Electrical contact

An electrical contact is a conductive interface that transfers current between joined components. Its performance depends on the interface materials, pressure, geometry, and surface condition.

Contact resistance: Electrical resistance arising where two conductive surfaces meet, including effects from constriction and surface films. It quantifies the voltage loss and heating at an electrical contact.
Electrical conductivity: A material property describing how readily electric charge moves through a substance. It determines whether a contact material can carry current with low bulk resistance.
Electrical connector: A device that joins electrical conductors through one or more separable contacts. Connectors package contacts for repeatable assembly and disconnection.
Solder joint: A permanent electrical and mechanical connection formed by melting solder between joined conductors. Unlike a separable contact, it bonds conductors with a solidified filler metal.
Constriction resistance: Resistance caused by current narrowing through small real contact spots between larger conductive surfaces. Only microscopic spots often carry current across an apparently broad contact.
Electrical resistivity: An intrinsic measure of how strongly a material opposes electric current. It helps distinguish resistance within contact materials from resistance at their interface.
Relay: An electrically operated switch that opens or closes contacts using an actuator. Its contacts switch circuits while facing wear, arcing, and resistance constraints.
Welding: A joining process that fuses materials through heat, pressure, or both. Welded electrical joints replace pressure-dependent interfaces with fused material.
Contact force: The mechanical force pressing two electrical contact surfaces together. Greater force can enlarge real contact areas and disrupt weak surface films.
Oxide layer: A thin layer of oxygen-containing compounds formed on a material's surface. Oxides on metals can obstruct current across otherwise touching contact surfaces.

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