During the wave soldering process, the gases generated inside the solder joints and through holes of the high temperature solder bar will escape to the outside. When the solder on the top layer of the solder joint no longer provides an escape channel for the released or captured gas, part of the gas inside the solder joint continues to expand and escapes from the bottom to form a blow hole, while the unescaped gas is wrapped in the solidification voids are formed inside the solder. During the soldering process, the gas generated inside the solder joint of the high temperature solder bar is mainly caused by the volatilization of the flux and the release of moisture. This was also confirmed by the presence of flux residues in the blow hole orifices as well as solder beads, solder slag and flux residue particles around the solder joints. Excessive flux or insufficient volatilization of the solvent before soldering, or damping of the substrate, etc., will cause a large amount of gas during the soldering process to easily form blow holes or voids in the solder. If the hole wall of the plug-in hole is rough and the base material next to the hole is loose, these factors are likely to cause excess moisture inside the PCB to generate more gas during the soldering process, so these factors should also be one of the reasons for the blowing hole. Whether it is an ordinary solder bar or a high-temperature solder bar, there will be blow holes. In the long run, the phenomenon of rough hole walls and loose substrates should be eliminated by controlling the PCB manufacturing process, and the remaining channels of moisture inside the PCB should be eliminated. Strict control and optimization of the welding process to fundamentally eliminate blow holes and voids.