Reflow soldering is a core process for connecting surface mount components to printed circuit boards. Through preheating and solder melting, reliable solder joints are formed. The following uses an eight-zone reflow oven as an example to describe the operating procedures and precautions in detail.
1. Equipment Startup Procedure
Power and exhaust system
Turn on the main power supply, usually the circuit breaker inside the electrical cabinet at the lower left of the machine, and start the workshop exhaust system to ensure proper ventilation.
System login and parameter setting
Press the POWER button on the upper right of the machine to start the computer and log into the reflow oven control system. After confirming normal communication, load the lead-free solder paste reflow program.
For leaded processes, the target temperature values for each zone are 165°C, 160°C, 175°C, 185°C, 190°C, 190°C, 240°C, and 200°C, with a conveyor speed of 75 ± 10 cm/min.
Starting equipment operation
Click the main start button in the control software, then switch on the air circulation, conveyor, heating, and cooling functions in sequence to bring the equipment into operation.
Preheating and temperature stabilization
A cold machine needs 20 to 30 minutes of preheating. Observe whether the actual temperature (PV) and set value (SV) are stable. If not, adjust the PID parameters of the temperature controller and check again after 5 to 10 minutes.
2. Temperature Profile Calibration
Measured temperature profile
Fix the temperature profiler and its three probes onto a test board with the same dimensions as the actual PCB, then send it through the oven on the conveyor. After the board exits, use the profiling software to read the actual board surface temperature at each time point.
Profile comparison and adjustment
Compare the measured profile with the standard profile. If the deviation is large, adjust the SV values of the temperature controllers in 5°C increments, or modify the conveyor speed as needed until the profile meets production requirements.
3. Functional Zones and Temperature Settings
Eight-zone function division
Zones 1–3: preheat zone for gradual temperature rise and reduced thermal shock.
Zones 4–5: drying zone for removing solvents from solder paste.
Zone 6: activation zone for activating flux.
Zone 7: soldering zone for melting solder and forming joints.
Zone 8: rapid cooling zone for solidifying joints and reducing intermetallic compound growth.
Temperature setting ranges
Zone 1: 165 ± 2°C; Zone 2: 160 ± 2°C; Zone 3: 175 ± 2°C; Zone 4: 185 ± 2°C; Zone 5: 190 ± 2°C; Zone 6: 190 ± 2°C; Zone 7: 240 ± 2°C; Zone 8: 200 ± 2°C.
4. Temperature Controller Parameter Adjustment
Main set value adjustment
On the HMI main screen of the control software, click the numerical window of the zone to be adjusted, enter the SV value, and press "OK" to save. The range is 0–399°C.
PID parameter setting
Enter the settings menu and log in with a username and password. This operation is restricted to authorized technical personnel. Click the zone numerical window, enter the P or I parameter value, and press "OK" to save. The range is 0–399.
5. Soldering Quality Requirements
During soldering, components must not shift, tilt, or stand upright due to vibration. The total reflow soldering time should be controlled within 3 to 5 minutes. Solder joints should be bright and uniform, with solder fully wetting the pads and component leads. The PCB should show no discoloration, copper foil warping, or delamination.
6. Equipment Shutdown Procedure
Normal shutdown
Confirm that all PCBs inside the oven have completed soldering. Turn off the heating, wait 20 to 30 minutes, then switch off the air circulation, conveyor, heating, and cooling functions in sequence, followed by the computer. Alternatively, use the automatic delayed shutdown function by clicking the auto shutdown button. Finally, turn off the main power supply at the lower left rear of the machine.
Emergency shutdown
Press the red mushroom-shaped emergency stop switch on the left side of the machine, then immediately turn off the main power supply.
7. Operating Precautions
Zone parameter adjustment
Zone settings should be optimized according to PCB size and conveyor speed. When the PCB area is small, the conveyor speed can be slightly faster; when the area is large, the speed should be reduced to ensure soldering quality.
PID parameter protection
PID parameters should only be modified by authorized technical personnel to avoid temperature fluctuations that could affect process stability.
Environmental control
Prevent outside airflow from entering the oven and disturbing the dynamic temperature balance.
Outlet safety
Avoid burns to operators and prevent PCB accumulation that could cause component fallout or board dropping.
Equipment maintenance
Clean the equipment surface daily. Lubricate the roller chain weekly in manual mode using BIO-30 high-temperature lubricating oil. Check the motor and rotating shaft lubrication monthly. Before startup each day, confirm that the grounding wire is securely connected.
For non-standard guide rails, custom mesh belts, or precision tooling used during maintenance or board handling, Hansheng Automation can provide custom machining based on customer drawings.
Fault recovery
After troubleshooting, rotate the emergency stop switch clockwise to restore the equipment. During shutdown, wait until the oven temperature has dropped before stopping the conveyor.
By strictly following the above operation guide, the stability of the SMT reflow soldering process and soldering quality can be ensured, while also extending the service life of the equipment.
