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The objective of this work is to evaluate the effect of scale dependent mechanical and electrical properties on electrical contact resistance (ECR) between rough surfaces. This work attempts to build on existing ECR models that neglect potentially important quantum- and size-dependent contact and electrical conduction mechanisms present due to the asperity sizes on typical surfaces. The electrical conductance at small scales can quantize or show a stepping trend as the contact area is varied in the range of the free electron Fermi wavelength squared. This work then evaluates if these effects remain important for the interface between rough surfaces, which may include many small scale contacts of varying sizes. The results suggest that these effects may be significant in some cases, while insignificant for others. It depends on the load and the multiscale structure of the surface roughness. [ABSTRACT FROM AUTHOR]

We report high lateral resolution Auger electron spectroscopic (AES) measurements on high aspect ratio Sn whiskers. The whiskers were grown from compressively stressed thin films (\sim \ 6000\ \\rm\AA) of Sn on brass using a magnetron sputtering system. The Auger spectra show that, after sputter cleaning, the whisker is nearly 100% Sn at all locations along the whisker shaft, at the growing blunt end of the shaft, and with depth (\sim \ 1000\ \\rm\AA) into the side of the whisker. The “as received” Sn whisker surface shows the expected \sim \ 200\ \\rm\AA of native Sn oxide at all locations and the O signal nearly disappeared (\sim3 atom%) after 200 \\rm\AA of sputter cleaning. There was no evidence of high amounts of oxygen within the bulk of the whisker. That brass is not observed in the whisker shaft supports the notion that whisker formation is accompanied by material mass transport through interfaces and grain boundaries which causes stress (usually compressive) relief. This is supported by the most remarkable aspect of the whisker growth; namely, that high aspect ratio Sn whiskers \sim \ 100–500\ \mu\ m in length containing no brass can be grown from a \sim \ 0.6\ \mu\ m thin film of Sn. [ABSTRACT FROM PUBLISHER]