[Premium-Rx] Nonsmoking Tantalums

[Gary Geissinger]

Guys,
 
I have a couple suggestions with regard to Tantalum capacitors.
 
1.  I use them in my spaceflight flight hardware...with serious
derating.  On 5 VDC lines I use 50 VDC capacitors with a 320 hour high
temperature burn-in.
 
2.  On my power supply outputs I used to use "wet slug" Tantalums.
Again with serious derating the ESR is good and they seem to last
forever.  In the last 10 years I've gone to stacked mono-ceramics.
Inspite of the cracks in the lead frames they are pretty good.
 
On the other side, I once tested 50 VDC Tantalum capacitors for a 19 -
37 VDC application.  I could stroke them out with about a 25% failure
rate.  And those were the hi-rel spaceflight parts.
 
Gary WA0SPM
 
Gary A. Geissinger
Chief Electrical Engineer
DigitalGlobe Inc.
1601 Dry Creek Drive
Suite 260
Longmont, CO 80503
(303) 684-4026
(303) 684-4048 (fax)
ggeissinger at digitalglobe.com
see www.digitalglobe.com <http://www.digitalglobe.com/> 
"An imaging and information company."
 

________________________________

This mailbox protected from junk email by MailFrontier Desktop
from MailFrontier, Inc. http://info.mailfrontier.com
<http://info.mailfrontier.com/> 


	-----Original Message-----
	From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org] On Behalf Of
DAVEINBHAM at aol.com
	Sent: Thursday, April 28, 2005 10:58 AM
	To: premium-rx at ml.skirrow.org
	Subject: [Premium-Rx] Nonsmoking Tantalums
	
	
	I have replaced a few dozen shorted tantalums in my 6 pack of
Racal RA6790/GM's in last 3 years or so.
	However, only one was a smoker. Mostly they just short and the
+15 power supply shuts down. 
	 
	Regards,
	Dave
	
************************************************************************
****************
	 
	Rick,
	 
	You might also check if the power supply has any tantalum
capacitors in it, such as 10uf at 25V match-head epoxy dipped style.
They are sometimes used as filters on VCC lines, usually downstream from
a 10 ohm 1/4 watt resistor.  I don't know why, but in the last five
years I have run into literally hundreds of shorted ones in Racal,
Fluke, Datron and other equipment.  In all cases they were adept at
sending smoke signals.
	 
	The HF-1000 supply sounds almost like a PC power supply...5V,
12V and a power good signal line...
	 
	Geoff Fors


-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.qth.net/pipermail/premium-rx/attachments/20050428/9eb8cfc0/attachment.htm