As electric vehicles and AI systems continue to push the boundaries of performance, power, and reliability, the demands for high-performance, reliable power devices are escalating accordingly. WBG (Wide Bandgap) semiconductors, known for their high breakdown voltage, high-temperature tolerance, fast switching capabilities, and low power consumption, are emerging as the cornerstone of next-generation 800V high-voltage DC (HVDC) architecture for AI power systems. It enables direct on-board power conversion on servers, delivering power efficiently and stably to AI chips.
On July 4, DEKRA iST was invited to speak at the “Next-Generation Power Management Forum” organized by DIGITIMES. Max Chen, Senior Manager of the Component Engineering Department gave a presentation that delved into the dynamic reliability of WBG semiconductors and offered an in-depth analysis of the 2025 revision of automotive standards. The talk highlighted key updates in the new standards, shared the latest industry trends, and provided real-world experience.
Traditionally, power device has mostly been assessed through reliability testing in a static environment. However, for WBG devices operating under high-frequency, high-voltage, and high-temperature conditions, the failure mechanism and aging behavior differ significantly from those of conventional silicon devices. As a result, static testing alone is no longer sufficient to capture real-world risks. Lifetime validation under dynamic conditions has gradually become the trend.
Key Updates in AQG 324 Revision
With growing demands for reliability in electric vehicles and power electronics, the updated 2025 version of the AQG 324 automotive module standard was officially released on April 1. The updated structure consists of three primary test categories: QC (Characterization), QE (Environmental tests), and QL (Lifetime tests). This update places particular emphasis on lifetime testing, where QL-08 to QL-11 reliability tests in dynamic conditions have been made compulsory. This is especially relevant for silicon carbide (SiC) modules to better reflect real-world operating environments and improve their quality and reliability.
There are three key updates in the 2025 AQG 324 revision:
1.Dynamic tests are now included in QL (Lifetime tests), and it is considered as compulsory.
- QL-08：HTFB (High Temperature Forward Bias)
- QL-09：DGS (Dynamic Gate Stress)
- QL-10：DRB (Dynamic Reverse Bias)
- QL-11：Dyn H3TRB (Dynamic High Humidity High Temperature Reverse Bias)
3.The revised standard offers detailed guidelines for test parameters and procedures. For example, in QL-09 (DGS), if a chip foundry or assembly factory already has a valid test report, redundant testing may be waived. However, in the absence of such data, a new test plan must be established to ensure consistency and traceability across the supply chain.
AEC's Emerging Technical Development
At the AEC 2025 WorkShop held in the United States in April 2025, discussion was centered around updated testing methodologies for Wide Bandgap (WBG) devices, including silicon carbide (SiC) and gallium nitride (GaN). A revised version of the relevant standards is expected to be released in the third quarter of 2025. For SiC, the AEC-Q101 standard will undergo further revision to introduce additional testing requirements and recommendations. Meanwhile, for GaN, the formulation of its standard is scheduled to begin in Q2 2025. To support this effort, four dedicated working groups will be created in collaboration with JEDEC JC-70 to consolidate the connection with industry consensus.
AEC-Q101 plans to announce the following technical updates. Final content is subject to official release.
- HAST: For SiC components, H3TRB is recommended as a replacement for traditional HAST testing to mitigate the risk of electrical arcing.
- IOL or PTC: For WBG devices, the standard prioritizes IOL testing.
- TC: The revised guidelines add testing requirements to bare die.
- GSS: It will shift to dynamic simulation and involve different gate voltage switches to ensure long-term reliability of the gate and gate oxide of the tested device.
- BDOL: Body diode operating life is used to verify the lifetime and stability of the body diode.
- HV H3TRB: The previous 100V cap is removed.
- UHAST: The Autoclave (AC) JEDEC document is no longer valid.
Max Chen provided insights into dynamic reliability testing standards, so the industry could have a clearer picture of testing trends and key applications:
For the AQG 324 Dynamic Reverse Bias (DRB) test, the previous version specified a test duration of 1,000 hours. The updated version now uses the number of cycles instead. It also introduces new requirements, including a duty cycle of 40%–60% and IDS ≥ 0 A, to better simulate real-world scenarios. Additionally, the temperature has been revised from ambient temperature to virtual junction temperature (Tvj), with Tvj ≥ 25°C.
- AQG 324 Dynamic Gate Stress (DGS) Test: Previously, this test was conducted using a fixed DC gate voltage. In the updated standard, the test must alternate between the maximum and minimum gate voltages. After the stress test, electrical parameters such as Vth (threshold voltage) and RDS(on) must be measured to monitor potential Vgs drift of SiC devices under dynamic conditions, in order to reflect the dynamic stress under real loads.
- AQG 324 Dynamic High Temperature High Humidity Reverse Bias Test (Dynamic H3TRB): This test combines high temperature, high humidity, and high reverse voltage bias and places stricter demands on the device’s capabilities of pressure, moisture, and heat resistance. The updated standard introduces a duty cycle requirement of 40%–60% and sets IDS = 0 A, ensuring the test accurately reflects the extreme conditions encountered in real-world applications.
- AEC-Q101 Intermittent Operation Life Test (IOL): For WBG (Wide Bandgap) devices, the IOL test is prioritized. This is a fixed-duration stress test. However, in AQG 324, the IOL (PC) test adopts a Test-to-Fail approach—testing until the device fails. This method is more beneficial during the product design phase, as it allows for lifetime estimation and early identification of potential weaknesses in the product.
- JEDEC JEP180.01 DHTOL: This test simulates the long-term reliability of power devices under conditions of high temperature, high voltage, and high-frequency dynamic switching. Currently, it is specifically required for GaN devices, and is deemed a critical dynamic reliability test. However, this test involves custom-designed peripheral circuits, and can only be carried out after a series of validation.
As Wide Bandgap (WBG) technology surges forward, dynamic reliability testing is quickly becoming a key part of product design and launch. In high-stake fields like automotive, energy, and AI, where failure in reliability isn’t an option, the ability to faithfully mirror real-world stress conditions and ensure devices perform stably under pressure isn’t just important—it’s a game-changer to stay ahead in the industry.
In 2025, DEKRA iST achieved ISO/IEC 17025 accreditation for key items that work to AQG324 and AEC-Q101, underscoring our technical excellence and global alignment in the field of dynamic reliability testing. Backed by a comprehensive testing platform and an expert engineering team, we offer tailor-made valodation solutions to meet customer needs and are able to accelerate product deployment while keeping full compliance with the latest standards. DEKRA iST always upholds a mission, “Problem Solved,” as we remains committed to tracking evolving regulations and technology trends. We look to work hand-in-hand with the industry to build a highly reliable future.
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