Hi Inge,
Here's your cross section photo:
http://stevezeva.homestead.com/VD0_8073_NEWXSECTION_6.jpg
I haven't tried posting a picture to the IPC photo library yet, don't really
need to, I have my own page ;^>
Steve
--------------------------------------------------
From: "Inge" <[log in to unmask]>
Sent: Tuesday, April 27, 2010 4:22 PM
To: <[log in to unmask]>
Subject: Re: [TN] Failure fatigue photos
> Hi both of you,
>
> I made a job for Siemens once, about fatigue. The board behind the
> instrument panel of a truck vibrated on the roads in South America,
> resulting in lifted leads and the trucks became inoperable. I simulated
> the situation in the vibrator lab, and could see clearly what happened.
> Just as Dave told you, the crack will finally occur in a band which is
> represented by fine structure on the one side and a coarse and elongated
> on the other. It has partly to do with the solidification to do, fine
> grains closest to the legs and coarser the more you are from that site.
> I'll send one very illustrative photo. I've missed how to fix that
> instantly. How do you bring the photos to that fast presentation URL?
>
> Inge
>
> --------------------------------------------------
> From: "David D. Hillman" <[log in to unmask]>
> Sent: den 27 April 2010 06:33
> To: <[log in to unmask]>
> Subject: Re: [TN] Failure fatigue photos
>
>> Hi Ioan - Do you have any optical photos of the fracture? Thermal cycle
>> fatigue failures typically develop "banding (aka microstructure
>> coarsening)" in the solder joint shear zone. The solder joint
>> microstructure evolves into distinct grains of tin and lead which shows
>> up
>> better in optical photos. The fracture in your photos appears to be
>> fatigue but its hard to see the microstructure in your photos. I added a
>> photo of what typical thermal cycle induced SnPb coarsening looks like
>> on
>> the IPC Photo Gallery.
>>
>> http://ipc-technet.groupsite.com/gallery/13118
>>
>> Dave Hillman
>> Rockwell Collins
>> [log in to unmask]
>>
>>
>>
>> Ioan Tempea <[log in to unmask]>
>> Sent by: TechNet <[log in to unmask]>
>> 04/27/2010 07:59 AM
>> Please respond to
>> TechNet E-Mail Forum <[log in to unmask]>; Please respond to
>> Ioan Tempea <[log in to unmask]>
>>
>>
>> To
>> [log in to unmask]
>> cc
>>
>> Subject
>> [TN] Failure fatigue photos
>>
>>
>>
>>
>>
>>
>> Dear Technos,
>>
>>
>>
>> It looks like, for the first time, I have the occasion to look at fatigue
>> failed joints. The lab analysis we've got states this, but does not
>> abounds in details.
>>
>>
>>
>> One of the conclusions is "the crack propagates around harder Sn shearing
>> the softer Pb, but the Sn and Pb zones seem fairly large for regular
>> solder structure". Citing from Klein Wassink "During cyclic plastic
>> deformation the microstructure inside the material changes in the zones
>> where the deformation is concentrated. This leads to local grain
>> growth..."
>>
>>
>>
>> I have deposited the micro-sections on the IPCs website
>> http://ipc-technet.groupsite.com/gallery/13116
>>
>>
>>
>> I would need your expert opinion regarding the failure. Is this fatigue?
>> The big pure Sn and pure Pb areas, are they normal size for fatigued
>> joints?
>>
>>
>>
>> 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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