Electronic assemblies consist of any number of electronic and nonelectronic devices (screws, heat sinks, carrier plates, etc.) grouped together to perform a function. Each assembly is a self-contained production item, built within a particular facility in which it follows its own process fl ow. For example, an insertion-mounted printed wiring board (PWB) can be built in the same facility as a surface-mounted PWB; however, different equipment and processes are used. Both boards can be populated by the same pick-and-place machine, but a wave solder system is commonly used for insertion boards, while surface-mount boards use solder paste or thick solder plate refl owed in a vapor-phase or infrared (IR) furnace.