Characteristics of electrically conductive adhesives filled with copper nanoparticles with organic layer

Electrically conductive adhesives (ECAs) have been investigated for the use in microelectronics packaging as a lead-free solder substrate. As metal filler in conductive adhesives, silver is the most commonly used due to its high conductivity and stability. However, the cost of conductive adhesives with silver fillers is much higher than conventional lead-free solders and silver has poor electro-migration performance. Copper is a promising candidate for conductive filler metal due to its low resistivity and low cost, but oxidation causes this metal to lose conductivity. In this study, ECAs using surface-modified copper fillers were developed. In particular, to overcome the problem associated with the oxidation of copper, copper nanoparticles were coated with organic substance from when nanoparticles were made. The organic-coated copper was tested as a filler metal. Especially the effect of organic layer on the electrical resistance just after curing and after high-temperature exposure was investigated. As a result, it was found that the electrical resistance of ICA with organic-coated copper filler was more stable than that of ICA with pure copper filler.