PCB is the abbreviation of Printed Circuit Board. The industry is commonly known as "bare board" and "substrate", that is, there are no components on the surface. PCBA is the abbreviation of PCB + Assembly, which refers to a board with OK hardware functions formed by welding electronic components (such as IC, resistors, capacitors, inductors, LEDs, crystal oscillators, etc.) to the bare PCB board. A bit similar to the construction industry, PCB is the foundation, and PCBA is the entire building after construction on the foundation is completed. The following figure explains the image difference between PCB and PCBA more intuitively.