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I have literally 1 million of these. How are they attached and used? Are they capacitors? Are they something still used?

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They are indeed capacitors - this is an example of a distributor sales page that lists this part.

They're attached by surface-mount soldering on a printed circuit board; plated/coated copper is exposed on the circuit board in a "land pattern" or "footprint" matching the location and size of the two metal ends of the capacitor, solder is applied (possibly as paste with a stencil):

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and then the part is placed on top and the solder is heated (either in a temperature-controlled oven or with a soldering iron by hand) to attach the part:

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As Spehro Pefhany's answer points out, components like these capacitors are often packed onto a tape (rather than loose in a bag), making it easier for automated machinery to pick and place them onto circuit boards at high speed and efficiency for mass production.

The exact part number you have is no longer manufactured, so that exact part is probably not used anymore. However, capacitors like this are a commodity part where the specs matter more than the part number, and there are a number of capacitors with the same dimensions, capacitance, as well as better-or-equal voltage rating, tolerance, and ability to withstand hot/cold temperatures. Think of it as replacing a standard machine bolt - it's the material, length, thread standard, and drive type that matter most, even if the part number or manufacturer changes.

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    \$\begingroup\$ username checks out \$\endgroup\$
    – pipe
    Feb 10 at 20:46
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They are 22nF +/-10% X7R dielectric 0805 (metric 2012) SMT capacitors rated at 50VDC (1H).

If the 2003 corresponds to the date of manufacture then they are more than 20 years old and I doubt any reputable company would want to buy them because of solderability concerns. They're also not on tape and reel so difficult to use in automated production. Note also that 0805 is also pretty large for a modern capacitor of that rating- we've moved on.

Maybe you can get a few bucks for them on an auction site. They probably cost thousands of dollars new.

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    \$\begingroup\$ I doubt whether they were ever that expensive, even brand new. And 0805 is a nice size for hand soldering in hobbyist projects. \$\endgroup\$
    – Dave Tweed
    Feb 10 at 16:20
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    \$\begingroup\$ @DaveTweed The cheapest I see right now is Chazou at a mere $500 USD for \$10^6\$ pieces, FOB Shenzhen (100 reels of 10,000), but that's in 0402. The cheapest 0805s are more like 10x that or more, and they're not even automotive spec. 0805 and 1206 are not mainstream anymore, so the price has gone up substantially for those who need them. \$\endgroup\$ Feb 10 at 16:50
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    \$\begingroup\$ Just as a note- decade value parts are also more marketable than the ones you have- 1nF/10nF/100nF because engineers and tinkerers alike like to sprinkle those values around boards. A knowledgeable hobbyist may know when they can sub a 22nF for a 10nF (usually not an issue if it's a bypass capacitor, but even then there are exceptions where it can cause problems with stability). \$\endgroup\$ Feb 12 at 14:33
  • \$\begingroup\$ I suspect you could get a few bucks per bag on an online auction site. The problem is 1. fees and postage costs are significant and 2. I suspect it would take quite a long time to sell through a thousand bags of a relatively obscure value that way. \$\endgroup\$ Feb 12 at 15:15
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    \$\begingroup\$ You could almost certainly get more per capacitor by re-bagging them into smaller bags but that would be a bunch of extra effort and it would take even longer to sell through the stock. \$\endgroup\$ Feb 12 at 15:17
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You literally have the TDK part number (TDK ITEM NO) to look up via google. It will bring up a datasheet. Yes, those are surface-mount capacitors. Are they something still used? Such capacitors are fungible parts. There's nothing too special about them, so as long as the specs are what's needed in a design, they are as good as any other capacitor with similar specs. So yes, they'd be very much still used.

If you think of selling them, a reasonable price would be like $10 per 5,000, free shipping in a small first class envelope. They are extremely cheap, and even cheaper when in bulk packaging and not on a tape. Normally they are sold in a tape that can be loaded into part placement machines as nobody is assembling these things by hand in volume production. When not on a tape, they need to be re-spooled before use, and that takes time and hassle. So, in the form you have, they are only of use to hobbyists, who have thousands of other sources to buy the same parts from.

Even if this particular model of a capacitor is not made any more, they are fungible, so nobody really cares about the model. They care about capacitance, voltage, dielectric material, and maybe ESR, and that's about that for most users. So you have to be selling seriously under the price of new parts for anyone to bother buying them from you and not from a legit vendor.

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