Geometry-defined electrical interconnection by a homogeneous medium

Abstract

We describe a geometry-defined electrical interconnection medium based on a composite of small metal particles dispersed uniformly in an insulator. The volume fraction of metal particles, p, is just below the critical value pc, which corresponds to the percolation threshold. As a result, the conductance between two points drops sharply by several orders of magnitude as their separation increases beyond a well-defined short range coherence length ξ. We show how, by careful control of p, a homogeneous composite can provide isolated electrical interconnection paths, or ‘‘vias’’. These vias are simply defined by controlling their geometry; thus, they provide an easily processable, solderless means for vertical interconnection in a variety of high density packaging schemes.