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Contact resistance may vary with temperature. It may also vary with time (most often decreasing) in a process known as resistance creep. Electrical contact resistance is also called interface resistance, transitional resistance, or the correction term. Parasitic resistance is a more general term, of which it is usually assumed that contact ...
When the total resistance between circular pad and holohedral coating is measured three distinguishable components contribute to the measured value, namely the gap resistance and the contact resistances at the inner and outer end of the gap area (and ). This is expressed in the following formula:
A temperature drop is observed at the interface between the two surfaces in contact. This phenomenon is said to be a result of a thermal contact resistance existing between the contacting surfaces. Thermal contact resistance is defined as the ratio between this temperature drop and the average heat flow across the interface. [1]
In electrical and electronics engineering, wetting current is the minimum electric current needing to flow through a contact to break through the surface film resistance at a contact. [1] It is typically far below the contact's nominal maximum current rating. [2]
Normal contact mechanics or frictionless contact mechanics focuses on normal stresses caused by applied normal forces and by the adhesion present on surfaces in close contact, even if they are clean and dry. Frictional contact mechanics emphasizes the effect of friction forces. Contact mechanics is part of mechanical engineering.
Contact force or pressure increases the size of the a-spot which decreases the constriction resistance and the electrical contact resistance. [11] When the size of contacting asperities becomes larger than the mean free path of electrons, Holm-type contacts become the dominant transport mechanism, resulting in a relatively low contact ...
The van der Pauw Method is a technique commonly used to measure the resistivity and the Hall coefficient of a sample. Its strength lies in its ability to accurately measure the properties of a sample of any arbitrary shape, as long as the sample is approximately two-dimensional (i.e. it is much thinner than it is wide), solid (no holes), and the electrodes are placed on its perimeter.
The problem of contact resistance can be overcome by using four electrodes. The two end electrodes are used to inject current as before, but the voltage is measured between the two inner electrodes. The effective length of the sample being measured is the distance between the two inner electrodes.