The following are some methods and points to evaluate the reliability of the selected IGBT chip:

1. thermal cycling test
Principle
By simulating the working and stopping state of the chip under different temperature conditions, the effect of physical changes caused by thermal expansion and contraction on the performance of the chip was observed.
Method
The IGBT chip is placed in an environment of alternating high and low temperatures, for example, cyclically varying from -40°C to 125°C.
After multiple cycles, check whether the electrical performance parameters of the chip change, such as on-resistance, threshold voltage, etc.
Example
In automotive electronics applications, due to the large temperature changes in the vehicle operating environment, thermal cycle testing is essential to evaluate the reliability of IGBT chips under such conditions.

2. Power Cycle Test
Principle
The performance degradation caused by thermal fatigue is investigated by simulating the repeated power load of the chip in actual work.
Method
The high power and low power states are applied periodically.
The junction temperature change and electrical performance parameters of the chip are monitored.
Example
In industrial frequency converters, frequent starting and stopping will cause the IGBT chip to experience power cycles. Through this test, its long-term reliability can be evaluated.

3. short-circuit withstand test
Principle
The time and current that the chip can withstand in the case of short circuit are detected to judge the reliability of its protection mechanism and structure.
Method
Artificial short circuit fault.
The parameters such as current, voltage and temperature of the chip are measured when the chip is short-circuited.
Example
In the power system, short-circuit faults often occur, and the short-circuit tolerance of IGBT chip is directly related to the stability of the system.

4. high temperature aging test
Principle
The chip is placed in a high temperature environment for a long time to accelerate its aging process and observe performance changes.
Method
Work at a set high temperature (e. g. 150°C) for a certain period of time (hundreds of hours).
Periodically check the performance of the chip.
Example
In high temperature applications such as aerospace, high temperature aging test is of great significance for evaluating the reliability of IGBT chips.

5. electrical performance parameter monitoring
Principle
Continuously measure the key electrical performance parameters of the chip under normal operating conditions, such as on-resistance, threshold voltage, leakage current, etc., to observe whether they change significantly over time.
Method
During the operation of the chip, the above parameters are monitored in real time using professional test equipment.
Example
In the new energy power generation system, potential reliability problems can be found in advance by monitoring the electrical performance parameters of the IGBT chip for a long time.

6. Package Reliability Assessment
Principle
Check the integrity and stability of the chip package, including pin welding, corrosion resistance of the packaging material, etc.
Method
X-ray inspection to check the internal welding.
A salt spray test was performed to evaluate the corrosion resistance of the encapsulating material.
Example
In wet and corrosive environment applications, the reliability of the package is very important for the normal operation of the IGBT chip.

7. vibration and shock testing
Principle
The mechanical stability of the chip is evaluated by simulating the vibration and shock that may be encountered during transportation, installation and use.
Method
The corresponding vibrations and shocks were applied using a vibration table and an impact tester.
Example
In the application scenarios with strong vibration such as rail transit, vibration and shock testing can verify the reliability of IGBT chip.

8. failure analysis
Principle
The faulty chip is dissected and analyzed to find out the root cause of the failure.
Method
Using physical analysis methods, such as scanning electron microscopy (SEM), energy spectrum analysis (EDS) and so on.
Example
Through the analysis of the failure of the IGBT chip, we can summarize the experience and improve the subsequent selection and design.
The comprehensive use of the above methods can comprehensively evaluate the reliability of the selected IGBT chip and provide a reliable guarantee for practical applications.