Experimental modal analysis and dynamic response of PC boards with surface mount electronic components

Experimental modal analysis was conducted on a FR-4 epoxy fiber glass electronic printed circuit board (PCB) and a same size PCB with surface mount component to determine the modal parameters of the first four flexural vibration modes. Structural dynamic modification (SDM) and finite element analysis (FEA) techniques were utilized to predict the dynamic behavior of the boards when surface mount assemblies were attached. Details of modal testing procedures and analytical modeling involved in SDM and FEA were described. Processes of investigating suitable predicting model were presented. Results from the study indicate that the component can be modeled as a point mass under certain circumstance. But it is important to include the rotary inertia effects of the component in response prediction for the modes involving torsional vibration.