4 ms·
The commenters point is that even typical SMT tantalums have leads: - A/B/C/.. type cases have tiny leads going outwards - more modern cases have metal sheet
by xondono 8y ago
The commenters point is that even typical SMT tantalums have leads:
- A/B/C/.. type cases have tiny leads going outwards
- more modern cases have metal sheet like leads bent down and inwards.
The thing is that tantalums capacity density is hard to beat, specially if you are cost-restricted (those polymers are pricey).
There’s also a lot of research from NASA about the safety of tantalums, and they actually think they’re fairly safe provided you don’t expose them to voltage ripple (so don’t place them on SMPS)
- arcticbull 8y agoTotally possible I misread it, agreed about the density and ripple, though due to failure mode I’ve always derated them 50% in designs where I’ll derate niobium or (admittedly expensive) polymer 20% to mitigate the risk of thermal runaway.
- blattimwind 8y ago> There’s also a lot of research from NASA about the safety of tantalums, and they actually think they’re fairly safe provided you don’t expose them to voltage ripple (so don’t place them on SMPS) Besides even the shortest over-voltage incidents, Tantalums also don't like high current pulses. Low-ESR power sources with quick ramp ups are a no-no.
- xondono 8y agoYes, I read a lot about tantalums and their failure modes some years ago because we wanted to set some kind of use policy for our own products. After a lot of research and testing we ended up forbidding the use of tantalums in our designs and taking the cost hit whenever density was an issue. It’s a drastic measure but I think it was the right call, our products were a perfect mixture of all the things that tantalums don’t support well.