Right. It does look like a Brittle Fracture at the ENIG interface.
However, at the virtical termination, I think it's just a n optical
effect. A higher mag image, or an SEm one would give a better idea on
that. Also, I'm not sure how good or bad the layer of electroless Ni is.
regards,
Vladimir
SENTEC Testing laboratory Inc.
Quoting "Stadem, Richard D." <[log in to unmask]>:
> There is definitely a crack, and it is actually more of a separation of the
> solder from the endcap perpendicular surface. It is more pronounced on the
> endcap face than on the area underneath the endcap (faying surface
> between the
> bottom of the endcap and the top of the pad).
> This indicates that the separation or crack is due to flexural
> stress. It may be
> due to CTE mismatch, but I doubt it.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea
> Sent: Wednesday, December 15, 2010 9:09 AM
> To: [log in to unmask]
> Subject: [TN] Intermitent capacitor
>
> Dear Technos,
>
>
>
> We see intermittence in the functioning of 1206 ceramic caps after mechanical
> assembly. Everything OK in Test, prior to assembly. Due to mechanical
> constraints, the board is rather roughed up during integration, so I was not
> surprised with the issue. But now the things get complicated: if the caps are
> touched up, the intermittence goes away and everything works again.
> So we've had
> the capacitors x-sectionned, see images at
> http://ipc-technet.groupsite.com/gallery/17220
>
>
>
> So here come the questions:
>
> · If I am not wrong, I have seen comments on this very forum about
> touch-up of ceramic caps actually fixing internal damage of the component,
> rather than the joints, which is misleading and just a temporary fix, the cap
> will stop functioning in a short while. Do I see it right?
>
> · Although there is an 0603 in close neighbourhood of the
> problem 1206,
> see image, the damage is only on the 1206. Am I wrong considering
> this normal,
> bigger size, higher bending, more damage?
>
> · The lab couldn't find anything wrong, neither in the joints, nor
> internally in the part. I see a dark line at the interface between the solder
> and the part in the right side image; is this normal, or an actual crack?
>
> · It seems the plates of the caps are perpendicular to the
> PCB, instead
> of parallel. This is how they came in the tape, we are not flipping
> them. Would
> this orientation of the plates make the component more prone to internal
> cracking than parallel?
>
> · There indeed does not seem to be any 45 degrees cracking of the
> ceramic package at the corners (indicative of mechanical stress).
> Since nothing
> internal has been detected either and the joints were deemed good, what else
> could be the issue?
>
>
>
> Thanks,
>
>
>
> Ioan Tempea, ing.
> Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
> T | 450.967.7100 ext.244
> E | [log in to unmask] <mailto:[log in to unmask]>
> W | www.digico.cc <http://www.digico.cc/>
>
>
> N'imprimer que si nécessaire - Print only if you must
>
>
>
>
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