Could shock tests adequately replace drop tests?

Drop tests are often replaced in qualification evaluations of microelectronic and optoelectronic products by shock tests. The objective of the study is to develop simple analytical models for the evaluation of the dynamic response of a vulnerable structural element in a microelectronic or optoelectronic product/package to an impact load occurring as a result of drop or shock tests. We use the developed models to find out if shock tests could adequately mimic drop test conditions and correctly reflect the corresponding response. We use the case of an elongated rectangular simply supported plate to illustrate the suggested concepts and findings. We show that in order to adequately mimic drop test conditions, the shock test loading should be as close as possible to an instantaneous impulse, and that the duration of the shock load should be established based on the lowest (fundamental) natural frequency of vibrations. We demonstrate that, if the shock test loading is not short enough, the induced curvatures and accelerations can exceed significantly the curvatures and accelerations in drop test conditions.