RF engineering covers the heavy stuff you need a really large spanner to install, to really small surface mount components.
These days for board level work, that means a good illuminated stereo microscope, temperature controlled soldering station, and tweezers.
I am old enough to remember when people were complaining that through hole DIP packages were so small they were impossible to work with.
And over the years the miniaturisation problem has become steadily worse.
The way its going, in another twenty years you might need an electron microscope to even see the circuit board.