Definition

Selective soldering applies solder to specific through-hole locations rather than the entire board bottom, enabling through-hole assembly on boards with SMT components on the solder side. A programmable nozzle or mini-wave applies molten solder only where needed. This is essential for mixed-technology boards where wave soldering would damage bottom-side SMT components. For PCB designers, selective soldering affects layout: provide 2-3mm clearance around through-hole pins for nozzle access, use thermal relief on through-hole pads connected to planes, and group through-hole components to minimize soldering time. Selective soldering costs more per joint than wave soldering but enables designs that combine SMT density with through-hole connector strength.