Solder composition is not standard or zinc, aluminum, cadmium and other impurities exceed the standard, as well as welding Angle, strength and other factors will affect the wettability and fluidity of the solder, thus affecting the quality of the solder. The welding moment is recorded by high-speed camera, and the reasonable solder joint geometry is analyzed, which plays a vital role in ensuring the quality of solder welding. Due to the limited strength of tin material, it is difficult to ensure the sufficient strength of solder joints, and the joint design has been greatly improved.