The skill of tin wire welding is a proficient process. The speed of soldering mainly depends on the selection of solder wire. The speed of tinning on high-quality solder wire is fast. For the ordinary soldering structure of PCB, it is usually required that the size of the solder joint between the solder wire and the PCB should be Select the solder wire with high tensile strength and high activity for the alloy structure of the solder joints of the PCB board. When the metal of the solder joints of the PCB contains nickel and gold, the composition of the solder wire and the requirements for additives should be increased. Meet the requirements of solder wire welding. When the content of solder wire additive increases, the solder wire is prone to spatter and cracks. The crack resistance of solder wire should be improved. For solder joints that bear dynamic loads and impact loads, in addition to meeting the strength requirements, it is also necessary to ensure that the solder joint metal has high impact toughness and plasticity. Solder wire with high toughness indicators should be selected. The welding part of the solder wire should use a solder wire with strong oxidation and high leveling performance to increase the welding speed. The selection of solder wire must understand the chemical composition and mechanical properties of the solder wire, the crack sensitivity of the solder joint after welding, the electrothermal performance and corrosion resistance after welding. Comprehensive consideration should be given to the operating conditions of high and low temperature changes.