A method of board — Level solder degradation analysis under harmonic excitation using regression approximation model

The paper investigates the problem of degenerative model of board-level solder joint subjected to harmonic vibration load with the constant frequency fixed amplitude. Based on the experimental monitoring signal, square root amplitude, waveform factor and kurtosis factor can be used as the degradation quantity by analyzing ten amplitude domain statistics' correlation and significance. Square root amplitude is the highest degree of nonlinear correlation with the experimental time. Waveform factor and kurtosis factor are more sensitive to the failure state of solder joint. The fourier approximation model, the sine approximation model and the polynomial approximation model based on degradation quantity, have been used for the solder joint degradation model. And the superiority of the models has been compared from three aspects: goodness-of-fit index, multi-stage characterization and tail data test. It is shown that the sine approximation model and the fourier approximation model are similar to the signal fitting effects of solder joint in the different failure states. And the two models are superior to the polynomial approximation model. The tail data of the sine approximation model is the best, and the degenerative model is more accurate, which characterizes the degradation of the joint under constant stress.