PCBA, an acronym for Printed Circuit Board Assembly, also called PCA ( an acronym for Printed Circuit Assembly), refers to the process of electronics addition or soldering onto a printed circuit board. In this way, a bare board without electronic components soldered on is a PCB while that with electronic components soldered on is PCBA in a real sense. Therefore, PCB manufacturing process
is totally different from PCB Assembly
To populate electronic components firmly onto a circuit board, firstly, electronic parts have to be precisely placed at corresponding positions on the board as the design files present. Secondly, they have to be firmly attached to their correct positions to actually perform their electronic functions. In addition, efficiency has to be taken into consideration during assembly. Components vary from each other in terms of size, types, packages, property etc., leading to different types of assembly technologies and methods.
Two types of mounting technologies are prevailing in the modern assembly industry: Thru-Hole Technology (THT) (AKA Thru-hole Mounting) and Surface Mount Technology (SMT).
Thru-Hole Technology: works well on components with leads or wires that have to be mounted on board by plugging them through holes on board. The extra lead part has to be soldered on the other side of the board. This technology is applied on large components such as capacitors, coils.
Surface Mount Technology: Sensitive components, some very small, such as resistors or diodes are placed automatically onto the surface of board. This is called SMD assembly, for surface mount device. Surface mount technology can be applied on small size components and integrated circuits (ICs). For example, PCBCart is capable of mounting package with min. size 0201, which is approximately the size of a pencil point.
Due to distinctions between THT and SMT, they have to go through different assembly processes as well. The following paragraphs introduce detailed assembly processes for both technologies step by step.