Influence of Heating Time on the Lifetime Prediction of Aluminium Wires in Power Modules

To improve the accuracy of fatigue life predictions for power modules under anticipated operating conditions, a fully-reversed cyclic bending test method was developed for aluminum wires with a diameter of 0.4 mm. The Experiments were conducted at 175 ℃with loading frequencies of f = 10, 4, 1, 0.4, and 0.1 Hz. The results indicate that fatigue life increases with higher frequency. When the frequency was converted to the heating time of the power module (ton), it was observed that the slope α of the double-logarithmic relationship between ton and fatigue life decreases as ton increases, approaching zero. This suggests that α is a function of ton at 175 ℃. Incorporating this relationship into fatigue life prediction models significantly enhances their accuracy. For example, when ton = 100 s, the prediction accuracy improves by approximately 1.56 times.