The process control of wave soldering is the main factor that directly affects the soldering quality of electronic products, especially the soldering quality of lead-free electronic products. The process control of wave soldering is stricter and involves more skill scales. Below is a specific explanation of the precautions for controlling the wave soldering process.
1、 Flux coating amount
It is required to have a thin layer of solder on the bottom of the printed board, which should be uniform and not too thick. Regarding the no cleaning process, special attention should be paid to not excessive. The flux coating method adopts a quantitative spraying method, and the flux is sealed in a container, which will not evaporate, absorb moisture from the air, or be contaminated, so the composition of the flux can remain unchanged. The key requirement is that the nozzle can control the amount of spray, and the nozzle should be cleaned frequently, and the spout hole should not be blocked.
2、 Preheating temperature of electronic product circuit board
The function of preheating is to allow the solvent in the flux to evaporate sufficiently, avoiding the influence of moisture on the printed board and the composition of solder joints during soldering; Raise the printed circuit board to a certain temperature before soldering to avoid warping and deformation caused by thermal shock. The general preheating temperature is controlled between 180~200 ℃, and the preheating time is 1-3 minutes.
3、 The inclination angle of the wave soldering trajectory
The inclination angle of the trajectory has a significant impact on the welding effect, especially when welding high-density SMT equipment. When the tilt angle is too small, bridging is more likely to occur, especially in welding, where the covered area of SMT equipment is more prone to bridging; However, if the inclination angle is too large, although it is conducive to the elimination of bridging, the amount of solder eaten by the solder joint is too small, which can easily lead to virtual soldering. Therefore, the inclination angle of the trajectory should be controlled between 5 ° and 7 °.
4、 Peak height of wave soldering
The height of the wave peak may change due to the passage of soldering work time, and appropriate correction should be made during the soldering process to ensure the ideal height for soldering, with the soldering depth being 1/2-1/3 of the PCB thickness.
5、 Welding Temperature of Electronic Products on Wave Soldering Furnace
Welding temperature is an important process parameter that affects welding quality. When the welding temperature is too low, the expansion rate and moisture function of the solder material deteriorate, because the solder pad or component welding end cannot be sufficiently moist, resulting in defects such as virtual soldering, pulling, bridging, etc; When the welding temperature is too high, it accelerates the oxidation of solder pads, component pins, and solder, which can easily lead to virtual soldering. The welding temperature should be controlled at 250+5 ℃.
