Surface mount technology (SMT) is a method for constructing electronic circuits in which the components (Surface Mounted Components/SMC) are mounted directly onto the surface of printed circuit boards (PCBs). In the industry it has largely replaced the through-hole technology construction method of fitting components with wire leads into holes in the circuit board.
An SMT component is usually smaller than its through-hole counterpart, because it has either smaller leads or no leads at all. It may have short pins or leads of various styles, flat contacts, a matrix of solder balls(BGAs), or terminations on the body of the component.
Surface mount technology(SMT) became widely used until the 1980’s. Virtually all of today's mass produced electronics hardware is manufactured using surface mount technology(SMT). The associated surface mount devices (SMDs) provide many advantages over their leaded predecessors in terms of manufacturability and often performance.