ABSTRACT
The size of asperities can vary from the length of the sample to the atomic scale. By convention, the surface irregularities are classified into errors in form, waviness, roughness, and sub-roughness. Those levels of roughness are associated with corresponding types of contact area. The fundamental monograph of Holm considered most of the contact phenomena important for mechanical and electrical engineers. Ring-shaped constrictions occur when one contacting surface carries a highly conductive cladded layer on a knurled surface. Passage of electrical current occurs largely through the cladding material of the knurls in contact with the mating surface. A nanocontact is an area between two macroscopic bodies where the dimensions are comparable to the mean free path of the electrons traversing the contact interface. The rapid development of electronic devices having nanometer-scale dimensions imposes very stringent requirements, such as low contact resistance and spatial uniformity at the nanometer-length scale.
