Electrical solderless or soldered connectors

Have a look at a printed cct board. The connections are soldered, not crimped, because soldering ensures maximum continuity & reliability of the joint. Many wires are copper, but not tin plated. Non plated copper will oxidise in the atmosphere & lead to elusive high resistance connections. Soldering covers the joint with conductive solder & stops air getting to the joint & prevents corrosion.