Effect of damping and air cushion on dynamic responses of PCB under product level free drop impact

The dynamic response of printed circuit board (PCB) is a major concern to electronic manufacturers when it is subjected to drop impact. In this work, more realistic drop condition is achieved through product-level free drop test. A repeatable free-drop system is developed with an adjustable pair of forks to control the impact orientation during the guided free drop. Digital image correlation (DIC) technique is applied to measure and produce the full-field dynamic responses of PCB. Air cushion effect between mobile phone and impact surface is found experimentally, which may be considered significant for the product-level free drop test. The rebound test has been performed to measure the actual impact velocity and to provide a better insight into the drop impact event. The effect of impact velocity is investigated to assess dynamic responses of PCB. Along with the drop impact experiments, the 3D FEA models are analyzed using ANSYS/LS-DYNA. The energy loss from the damping is considered by including the Rayleigh damping in this FEA model. Vibration analysis is performed experimentally and numerically to choose the proper damping parameters.