What does a “PCB” and a “PCBA” mean?
Usage of these two acronyms is sometimes not well understood and often used interchangeably, nonetheless they are different terms.
Quick answer: PCBs are bare circuits boards without components, PCBAs are PCBs + assembled components.
PCB definition
The PCB acronym means “Printed Circuit Board” in plain English. It refers to the plate or laminate or board used to support the electronic components. A PCB contains copper conductive tracks and pads, usually protected by a solder mask and finished with a suitable surface treatment on the exposed pads. PCBs are sometimes called electronic board.
PCBs can be of different materials, the most common being FR4, a green rigid glass-fibre-reinforced epoxy laminate, but can also be made of flexible plastics and aluminium which is preferred for better heat exchange.
They also can come in different thicknesses and can include several layers, each layer having its own connecting route.
PCB are also usually marked with silkscreen in order to show component position and component naming.
PCBA definition
The PCBA acronyms refers to “Printed Circuit Board Assembled”.
PCBAs are electronic boards assembled with electronic components. Components are often soldered, but they can also be set or glued. PCBA can also include a varnish top layer applied after components assembly to protect against dust and humidity for harsh environment usage.
Component assembly on the electronic board can be done on one face or both faces of the board. It can be done very quickly on high technology automatic machine (SMT) or manually by operators working on a production line. Manual assembly is preferred for big electronic components and connectors.
For SMD components welding can also be made automatically on welding wave equipment. It is important to notice that the welding of components on the PCBA can be made with leaded welding paste, which is restricted in EU, it is therefore recommended to request assembly lines dedicated to RoHS-compliant assembly in order to reduce pollution risk.
Contrary to the PCB production which is a very polluting chemical process with most of the suppliers located in Asia, PCBA assembly is a relatively clean operation done in clean-rooms. Assembly process is even less polluting with RoHS products, therefore there are PCBA manufacturers (EMS) almost everywhere in the world. Differentiating factors for EMS being modernity of equipment, labor cost and component availability.
In a nutshell
A PCBA is a PCB assembled with electronic components. Though in usage, many used indistinctly these two terms we recommend to use correct terms to avoid misunderstanding.
