What is the three temperature test
Three temperature testing refers to the performance testing of chips under three different temperature conditions (normal temperature, low temperature, high temperature), aiming to comprehensively evaluate the reliability and stability of chips under different environmental temperatures. Specifically, it includes:
Room temperature test: Conducted at room temperature (around 25 ℃) as a benchmark test condition to evaluate the performance of the chip under normal operating conditions.
Low temperature testing: Conducted below the minimum operating temperature of the chip, generally ranging from -40 ℃ to 0 ℃ or even lower, to test the chip's low-temperature start-up capability and stability under cold conditions.
High temperature testing: Conducted above the maximum operating temperature of the chip, typically ranging from 70 ℃ to 125 ℃ or even higher, to accelerate physical and chemical changes inside the chip and expose potential reliability issues.
Why conduct a three temperature test in FT
Introducing three temperature testing in the FT phase is mainly based on the following key requirements:
1. Capture temperature sensitive defects and improve testing coverage
Chips are prone to hidden defects that cannot be detected by room temperature testing at extreme temperatures: high temperature: increased leakage current, timing offset, heat dissipation failure, and material thermal expansion leading to connection breakage. Low temperature: material embrittlement, abnormal power startup, clock jitter, transistor threshold voltage drift.
Through the three temperature test, a wider range of failure modes can be covered, the defect detection rate can be improved, and the risk of customer returns can be avoided.
2. Verify the reliability of wide temperature range to meet harsh application scenarios
Industry standard requirements: Automotive electronics (AEC-Q100), industrial equipment, etc. require chips to support a temperature range of -40 ℃~125 ℃ or even wider. Practical application requirements: For example, automotive grade chips need to operate stably in high temperatures (>85 ℃) or extremely cold areas (-40 ℃) in the engine compartment. Three temperature testing simulates real environments to ensure the reliability of the chip throughout its entire lifecycle.
3. Determine the operating temperature boundary of the chip and guide design optimization
Determine the effective operating range of the chip by testing its performance parameters under high and low temperature conditions, such as maximum frequency, power consumption, and signal integrity. Identify temperature sensitive parameters and promote design reinforcement, such as adding temperature compensation circuits.
4. Evaluate thermal stress tolerance and prevent early failure
Temperature cycling test: Insert high and low temperature fast switching in FT to detect mechanical failures such as solder cracking and delamination caused by differences in material thermal expansion coefficients of the chip. Accelerated aging test: Running chips in high-temperature environments accelerates faults such as electromigration and oxide layer degradation, predicting long-term reliability.
5. Optimize mass production yield and cost-effectiveness
Screening potential defects: Remove chips with excessive temperature drift caused by process fluctuations (such as metal line width deviation) to improve factory yield. The three temperature scheme covers the main failure modes at a lower cost, which is more suitable for the pace of mass production and greatly improves the quality and competitiveness of the product.
Process of Three Temperature Testing
1. Preparation work
Determine temperature range: Determine the temperature range for testing based on the chip specifications, typically ranging from -40 ℃ to 125 ℃ for three temperature testing.
Prepare testing equipment: Prepare a three temperature testing machine or instrument, generally including a constant temperature bath, temperature controller, temperature sensor, and other equipment.
2. Device connection and settings
Set temperature range: Set the temperature range of the testing equipment according to the testing requirements, usually requiring preheating operation to achieve the target temperature.
Calibration temperature: Use temperature sensors and other equipment to calibrate the testing equipment to ensure accurate and reliable temperature control.
Connect chip samples: Place the chip samples into the testing equipment and ensure that all connection lines are properly connected.
3. Conduct testing
Cold start test: Cool the testing equipment to the desired low temperature and conduct a cold start test after the temperature stabilizes, that is, test the chip performance in a low temperature environment.
Stability testing: After the device is stabilized, a long-term stability test is conducted, usually lasting several hours, to verify the stability of the chip at different temperatures.
Hot start test: Raise the temperature to a high temperature range and conduct a hot start test to verify the performance of the chip in high temperature environments.
Cyclic testing: Conduct multiple cyclic tests as needed to simulate the temperature changes that the chip may encounter in actual usage environments.
4. Test completed
Data recording and analysis: Record all data during the testing process, including chip performance parameters, temperature changes, etc., and conduct detailed analysis.
Result judgment: Determine whether the chip meets the design requirements and quality standards based on the test results.

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