[bluGill]

I wouldn't count on it. I work for John Deere, and am often in discussions about some part going out of production. Sometimes we guess how many we need for the next X years and buy that many, othertimes we rewrite software for a new part. Care to guess how many boards can sit in a warehouse for many years and still have good capacitors.

I can't tell you how many years, but there is always someone in these discussions who points out with pride that we still tractors from the 1950 in use by customers who demand replacement parts for anything that breaks.

[cvccvroomvroom]

In case anyone here weren't a farmer, John Deer is the Apple Tesla of industrial equipment with not just built-in planned obsolescence but built-in inability to self-repair or self-diagnose without proprietary equipment. Much hay has been made in R2R about John Deer's customer-hostile practices.

The harvest time sensor reset tax is why some small-time farmers stick to old and overseas equipment they can repair without a tech visit. It's not about the customer being unreasonable about NLA parts, but the modern unreasonableness of how the manufacturer impedes the customer with artificial scarcity and artificial limitations on knowledge, diagrams, diagnostic equipment, diagnostic equipment manuals, and the nature of some repair parts.

[midoridensha]

Exactly: farm equipment is one place where you really do not want to Buy American.

[deaddodo]

> Care to guess how many boards can sit in a warehouse for many years and still have good capacitors.

If you guys are having trouble storing boards for 10+ years with caps regularly going bad, I would highly recommend you look into a new supplier. Well-built caps should have no problem going for 25+ years in storage (especially cold).

In addition, this is probably the easiest component on the board to replace. If you can’t find functional new stock and this is the only issue, just recap them.

[bluGill]

I have no insight into how we store things. I sometimes have input into the buy or port to a replacement decision, but if we decide to buy there is a completely different department that handles the details.

Caps are an issue that is easiest for people here to understand, but we have a long list of similar issues to watch for in storing parts

[cvccvroomvroom]

Or ditch electrolytic and tantalum caps wherever possible because they're crap. It's often possible to engineer a more expensive, reliable LR circuit for the impedance of a cheap RC one.

[jacquesm]

Tantalum have their own issues. Yes, they live longer. But they're nice little fire starters and are much more critical than electrolytic capacitors when it comes to voltage tolerance.

[dreamcompiler]

It's kind of amazing to me that we can build 3nm chips but we still haven't figured out how to build a uF-range cap that has long MTBF, good overvoltage tolerance, low series resistance, and doesn't blow up.

[jacquesm]

Indeed. But... caps are improving, but slowly. The size difference between say a 100 uf 25V cap today compared to one from the 80's is considerable, and if you add another decade it is hard to believe it is the same component.

By contrast inductors have not changed in size at all and resistors are very much limited by power dissipation.

[BoorishBears]

I work on automotive HMI and don't have to guess how many can sit in a warehouse for many years and still have good caps.

They're subject to a lot worse than that for design verification. And I assure you John Deere has many _many_ PCBs that have sat for 10 years to enable service needs today, it's not like they just started using complex circuit boards yesterday...