Dipped tantalums in old computers and similar devices can be also replaced with modern low ESR electrolytic or polymer capacitors. They were using tantalums back then because they didn't have anything better.
Let’s not forget that ceramics don’t explode. Tantalum is an inferior capacitor unless you need an absolutely massive capacitor, in which case it’s superior to aluminum electrolytic. At small values, ceramic is 100% better.
ESR is also frequently dependent, I'd imagine your meter is testing somewhere from 100Hz to 100KHz ceramic caps are much better at high frequency. In the region of a few milliohms at 1Mhz and above.
the standard ESR measurement is always done at 100kHz and not 1kHz. Datasheets only report ESR at 100kHz. But that's probably not the main reason to use Tantalums. Ceramics can be highly voltage dependent and thus bring a lot of nonlinearity with them that Tantalums dont. The most important thing about Tantalums is their temperature stability and moisture independence. So, no they should not be replaced with ceramics. Doing the opposite is OK but hugely expensive.
I don't know how many times I've seen old teardrop tantalum's just going into full short mode and clamp a voltage bus. I know the engineers use them because of their ESR values but I've started just replacing them in old equipment when I run across them. BTW when they short they'll pump out a ton of the magic smoke. 🙂
I like the fact that there is still some voodoo and black magic in electronics. I'm a big Bob Pease fan (RIP) and would cackle whenever he would suggest a "whiff" of capacitance. One technique he described involved using a length of twisted pair as a capacitor, snip the length shorter until the circuit behaved as intended. I am the proud owner of a Tektronix 485, and came across a warning in one of the repair manuals not to wiggle certain transistors in their sockets, because they had been positioned deliberately during factory calibration.
My company makes hi temp downhole equipment, we have given up using tantalum long time ago, they where trouble makers getting shorted every time, we replaced them all with ceramics and standard wet capacitors for the high capacitance. I am sure there must be a specific application where tantalum performs better, but in my experience, whenever I see a tantalum cap I see failure coming soon !😂
I agree. Tantalums were just fairly high capacity, fairly low esr, very low microphonics, in a fairly small package. That used to make them irreplaceable. That's not so true anymore. They are also volatile, so if something else more stable will do the job, by all means, use that something else.
used to use a lot of solid tants in our products at the time, they were quite big and heavy compared to the standard wet electrolytic ones. our units went in the cockpits of jet fighters and big turbine transports. vibration was a big thing and solid tants seem to survive it well.
Solid Tantalums have really good electrical characteristics but, like all the different capacitor types, the application must make best use of that particular set of component tradeoffs. Solid Tantalums should NEVER be used to bypass a power supply line, unless a series resistor of at least 3 ohms per volt is used. These capacitors cannot tolerate ripple current or voltage surges. You commonly see solid tantalums used on power supply lines, and they appear to work fine but, they will short out without warning and catch on fire.
An early lesson for me in electronics was building up a small switching converter that specified electrolytic or tantalum decoupling capacitors. Being too clever for my own good, I decided to use some of the much smaller and more convenient ceramics I had on hand.
This brings up an interesting case: the TruSDX website says that the Tayloe detector integrating capacitors (100nF each iirc) can be replaced by some (expensive) 0603 Tantalum caps for better performance. If Tantalum actually has worse ESR at those values (and likely also at the frequencies it's working with), why would Tantalum be better than ceramic in this case? Maybe it's because X7R ceramics change capacitance with voltage and temperature and have piezoelectric effects while Tantalums don't (at least as much).
Dipped tantalums in old computers and similar devices can be also replaced with modern low ESR electrolytic or polymer capacitors. They were using tantalums back then because they didn't have anything better.
Let’s not forget that ceramics don’t explode. Tantalum is an inferior capacitor unless you need an absolutely massive capacitor, in which case it’s superior to aluminum electrolytic. At small values, ceramic is 100% better.
