scholarly journals Clustering and the spatial distribution of contact spots at a real un-dismantled electrical contact interface

2010 ◽  
Vol 43 (14) ◽  
pp. 145302 ◽  
Author(s):  
J Swingler
Keyword(s):  
Spatial Distribution ◽  
Electrical Contact ◽  
Contact Interface ◽  
Contact Spots

Friction, Wear, and Interfacial Electrical Resistance. Part I: The Hoop Apparatus

1987 ◽  
Vol 109 (4) ◽  
pp. 604-608 ◽  
Author(s):  
D. Kuhlmann-Wilsdorf ◽  
Y. J. Chang ◽  
L. B. Johnson ◽  
L. J. Bredell
Keyword(s):  
Coefficient Of Friction ◽  
Electrical Resistance ◽  
Electrical Contact ◽  
Constant Load ◽  
Simultaneous Recording ◽  
Contact Spot ◽  
Interfacial Resistance ◽  
Stick Slip ◽  
The Coefficient Of Friction ◽  
Contact Spots

An apparatus has been developed for the gathering of data from which, through suitable analysis, detailed information on the momentary condition of a sliding interface may be obtained. The information includes the number of the contact spots, the electrical resistivity of the interfacial film, and the flash temperature at the contact spots. The apparatus provides for the continuous simultaneous recording of the coefficient of friction and of the interfacial electrical resistance of a slider in stick-slip motion at constant load and controllable average speed, and/or of the interfacial resistance of a slider at constant speed under controllable load. Loads between 0.3 and 10N and speeds up to 0.15m/s may be selected, in a variety of atmospheres and ambient pressures, as the apparatus is enclosed in a bell jar. It consists of a rotating cylindrical metal hoop inside of which a metal slider moves under the forces of friction and gravity, giving stick-slip behavior full play, and a slider in fixed position subjected to controllable, hydrostatically applied loads. The entire apparatus can be used with a controlled atmosphere or vacuum. The motion of the stick-slip slider, from which the coefficient of friction is inferred, is recorded on one pen of a three-pen strip-chart recorder and the electrical contact resistances between the two sliders and the hoop on the other two pens. The dependence of contact resistance on load, obtainable from the fixed slider without removing the bell jar, permits a determination of the number of contact spots provided the constriction resistance is not negligibly small compared to the film resistance. Deliberate changes of the contact spot temperature can be made by adjusting the current through the slider/hoop interfaces.

Electrical conduction in solids II. Theory of temperature-dependent conductors

1958 ◽  
Vol 246 (1244) ◽  
pp. 13-31 ◽  
Keyword(s):  
Spatial Distribution ◽  
General Problem ◽  
Electrical Contact ◽  
Critical Value ◽  
Anomalous Behaviour ◽  
Electrical Heating ◽  
Mathematical Treatment ◽  
Theoretical Predictions ◽  
New Treatment ◽  
Welding Processes

The experiments in part I on the behaviour of the contact between metals when large currents pass the interface have yielded results which cannot be explained by the classical theory of constriction resistances. In an attempt to provide an account of this anomalous behaviour a new mathematical treatment of the general problem of the electrical heating of conductors has been developed. This treatment gives, under the appropriate conditions, a concise derivation of all the main results of the accepted theory; in addition it leads to three new conclusions. First, it is shown that the general problem of finding the spatial distribution of the potential, the current, and the temperature within a medium whose thermal and electrical conductivities vary with temperature may be reduced to the corresponding problem with constant conductivities, and a simple numerical integration. Secondly, it is shown that the spatial distribution of the current within the conductor is independent of the thermal and electrical properties of the medium, and that it is unaltered by variation s of the total current passing. Finally, it is demonstrated that there are certain conditions under which a steady solution of the problem is impossible. For many conductors steady conditions are possible only when the current is below a certain critical value. If a current greater than this critical value is maintained the temperature will rise continuously, and eventually the process will be limited by some other phenomenon, for example, melting. The new treatment is applied to the calculation of the spatial distribution of current for a particular shape of conductor, one which is relevant to many resistance welding processes. The predictions agree accurately with experimental data obtained from the examination of a series of welds. The theory is then applied to the special case of the electrical contact between gold pieces and shown to offer an explanation of the anomalous behaviour mentioned above. Good agreement is demonstrated between the theoretical predictions and the experimental results.

Moisture Effects Including Stiction Resulting From Adsorbed Water Films

1992 ◽  
Vol 114 (1) ◽  
pp. 174-180 ◽  
Author(s):  
Chao Gao ◽  
D. Kuhlmann-Wisldorf ◽  
D. D. Makel
Keyword(s):  
Electrical Contact ◽  
Slow Motion ◽  
Adsorbed Water ◽  
Copper Surface ◽  
Contact Spot ◽  
Electrical Contact Resistance ◽  
Local Pressure ◽  
Water Films ◽  
Moisture Effects ◽  
Contact Spots

Stiction resulting from moisture effects at small elastic contact spots has been identified and studied using bundles of fine, gold-plated copper fibers sliding on a gold-plated copper surface. The relevant measurements were made in the hoop apparatus which permits simultaneous monitoring of the momentary coefficient of friction and electrical contact resistance. Previous studies made with the hoop apparatus have shown that under the action of high local pressure, adsorbed moisture is expelled from between the contact spots leaving only one monomolecular layer of adsorbed water on each of the contacting surfaces. Additional details of the observations are varied and permit a refined analysis. Stiction results during periods of very slow motion or rest through local energy reduction at the spots as excess water is slowly drained in the course of molecular ordering of the two absorbed layers. Complex variations of kinetic friction with humidity and sliding speed are explained through the interplay of excess molecules between the contact spot surfaces, meniscus formation, fluid drag about the spots, and shear thinning in that flow.

Electrical Performance of Degraded MEMS Ohmic Switches

2005 ◽  
Author(s):  
Lior Kogut
Keyword(s):  
Ohmic Contacts ◽  
Current Flow ◽  
Degradation Mechanism ◽  
Electrical Contact ◽  
Electrical Performance ◽  
Contact Interface ◽  
Growth Mechanisms ◽  
Electrical Contact Resistance ◽  
Asperity Contacts ◽  
Physical And Chemical

Electrical performance of degraded MEMS metallic switches (ohmic contacts) is studied analytically in this paper. The degradation mechanism is based on gradual growth of an insulating film at the contact interface and the characteristics of the insulating film are assumed to be known without considering details regarding the physical and chemical origins of the growth mechanisms. The present study relies on recently developed theories for electrical contact resistance (ECR) of clean and fully-contaminated (i.e., the entire contact area is coated with an insulating film) rough surfaces thus, bridging the gap between these two extreme cases. A relationship is obtained between the degraded ECR and the metallic conductance area. The effect of tunneling currents on the performance of partially-contaminated surfaces is found to be negligible due to the considerable current flow across the metallic asperity contacts.

scholarly journals The 3D nature of a real un-dismantled electrical contact interface

Wear ◽  
2015 ◽  
Vol 328-329 ◽  
pp. 115-122 ◽  
Author(s):  
Constantinos Roussos ◽  
Jonathan Swingler
Keyword(s):  
Electrical Contact ◽  
Contact Interface
Sign in / Sign up

Export Citation Format

Share Document