[Salmonfisher11]

100 years in a 100% controlled environment is easy.

Meaning: you are missing a lot of variables in your game that will mess with your plans.

So spend some times and do requirements engineering on an abstract level. Then select the techniques to solve them.

[owenversteeg]

OK, say constant operation at room temperature indoors.

No matter how well temperature and moisture controlled your environment is, I highly doubt that 100 years is easy. 100 years? 876,000 continued hours of operation? Large companies regularly have expensive recalls because of premature failures for all kinds of reasons. Components fail for myriad reasons and I think to get 100 years you’ll need careful component selection, de-rating, plating, thoughtful solder selection, conformal coating, etc.

[Salmonfisher11]

>OK, say constant operation at room temperature indoors.

Suddenly a wild humidity change appeared.

You must spend a lot of time defining your environmental parameters.

[owenversteeg]

Yes, obviously humidity changes with temperature. I don’t see how that’s important. 99% of dead boards out there are not dead because of indoor, room temperature level humidity fluctuations, and the plenty of PCBs still working from the 70s don’t seem much affected by them either. There’s thermal cycling concerns, but that’s dominated by the board’s own heat generation. Do you have some data that would indicate that modern boards are sensitive to this?