Implementing PEDOT:PSS as a Co-Filler for Electrically Conductive Adhesive Applications
Authors: Josh Trinidad, Wei Zhang, Boxin Zhao, Alex Chen, John Persic, and Robert Lyn Company: University of Waterloo, Celestica Inc., Microbonds Inc. Date Published: 5/9/2016
ICSR (Soldering and Reliability)
Abstract: Electrically conductive adhesives (ECAs) with hybrid fillers have attracted considerable attention due to their lower processing temperature, higher conductivity, simpler processability and finer-pitch capacity. Compared with traditional soldering technology, ECAs offer an environmental-friendly bonding solution in interconnections. In this work, we demonstrated that poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) could be applied as a conductivity enhancing agent in the epoxy and silver micro flakes system to develop a hybrid nanocomposite adhesive. The electrical conductivities of the hybrid ECAs with a constant total amount of silver flakes at various PEDOT:PSS weight concentrations were investigated. It was found that adding a small amount of PEDOT:PSS (0.09 wt%) remarkably improved the electrical conductivity to 289 S/cm, which is 3 times higher than that of the conventional ECA with 60 wt% sliver flakes. The maximum conductivity of 2422 S/cm was achieved at 0.89 wt% PEDOT:PSS concentration. The adhesive strength (or shear strength) was also evaluated for increasing weight loadings to determine whether there was an adverse effect when adding PEDOT:PSS into the composite. It was determined that as the weight loading of PEDOT:PSS was increased, the shear strength variance increased with it. Furthermore, the shear strength also appeared to have slightly decreased with higher weight loading. These results were presumed to come from various sources; however, it is suspected that the main culprit is excess water molecules remaining in the mixture even after evaporation as a result of the large amounts of PEDOT:PSS solution present in the process. Overall, the incorporation of PEDOT:PSS as a co-filler has shown a good potential in ECA applications.