Compared with other household appliances, the solder joint area of mobile phone circuit is much smaller, so it can bear little mechanical stress and has great fluidity, which is very prone to the failure of virtual soldering. Because of this, many mobile phone maintenance personnel also rely on a hot air gun to "conquer the world" to start a business. There is also a saying in the mobile phone maintenance industry that 70% of faults can be repaired by one washing, two blowing and three welding. It can be seen that the repair welding method is of great significance and position in the maintenance of mobile phones. The so-called repair welding method is to determine which unit the fault may be in through the analysis of working principle, and then carry out large-area repair welding and cleaning in this unit. That is, all relevant and suspicious welding points are repaired and welded again. Repair welding tools can be hot air guns and pointed anti-static soldering irons. Mobile phone maintenance training