Nanometer tin-silver-copper soldering paste for microwave composite heating and preparation method and welding method of nanometer tin-silver-copper soldering paste

The invention discloses nano tin-silver-copper soldering paste for microwave composite heating and a preparation method and a welding method thereof, and belongs to the technical field of brazing. According to the preparation method of the novel tin-silver-copper nano soldering paste, the problem that traditional lead-containing solder is harmful to the environment and the human body is solved, the melting temperature of nano brazing filler metal in the welding process is reduced in a solder nanocrystallization mode, then the temperature of a welding area in the device packaging process is reduced, and the reliability of the device is improved. The mechanical property of the welding seam and the reliability of a packaging device are improved. According to the method, microwave composite heating is adopted as a welding method, the problems that a temperature gradient exists in a connector and selective heating cannot be achieved in a traditional welding method can be solved, the welding efficiency is high, and