Gary,

Does your power supplies on the in-circuit test have any current limit
resistors?  The first power-up can see a large in rush of current that can
burn up the capacitor, before it can heal itself.  Is this a new design or
have you been doing the in-circuit test for awhile?  50% derating on chip
tantalums is also a very good idea to reduce failures.

Jim Carlson
Sr Quality Assurance/Reliability Engineer
Rockwell Collins EW-SIGINT
Phone 443-489-9121
Fax 443-489-9290



Gary Bremer <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
04/28/2005 10:26 AM
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Subject
[TN] Capacitor Failures






Has any one had any problems with Vishay Capacitor P/N 595D226X9050R2T
failing?
From our electrical engineers statement the most common failure is during
in-circuit test.  This is conducted at ambient temperature & humidity.
These
capacitors are used to decouple an input voltage, which is set to
increasing
values.  The failures have been occurring when a steady-state input
voltage of
around 38 VDC is used.  When the voltage is left on, the chances of
failure
increases.  For example, two different capacitors were blown when the
input
voltage was left on for about 2 minutes.

--
Gary Bremer
Senior Manufacturing Engineer

Curtiss-Wright Controls Inc.
Embedded Computing -Subsystem

28965 Avenue Penn
Santa Clarita, CA 91355-4185
Main: 661.257.4430 extension 2170
Fax: 661.257.4782
e-mail: [log in to unmask]
Web: www.cwcembedded.com

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