Constriction resistance of physical simulated electrical contacts with nanofabrication

Abstract

To establish a relationship between the physical structure of electrical contact boundary and constriction resistance in actual consumer connectors, we fabricated samples that represented the contact-simulated structure. The sample was created on silicon substrates via nanofabrication, and we measured the sample's electric resistance precisely. In these samples, the physical structure can be designed and fabricated arbitrarily with an electron-beam lithography system, so that the complicated contact structure can be simulated physically. We measured the resistance of a number of samples that had various "contact areas" to observe the effect of the areas on constriction resistance. We found that the observed effect qualitatively agreed with the result of the formula of the Holm theory on constriction resistance. However, the absolute values of the resistance differed from the results of the equation. This is attributed to the fact that the equation is intended for an ideal condition. Under the ideal condition, electrodes are infinitely sized, and at any point, there is zero distance between them. By contrast, in actual contacts, electrodes are finitely sized, and there is some insulator, including air, between them. Our measurements suggest that the constriction resistance of actual contacts can be described by introducing additional parameters into the classical Holm theory.

Computation of the Electrical Resistance of a Low Current Multi-Spot Contact

“…On the other hand, Greenwood’s model is suitable for multiple spots within a cluster, and it depends on the distances between the set of the circular spots within that cluster. Though this is an upgrade from Holm’s model, it will be difficult to calculate the constriction resistance when the contact consists of more than one cluster [ 26 ].…”

Electrical Reliability of a Film-Type Connection during Bending

“…Although the contact pressure is not measured experimentally, we can assume that the connection pressure between the electrodes results from the elastic restoring force of the adhesive. The experimental and mathematical investigations in this study indicate that the real contact area allows for electrical conductance because the two metals are in contact with each other over some of the apparent contact area [51][52][53][54][55][56]. Thus, the film-type connector forms a plate-to-plate contact between the electrode and the connecting unit, which ensures the maximum apparent and real contact areas.…”

Simulation of Electro-Thermal Condition in a Faulty Low-Current Contact

“…Greenwood made a further approximation of equation (3). When there is no correlation between the size of a given contact spot and its position, equation (3) becomes:…”

“…1). As the current passes through these small contact areas, it gives rise to constriction resistance which can eventually cause a cut in the transmission of signal or loss of power to any electrical system through Joule heating [3]. Oxidation, mechanical wear, and harsh atmospheric conditions (dust, temperature, moisture, etc.)…”