| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 90 === Traditionally, packaging reliability is characterized by thermal-cycling fatigue testing. However, the testing speed is slow. In addition, the coupling between mechanical fatigue loading, the variation of temperature dependent material properties, and time dependent effect such as stress relaxation causes difficulty to develop useful analytical models for understanding the reliability of solder joints. By replacing the thermal cycling with this piezoelectric actuation system under temperature controlled environment plus additional creep/relaxation experiments, it is possible to identify the contribution from each aspect, to gain fundamental understanding, and to develop theory to improve packaging design in the future.
This thesis presents the analysis, design, and control of a piezoelectric driven material testing system for electronic packaging applications with emphasis on the mechatronics and control system design. A piezoelectric actuator is used to exert shear fatigue load and the displacement and reaction forces are monitored by both displacement and force sensors. A proper control of experimental conditions is vital for the validity of testing data for the future data reduction. In addition, the parameter variations due to fatigue crack propagation during testing could effectively change the system dynamics and results in unsatisfactory results. In this thesis, both PID and STR adaptive controllers are designed to perform displacement control for this time varying system during testing. By integrating with feedback control, this testing system can effectively accelerate the testing speed from 10-3 to 100 Hz without causing instability. The associated fatigue crack growth can also be obtained from the embedded parameter estimator by the in situ data processing from both displacement and load sensors.
In the future, it is possible to integrate this system with temperature control unit to perform testing at different temperature to fully characterize thermal-mechanical properties of materials. The measured crack propagation rate will be helpful for constructing relevant theories to prevent failure. In addition, the proposed adaptive controller can also be applied in other time-varying mechatronics systems such as hydraulic actuated universal material testing machines.
Keywords: Fatigue, Adaptive Control, Self-Turning Regulator, Piezoelectricity, Electronic Packaging
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