The most direct way to verify the working life of a product is to directly simulate its actual working environment and observe its normal working time. For example, if an electronic device works at 85 ℃ for 100 hours, then during the test, it only needs to be placed in an environment at 85 ℃ to observe its normal working time. If it exceeds 100 hours, the device is qualified. At the same time, the time from the start of operation to the inability to work normally at 85 ℃ is its life. At present, the working life of our electronic devices is relatively long, exceeding 1000 hours or even hundreds of thousands of hours. If we spend a long time to verify, the testing cost is very huge, especially for those who need to find third-party organizations for verification. The testing cost is relatively expensive, and the actual selling price of electronic products may be low. Spending hundreds of thousands of hours on testing makes it impossible to implement. At this point, it is quite necessary to use accelerated testing methods, and accelerated life testing can be used to solve the problem of long life testing time; The lifespan acceleration model can be used to evaluate the lifespan of the device.
Accelerated life testing is to shorten the testing time by increasing the test stress of the device. For example, to verify whether the device can work for 10000 hours at 25 ℃, the testing temperature can be raised to 150 ℃, which will shorten the duration of the test.
The Arrhenius model is suitable for accelerated models that solely consider thermal effects testing. When temperature is the absolute factor affecting product aging and service life, this accelerated model is used to simulate the reliability performance of the entire life cycle.

Formula expression for acceleration factor

AT, i: Acceleration factor, which expresses a meaning in all acceleration models, is equivalent to acceleration coefficient. Calculating it can convert the entire life cycle time into acceleration test time;
Ea: It is the energy consumed by the precipitation of faults, also known as activation energy. The activation energy of different products is different. Generally speaking, the value of activation energy is between 0.3ev and 1.2ev;
K: It is the Boltzmann constant, with a value of 8.617385 × 10-5 ev/K;
Ttest: Temperature value under test conditions (accelerated state). The temperature value here is an absolute temperature value, measured in Kelvin (K);
Tfield: is the temperature value under usage conditions (non acceleration state). The temperature value here is an absolute temperature value, measured in K (Kelvin)
From the formula, it can be seen that the larger the activation energy, the greater the acceleration coefficient, and the easier it is to be accelerated and fail, resulting in a more significant acceleration test effect. If the activation can be determined, the larger the temperature difference, the greater the acceleration coefficient.
However, it should be noted that when performing acceleration testing, increasing stress generates the same failure mode. If the acceleration stress exceeds the limit temperature range of the product or material itself, new failure modes can be generated, and the acceleration coefficient obtained from acceleration testing is meaningless.
Activation energy Ea and failure mode:

For the activation energy Ea of consumer electronics products, the recommended range is 0.5-0.8, with a suggested value of 0.6 or 0.7. The basic idea is that if the temperature rises by 10 degrees, the lifespan will be reduced by half. 0.65 is the closest value, but engineers usually take the whole value, so 0.7 appears more frequently.
For the activation energy Ea of automotive products: The safety requirements of automotive products are very high, so they are usually relatively conservative, with a general value of 0.4-0.5, depending on the company's strategy.
The Arrhenius model is only applicable to acceleration tests under a single high-temperature stress, and for acceleration under other multiple stresses, other acceleration models need to be used.

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