Preliminary circuit board
Questions 1; What is printed circuit board?

A conductive copper foil is printed on a plastic sheet, replacing the wires with copper foil, which connects the various components to form a circuit as long as they are mounted on the printed circuit board.

Question 2; What is a PCBA? :
The difference between

1) PCB without any components (2) the PCBA is manufacturer, after get as raw material of PCB in SMT or plug-in processing on the PCB welding assembly required electronic components, such as IC, resistors, capacitors, crystal, transformers and other electronic components, after reflow furnace heating, will form the mechanical connection between the components and PCB, forming a PCBA. In Printed simply, PCB blank is Printed through SMT, and then through the whole process of DIP plug-in, referred to as PCBA. In common terms, PCB is Printed circuit board without components, while PCBA is Printed circuit board with electronic components welded.