Surface treatment of micron silver flakes with coupling agents for high-performance electrically conductive adhesives

Coupling agents are widely used in order to improve the properties of electrically conductive adhesives (ECAs). The effects of different coupling agents on the characteristics of epoxy-based ECAs were investigated in terms of thermal, rheological, electrical and mechanical properties. Results showed that the ECAs had favourable flow, adhesion and good conductivity. In particular, the ECAs filled with Ag flakes treated with the silane coupling agent 3-aminpropyltriethoxysilane (KH-550) exhibited the lowest electrical resistivity (5.22 x 10-4 omega cm) and the highest shear strength (20.32 MPa) among the ECAs. Besides, it had the minimum viscosity 154 Pa s at 5 rpm/25 degrees C. It was also found that the adding of coupling agents had different effects on the aging electrical and shear strength of the ECAs. According to this study, the use of KH-550 had a significant electrical conductivity improvement and shear strength increase before and after aging. In addition, a strong adhesion/bonding between the conductive fillers and the resin matrix was revealed by scanning electron microscopy studies.