External electric leads, soldered into plated through-holes (PTHs) of printed circuit boards (PCBs), provide, in addition to electrical interconnection, mechanical support for heavy electronic components (such as, say, power ones) mounted on the boards. The leads can possibly break (most likely by fatigue), if the PCB support contour is subjected to excessive oscillations. Such oscillations typically occur at the lowest resonant frequency (fundamental frequency). The ability to predict this frequency and possibly avoid resonance conditions is of obvious practical importance. Accordingly, in this analysis, we develop a simple formula for the evaluation of the fundamental vibration frequency of a heavy electronic component mounted on a PCB. The formula is obtained for the case, when the component has only one row of leads, and the vibrations occur in the direction of the least flexural rigidity of this row.
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