ELECTRICAL ENGINEERING

SMD stands for Surface Mount Device. An SMD is any electronic component that is made to use with Surface Mount Technology (SMT). SMT was developed to meet the ongoing demand for printed circuit board (PCB) manufacturers to use smaller components that are faster, more efficient, and cheaper. SMDs are smaller than through-hole resistors and instead of having wire leads that go through PCB, they have terminations that are soldered to pads on the surface of the board. This eliminates the need for holes in the board and allows both sides of the board to be used more fully. SMDs are made by placing end connection electrode bases onto an alumina or ceramic substrate. The resistor is then fired to ensure the electrodes are held in place. Next, a film of resistive material is printed or deposited and the resistor is fired again. The resistor is then covered with successive layers of a protective coat that dry between applications. These layers prevent mechanical damage and ingress of moisture a...

Surface-mount technology   ( SMT ), originally called   planar mounting ,   is a method in which the electrical components are mounted directly onto the surface of a   printed circuit board   (PCB). ]   An electrical component mounted in this manner is referred to as a   surface-mount device   ( SMD ). In industry, this approach has largely replaced the   through-hole technology   construction method of fitting components, in large part because SMT allows for increased manufacturing automation which reduces cost and improves quality.   It also allows for more components to fit on a given area of substrate. Both technologies can be used on the same board, with the through-hole technology often used for components not suitable for surface mounting such as large transformers and heat-sinked power semiconductors. Surface-mount components on a  USB flash drive 's circuit board. The small rectangular chips with numbers are resistors,...