Accuracy of simplified printed circuit board finite element models

Electronic components are prone to failure due to shock or vibration loads. To predict when this failure may occur it is necessary to calculate the vibration response of the printed circuit board (PCB); this is most usually achieved through use of simplified finite element (FE) models. The accuracy of these FE models will be mainly dependant on various sources of error, including: manufacturing variability, which will cause supposedly identical printed circuit boards to behave differently (including variability in materials and assembly, as well as dimensional tolerances); inaccuracy in the model input parameters, which is caused by either the modelling assumptions used or poor measurement technique; and errors in the solution process (e.g. linear solutions in non-linear situations). This paper investigates experimentally the contribution of these effects, this is achieved by first looking at measurement of input parameters and to what accuracy a PCB can reasonably be modelled, and then secondly measuring the extent of manufacturing and assembly induced variability. When these contributions have been defined, it will be possible to assess the confidence in any FE PCB model.