Dear readers,
I was recently trying to assist Chanc3 with a repair to a FLIR S45 thermal camera. It had suffered a Tantalum capacitor failure.
In that thread I learned a lot about the different series of Tantalum capacitors that are available to the designer and repairer of electronics. Comments from Bill W and SeanB highlighted how using a Solid Tantalum of the wrong series or location in a piece of electronics can end in premature failure of the capacitor. As those who have witnessed such failures will know, Solid Tantalums can have nasty failure modes ranging from becoming short circuit, to burning a hole through the PCB ! You do not want to get it wrong with these components in your designs.
The S45 repair thread is here....
https://www.eevblog.com/forum/thermal-imaging/flir-s45-repair/Having looked at the KEMET web site, I see that they offer all manner of different Tantalum Capacitor series to suit differing use scenarios. There is the R series with Robustness built in, and the Fused series (F) that fail open circuit to prevent pulling down of supply rails....... kind of important in mission critical systems as found on satellites etc. There are also Space Rated series (S) for ultimate reliability.
There has been discussion of Tantalum capacitors on this forum previously. Some forum members consider the technology a liability in any new design due to experience of past component failures. We have to consider whether the Tantalum capacitors were to blame for such failures, or the designer, who used them in a particular situation that may not have suited the technology of the time. Are they really that bad ? If so, why is the Tantalum Capacitor in common use within Miitary equipment where reliability is important ?
We also need to consider whether Tantalum capacitor technology has been equalled, in terms of performance, by less 'sensitive' capacitor technology that is now available. Solid Electrolytics etc.
Is it a good idea to remove old Solid Tantalum capacitors from aged equipment and fit electrolytic capacitors in their place. What are the pitfalls of such action ? ESR, performance, size etc.
I read a statement from one Tantalum Capacitor manufacturer that highlighted a high failure rate of some poorly designed black epoxy cased Solid Tantalum capacitors in the past. They were keen to state that their black cased capacitors were not the same and did not suffer the failure issue of others. Marketing talk, or was this the Solud Tantalum version of the infamous Electrolytic capacitor failure plague ?
I thought this thread might courage some discussion of these most common and important components. I have learned much about them over the last couple of days. I am 50 and have not had need to study them in any great depth before.
Please share your life experiences and thoughts about Solid Tantalum capacitors here
I attach a picture of the failed Tantalum capacitor in the S45 camera for interest. They can literally catch fire and burn through the PCB layers ! This camera was lucky.
Fraser
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