Common Failures and Maintenance of Reflow Oven


  • The industrial ovens used to reflow solder on a printed circuit board are intricate tools. Using a combination of radiated heat and heat convection, the solder reflow oven delivers a carefully regulated flow of consistent heat to the PCB. This process completes the assembly of the board by melting the solder to form good solid solder joints between the components and the board.

Failures and Maintenance

  • When the red light is on, the buzzer long beeping non-stoppably
    Cause: Control buzzer time relay does not work; control thermocouple opens circuit; control section of the main circuit SSR is damaged.
    Solution: Check the control buzzer time relay; check the control thermocouple; check the control section of the main circuit SSR.
    2. The system automatically enters the cooling state
    Cause: PCB dropped or jammed; transport inlet and outlet electric eye damaged.
    Solution: Take out the dropped board; replace the electric eye.
    3. The start-up process heating area temperature does not rise to the set temperature
    Reason: Damaged heater; Heating point pair faulty; Solid state relay output disconnection; Exhaust too large or unbalanced left and right exhaust; Damaged photoelectric isolation device on the control board.
    Solution: replace the heater; check or replace the electric thermocouple; replace the solid-state relay; adjust the exhaust valve air plate; replace the opto-isolator.
  • Emergency switch pressed, the system is in the waiting state
    Cause: Emergency switch is pressed; line is damaged.
    Solution: Reset the emergency switch and press the start button; repair the circuit.
  • Inaccurate counting
    Cause: The sensing distance of the counting sensor is changed; the counting sensor is damaged.
    Solution: Adjust the sensing distance of the counting sensor; replace the counting sensor.


  • Reflow oven must completely reach the set temperature (green light on) before starting to solder.
  • In the reflow soldering process, observe the temperature change in each temperature zone often, the change range is 1 ℃ (according to the reflow oven).
  • When abnormalities occur in smt reflow production, stop it immediately.
  • The size of the substrate should not be larger than the width of the conveyor belt, otherwise cardboard accidents are likely to occur.
  • Before reflow soldering, based on documents or component packaging instructions, the components can not withstand the normal welding temperature must be taken protective measures (shielding) or not be processed by reflow soldering, instead by post-welding with manual welding, or welding robot.
  • In the reflow soldering process, prevent vibration of the conveyor belt, otherwise it will cause displacement of components and disturbance of the solder joint.
  • Regularly measure the amount of air exhausted at the reflow oven vent, the amount of air exhausted directly affects the soldering temperature.

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