How to Maintain Insulated Gate Bipolar Transistors (IGBT)

Insulated Gate Bipolar Transistors (IGBTs) are composite power semiconductor devices for high voltage, high current, and high-frequency switching. They are widely used in systems such as new energy vehicles, inverters, and photovoltaic inverters.

 

Common Failure Causes of IGBTs
According to authoritative sources, IGBT failures are mainly caused by the following factors:

Electrical Stress (approximately 48%): overvoltage, overcurrent, abnormal gate driving.
Thermal Stress (approximately 32%): poor heat dissipation leading to junction temperature exceeding limits.
Electrostatic Discharge (ESD): gate oxide layer is extremely thin (0.1–0.2 μm), easily damaged by static electricity.
Mechanical Stress: poor welding or vibration causing pin breakage or poor contact.

 

Key Maintenance Measures for IGBTs
ESD Protection
Before operation: wear an anti-static wrist strap and ensure the workbench is grounded.
Storage and transportation: short-circuit the three electrodes of the IGBT and place it in a shielded metal box.
During soldering: ensure the soldering iron is well-grounded and, if necessary, power off during soldering; avoid directly touching the driver terminals.

 

Driver Circuit Maintenance
Parallel resistor between gate and emitter: typically a 10kΩ–100kΩ resistor to prevent unintended turn-on when the gate is open.

Use twisted pair wires to transmit drive signals to reduce parasitic inductance and oscillation.

Series gate resistor (e.g., 10–47Ω) to suppress high-frequency oscillations.
Ensure the drive voltage is within ±20V to avoid exceeding the gate voltage rating.

 

Overvoltage and Overcurrent Protection
Add buffer circuits (such as RCD snubber circuits) to suppress voltage spikes during turn-off.
Set up overcurrent detection: can be achieved by monitoring VCE(sat) or using a current transformer.
Reasonable derating design: choose devices with sufficient voltage/current margin.

 

Thermal Management
Ensure good thermal contact of the heatsink: use thermal grease, and the mounting torque meets specifications.
Install temperature relays or thermistors to monitor junction temperature in real time, automatically cutting off the main circuit if overheating occurs.
Regularly clean heatsink dust to ensure good ventilation.

 

Regular Inspection and Testing
Static testing: measure C-E and G-E with a multimeter after power off to check for short or open circuits.
Dynamic testing: observe the gate drive waveform with an oscilloscope when powered on, confirming no oscillation and normal rise/fall times.
Infrared temperature measurement: check whether the IGBT surface temperature is abnormal.