Electrical property of conductive adhesives using silver-coated copper filler

As metal fillers used in conductive adhesives, silver is the most commonly used due to its high conductivity and the stability. However the cost of conductive adhesives with silver fillers is much higher than usual lead-free solders So, copper can be a promising candidate for conductive filler metal due to its low resistivity and low cost, but oxidation causes this metal to lose its conductivity. In this study, isotropic conductive adhesives (ICAs) using surface modified copper fillers were developed. Especially, in order to overcome the problem associated with the oxidation of copper, the silver was coated with copper filler, and the silver-coated copper was tested as a filler metal. As a result, it was found that the electrical resistance of ICA with silver-coated copper filler was clearly lower and more stable than that of ICA with copper filler after curing and after reliability tests.