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June 2001

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Subject:
From:
Lou Hart <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 13 Jun 2001 12:42:20 -0400
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John, you did not say what kind of dielectric(s) are in the capacitors.
 Some ceramics are unstable with thermal shocks and are sensitive to
temperature changes.  So if a capacitor was at -9% to begin with, and
thermal stress led to -2%... You say "drifted" from nominal.  Were they all
at nominal before the stress?  Lou Hart

-----Original Message-----
From:   John Fahey [SMTP:[log in to unmask]]
Sent:   Wednesday, June 13, 2001 11:46 AM
To:     [log in to unmask]
Subject:        [TN] Capacitor Values drifting after temperature cycling

Is it common to see values of capacitors drift after temperature cycling? I
had a 15% ICT fallout on some caps after 48 hrs temperature (85deg)
cycling.
The values drifted @+/- 11% from their nominal. The component specs allow a
+/- 10%, but I am curious why the moderate temperature cycling would cause
a 15% failure rate for capacitor value drifting when they were tested on
the ICT second time around.

The ICT parameters/set up did not change and I had 100% ICT pass rate first
time around.

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