended a very excellent
seminar given by John Maxwell entitled: "Surface Mount Problem Solving:
Design and Production" where a great deal of time was spent on ceramic chip
cracking.  

Two items mentioned which may get you started are (A) most failures of this
type occur at the de-paneling stage and (B) the positioning of the crack on
the chip may point to the failure mechanism.

I surely hope that at least the s.m.t.a. reference source may assist you.

Happy Holidays!

Tom Eshelman, Enthone-OMI
1.800.548.9801 ext. 7257
[log in to unmask]


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