For given physical and mechanical material properties, parameters that govern the magnitude of electrical contact resistance (ECR) and its variation at an interface relate primarily to surface structure and applied load (Contact mechanics). Surfaces of metallic contacts generally exhibit an external layer of oxide material and adsorbed water molecules, which lead to capacitor-type junctions at weakly contacting asperities and resistor type contacts at strongly contacting asperities, where sufficient pressure is applied for asperities to penetrate the oxide layer, forming metal-to-metal contact patches. If a contact patch is sufficiently small, with dimensions comparable or smaller than the mean free path of electrons resistance at the patch can be described by the Sharvin mechanism, whereby electron transport can be described by ballistic conduction.
The magnitude and variation of electrical contact resistance (ECR) are influenced by surface structure and applied load in physical and mechanical material properties. Metallic contacts typically have an oxide layer and adsorbed water molecules on their surfaces, leading to capacitor-like junctions at weakly contacting asperities and resistor-like contacts at strongly contacting asperities when sufficient pressure is applied for the asperities to penetrate the oxide layer and form metal-to-metal contact patches. If a contact patch is small enough, its resistance can be described by the Sharvin mechanism, which describes electron transport as ballistic conduction.