You can "google" and study what happens with "transistors" (or FETs) at low temperature (e.g. lower resistance but also less free electrons - the characteristics changes dramatically (e.g. at 100K and there is a "freeze out" temperature as well)).
Your main concern should be more on the mechanical side:
- what happens with the plastic package at low temperature?
- what happens with the glue use for the package at low temperature?
- what happens with the pin soldering, the tin, at low temperature?
- how much will everything shrink, e.g. the chip package, the PCB, in an different way, so that it creates mechanical stress on the parts?
And: I am sure: when you let drop a PCB with chips on it into liquid nitrogen - they will crack immediately.
Assume, a plastic package is not really hermetically sealed. There is moisture in the package. When you freeze water - it will expand. This cracks everything!
You have to gradually freeze down the chips (and PCB). And it would not solve the problem with moisture still remaining in the package.
For space mission: you should consider going with MCU, parts, chips, in a ceramic package. But the issue with the glue at low temperature and the mechanical stress on PCB due to different "shrinking coefficients" remains there.
I am pretty sure, the spec., e.g. as "automotive" or "military" standards (e.g. MIL-STD) and temperature ratings is not there due to the chip fails at this temperature: potentially your package fails first. Silicon is very brittle and plastic becomes brittle at low temperatures as well. Just the internal stress will cause the major issues.
