| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 105 === Epoxy molding compound (EMC) is widely used in electronic packages for encapsulating the Si die. During packaging thermal processes, the thermal expansion mismatch between various packaging materials and physical or chemical aging induced EMC volume change would lead to residual stress and warpage. For the purpose of accurately predicting warpage and residual stress in the overmolded electronic packages, the viscoelastic constitutive behavior and the physical aging characteristics were investigated in this study. The viscoelastic behavior of the EMC were measured by quasi-static stress relaxation and creep experiments. Consistency of the viscoelastic behaviors measured from these two experiments were examined and compared to the viscoelastic model constructed from time-harmonic oscillation experiment. From the comparisons between the results of these different characterization approaches, it was found that the viscoelastic behavior measured by creep and relaxation tests are highly consistent, and the presence of physical aging in the test specimen delays the viscoelastic relaxation. In addition, physical aging leads to additional EMC volume shrinkage after cooling from above to below glass transition temperature. Warpage simulations for molded package strips by using the viscoelastic models were validated by the experimentally measured values. It was shown that the strip warpage is significantly influenced by viscoelastic relaxation and physical aging of the EMC.
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