Rapid soldering of flexible graphene assembled films at low temperature in air with ultrasonic assistance

Gaphene assembled film (GAF) has shown great potentials in practical applications. However, it is still a big challenge to reach reliable soldering of GAF at low temperature, and overcome the exfoliation tendency and the electrical loss resulted from anisotropy of GAF. In this work, we developed a rapid low temperature soldering process for GAF inspired by an ultrasonic assistance technology. As a result, Sn solder spots were prepared on the surface of GAF by ultrasonic metallizing treatment for 10 s in molten Sn at 300 °C. The shock waves and micro-jets induced by ultrasonic waves were supposed to improve the poor wettability of GAF, which propelled molten Sn to penetrate into GAF interlayers, and drove Sn atoms to impinge GAF surface to form an amorphous carbon (a-C) layer at GAF/Sn bonding interface. Specially, the penetration bonding between GAF and Sn solder could not only overcome the exfoliation tendency of GAF, but also reduce the electrical loss between GAF interlayers. The GAF/Sn/GAF soldered joints prepared by remelting Sn metallization layers exhibited excellent tensile resistance and electrical conductivity. Such efficient and reliable soldering technology can facilitate the development of high-performance carbon-based materials in electronic industry.