Effect of nano-sized silver particles on the resistivity of polymeric conductive adhesives

In this work, conductive adhesives were made by adding micro-sized silver flakes, mixed-sized silver particles or nano-sized silver colloids to the polyvinyl acetate (PVAc) emulsion. Film resistivity was then measured as a function of silver volume fraction. Our results indicated that the addition of nano-sized silver colloids to micro-sized Ag flakes usually increased its resistivity, probably due to increased contact resistance. Only near the percolation threshold, would the addition of nano-sized silver particles decrease the resistivity by helping to form the conductive path. Films made with only nano-sized silver colloids at the volume fraction of 0.848 showed a rather low resistivity of 1.93×10−4 Ω cm. Increase in heating temperature helped to form necks between particles and thus improve the conductivity to some extent.