The AQG324 standard provides comprehensive test methods for evaluating the performance of automotive power modules. This standard was established by the European Center for Power Electronics (ECPE) in Europe and is intended for evaluating the characteristics of power electronic converter units (PCUs) that are primarily installed in vehicles weighing 3.5 tons or less. The formally titled of AQG324 is "Automotive Qualification Guideline 324" and defines common procedures for module test characterization, as well as environmental and life tests for power electronic modules for automotive applications based on the German LV324. The AQG324 standard contributes greatly to improving the reliability of power electronics not only in the automotive industry but also in railways and aircraft.
Main test contents
The following tests are used to verify the characteristics and service life of power electronic modules used in the automotive industry. The tests involve measuring the parameters of power semiconductor components such as IGBTs, MOSFETs, and diodes used in power electronics modules.
Characterizing module testing
- QC-01: Determining parasitic stray inductance (Lp)
- QC-02: Determining thermal resistance (Rth value)
- QC-03: Determining short-circuit capability
- QC-04: Insulation test
- QC-05: MDetermining mechanical data
Environmental Testing
- QE-01: QE-01 Thermal shock test (TST)
- QE-02: Contactability (CO)
- QE-03: Vibration (V)
- QE-04: Mechanical shock (MS)
Lifetime Testing
Here we will explain the contents of Lifetime Testing.
Lifetime tests are conducted to verify the reliability of power modules, and primarily involve applying thermal and electrical stress to evaluate the module's aging degradation and failure mechanisms. The contents of each test are explained below.
QL-01: Power Cycling - PCsec (Short Time)
Purpose: To evaluate thermal fatigue due to short duty cycles and investigate degradation of bond wires and semiconductor joints.
Test method: The semiconductor element is repeatedly turned on and off to generate a sudden change in temperature. The focus will be on the "interconnection area near the chip" where temperature changes are greatest.
Evaluation: Observation of bonding wire breakage and peeling between the chip and Printed circuit board (PCB) due to thermal fatigue.
QL-02: Power Cycling - PCmin (Long Term)
Purpose: To investigate the degradation caused by thermal expansion and contraction of the entire module (especially fatigue of the solder between the chip and the substrate and the Printed circuit board (PCB) through long-term power-on/off cycles.
Test method: Unlike the short-term power cycle test, the heating time is set long. The temperature change of the entire module is gradual, focusing on deterioration of remote parts such as the "chip-to-Printed circuit board (PCB) joint."
Evaluation: Check for cracks in the solder layer and peeling of the Printed circuit board (PCB).
QL-03: High-temperature storage (HTS)
Purpose: To evaluate material degradation due to long-term storage in a high-temperature environment.
Test method: Modules are stored in a high temperature environment (e.g. 125°C) for a certain period of time (e.g. 1000 hours). No electrical stress was applied, and the effect of temperature alone was evaluated.
Evaluation: Check for insulation deterioration, changes in sealing materials, and oxidation or embrittlement of internal connections.
QL-04: Low-Temperature Storage (LTS)
Purpose: To evaluate changes in material properties and the risk of brittle fracture in cryogenic environments.
Test method: Store the module in a low temperature environment (e.g. -40°C) for a certain period of time (e.g. 1000 hours). As with the high-temperature storage test, no electrical stress was applied and the low-temperature resistance of the material was investigated.
Evaluation: Cracks were found in the Printed circuit board (PCB)s and plastic parts, and deterioration of insulation performance was confirmed.
QL-05: High-temperature reverse bias (HTRB)
Purpose: Apply reverse bias (voltage 80-100% of the rated voltage) at high temperature to evaluate increase in leakage current and insulation deterioration.
Test method: A high reverse voltage is applied to an IGBT or MOSFET in a high temperature (e.g. 150°C) environment and maintained for a long period of time (e.g. 1000 hours).
Evaluation: Increase in leakage current, insulation breakdown, and deterioration of gate oxide film were confirmed.
QL-06: High-temperature gate bias (HTGB)
Purpose: To apply gate voltage in a high temperature environment and investigate the deterioration of the oxide film and the increase in leakage current.
Test method: Rated voltage is applied between gate-emitter or gate-source in a high temperature (e.g. 150°C) environment.
Evaluate changes in characteristics after a certain period of time (e.g. 1000 hours).
Evaluation: Check for deterioration of the gate oxide film and increase in gate leakage current.
QL-07: High-humidity, high-temperature reverse bias (HTRB)
Purpose: To apply a reverse bias voltage in a high temperature and high humidity environment and evaluate the insulation degradation caused by humidity.
Test method: Apply reverse bias in a high temperature (85°C) and high humidity (85% RH) environment and hold for a long period of time (e.g. 1000 hours). We investigated the increase in leakage current due to humidity and the deterioration of insulation materials.
Evaluation: Check for deterioration of insulation resistance, increase in leakage current, and insulation breakdown.
Summary
Life testing is an important process to evaluate the durability of power modules against various environmental factors such as heat, electricity, and humidity.
Thermal cycle test (PCsec, PCmin) → Evaluate the deterioration of joints due to thermal fatigue.
High temperature and low temperature storage tests (HTS, LTS) → Investigate material degradation due to long-term temperature changes.
High temperature bias test (HTRB, HTGB, HTRB) → Check the change of insulation and leakage current under voltage stress.
This test makes it possible to ensure the long-term reliability of automotive power modules.
Matsusada Precision offers a wide range of DC power supplies, high voltage power supplies, bipolar power supplies, high voltage amplifiers, regenerative power supplies, electronic loads, and other products required for testing the AQG324 standard. We also provide X-ray inspection system and X-ray CT equipment required for inspecting semiconductor modules.
- keyword:
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- AQG324
- LV324
- SiC-MOSFET
- SiC-SBD
- SiC-diode
- Power semiconductor
- Leakage current
- X-ray
- CT
