Material characterization of short-range conduction in metal- insulator-composites.

Elastomeric composites filled with metallized glass beads have been formulated and characterized for detachable chip carrier applications. These isotropic materials do not exhibit bulk conductivity but are conductive across thin sections. This is because the resistivity increases sharply by ten orders of magnitude as sample thickness is increased 1 to 2 mils past a critical value. In percolation theory, this parameter is called the short-range coherence length and depends on the filler concentration and particle size.