The following is a comprehensive analysis of common faults and solutions for vacuum reflow soldering furnaces:

1、 Vacuum system malfunction

Insufficient vacuum

Reason: The aging and wear of the sealing ring caused air leakage.

Solution: Regularly inspect and replace aging sealing rings; Use high-precision vacuum gauges to monitor the vacuum level in real time, ensuring that it meets the set standards.

Abnormal vacuum pump

Reason: Pump oil contamination or mechanical failure leading to a decrease in pumping efficiency.

Solution: Regularly replace the pump oil and clean the pump body; If the pump body makes abnormal noise or overheats, it needs to be stopped immediately for maintenance.

2、 Temperature control system malfunction

Temperature fluctuations or inability to raise temperature

Reason: Damaged heater, poor contact of thermocouple, or open circuit at the output terminal of solid-state relay.

Solution: Use a multimeter to check the continuity of the heating circuit, replace damaged heating tubes or thermocouples; Clean the contacts of the solid-state relay and replace them with new components if necessary.

Abnormal temperature display

Reason: Damage to optoelectronic isolation devices or signal transmission interference.

Solution: Replace the photoelectric isolator on the control board.

3、 Transmission system malfunction

The conveyor belt is stuck or stopped

Reason: Motor carbon brush wear, frequency converter malfunction, or chain breakage.

Solution: Replace the carbon brush and clean the carbon deposits; Check the parameter settings and communication status of the frequency converter; Regularly lubricate the transmission chain and tighten any loose parts.

Transport motor overload

Reason: Mechanical jamming or thermal relay misoperation.

Solution: Manually rotate and check the flexibility of the transmission mechanism; Re calibrate the current threshold of the thermal relay.

4、 Security protection fault

Red light alarm and buzzer sounding continuously

Reason: Time relay failure, thermocouple open circuit, or SSR damage.

Solution: Short circuit test relay contacts for continuity; Measure the resistance value of the thermocouple (normally around 100 Ω); Replace the faulty SSR module.

Emergency stop or inability to start

Reason: Emergency stop switch not reset, power outage, or PLC communication interruption.

Solution: Check if the control circuit voltage is normal; Restart the Human Machine Interface (HMI) and reset the alarm log.

5、 Welding quality related issues

Defects in solder balls/beads

Reason: Slow heating rate leads to residual oxidation of solder flux.

Solution: Adjust the heating slope to 1-3 ℃/s and shorten the preheating zone time to reduce the risk of metal oxidation.

Poor melting and wetting properties or monument phenomenon

Reason: Unreasonable temperature curve or uneven heating of components.

Solution: Extend the insulation time below 150 ℃ to activate the flux activity; Reduce the heating rate of the temperature zone near 183 ℃ to ≤ 2 ℃/s to balance the melting and wetting forces.

The troubleshooting of vacuum reflow soldering furnaces requires a multidimensional analysis of mechanical, electrical, and process aspects. It is recommended to establish a preventive maintenance plan to reduce equipment failure rates and ensure production continuity and product reliability.