Conductive adhesives with improved thermomechanical properties

In this work, a new type of isotropically conductive adhesive (ICA) for microelectronic applications is presented. An extremely low value of ionic impurity content in the ICA is realized by using a cycloaliphatic epoxy resin. The brittle behaviour of this type of resin has been counterbalanced by introducing porous silver nanopowders as a conductive filler material instead of conventional silver flakes. In this way, a considerable reduction in metal filler content is achieved at still acceptably low values of electrical resistivity. It is shown that the mechanical properties under shear loading are improved considerably when using the nanopowder/epoxy composites as compared to ICAs based on Ag flakes. This new ICA is therefore particularly suited for bonding substrates and components which differ strongly with respect to their coefficient of thermal expansion.