Meaning
Electrical measurement quantifying the opposition to current flow across the physical interface of two mated conductors. Monitoring direct current contact resistance identifies oxidation or contamination on the surface of a connector. This value remains independent of inductive or capacitive effects present in alternating current circuits and is only valid for low-frequency or static connections.
Interface Quality
Surface roughness and contact force determine the effective area of conduction at the microscopic level. Measuring direct current contact resistance requires a four-wire Kelvin method to eliminate the influence of test lead impedance. High readings suggest that the plating has failed or that the normal force of the spring is insufficient.
Low force allows thin films of oxides to remain between the pins, which restricts the flow of electrons to a few metallic bridges.
Thermal Load
Dissipation of power at the junction follows the formula of current squared times resistance. High direct current contact resistance leads to localized heating that can melt plastic housings or accelerate the growth of insulating films. This heat cycle further degrades the electrical path.
Acceptance Boundary
Specifications for high-current modules define a maximum milliohm value that must not be exceeded. The direct current contact resistance is recorded during the initial mating cycle and again after environmental stress testing. Parts exceeding this limit are rejected to prevent field failures.
