PCB, printed circuit Board, also known as printed wring board, it isused in electronics to build electronic devices. A PCB serves two purposes inthe construction of an electronic device; it is a place to mount the componentsand it provides the means of electrical connection between the components.

PCBA, printed circuitboard assembly, in through-hole technology component leads areinserted in holes. In surface-mount technology (SMT) the componentsare glued on pads or lands on the surfaces of the PCB. In bothcomponent leads are then mechanically fixed and electrically connected to theboard by soldering. 
 
Since2009, more and more electronic manufacturers, in order to save time to findassembly factory, they always have two choices: let the PCB factory do OEM atsame time, or purchasing PCB by assembly factory directly.  By both of models, the electronicmanufacturers only need to fit the housing and set the program, a full productfinished then.
 
Generallyspeaking, electronic manufacturer always choose the supplier who can provideone-stop service; or would like to choose the assembly factory, and then letthem purchase PCB for them. Because now the PCB price is gradually transparent,and so easy to purchase, but the PCB factory isn’t familiar with differentcomponents and price, it is harder for them then. 
 
Since2010, More PCB manufacturer begin to add SMT process line. This kind of one step style, have been acceptedby more and more electronic manufacturers. Of course, there also have bothadvantage and disadvantage. The OEM plant will get more benefit, but more risks exist at the same time. The main reasondue to purchase components for customer, every electronic products need differentcomponents, even though for same products, if design with different drawing,the different components need also. So if purchased wrong components, the full PCBand components will have to been scrapped, direct economic losses, it is difficultestimate also… An increase in human and material resources, it is then hard toavoid. However, under the pressure of market competition, PCB and PCBA producedby one package service, it is inevitable.