David, Even under normal conditions, Tantalum capacitors are prone to failing, with the failure mode being a short-circuit.
At Sun, we use ceramic capacitors instead of Tantalum capacitors where ever possible. In applications where high capacitance is needed, (i.e. 47 uF and higher,) fused Tantalum capacitors are used. We used to derate Tantalum capacitors 40% (example: for bypassing 12 VDC, a 30 VDC rating was used (30 V = 12 V / 0.4) Even with this guideline, we were still getting failures resulting in power supply shut-downs, or smoke and flames in some cases. BTW, the Japanese "smoke emissions" requirements drove most of these guidelines. I hope this helps. Dan > From [email protected] Tue Jun 30 14:32:05 1998 > From: "Brumbaugh, David" <[email protected]> > To: "'emc-pstc'" <[email protected]> > Subject: Tantalum Capacitors > Date: Tue, 30 Jun 1998 08:46:29 -0700 > X-Priority: 3 > MIME-Version: 1.0 > X-Resent-To: Multiple Recipients <[email protected]> > X-Listname: emc-pstc > X-Info: Help requests to [email protected] > X-Info: [Un]Subscribe requests to [email protected] > X-Moderator-Address: [email protected] > > 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 > >
