Soldered

Soldered describes a joint or connection created by soldering, a metal-joining process in which a filler metal, called solder, is melted and drawn into the joint by capillary action. In soldering, the base metals are not melted; the soldered joint relies on adhesion between the molten solder and the surfaces, and on flux to promote wetting and oxide removal.

Solders are typically tin-based alloys. Historically Sn-Pb solders were common, but many jurisdictions limit lead in consumer products. Lead-free alternatives such as tin-silver-copper (SAC) or tin-copper are common in electronics. Flux cleans oxides and improves wetting, and can be rosin-based or water-soluble. Techniques include hand soldering with a soldering iron, wave soldering for through-hole parts, and reflow soldering for surface-mount components.

A well-soldered joint wets the surfaces and forms a smooth fillet; bad joints include cold joints, voids, bridges, or tombstoning. Soldered connections provide electrical conductivity and mechanical hold, but are generally not as strong as brazed or welded joints. Electronics rely on reliable solder joints under thermal cycling and vibration; plumbing solder joints must withstand pressure and corrosion.

Safety and standards: Soldering produces fumes and requires ventilation. Lead-containing solders pose health risks; many regions restrict lead use. Flux residues can be corrosive and may require cleaning. Good practice includes temperature control and proper inspection, with visual checks and, for critical work, X-ray or microsection.