Английская Википедия: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
- <math>AF_\text{H} = e^{\text{const} \cdot (RH_\text{s}^n - RH_\text{o}^n)},</math>
- <math>\text{const} </math> 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
- <math>AF_T = e^{(E_\text{a}/k)(1/T_\text{o} - 1/T_\text{s})},</math>
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
- <math>AF_\text{HAST} = AF_\text{H} \cdot AF_T =
e^{\text{const} \cdot (RH_\text{s}^n - RH_\text{o}^n)} e^{(E_\text{a}/k)(1/T_\text{o} - 1/T_\text{s})}.</math>
References