Printed Circuit Board

How extremely small components soldered to a PCB (Printed Circuit Board)?

For example, how to weld something like a microcontroller in a conventional PCB (the pins are 1mm apart). Should I weld the components with a microscope with a very small soldering tip, or use a technique for example, wave soldering? Thanks, any help is much appreciated – as you can see I'm a bit novice in the field of electronics! Salud!

I made very small extensometer devices with the help of a microscope and a small iron tip. But it is not easy. Wave I could see that work best for environment Production of PCBs.

Photo-etching printed circuit board (homebrew PCB)