PCB assembly is the process by which electronic components are adhered to a Printed Circuit Board. PCBs are used in almost all electronic devices that you come across. There are many companies which offer different types of PCB assembly services.
Some companies specialize in prototype PCB assembly. Once the designing of a PCB is done by the engineers, the designed PCB assembly is manufactured in order to test whether it functions in the required way. This is known as a prototype PCB assembly. After its testing, certain changes are usually made and a second batch of PCB is manufactured which meets majorly all the design requirements.
PTH or Pin through Hole PCB assembly uses designated holes in the board through which the components are soldered. This is used to manufacture products which have no space constraints or when the components are cheap. This is the conventional type of PCB assembly process.
Surface mount assembly is a technique of assembling electronic circuits in which components are soldered directly on the surface of bare printed circuit boards instead of wiring them through holes. The general term SMT is used for all the process regarding surface mount technology. SMT PCB assembly process typically includes screen printing with solder paste, placing components and soldering them with the help of a reflow oven.