Sine and Random Vibration Analysis of SAC305 Electronic Assemblies Based on PCB Strain

This paper presents a High Cycle Fatigue (HCF) analysis of a SAC305 electronic assembly subjected to random vibration loading. Sinusoidal durability tests are first conducted at various imposed central displacements to determine the SAC305 fatigue curve. A strain gauge placed on the Printed Circuit Board (PCB) enabled the derivation of a transformation function that relates the PCB strain to the equivalent total strain in the critical solder joints, modeled as a non-linear material in Finite Element Analysis (FEA). Using this local fatigue criterion, various fatigue damage models (rainflow counting method, Narrow-band approximation, and Steinberg's 3-band model) were then assessed and compared against experimental times to failure measured during random vibration tests.