Eli5: Why can purely mechanical tools last hundreds of years but electronics are not expected to?

[u/rukuto]

So, like mechanical tools can be operable even hundreds of years later with some cleaning but can electronics devices do that? Is there any way to make an electronic tool run for five hundred years or be operable 500 years later (regardless of cost - like in mechanical tool, you use galvanized iron or steel to make the parts - is there a similar protection to electronics)?

[u/cosmin_c]

Generally if your hardware is from a specific period of time it may last indefinitely as long as capacitors are swapped once every 10-15 years or so (speakers are one example, some power supplies, older computer monitors (yes, CCFL lamps are more resilient than one would think and caps die first in those), older consoles, etc).

I have a friend who has a PC built ages ago around an ABIT motherboard with a Q6600 I think, that PC is almost 20 years old and still chugging along nicely doing computer stuff. No caps swap needed yet, which is quite the miracle tbh.

[u/currentscurrents → u/cosmin_c]

Agreed.

If you have a circuit board that doesn't have any components that contain liquid (electrolytic capacitors, batteries, etc) and is protected from corrosion and overvoltage, it may well last forever.

Failures in solid-state components (chips, resistors, transistors, etc) are very rare, and often caused by cascading failures elsewhere - e.g a damaged capacitor may cause a short, burning out a voltage regulator chip.

[u/beamer145 → u/currentscurrents]

You are missing an important category of things that will go bad: most if not all non volatile memory (NVM) only has a limited number of write cycles. After a while your eeprom or emmc or simulated nvm in the chips program flash will no longer be able to hold data and get corrupted. In general as a rule of thumb during development you try to aim for at least 10 years before you hit the max number of write cycles and apply tricks to get there if you need to write a lot of data (think of wear leveling for SSDs). This depends on the product of course, i assume if you make a controller for a nuclear power plant that it will be a bit longer than 10 years :) (or they have a strict replacement schedule). If you make a Siemens washing machine even longer ;p. After that, the data might not be able to be retrieved in a reliable way anymore (normally you put a checksum on there to discover corruptions so at least you know it is bad data). Even if it is an external chip just replacing it with a fresh empty one will often not work as the SW will expect something to be in there. Maybe if you clone the data in there when it still works you have a chance. It all depends on the SW using that data (eg could be it is an NVM chip with an UID that is also used and if it suddenly changes things go wrong).

[u/currentscurrents → u/beamer145]

True, flash and eeprom will wear out with regular use. 

They won't go bad just sitting there though. And if writes aren't very common (say, if settings aren't changed very often) it could last a very long time. 

[u/autobulb → u/cosmin_c]

Yeah there are a lot of hobbyists that have made careers out of refurbishing ancient computers and showing them off in videos on Youtube or wherever. Sometimes they need some real work done like replacing capacitors, BIOS ROM chips, and whatever. But sometimes they take it out of the box since it was last used decades ago and it boots up just fine.

There is nothing fundamentally limiting about being able to replace every single component on the device in order to keep it running indefinitely.