Surfacemount

Surface-mount, commonly referred to as surface-mount technology (SMT), is a method for assembling electronic circuits in which components are attached to the surface of a printed circuit board (PCB) rather than inserted through holes. SMT enables smaller components and footprints, higher component density, and automated assembly, which together improve production throughput and reduce overall costs for many applications.

In SMT, components are designed with contacts on their surfaces and are mounted on pads on the PCB. Common surface-mount devices include resistors, capacitors, inductors, diodes, and transistors, as well as integrated circuits packaged in formats such as SOIC, QFP, QFN, and BGA. This palette supports compact, complex circuits and mixed-technology assemblies.

The assembly process typically involves applying solder paste to the PCB via a stencil, placing components with automated pick-and-place equipment, and reflow soldering to form permanent joints. Post-assembly steps may include inspection, testing, and, if needed, rework or repair. Design considerations for SMT include pad geometry, land patterns, solder joint reliability, and thermal management, as well as compatibility with surface finishes and component availability.

Compared with through-hole mounting, SMT offers higher density and shorter electrical paths, but can pose challenges for heat dissipation, mechanical robustness, and repairability in some contexts. SMT remains dominant in consumer electronics, computing, automotive, telecommunications, and many other industries.