Electrical and tribological properties of heat-treated polyacrylonitrile layers for contact application

Thin polymer films have emerged for a few years as a promising alternative to the different terminal coatings classically used for the protection of low-level contacts. We show that polyacrylonitrile (PAN) films 1 /spl mu/m thick, deposited on a metal substrate by spin-coating and properly heat-treated, can lead to covering and adherent organic layers which correctly resist to friction and present satisfying electrical properties for a contact application. The evolution of the molecular structure of the material due to the pyrolysis was investigated by IRRAS and XPS techniques. Series of contact resistance and friction coefficient measurements were performed in a ball/plane configuration simulating real conditions of use, pointing out a considerable increase of both the conductivity and the tribological performances of the treated films. Various types of samples were tested involving different treatment conditions. Outstanding results were obtained concerning contact resistance measurements, since R/sub c/ values, initially above 10/sup 9/ /spl Omega/ for the raw polymer, drastically diminished to a few tens of m/spl Omega/ for the most intense heat-treatment The evolution of the contact resistance when varying the normal load or the ambient temperature tends to prove the films are neither porous nor pierced by the contact.