Method for improving reliability of SAC/Cu welding spot

The invention relates to a method for improving the reliability of SAC/Cu welding spots, and belongs to the technical field of lead-free solder. According to the method, nano Ag3Sn particles and nano Cu6Sn5 particles are added into the SAC305 composite solder paste to prevent coarse intermetallic compounds from appearing in SAC/Cu welding spots and improve the reliability of the SAC/Cu welding spots, namely, the nano Ag3Sn particles and the nano Cu6Sn5 particles are added into the Sn3. 0Ag0. 5Cu solder paste, and the modified Sn3. 0Ag0. 5Cu solder paste is obtained through ultrasonic uniform mixing. According to the modified Sn3. 0Ag0. 5Cu soldering paste, on the basis that the original performance of soldering flux is not changed, the wettability and the mechanical property of the soldering flux can be improved, meanwhile, growth of an interface IMC layer can be effectively restrained, and the reliability of welding spots is improved. 本发明涉及一种提高SAC/Cu焊点可靠性的方法，属于无铅焊料技术领域。本发明通过在SAC305复合锡膏中添加纳米Ag3Sn颗粒和纳米Cu6Sn5颗粒