[dschuetz]

Thanks for sharing, cryptomuseum.com on itself is quite interesting.

A question though: how is humidity handled in modern electronics? Is there any sacrificial used on mainboards, or is there any design pattern used on PCBs in general to achieve the same effect?

[snops]

Conformal coating is used, which is a thin layer of polymer sprayed as a film over the finished and soldered PCB.

As modern components are normally much smaller and sit fairly flush with the PCB, there are less nooks and crannies, and so the coating manages to fill them all or bridge them over quite well. It's still not a step used in most PCBs, there are downsides like requiring connectors and switches to be masked off with tape, and so it is reserved for more extreme applications than consumer electronics. Think electric gate control boxes, or marine electronics.

It would probably have existed in some form at the time of the OPs radio, but spraying the PCBs in it wouldn't have saved all the connectors, switches pots and other front panel controls from moisture, and so a more general method was needed.

Finally, a more extreme step is to "pot" the entire PCB by putting it in a sealed container and filling the container with a "potting compound", a liquid resin that sets solid or to a rubbery finish. This makes replacing or repairing the PCB very difficult, requires a lot of thought as to connectors, and it doesn't work well for high power electronics as the potting compound traps heat. It allows you to fully submerse a PCB in water forever, stops sparks if your PCB is working around explosive gases/powders, and is sometimes used as a "security" method in hardware security modules or "secure" USB keys.

For security, potting only really works if tiny wires are embedded in it, which on breaking wipe the encryption keys. Scraping off potting compound can otherwise be done by anyone if they are willing to spend a long time.

[blattimwind]

> A question though: how is humidity handled in modern electronics? Is there any sacrificial used on mainboards

For consumer electronics it generally isn't handled. If you look at the edges of the boards you'll see that they are rough-sawn and not sealed and that there is not conformal coating elsewhere on the boards. Note that while FR and hardpaper material are hygroscopic, the epoxy cases of chips let moisture pass as well.

[stan_rogers]

Conformal coating or potting. Simply not exposing the components and board traces to environmental conditions at all is simpler and more effective - but then we no longer expect to need to replace vacuum tubes very often.