The biggest drawback with tantalums is that their normal failure mode is
a short circuit. I once spent a lot of time over a period of several
months trying to get MTBF figures from manufacturers, but had no
success.
I finally decided to use tantalums in the design anyway, primarily
because of the real-estate savings. With the new low-voltage power
technology, they are used widely through out the computer industry. So,
I figured that I was at least in good company.
In the last year or so, in prototype systems, I haven't had any failures
yet. There was one case where a half-dozen of them were reversed,
resulting in the predictable explosion, but the board wasn't damaged. I
have seen boards previously that were damaged by tantalums, however.
If you have an option, though, I would recommend electrolytics. They're
like old soldiers; they never die, they just fade away. Another option
is to use the new organic type of capacitor. As I recall (not sure)
Sanyo is the major supplier for these.
Max Kelson
Evans & Sutherland
-----Original Message-----
From: Brumbaugh, David [SMTP:[email protected]]
Sent: Tuesday, June 30, 1998 9:46 AM
To: 'emc-pstc'
Subject: Tantalum Capacitors
Can anyone tell me if there are any drawbacks in using
tantalum capacitors in dc power supply filters? My recollection
is that they can "pop" if the voltage polarity is reversed, or
if
there are large negative voltage swings during transients.
TIA,
David Brumbaugh
The BOEING Company
Information, Space & Defense Systems
Electromagnetic Effects
M/C 8H-11
POB 3999 Seattle, WA 98124-2499
Phone: Kent Space Center (253) 773-3733
