Author Topic: Tantalum substitute  (Read 1088 times)

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Offline Howardlong

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Re: Tantalum substitute
« Reply #25 on: September 18, 2020, 08:06:10 pm »
If I'm not wrong TAJ series is of a general use type and easy to get. I don't see a reason to change it to anything else (non-tantalum).
There must be a strong reason to change it to non-tantalum type. And of cause you need to check if that other type can be used there taking into consideration all the parameters (ESR and it's stability, if it can be lower, resonating frequency and signal frequency range, temperature range, humidity variation, vibration, ... etc).

Reliability and failure mode? Tants typically die short, not great in a decoupling scenario, where there could well be secondary failures too as a result.

MLCC also fail short (unless specified otherwise) which is why you can often see two of them in series in automotive boards

Interesting, all of the MLCC failures I’ve seen are o/c, cracked caps due to thermal cycling.

Offline JPortici

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Re: Tantalum substitute
« Reply #26 on: September 20, 2020, 06:22:05 pm »
There is also overvoltage :)

Offline KT88

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Re: Tantalum substitute
« Reply #27 on: September 20, 2020, 09:19:33 pm »
A widely unknown fact: Capacitors do have data sheets!
If the specs are violatetd they trend to fail  :--.
Some specs are implied - like temperature cycling - others are not mentioned.
If specs or a DS are not provided I consider the parts to be unusable.
Ideally the manufacturer provides SPICE models as well. More detailed ones could be obtained under NDA in some cases. These models could take voltage coefficients into account for example.

My strong reccomendation is to RTFDS and simulate the sh*t out of your circuit...



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