Alan I do not have an answer for your tantalum capacitor problem. However, if you are experiencing unwanted damage to your electronic assembly as a result, you should consider repairing the damage, rather than scrapping the boards. There are a variety of acceptable methods and procedures found in IPC-7721. For more information you can visit circuittechctr.com. The web site is full of useful information. Mike Connolly Circuit Technology Center --- Alan Peters <[log in to unmask]> wrote: > I have been asked to investigate two failures of 10u > 25v solid tantalum capacitors. > > They are rectangular plastic/resin encapsulated, > sintered tantalum/ manganese > dioxide/ graphite-silver types. > These items are "cremated" beyond investigation! > > I am lead to believe (hmm!) all correct operating > conditions have been met/not > exceeded i.e. excessive voltage, ripple and reverse > voltage. > The capacitors have seen service for at least 5 > years in a very humid environment. > I am not aware if they are from the same batch. One > was fitted across a +15v rail > in one unit and the other was fitted across a -15 > rail in another unit. > > Question? Does anyone know of an ageing condition, > or what the effects of humidity > are that can lead to failure of these capacitors? > > Alan Peters > Failure Analysis Engineer > Materials & Components Labs > > ############################################################## > TechNet Mail List 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://www.ipc.org/html/forum.htm) for additional > information. > If you need assistance - contact Keach Sasamori at > [log in to unmask] or > 847-509-9700 ext.5315 > ############################################################## __________________________________________________ Do You Yahoo!? Kick off your party with Yahoo! Invites. http://invites.yahoo.com/ ############################################################## TechNet Mail List 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://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################