Synthesis of Highly Reliable Conductive Pastes with Silver-Graphene Composites

This study focuses on the synthesis and optimization of Ag-graphene composite particles and their incorporation into conductive pastes for electronic applications. The composites were synthesized by mixing organic solvents to facilitate graphene formation on silver particle surfaces, followed by ultrasonic irradiation. Main parameters, including solvent ratio and ultrasonic power, were adjusted to optimize the carbon matrix, targeting a thickness of less than 2 nm for effective dispersion in paste formulations. The optimal synthesis conditions were identified as 100 °C for 2 hours, using 80% ethanol and 1500 W ultrasonic power. For binder preparation, an epoxy resin was designed with specific curing agents, solvents, and additives to achieve stable room-temperature curing and minimal viscosity fluctuations. The final binder formulation (epoxy, curing agent, solvent, dispersant, and thixotropic agent in a 60:2:30:5:3 ratio) provided excellent stability and dispersion properties. The conductive paste was then produced by combining the optimized Ag-graphene particles with the epoxy binder using a three-roll dispersion process. By varying the particle-to-binder ratio, the 80:20 ratio was found to offer the best balance of shear strength and low resistivity. The paste showed stable viscosity over time, ensuring reliable printability, and scanning electron microscopy (SEM) confirmed strong particle connections, supporting its expected conductivity.