Surface mount technology

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.

Simulations of bending and twisting of surface mounted assemblies have been performed using the hybrid analytical/experimental analysis approaches, and the results are presented. Analytical analyses were combined with experimental load-deformation characteristics of the surface mounted assemblies to predict the maximum allowable loadings and deflections that surface mounted assemblies can withstand before incurring failures. Simulation results obtained were in close agreement with the real loading situations.