| Summary: | 碩士 === 元智大學 === 機械工程學系 === 91 === When electronic devices are subjected to vibration loading for a certain period of time, it is always found the component fatigue failure especially results from resonance. In fact, how long can it last before failure is a problem of interest? In this study, it is aimed to check the electronic component life with a vibration failure test for PBGA components, and combining with finite element analysis(FEA) technique and theoretical calculation to calculate the relating component life.
The experiment is conducted first by taking PBGA components with daisy chain circuit and mounted on a PWB. It is then excited by sinusoidal vibration with the same frequency as the fundamental frequency of component and tested until components failed. The stresses of solder balls itself are always not easily to be acquired from experiment. It is checked with FEA by using the real displacements in vibration test as an input to the model. The resulting stresses of solder balls are then obtained. By combing these stresses and the number of fatigue cycle in vibration test, it is then possible to get the S-N curve of the fatigue life by the curve fitting method. Furthermore, the Weibull’s reliability analysis and Miner’s rule are used to calculate the fatigue life.
The experimental results indicate that the failure cracks are located at the interface between solder balls and PWB. They are fairly close to the findings of the failure locations as often seen in relevant literatures. The procedures as described in the study provide an effective way in verifying the life of the electronic system. The method can be applied to the study of reducing the occurrence of unexpected electronic component failure and also improvement of their reliability in the system design.
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