1. Influencing factors of solder paste The quality of reflow soldering is affected by many factors. The most important factors are the temperature curve of the reflow soldering furnace and the composition parameters of the solder paste. Nowadays, the commonly used high-performance reflow soldering furnaces can already be compared It is convenient to accurately control and adjust the temperature curve. In contrast, in the trend of high density and miniaturization, the printing of solder paste has become the key to the quality of reflow soldering. The particle shape of the solder paste alloy powder and the narrow pitch device The quality of the soldering is related to the viscosity and composition of the solder paste. In addition, the solder paste is generally stored in refrigeration, and the lid can be opened after returning to room temperature when taking it. Special care should be taken to avoid mixing the solder paste with moisture due to temperature differences, and use it when needed. The mixer stirs the solder paste evenly. 2. The influence of the welding equipment. Sometimes, the excessive vibration of the conveyor belt of the reflow soldering equipment is also one of the factors that affect the quality of the welding. 3. The influence of the reflow soldering process excludes the solder paste printing process and patch After the quality of the process is abnormal, the reflow welding process itself will also cause the following quality abnormalities: ①, cold welding is usually the reflow temperature is low or the time of the reflow zone is insufficient. ② The temperature of the solder ball preheating zone climbs too fast (General requirements, the slope of the temperature rise is less than 3 degrees per second). ③, the continuous tin circuit board or components are damp, and too much moisture can cause the tin to explode and produce the continuous tin. ④, the crack is generally the temperature drop in the cooling zone too fast ( Generally, the temperature drop rate of lead soldering is less than 4 degrees per second).