Study on Fatigue Life Design Method for Solder Joints of Electronic Components on Spacecraft Under Random Vibration

A life prediction method for solder joints of spacecraft was investigated. It is considered that the difference in crack propagation paths is the cause of significantly shortened fatigue life of solder joints under combined thermal and vibration loading. Therefore, as the first step of this study, a crack propagation simulation under random vibration was conducted. Stress analysis was performed on a model of a printed circuit board with lead components soldered to it by applying static acceleration that approximates random vibration. The solder joints on the model are divided into crack paths and others. The crack growth is reproduced by removing small elements on the crack path based on the accumulated damage. Comparing the fatigue life predicted by the analysis with the actual fatigue test results, the fatigue life predicted by the analysis is 1/5 of the actual fatigue test. The optimal method of predicting the fatigue life is the subject of future work by adjusting the conditions of the simulation and increasing the number of fatigue test samples.