Surface-Mount Technology (SMT)

Surface-mount technology replaces the "through-hole technology," wherein components are mounted by linking up "leads" inserted into circuit board holes to pads on the opposite side of the board. Through-hole technology was used throughout the 1950s and into the 1980s until SMT started gaining popularity. Some advantages of SMT include the ability to create smaller components, higher component density and greater efficiency in assembly, since fewer holes need to be drilled in the circuit board. SMT also provides better presentation of the structure of circuit boards, which allows easy examination of the placement of components because they are surface mounted rather than connected to the soldered holes.