The effect of coating thickness on the electrical performance of novel isotropic conductive adhesives prepared using metallised polymer micro-spheres

Traditionally, isotropically conductive adhesives (ICAs) have been prepared using a high volume fraction of solid silver flakes and particles in a non-conducting adhesive matrix. However, this paper focuses on newly developed ICAs containing a large volume fraction of silver coated polymer spheres (Ag-PS) as the filler in a non-conductive adhesive matrix. This paper mainly investigates the effect of thickness/morphology of the silver coating on the electrical conductivity and percolation threshold of such ICAs. For this study 30μm polymer spheres with four different coating thicknesses have been used. B oth the percolation threshold and the resistivity for a given volume fraction have been found to decrease with increasing thickness of the Ag coating.