Multi-Axis Vibration Testing And Strain Analysis Of Printed Circuit Boards In Truck Transport

Printed circuit boards (PCBs) in electronic devices are subjected to complex mechanical loading during truck transportation, where road-induced vibrations can cause degradation and failure. Conventional qualification tests rely on uniaxial vertical excitation, which does not represent the simultaneous multi-axis inputs encountered in practice. This study compares uniaxial (1DOF) and three-degree-of-freedom (3DOF) vibration testing using a shaker driven by measured vertical, pitch, and roll signals from real transport. PCB assemblies with mounted capacitors were tested under both loading conditions at equivalent energy levels. High-resolution digital image correlation (DIC) was used to obtain full-field strain distributions on the PCB substrate and components. Multi-axis excitation produced more complex deformation modes, including combined bending, torsion, and localized strain concentrations not observed under uniaxial loading. Transverse strains under purely vertical excitation further indicate coupled dynamic behavior. Component-level results show that capacitors experienced higher and more variable strain amplitudes than the PCB substrate under both loading conditions, indicating localized stress amplification. Overall, multi-axis vibration generated substantially higher strain levels and more complex spatial distributions than single-axis excitation. These findings demonstrate that uniaxial testing can underestimate critical mechanical responses and overlook relevant failure mechanisms. Incorporating multi-axis vibration testing with component-level strain assessment can provide a more representative evaluation of electronic packaging and support improved design for enhanced transport reliability.