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November 2000

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Subject:
From:
Craig Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 2 Nov 2000 16:57:56 -0500
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Arturo,

        To really know the root cause, you will have to cross-section your
capacitors. The one nice thing about capacitor cracking is that different
root-causes (internal flaws, excessive placement stress, thermal shock)
produce different crack signatures.

Best Regards
Craig


-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Arturo Urias
Sent: Thursday, November 02, 2000 2:21 PM
To: [log in to unmask]
Subject: [TN] Cracked capacitors question


Dear subscribers:

I have seen in a few of our products some cracked capacitors. The cracks
are very small and it is usually very difficult to see them, even under a
high maginification microscope. When we reflow one side of the capacitor
with the solder iron, the capacitor completely separates. In a few cases I
have seen the cracks even before we touch it up with the solder iron, so I
know that somehow it is happening before touchup. This problem has been
experienced on boards that do not go through the wave. There are other
components like resistors and even other capacitors that do not show the
same problem, even on the same product. The capacitors are 805s.

Any ideas as to what is causing this?

Thanks!

Arturo Urias
National Instruments

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