Wave soldering is to make the soldering surface of the plug-in board directly contact with high-temperature liquid tin to achieve the purpose of welding. The high-temperature liquid tin maintains a slope, and the liquid tin is formed by a special device to form a wave-like phenomenon, so it is called "wave soldering", mainly The material is
solder bar. At present, wave soldering machines basically use heat radiation to preheat.
1. Preparation before wave soldering
Check whether the PCB to be soldered (the PCB has been coated with patch adhesive, SMC/SMD patch, glue cured and completed the THC insertion process) and whether the soldering surface of the attached component jack and the golden finger are coated with solder resist or Attach it with high temperature resistant adhesive tape to prevent the jack from being clogged with solder after the wave. If there are large-sized slots and holes, they should also be pasted with high-temperature resistant adhesive tape to prevent solder from flowing to the upper surface of the PCB during wave soldering. Attach the flux to the hose of the sprayer.
2. Open the wave soldering furnace
a. Turn on the power of wave soldering machine and exhaust fan.
b. Adjust the width of the wave soldering machine conveyor belt (or fixture) according to the PCB width.
3. Set wave soldering parameters
Flux flow rate: Determined based on how the flux contacts the bottom surface of the PCB. Apply the flux evenly to the underside of the PCB. It can also be observed from the through hole on the PCB that a small amount of flux should penetrate upward from the through hole to the pad on the through hole surface, but not to the component body.
Preheating temperature: set according to the actual situation in the preheating zone of the wave soldering machine (the temperature of the upper surface of the PCB is generally 90-130°C, and the upper limit is taken for large boards, thick boards, and assembly boards with many SMT components)
Conveyor belt speed: set according to different wave soldering machines and PCBs to be soldered (generally 0.8-1.92m/min)
In the tin pot, so the temperature displayed on the meter head or LCD is about 5-10℃ higher than the actual temperature of the peak)
Measure the peak height: adjust to exceed the bottom surface of the PCB, at 2/3 of the PCB thickness.
4. Wave soldering and inspection of pieces (after all welding parameters reach the set value)
a. Gently place the PCB on the conveyor belt (or fixture), and the machine will automatically spray flux, dry, preheat, wave solder, and cool.
b. Catch the PCB at the exit of the wave soldering.
c. According to the factory inspection standard.
5. Adjust the wave soldering parameters according to the welding results of the parts
6. Continuous wave soldering production
a. The method is welding with the same piece.
b. Catch the PCB at the outlet of wave soldering, and after inspection, put the PCB into the anti-static turnover box and send it to the post-repair process.
c. During the continuous welding process, the quality of each printed board should be checked, and printed boards with serious welding defects should be welded again immediately. If there are still problems after repeated welding, the reason should be checked and the process parameters should be adjusted accordingly before welding can be continued.
7. The inspection standard is in accordance with the factory inspection standard
8. Matters needing attention:
a. The heating rate of the reflow soldering preheating temperature does not exceed 3°C per second, and the inside is a high-temperature heating device, so be careful not to burn it.
b. When passing through the furnace, the minimum distance between PCB placement is 3cm.
c. When the wave soldering temperature is unqualified, stop using it immediately, and the equipment technician or engineer of the relevant engineering department will check and adjust the wave soldering temperature before checking, and continue to put it into the computer B board for operation after it is judged to be qualified.
d. Technicians must check the temperature settings of wave soldering every day and use a thermometer to make actual measurements.
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