One of the key concepts in electronics is the printed circuit board (PCB).
A printed circuit board (PCB) mechanically supports and electrically connects electrical or electronic components using conductive tracks. Simplest PCBs have only insulation board with copper traces on one side. More complicated PCB is sort of like a layer cake or lasagna- there are alternating layers of different materials which are laminated together with heat and adhesive such that the result is a single object.
But how those PCBs are made in factories? Hare are few videos that describe how PCBs are made and how PCB factories work.
Inside a Huge PCFactory – in China
How PCB is Made in China – PCBWay – Factory Tour
PCBWay – Full feature custom PCB prototype service
Inside a PCB Soldering Factory – in China
Fujitsu TS Mainboard Production Augsburg HD
How a motherboard is made: Inside the Gigabyte factory in Taiwan