PSI - Issue 79

Giulia Morettini et al. / Procedia Structural Integrity 79 (2026) 440–448

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Fig. 1. Representative examples of electronic component mounting technologies: (a) SMT no-lead package, (b) SMT leaded package, (c) THT radial-leaded component, and (d) THT axial-leaded component.

Focusing now on Through Hole Technology (THT), and in particular on radial-leaded components, the scientific literature shows a broad consensus regarding the main causes of failure for these devices.

2.1. Analysis of the Stresses Induced by PCB Curvature Starting from the assumption of a dynamic excitation parallel to the plane of the board, hence oriented along the same direction as the component leads, and considering the component body to be significantly stiffer than its metallic terminals, it can be assumed that the primary deformation is concentrated within the leads. Under these conditions, the curvature assumed by the PCB during vibration induces relative displacements at the constraint points of the leads, shifting laterally and vertically, as schematically illustrated in Fig. 2.

Fig. 2. Schematic representation of the PCB curvature under vibration and the resulting lateral and vertical displacements at the component leads.