Meaning
Electrical resistance across a closed contact interface over repeated cycles or prolonged exposure determines the reliability of mechanical connectors and switches. High contact resistance stability prevents signal degradation in RF signal lines and sensor circuits. When the resistance fluctuates, it introduces noise and attenuates weak signals.
Designers specify plating materials like gold or palladium to maintain a low and consistent interface resistance over the product life.
Mechanical Wear
Repetitive insertion and extraction of connectors causes physical degradation of the contacting surfaces. This friction can wear away thin protective plating layers, exposing the base metal underneath to the environment. The loss of protective metal increases the likelihood of fluctuating contact resistance over time.
Engineers select connectors with high normal force and appropriate plating thickness to withstand these friction cycles.
Environmental Resistance
Atmospheric pollutants and moisture can cause oxidation on exposed metal surfaces at the contact point. Plating materials with low reactivity prevent the formation of non-conductive oxides. In harsh environments, sealed enclosures protect contacts from corrosive gases like hydrogen sulfide.
Testing Sequence
Validation of this property involves measuring contact resistance before, during, and after exposure to thermal shock or mechanical vibration. Low-level contact resistance tests use limited current to avoid breaking down thin oxide layers, ensuring an accurate measurement of the interface. This test sequence confirms that the component can maintain its electrical performance in the field.
