Rheology and processability of Diglycidylether of bisphenol-A (DGEBA) and Polyurethane (PU) based isotropic conductive adhesives filled with different size-distributed silver flakes and silver particles

The study investigates the rheological behaviour of Diglycidylether of bisphenol-A (DGEBA) and Polyurethane (PU) based isotropic conductive adhesives (ICAs). Each of the systems were formulated with the following fillers: a) silver flakes, b) silver powder and c) mixture of silver flakes and silver powder. A volume fraction ranging from 0.2 to 0.8 silver fillers were added to the epoxy systems. Oscillatory stress sweep test was performed to evaluate the G' and G of the DGEBA and PU based isotropic conductive adhesive pastes. The results show that the structural breakdown of DGEBA and PU pastes could be used to understand the processability and stability of the formulated system. The solid and liquid characteristics of the PU based ICAs were lower when compared to the isotropic conductive adhesives formulated with DGEBA epoxy resin.