Surface-mount technology

Surface-mount technology was developed in the 1960s, gained momentum in the early 1980s and became widely used by the mid 1990s. Components were mechanically redesigned to have small metal tabs or end caps that could be directly soldered to the surface of the PCB. Components became much smaller and component placement on both sides of the board became far more common with surface-mounting than through-hole mounting, allowing much higher circuit densities. Surface mounting lends itself well to a high degree of automation, reducing labour cost and greatly increasing production and quality rates. Surface mount devices (SMDs) can be one-quarter to one-tenth the size and weight, and passive components can be one-half to one-quarter the cost of through-hole parts. Integrated circuits (where the chip itself is the most expensive part) are often priced the same regardless of package type however. As of 2006, some wire-ended components, such as small signal switch diodes, e.g. 1N4148, are actually significantly cheaper than corresponding SMD versions.