Scalable synthesis of the mono-dispersed silver micro-dendrites and their applications in the ultralow cost printed electrically conductive adhesives

Electrically conductive composites have been intensively studied as the interconnects and the printed lines in the next generation of electrical devices. Silver fillers have been widely accepted as the key conductive filler material due to their excellent electrical conductivity, malleability, chemical and mechanical stability. Here we for the first time introduce a scalable synthesis of the mono-dispersed silver dendrites with 3-D micro- and nano- structures, and their uses as the conductive filler for the electrically conductive adhesives (ECAs) with ultralow silver content. These silver dendrites have a unique 3-D fractal structure, which are able to provide excellent low-temperature sintering ability due to the abundant nanostructures at the edge of the dendrite leaves. This feature renders them form excellent electrical percolation network with ultralow concentration (percolation threshold down to 20 wt%) in conventional engineering resins, which is currently the one with the lowest percolation threshold for the micro-metal-filler based ECAs. Thermal analysis (TGA/DSC) and scanning electron microscopy (SEM) suggest that the silver dendrite powders go through a sintering process at the temperature below 150°C, thus the adjacent dendrites are able to form effective ohmic conductance. Considering the low materials preparation cost and negligible environmental risk, this method suggests an effective way to develop environmentally benign materials for the flexible printed electronics devices.