I don't know a great deal about their construction but are you seeing 
delamination of two of the multiple layers of the capacitor?

I can imagine CTA mismatch between the PWB and cap causing a difference 
in stress between the top and bottom of the cap irrespective of which 
way it was aligned to the PWB edges.

Regards,



Igoshev, Vladimir wrote:
> Different locations, identical caps placed along and normal to the board. :-)
>
> Regards,
>
> Vladimir
>
> ----- Original Message -----
> From: Allen Maddox <[log in to unmask]>
> To: TechNet E-Mail Forum <[log in to unmask]>; Igoshev, Vladimir
> Sent: Mon Jul 14 11:19:16 2008
> Subject: Re: [TN] Ceramic caps
>
> Just curious if there is any consistency in the size of the cap or it's place on the board and direction it faces?
> It seems like you've covered all the obvious failures so far.
>  
> Allen Maddox, CID+
>
>
> "Igoshev, Vladimir" <[log in to unmask]> wrote:
>
> 	That was the first thing I asked and was told "No", they hadn't been re-worked or placed manually.
> 	
> 	What bugs me the most is that I have a hard time imagining how a top half of a cap can be separated from the bottom one. If it wasn't a manufacturing problem, then how it should have been loaded (mechanically) to crack like that.
> 	
> 	Regards,
> 	
> 	Vladimir
> 	
> 	----- Original Message -----
> 	From: TechNet 
> 	To: [log in to unmask] 
> 	Sent: Mon Jul 14 10:39:57 2008
> 	Subject: Re: [TN] Ceramic caps
> 	
> 	In addition to the very good info you have already received, consider
> 	how the caps are being soldered or reworked. I would check to make sure
> 	none were soldered by hand using conventional solder irons. Rework such
> 	as solder touchup should only be done with a hand-held hot air device
> 	such as a Hakko or JVC.
> 	Never, ever allow an MLCCC to be soldered with a conventional soldering
> 	tool, as the sudden thermal shock will crack the body of the connector,
> 	and/or the large heat transfer can melt the high-temp solder connections
> 	internally (plate to terminal connections). 
> 	
> 	-----Original Message-----
> 	From: TechNet [mailto:[log in to unmask]] On Behalf Of Igoshev, Vladimir
> 	Sent: Monday, July 14, 2008 8:08 AM
> 	To: [log in to unmask]
> 	Subject: [TN] Ceramic caps
> 	
> 	Hi TechNeters,
> 	
> 	I came across an unusual (at least to me) failure mode of ceramic caps.
> 	They crack along the component body in either normal (from top all the
> 	way through to the bottom), or parallel (from one side all the way
> 	through to the other side) direction to the board the caps are mounted
> 	on.
> 	
> 	Has anyone seen something similar?
> 	
> 	Thanks a lot in advance.
> 	
> 	Regards,
> 	
> 	Vladimir
> 	
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-- 
Eric Christison Msc
Mechanical Engineer
Consumer & Micro group
Imaging Division

STMicroelectronics (R&D) Ltd
33 Pinkhill
Edinburgh EH12 7BF
United Kingdom

Tel:	+44 (0)131 336 6165
Fax:	+ 44 (0)131 336 6001

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