What is Surface Mount PCB Assembly?

Surface mount in a PCB assembly means that each component on the PCB is mounted on the surface of the board. In the PCB Assembly process for surface mount components, solder paste is placed on the PCB board at areas where surface mount components will be placed on the board. PCB Stencils are usually used to apply solder paste on the PCB board and a pick and place machine is used to place SMT components on the board. 

Surface Mount Assembly is very cost effective, takes up less board space and requires short production times as compared to thru-hole assembly, as it does not require the drilling of holes through the board. However, the component grip is not as good as thru-hole and also the connection can be faulty if not soldered properly.