ESR is also frequently dependent, I'd imagine your meter is testing somewhere from 100Hz to 100KHz ceramic caps are much better at high frequency. In the region of a few milliohms at 1Mhz and above.
the standard ESR measurement is always done at 100kHz and not 1kHz. Datasheets only report ESR at 100kHz. But that's probably not the main reason to use Tantalums. Ceramics can be highly voltage dependent and thus bring a lot of nonlinearity with them that Tantalums dont. The most important thing about Tantalums is their temperature stability and moisture independence. So, no they should not be replaced with ceramics. Doing the opposite is OK but hugely expensive.
I don't know how many times I've seen old teardrop tantalum's just going into full short mode and clamp a voltage bus. I know the engineers use them because of their ESR values but I've started just replacing them in old equipment when I run across them. BTW when they short they'll pump out a ton of the magic smoke. 🙂
Tantalums also make fine crowbar protective circuit devices... you old timers know what I'm talking about.
I like the fact that there is still some voodoo and black magic in electronics. I'm a big Bob Pease fan (RIP) and would cackle whenever he would suggest a "whiff" of capacitance. One technique he described involved using a length of twisted pair as a capacitor, snip the length shorter until the circuit behaved as intended. I am the proud owner of a Tektronix 485, and came across a warning in one of the repair manuals not to wiggle certain transistors in their sockets, because they had been positioned deliberately during factory calibration.
Ceramics are not very temperature stable either, their value is kind of a suggestion, tantalum’s are quite stable though, great for timing circuits
My company makes hi temp downhole equipment, we have given up using tantalum long time ago, they where trouble makers getting shorted every time, we replaced them all with ceramics and standard wet capacitors for the high capacitance. I am sure there must be a specific application where tantalum performs better, but in my experience, whenever I see a tantalum cap I see failure coming soon !😂
I agree. Tantalums were just fairly high capacity, fairly low esr, very low microphonics, in a fairly small package. That used to make them irreplaceable. That's not so true anymore. They are also volatile, so if something else more stable will do the job, by all means, use that something else.
used to use a lot of solid tants in our products at the time, they were quite big and heavy compared to the standard wet electrolytic ones. our units went in the cockpits of jet fighters and big turbine transports. vibration was a big thing and solid tants seem to survive it well.
All these four decades since "E over I R" & Boolean became soldered to my Pre-Frontal Lobes, figured I was the only one who used 'Ohmage'. ;-]
Solid Tantalums have really good electrical characteristics but, like all the different capacitor types, the application must make best use of that particular set of component tradeoffs. Solid Tantalums should NEVER be used to bypass a power supply line, unless a series resistor of at least 3 ohms per volt is used. These capacitors cannot tolerate ripple current or voltage surges. You commonly see solid tantalums used on power supply lines, and they appear to work fine but, they will short out without warning and catch on fire.
I've once purchased 500 MLCC 1206 capacitors with a 47uF 50V rating and I tested to have an ESR of 0.08 ohms at 1kHz!
It is always the 16V tantalum on the 12V rail that shorts out the mainboard.
I hate to point this out, but the measurement is likely flawed.
An early lesson for me in electronics was building up a small switching converter that specified electrolytic or tantalum decoupling capacitors. Being too clever for my own good, I decided to use some of the much smaller and more convenient ceramics I had on hand.
Leaving a comment to show engagement for the TH-cam algos. This was a GREAT video. Well done. Bring on IMSAI Dog. :)
Really interesting. Thanks!
This brings up an interesting case: the TruSDX website says that the Tayloe detector integrating capacitors (100nF each iirc) can be replaced by some (expensive) 0603 Tantalum caps for better performance. If Tantalum actually has worse ESR at those values (and likely also at the frequencies it's working with), why would Tantalum be better than ceramic in this case? Maybe it's because X7R ceramics change capacitance with voltage and temperature and have piezoelectric effects while Tantalums don't (at least as much).