IGBT Module Repair Launched, Bringing a New Solution for Electric Control System Assembly Repair

As the number of new energy vehicles on the road continues to grow, demand for the repair of the three-electric system is rising rapidly. Against the backdrop of the industry's increasing acceptance of the "repair instead of replace" approach, chip-level repair of IGBT power modules is evolving from a specialized skill mastered by only a few technicians in the early days into a routine service offered by many independent repair shops.

1. From “Replacing the Entire Assembly” to “Repairing the Module”: A Technological Shift Driven by Cost Optimization

In the past, when a fault occurred in the motor controller of a new energy vehicle, the mainstream practice at 4S dealerships was to replace the entire electric control assembly. The cost of replacing a faulty motor controller assembly typically ranged from RMB 20,000 to RMB 50,000, representing a considerable expense for both vehicle owners and insurance companies. 

With the advancement of three-electric system repair technologies and the growth of independent service providers, a new approach is becoming increasingly widespread: repairing the module instead of replacing the entire assembly. Chip-level repair centered on IGBT power modules can significantly reduce maintenance costs. Some repair cases have shown that vehicles can be restored to normal power-up and driving conditions simply by accurately identifying and replacing the faulty IGBT module. 

The cost difference lies in the depth of the repair. Assembly replacement is essentially a "replace instead of repair" strategy, in which the entire electric control unit is swapped out as a whole. Module repair, by contrast, focuses on identifying and replacing or restoring the specific failed components. IGBT devices themselves account for approximately 40% of the total cost of a motor controller. Although the cost of an individual IGBT chip is relatively low, most of the expense comes from automotive-grade module packaging, aging tests, insulation technologies, and thermal resistance management. This means that when the fault can be accurately determined to originate from the IGBT module rather than other circuits on the control board, repairing the module alone offers clear economic advantages.

2. From “Blind Replacement” to “Precision Repair”: Practical Procedures for Fault Diagnosis and Module Replacement

The technical challenge of IGBT module repair lies first and foremost in accurate fault diagnosis.

• Step 1: Identifying the Type of Failure. Statistical data from damaged DC charging modules indicate that approximately 92% of failures are caused by hard breakdown of a single IGBT bridge arm rather than failure of the entire bridge. Blindly replacing a complete set of IGBT modules not only increases repair costs significantly but also tends to result in higher rework rates. In practical applications, IGBT failures can generally be classified into several categories: Catastrophic failures are characterized by visible damage such as cracked housings, silicone overflow, or even melted busbars. These failures are typically caused by a forward hard breakdown between the collector and emitter (C-E). Latent failures show no obvious external damage, but the system experiences intermittent overcurrent after power-up or suffers breakdown under load. Such failures are usually associated with soft breakdown of the gate oxide layer and are difficult to detect using conventional multimeters. There are also cases of false breakdown caused by failure of the Miller clamp circuit on the driver board. Under these circumstances, replacing the IGBT module alone cannot eliminate the fault.

• Step 2: Static and Dynamic Testing. Precise fault localization is the fundamental prerequisite for “module-level repair” instead of “full assembly replacement.” A practical diagnostic workflow typically includes the following steps: After powering down the system and forcibly discharging the DC bus capacitors, the module housing is opened for visual inspection of carbonization patterns on the DBC ceramic substrate. Carbonization concentrated on one side of the substrate generally indicates a single-device failure, while carbonization spanning the center across the bridge is often associated with a shoot-through condition between the upper and lower bridge arms. Next, a multimeter in diode test mode is used to measure three sets of voltage drops. Under normal conditions, the gate-emitter (GE) forward voltage drop is approximately 3.2–3.6V, with infinite resistance in reverse bias. The collector-emitter (CE) forward voltage drop is typically around 0.48–0.53V. If both forward and reverse CE measurements read 0V, a hard breakdown can be confirmed. If the GE reverse voltage drop falls within 0.7–1.2V, this usually indicates a soft breakdown scenario. For dynamic testing, without applying high voltage, only auxiliary power is supplied to the driver board. The switching behavior of the IGBT is then evaluated by measuring the voltage differential during turn-on and turn-off states. If the negative bias voltage during turn-off deviates significantly from the normal range, priority should be given to inspecting the gate driver circuit.

