Evaluating the effect of shock absorber layers in the dynamic behavior of PWB with viscoelastic insert

Portable electronic devices are prone to shock impact and vibration loads in real use environment, e.g., when a portable device is dropped into the floor, resulting in stresses in electrical interconnects that may lead to catastrophic failures. During an impact event, the printed wiring board (PWB) may undergo excessive flexing and high stress levels arise in solder joints due to the relative motion between the PWB substrate and the components mounted on it. Minimizing the resonant vibrations of the PWB would lead to lower stress levels in solder joints, and in turn, reduction in failure risks. PWBs, which are multilayer composite structures, usually have a glass-fiber reinforced resin substrate. In this study, it is proposed a modification of the substrate in order to reduce the amplitude of ressonant vibrations, consisting in the insertion of viscoelastic damping layers into the laminate. The effect of thin damping layers in the dynamic behaviour of PWBs is investigated through numeric simulations. A finite element (FE) model of a conventional PWB substrate is built and validated through experimental testing. The validated FE model is modified adding damping layers with viscoelastic material properties previously determined, and the responses of different laminate layups determined from virtual tests are compared with the response of the actual rigid PWB.