What is dome switch pcb

Metal shrapnel (also known as pot or piece, metal dome, snap dome), made of ultra-thin (0.05mm-0.1mm thickness) and ultra-thick (usually high hardness) stainless steel 301 or 304 material. Metal dome is an important part of the snap dome switch PCB.

They are momentary switch contacts that become normally-open tactile metal dome switch when used in conjunction with a printed circuit board (PCB).

PCB is also known as printed circuit boards because it is made by electronic printing. A printed circuit board is a substrate for assembling electronic components and is a printed board on which a point-to-point connection and a printed component are formed on a general-purpose substrate in a predetermined metal core printed circuit board design.