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Lets say for example, that I had a box full of transistors, resistors, capacitors, diodes, leds, this and that, and left it in a cool, average environment for lets say... 50 years.

Do these components have a lifespan while been unused? Do the insides end up degrading and become unusable like cars? Or do they just... Sit there?

I'm asking this, because I just got a thought that struck me, being that if you kept today's components, (and kept them for 50 years) will you be able to use them in the future?

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Yes, they will degrade little by little; they will grow tin whiskers, maybe oxidize little by little because their casing will never be 100.00% sealed. Also the pin plating will oxidize, so you'll have to treat them before soldering. Also moisture can creep in, little by little... difficult to say if it would affect discretes like transistors a lot, but ICs will suffer.

Oxidization plays a role in IC degradation if the passivation layer has defects, but the killer is metal whiskers between pins, pads and bond wires. It doesn't cause gradual degradation; basically the chip works fine until finally a whisker causes a short circuit between pads and the chip dies.

Zinc whispers

Image: whiskers on a piece of zinc. Source: http://commons.wikimedia.org/wiki/File:Zinc_whiskers.jpg

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    \$\begingroup\$ It's worth noting that modern, RoHS-compliant, components are worse in this aspect because lead is good anti-whisker agent. \$\endgroup\$ – Agent_L Jan 8 '15 at 16:15
  • \$\begingroup\$ You and Spephro Pefhany are on par. But you came first so your getting the correct answer. Thanks everyone for the answers. And ew... Those whiskers... \$\endgroup\$ – user62118 Jan 9 '15 at 0:05
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Like cars, if kept in an ideal environment (cool and dry) a few things will deteriorate but most will not (at least not very fast). In particular, electrolytic capacitors and batteries will tend to be dead (especially the latter). Rubber will tend to deteriorate (DVD door or cassette drive belts) and speaker cones can also deteriorate (my Keil AMT speakers need re-woofering). Electrolytic capacitors tend to dry out.

There's plenty of electronics around from 1965, and things have not changed so much in basic technology.. it's generally salvageable but perhaps not fully functional out of the crypt. Something like a UPS that is mostly battery cost-wise is probably scrap for economic reasons, even if 95%+ of the parts are still fine.

Semiconductors are usually pretty much immune to aging if they're kept cool and not powered.

The biggest reason why parts have a best-before date is corrosion that makes them difficult to solder reliably. That's not a problem if they're assembled into a product, but if you've got reels of diodes, for example, the diodes may be just fine, but so corroded they cannot be used reliably (at least not without some kind of uneconomical rework). Storing them in low-humidity cabinets and using sulfur-free packaging (brown cardboard boxes are often bad) will help.

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  • \$\begingroup\$ +1. Some additional points: Electrolytics can be "re-formed" with care (and some luck) if their oxide layer has degraded, but the electrolyte is still present. Soldered joints can recrystallize forming "dry joints". ICs may need to be "baked" before reflow oven assembly (otherwise their moisture content flashes to steam and the package explodes). Vacuum tubes mostly just keep going... \$\endgroup\$ – Brian Drummond Jan 8 '15 at 14:20
  • \$\begingroup\$ An UPS most likely can be used economically since the price of a new UPS includes price of new batteries and the price of new electronics. Just replacing the batteries in an old UPS would most likely be cheaper, especially if the UPS is not one of the cheapest ones. \$\endgroup\$ – Pentium100 Jan 8 '15 at 14:23
  • \$\begingroup\$ So through-hole components, with leads that can be cleaned up, should last better than surface-mount? \$\endgroup\$ – Chris H Jan 8 '15 at 14:35
  • \$\begingroup\$ @ChrisH I guess you could clean leads, but on a cheap part? For whatever reason (I suspect poor cleaning by the Chinese manufacturer) the only problem we've had recently with solderability is with through hole parts (LEDs packaged in poly bags of 1,000). One data point, so not very useful. \$\endgroup\$ – Spehro Pefhany Jan 8 '15 at 14:48
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    \$\begingroup\$ @ChrisH Yes, I'd rather clean the leads on some old unobtainium part than try to source it through the guys that have been hanging onto it for 20 years in the hopes of getting 1000x the purchase price for it. \$\endgroup\$ – Spehro Pefhany Jan 8 '15 at 14:53
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Do these components have a lifespan while been unused? Do the insides end up degrading and become unusable like cars? Or do they just... Sit there?

Sure, this lifespan is called shelf life.

What happens when it passes? Here is an analysis with nice pictures. Here is another one.

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  • \$\begingroup\$ The first "here" link points to the Wikipedia article. Mistake? \$\endgroup\$ – nitro2k01 Jan 9 '15 at 13:47
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In electronic reliability engineering the storage environment and temperature influence the reliability of the component and his lifetime, take for example the MIL HDBK 217f standard, the lifetime of the electronic component depend on the working environment (storage environnement in your case) and other factors like temperature, voltage setress (if is insid electrical circuit).

Take an exemple of ceramic capacitor of 0.1 uF commercial in the MIL HDBK 217f, if we suppose he is stored at ground, benign environment and at 30°C temperature the Failure rate will be equal to 0,00000001 failure/hour, but in case where the capacitor is stored in the same environment at 0°C the FR will be equal to 0,000000002 failure/hour.

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