léd

Löd is the Swedish term for solder, an alloy used to join metal parts by soldering. Solders melt at a lower temperature than the base metals and form a solid joint as they cool. Solder alloys are categorized as soft solders, with relatively low melting points, and hard solders, which require higher heat and are used for stronger joints in jewelry and metalworking.

Historically, tin–lead solders were standard, with a common eutectic composition around 63% tin and 37% lead melting at about 183°C. Lead-containing solders are increasingly restricted for health and environmental reasons, and many modern applications use lead-free alloys, such as tin–silver–copper (Sn-Ag-Cu, SAC) with higher melting temperatures around 217–227°C.

Löd is applied with flux to improve wetting and to remove surface oxides. In electronics, soft solders are used with soldering irons or reflow ovens to connect components to copper or PCB traces, relying on capillary action to fill joints. In plumbing and metalworking, solders join copper, brass, or other alloys in a similar manner, though higher-temperature brazing or welding may be chosen for strength.

Safety and environmental considerations are important, as lead-containing solders can release toxic fumes and pose health risks. Regulations such as RoHS have promoted lead-free alternatives in consumer electronics and other products.

See also: soldering, flux, RoHS.