Eric,
You get what you pay for.
Ideally you would affix strain gauges to your circuit packs, AFTER reflow
and follow the process. Proper equipment to gather the strain gauge data is
a tad more expensive than 10 cross-sections, but once you have the
equipment, you can use it again and again.
When I am at work tomorrow I will send you the name of the equipment we use
- and like.
Bev
RIM
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Eric Laroche
Sent: Tuesday, December 13, 2011 8:36 PM
To: [log in to unmask]
Subject: [TN] cracked capacitors
Hi all,
We've been witnessing some field failures related to cracked
capacitors. We have seen it on different PCBA's, different panel
configurations, different physical locations on boards even 3 different
capacitor suppliers. The only constant is that we always see it on the
0,1uF ceramic 0603. We've only had a couple of cross sections done as
they are relatively expensive. All cross sections done so far show
evidence of board flexing causing 45degree cracks.
There must be something along our process that causes this flexing. The
way I see it, pretty much every step can be the guilty one. From PnP,
reflow, repair, ICT, functional testing, depanelling and final
mechanical assembly...up to some extent, they could all possibly be
causing flexing and damage to capacitors. I would like to make a more
extensive study to isolate the source of our problems. Are there other
methods, less expensive than cross sectioning, to see if a capacitor is
cracked?
Have any of you faced this problem in the past? What methods did you
use to isolate the source of the problem? What were your results?
Thanks for your help,
Eric
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