The methodical approach presented for screening cards establishes values of critical parameters, such as apparent activation energy and maximum temperature hence shortest time for screening, and statistical life distributions of assemblies. We conducted one step-stress and two life tests at 120°C (248°F) and 135°C (275°F) using relatively small samples of 40 and 50 cards per test, which, nonetheless, gave us the desired information. The approximate screening parameters that resulted have been successfully used to tailor the stress screening of card assemblies. In our experiments, a trimodal, log-normal life distribution has been revealed, which seems to suggest that the traditional bathtub curve of a life distribution is not applicable to card assemblies.

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