Seed-mediated growth for aspect-ratio-tunable copper nanoplates

Copper materials with nanoplate structure combine the advantages of nano and micrometer dimensions, featuring excellent electrical conductivity, low-temperature sintering performance, and processability. They have considerable applicability and greater economic benefits compared with silver, and thus have attracted much attention in the field of microelectronic packaging. In this study, a seed-mediated growth method was proposed to synthesize copper nanoplates (Cu NPs) under mild conditions. By selecting pre-synthesized silver nanoplates as seeds, the synthetic efficiency and dimensional controllability of Cu NPs have been greatly improved. At 40 °C, Cu NPs with good dispersion can be obtained within 15 min. The formation mechanism of Cu NPs was proposed by studying the factors that influence it. The conductive adhesives formulated with as-synthesized Cu NPs achieve an impressively low resistivity of 35 μΩ cm at a filler content of 90 wt%, paving the way for the industrial application of copper-based conductive adhesives.