i have seen CSR13 Ta caps last for about 150 hours when reversed and then short. The failure rate is about 1000 to 10,000 times worse than correct polarity configuration. Reversed life also depends on series resistance in circuit (ohms/volt), See MIL-HDBK-217. Best way to really find out is to run some on a life test with actual reversed voltage and actual circit series resistance. The Ta2O5 oxide film probably starts to thin out, (the reverse of the forming process - DeForming) then it shorts out. There is also a very accelerated failure rate if you exceed the voltage rating with the correct polarity. Paul Signorelli Reliability Engineer RW Systems _______________________________________________________________________________ _ From: TechNet on Thu, Jun 25, 1998 18?41 Subject: Re: [TN] tantalum caps To: [log in to unmask]@inetgw I'd be very interested in hearing of anyone's experience with polarized caps that survive reverse polarity in circuit with power applied over a long period of time. We have done a test with a SMT style cap that just sits there for a while doing nothing. I'm familiar with reversed caps blowing up within a short period of time. These are different. 5 volt level but tons of current if demanded. Any ideas? We are talking to the cap mfr, but it's not getting anywhere ... ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################