UV - Curable conductive adhesives for 3-D MID application

In this work a new type of isotropically conductive adhesive (ICA) for 3-D MID applications is presented. An extremely low value of ionic impurity content in the ICA is realised by using a cycloaliphatic epoxy resin (CAE). Together with a new developed thermal initiator the CAE will be cured by UV-rays and heat below 100°C. To reach better mechanical behaviour, porous silver nanopowders (SNP) as conductive filler material, instead of conventional silver flakes, are introduced. In this way a considerable reduction of metal filler content is achieved at still acceptably low values of the electrical resistivity. It is shown that the curing regime and the mechanical properties are improved considerably, when using SNP / CAE composites as compared to ICA's based on epoxies with silver flakes. Therefore this new ICA is particularly suited for bonding substrates and components, which differ strongly with respect to their coefficient of thermal expansion.