• Step 3: Desoldering and Replacement. The desoldering and replacement of IGBT modules is one of the most technically demanding procedures in hands-on repair operations. Traditional methods using a soldering iron combined with a desoldering pump are time-consuming and often make it difficult to avoid damage to fine copper traces and plated through-holes. As a result, the industry has developed several practical field techniques. Some technicians use a fine enameled copper wire together with a soldering iron. The enameled wire is soldered onto the device pins, and once heated, a gentle pull allows the component to be removed intact. Another approach involves using a hollow needle combined with rosin flux; the needle is repeatedly inserted into the pin joints to reflow the solder, enabling easier extraction. For smaller modules with densely packed pins, controlled hot-air rework is also a viable method. In such cases, the temperature is typically maintained between 300°C and 350°C to ensure proper solder reflow without damaging surrounding components.

• Step 4: Waveform Verification.  After replacement, waveform inspection is a critical step in validating repair quality. Once power is applied to the IGBT board, an oscilloscope is used to measure switching waveforms, focusing on parameters such as rise time and turn-off time to ensure they fall within acceptable operating ranges. Waveform analysis serves not only as a final acceptance check for the repair but also as a diagnostic “health report” for evaluating whether the gate driver circuit is properly matched with the repaired IGBT module.

3. From “Repairable” to “Properly Repaired”: Component Matching and Technical Challenges

Although the economic benefits and technical feasibility of IGBT module repair have been widely validated, several practical challenges remain in real-world applications.

• Component Matching as the Primary Bottleneck. Component compatibility is the first major challenge. Different brands and vehicle models use distinct IGBT module architectures, with significant variations in electrical parameters. Repair technicians emphasize that replacing an IGBT module is not a simple swap operation but a system-level restoration process. In practice, supporting components must also be matched precisely, including gate driver ICs, optocouplers, and gate resistors. If components with mismatched parameters are used, it may lead to abnormal drive pulse behavior and unstable switching characteristics. For certain vehicle platforms, access to OEM IGBT modules is limited, making salvaged or second-hand components a common alternative in the repair market. However, this introduces additional uncertainty regarding device aging, thermal stress history, and performance consistency.

• Defining Repair Boundaries and Feasibility.  It is critical to clearly define the repair boundary. Not all IGBT module failures are suitable for standalone repair. When faults have propagated into other sections of the driver board, when the DBC substrate shows extensive carbonization, or when the internal multilayer structure of the module is severely damaged, replacing only the IGBT chip is insufficient to restore functionality. Industry data shows that repair strategies focusing solely on IGBT replacement—while neglecting associated components such as driver transistors—can significantly increase rework rates. Therefore, a comprehensive evaluation of the entire circuit board is essential before initiating any repair operation to determine whether the repair plan is technically viable.

• Technical Capability and Equipment Requirements.  IGBT module repair presents a high technical barrier, involving high-voltage safety handling, precision soldering, and waveform analysis. This requires strong theoretical knowledge as well as substantial hands-on experience. Essential equipment typically includes oscilloscopes, LCR bridges, hot air rework stations, and anti-static protection systems. With the implementation of new energy vehicle powertrain maintenance standards and the rapid development of third-party repair services, technical training and workforce development in this field are accelerating. However, there remains a significant gap between being “able to repair” and being “able to repair reliably and consistently.”

Overall, IGBT module repair provides a new and viable pathway for electric control assembly maintenance. It is not universally superior to full assembly replacement in all scenarios; rather, it delivers significant economic advantages under specific fault conditions and well-defined repair environments. For repair practitioners, mastering capabilities such as IGBT fault diagnosis, desoldering and replacement, and waveform verification translates into greater technical flexibility and stronger positioning within the “repair instead of replacement” trend. It also enhances negotiation leverage in service pricing and repair decision-making. From the perspective of the broader new energy vehicle aftermarket, the widespread adoption of module-level repair capabilities may represent a critical step toward the marketization and professionalization of three-electric system maintenance, accelerating its evolution into a more structured and competitive service ecosystem.