Highly accelerated stress test

The highly accelerated stress test (HAST) method was first proposed by Jeffrey E. Gunn, Sushil K. Malik, and Purabi M. Mazumdar of IBM.[1]

The acceleration factor for elevated humidity is empirically derived to be

is a value which normally goes from 0.1 to 0.15

where RHs is the stressed humidity, RHo is the operating-environment humidity, and n is an empirically derived constant (usually 1 < n < 5).

The acceleration factor for elevated temperature is derived to be

where Ea is the activation energy for the temperature-induced failure (most often 0.7 eV for electronics), k is the Boltzmann constant, To is the operating temperature in kelvins, and Ts is the stressed temperature.

Therefore the total acceleration factor for unbiased HAST testing is

References

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  1. ^ Gunn, Jeffrey E.; Malik, Sushil K.; Mazumdar, Purabi M. (April 7–9, 1981). Highly Accelerated Temperature and Humidity Stress Test Technique (HAST). 19th International Reliability Physics Symposium. Las Vegas: IEEE. pp. 48–51. doi:10.1109/IRPS.1981.362972.