Nanotomography of electrical contacts – new insights by high resolution 3D analysis of local material degradation

Functional Materials Chair, Dept. Materials Science & Engineering, Saarland University, Saarland, Germany

Corresponding author: n.jeanvoine@matsci.uni-sb.de

Received: 28 November 2008
Revised: 26 October 2009
Accepted: 19 November 2009
Published online: 22 December 2009

Abstract

The precise characterization of the local microstructure situation is a precondition to investigate and to understand the degradation phenomena occurring in electrical contact materials, because the microstructure is the unique and authentic monitor of the whole materials experience. However, it could not be fully exploited so far due to the lack of adequate characterization techniques. The recently developed FIB-nanotomography may solve this problem. It is based on the automatic serial sectioning by a focused ion beam (FIB) of the volume of interest at the nanoscale and offers an optimum resolution in x-y-z directions. For imaging all well established contrast information of the scanning electron microscopy (chemistry, phase composition, grain structure, texture, stress and strain) is available. After imaging, a detailed 3D image analysis enables the comprehensive quantitative evaluation of local microstructure degradation effects. This work gives an overview of these new possibilities using the example of a Ag/SnO₂ contact material in its initial state and after switch operations.