Electric Contact Performances and Electrical Conduction Mechanisms of an Elastomeric Conductive Polymer

Abstract

The conductive polymer is usually composed of dispersed electrically conductive particles such as carbon black or metal in a durable polymer matrix such as silicone rubber. As it is possible to obtain conductivity and elasticity in simple materials, this is useful for high density micro-sized electrical contacts as connector or as key-board switch. However, in spite of the excellent properties, it is difficult to obtain low electrical resistivity. In order to approach this problem, performances of the contacts between the polymer surface and metal were studied from the view point of surface contamination. The electrical conduction mechanism and a method to get low resistivity were also studied. The results show that the surface of the polymers containing carbon black shows contamination resistance properties because of their chemical sta-bility. The conduction mechanism changes with particle content. For large content, electric current flows through particles contacting each other; and for small content, the current passes through the gap between particles by Schottky conduction. Thus, as the resistance consists of particle resistance, constriction resistance and gap resistance, the resistance can be controlled by particle material, their content and size.