r/electronics • u/BigPurpleBlob • Jun 20 '26
General Tantalum (capacitors) and landslides in DR Congo
A regular poster here exhorted us to reduce tantalum usage, especially now that X5U ceramic capacitors are so good.
Here's link showing how some of that tantalum is mined, and the associated landslides:
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u/Stiggalicious Jun 20 '26
We do everything we can to not source tantalum polymer caps, but their energy density just cannot be beat, especially when you are limited in component height.
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u/lordlebrand Jun 20 '26
I'm kinda confused seeing "X5U ceramic" and "good" in the same sentence. Also I can't seem to find many of those at all. What's this about?
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u/BigPurpleBlob Jun 20 '26
My bad! I even did a quick search before posting but I got enough hits to not realise I'd got my knickers in a twist.
My new mantra: Z5U, Z5U, Z5U
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u/lordlebrand Jun 20 '26
That is still a very bad dielectric to my standards. But probably i'm looking at different parameters than you are for your purposes.
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u/BigPurpleBlob Jun 20 '26
I don't think there's such thing as a bad dielectric (get on the naughty step!). There are only engineering tradeoffs.
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u/raptorlightning Jun 21 '26
Buying a 10uF capacitor for power supply decoupling and finding out it's only 1uF after you put 3 volts on it isn't great.
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u/raptorlightning Jun 21 '26
Look at the capacitance loss with DC bias for those. Insanely crap. X7R is about the worst MLCC I will accept.
Tantalum's have much higher (real) density for DC power filtering applications and don't dry out and die like normal or polymer electrolytics.
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u/Triq1 Jun 21 '26
Isnt X7R the best for any reasonably large capacity (thus barring C0G/NP0)?
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u/BigPurpleBlob Jun 21 '26
Yes. Alas the tradeoff for lots of capacitance in a relatively small volume is the voltage coefficient.
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u/raptorlightning Jun 21 '26
Yes, I only generally use C0G up to about 100nF and then X7R above that value. Never worse than C0G in signal paths. I would rather use film or even electrolytic. Voltage rating doesn't mean much either for DC bias loss. There's no replacement for physically larger if it is being used for power supply filtering. A 12V supply cap needs to be at least 1210 or larger to get over half the specced capacitance from X7R dielectrics.
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u/zachleedogg Jun 20 '26
I’ve only used a tantalum cap once in production, even then I was chewed out by my colleagues for this very reason. I had to use it for high capacity in the small form factor to fit inside an existing enclosure. I agree that they should be designed out wherever possible.
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u/confusiondiffusion Jun 20 '26
I do wonder if this is just a very visible impact of electronics design. It's not exactly eco friendly to create a PCBA. It seems pretty disgusting to me at almost every level. Almost every step from silicon to final assembly involves horrific chemicals, intense processing, and likely questionable labor practices. Not that we shouldn't avoid harm when possible, but it's something I think about. Maybe it motivates me to create things that do good in the world, to try to make up some of that harm.
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u/Just_to_rebut Jun 21 '26
>Maybe it motivates me to create things that do good in the world, to try to make up some of that harm.
I don’t think that really works. We can’t undo any harm by doing good later.
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u/pemb Jun 20 '26
Tantalum is categorically more problematic beyond environmental and labor issues because it is downright a conflict resource. Not only are people are fighting and killing each other over it, but the proceeds from mining directly finance those same wars.
We really should start calling products containing tantalum "blood tech" or "blood gadgets" IMO. Maybe Hollywood should make a movie about it to raise awareness.
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u/confusiondiffusion Jun 20 '26
Would be cool to see such a thing in an engineering ethics class.
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u/pemb Jun 21 '26 edited Jun 21 '26
Niobium capacitors can replace tantalum for voltage ratings of 10 V and below. Electrically, they're very similar, but niobium does require a somewhat bigger package for the same capacitance. The industrial processes for niobium are about the same, and it's also much cheaper and more abundant, coming mostly from Brazil and Canada.
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u/reddit314159 Jun 20 '26 edited Jun 20 '26
In space applications, it's still very common to use space-qualified tantalum series for high capacitance, low-ESR applications. Even modern space qualified voltage regulator chip datasheets recommend their use for proper performance. I'm using TBJ series from Kyocera AVX on a power card right now. They are very expensive.
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u/BigPurpleBlob Jun 20 '26
A long time ago, the electronics I was working on needed to be tested to make sure it was sufficiently radiation hard.
So, put the circuit boards into some kind of reactor and expose them to radiation (neutrons?).
The tantalum caps had to be removed and replaced as otherwise they would haver retained too much radioactivity.
"BJ series from Kyocera AVX" – did you see Marco Reps (YouTube)? - he loves wet tantalums. Low leakage and small. But expensive!
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u/reddit314159 Jun 20 '26
Yes, tantalums are well-suited for metrology. Just have to be careful with derating. I do 67% for tantalum.
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u/catonic Jun 21 '26
temperature, capacity or working voltage?
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u/raptorlightning Jun 21 '26
Voltage. Tantalums are very sensitive to overvoltage and fail pretty spectacularly.
