Study of isotropically conductive bondings filled with aggregates of nano-sited Ag-particles

Isotropically conductive adhesives have been commercially available for decades and consist of high resistive polymers and dispersed metal filler particles stiffening the cured polymer. So as far as reliability is concerned the different thermal expansion coefficients of substrate and component may lead to exceeding thermal stress within the bonding which is a primary source of failure. In this investigation, highly porous aggregates consisting of nano-sited Ag particles are used as a new kind of conductive filler. The powders consist of sintered networks of ultrafine particles in the size range 50 nm to 150 nm, whereby the mean diameter of these aggregates could be adjusted down to some microns. The conduction mechanism of Ag flake filled resin is explained by the metallic behavior of the filler particles alone using the Ziman equation, whereas the porous Ag-filled resin shows a slightly different temperature characteristic. Shear stress-strain measurements have shown that, indeed, the thermo-mechanical properties can be improved by using porous Ag instead of Ag flakes.