Preparation of high strength silicone-based electrically conductive adhesives with excellent electrical conductivity at low content of Ag fillers

Silicone-based electrically conductive adhesives (Silo-ECAs) have found extensive application in flexible electronics. However, the achievement of Silo-ECAs that exhibit both high electrical conductivities and reliable mechanical strength is challenging due to the effects of the silicone matrix structure and numerous conductive fillers. Reducing the filler content while maintaining high levels of both electrical conductivity and mechanical properties is the key to solving the problem. In this study, a silicone matrix with high mechanical properties was synthesized by the hydrosilylation of vinyl-terminated polydimethylsiloxane, vinyl MQ silicone resin with polymethylhydrosiloxane and the modification using a silane coupling agent. Then Silo-ECAs with high conductivity at low Ag content were realized by incorporating flake and spherical Ag powders and adjusting the content, size and ratio. The results showed that Silo-ECAs with 60 wt% 1 μm flake Ag powders and 10 wt% 1 μm spherical Ag powders exhibited the lowest bulk resistivity of 4.56 × 10⁻⁵ Ω·cm, high shear strength of 1.28 ± 0.06 MPa, and excellent tensile strength of 3.20 ± 0.04 MPa, superior to the previously reported about 80 wt% Ag-loaded Silo-ECAs. We believe that our study provides valuable insights for developing high-performance Silo-ECAs.