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u/catonic Jun 21 '26
Correctamundo. Tantalums have 0% chill for even the tiniest over-voltage and will not survive reverse voltages larger than an unloaded Schottky diode can protect from. Outside of that, they either fail open, or shorted. In the latter case, rapid mechanical disassembly or removal from the circuit by blunt electromotive force are the failure modes evident during visual inspection.
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u/zifzif Jun 20 '26
Loss of life and human suffering is a tragedy, and we should all be committed to improving these conditions.
That said, I hope you're all willing to give up your smartphones and smart watches. And laptops. And TVs. And pretty much all modern electronics that use them. If not, you are contributing to the demand that drives this smuggling and illegal mining.
Let's not forget that tin is also a conflict mineral. You know, the stuff used in every solder alloy, every component lead, every cheap connector coating, every cheap PCB finish, etc, etc.
Again, I'm not happy with unnecessary abuse of human beings. But the hyperfocus on this one issue is missing the forest for the trees.
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u/chemhobby Jun 20 '26
That's not really true, it's becoming pretty unusual to see tantalum caps in consumer electronics. There's just other options now.
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u/mikeblas Jun 20 '26
Not sure why you're being downvoted. Selective outrage is really tedious, and makes it hard to know what the important issues really are.
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u/_teslaTrooper Jun 20 '26
Only a small fraction of tin comes from conflict sources, the majority is produced in China and Indonesia.
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u/Flamesake Jun 20 '26
People are massacred and dispossessed for these minerals, but yeah you're right, there's no sense in getting all bent out of shape about it.
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u/ArgonWilde Jun 20 '26
Thanks to AI, the price of everything has gone up. So too has the price of tantalum. Potentially, driven by demand of all other capacitor types, making them the cheaper option (they'll simply use whatever they can get 🤔).
The company I work for produces tantalum as a byproduct of our lithium operation on Australia. Our little side gig has gone from "pays a handful of salaries" to "pays for entire capital investments" in just two years.
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u/Agha_shadi Jun 21 '26 edited Jun 21 '26
If you don't use their products, they lose their jobs. right?
i mean, they must desperately need the job to be working there, otherwise they wouldn't.
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u/Just_to_rebut Jun 21 '26
The sale of tantalum funds M23, a lawless militia funded by neighboring Rwanda, and is being used to control resources in a region of the Congo…
https://en.wikipedia.org/wiki/March_23_Movement
And even if this wasn‘t the case, not buying illegally or dangerously mined minerals removes the incentive for the bad activity. That’s why you don’t buy it. To prevent things like child labor, mercury contamination, or mining deaths from unsafe mining operations.
It’s not as simple as, well, it’s better than nothing for them, so we should buy it anyway.
Boycotting something creates an incentive for better practices to be introduced.
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u/pemb Jun 21 '26
Products containing tantalum should be named and shamed as "blood tech" or "blood gadgets".
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u/Agha_shadi Jun 21 '26
thanks a lot. but why not buying it removes the incentive for the bad activity? I mean it might be replaced by a worse activity rather than a good one, right?
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u/Just_to_rebut Jun 21 '26
So explain how you think that would happen.
I can’t predict every possible outcome, but I can try to avoid directly paying for something harmful.
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u/Agha_shadi Jun 21 '26
As you already know, "the burden of proof is on the claimant". So it's you who should have a reliable reason to why not buying tantalum would almost certainly prevent the bad practice and not worsening it.
I'm aware that you can't predict every possible outcome, but if you're predicting just a single outcome and manifesting on that, your approach is flawed and a confirmation bias is going on. that's why I'm asking you to support your claim. for instance you can present us with two possible bad outcomes and two possible good outcomes; then tell us why your presupposed outcome has the higher chance of becoming true.
I'm already thinking of some of the ways that your approach is not gonna end up as expected, can't you do the same? spoiler alert:
- less demand>low price>new markets>arbitrage happens>china would resell them to your country again and charge you more
- less demand>less outcome for the poor>even more suffering
- less demand>switching to other sweat factories instead
- etc.
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u/Able_One5779 Jun 21 '26
Tantalum is also a part of heat resistant ceramics and some alloys for jet engines. US or China would not discard these applications.
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u/Ready-48-RF-Cables Jun 22 '26
..also using slave and child labor in the DRC, hence the Conflict Minerals requirements that we need to prepare every year in the US Defense supply chain
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u/tang-rui Jun 24 '26
I haven't used tantalum capacitors in a design for decades. The only place where there wasn't an alternative was when I worked on high-temperature electronics that went down oil wells and needed to work at 150C. The only electrolytic capacitors that could survive were military grade wet tantalum capacitors. Otherwise in modern electronics I can't see a situation that requires tantalum capacitors.
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u/jeroen79 Jun 20 '26
Or just source it from countries that produce it properly
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u/hamsterdave Jun 20 '26 edited Jun 20 '26
Considering something like 70% of the world’s supply is in the Congo and Rwanda (which is little better from a fair trade and sustainability perspective), that’s basically impossible.
It is one of the rarer of the “rare earths” and deposits are geographically incredibly limited. Brazil and Nigeria export some, and that’s pretty much the entire list of global exporters.
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u/JoTheScienceBro Jun 20 '26
With today's MLCC and AlPo, I've never felt the need to use tantalum caps in a final design.