超弹性本构在电子封装材料中的应用

电子封装的目的包括固定和保护芯片、连通芯片电极和外界电路等。封装材料包括热界面材料、环氧塑封料等复合材料和胶水材料等，材质包括聚合物、陶瓷、金属和复合材料等。其中，部分聚合物材料具有超弹性，可在多次变形后不易遭受损伤，从而提高封装的可靠性。然而，目前对这些材料在实际使用中的力学性能分析仍有不足之处。以热界面材料、光学透明胶和电池粘接胶三个典型应用为例，热界面材料的缺口拉伸行为研究中往往未考虑超弹特性对缺口处应变集中区域的影响、光学透明胶的弯折行为研究中经常未考虑光学透明胶的超弹特性，以及手机跌落行为研究中往往未考虑超弹性电池粘接胶对其余部件的影响，因此需要对其进行深入研究以增加认知。
基于此，本文采用实验与有限元仿真相结合的方法重点研究了热界面材料、光学透明胶和电池粘接胶三种典型应用场景下材料超弹性在拉伸、弯折和跌落加载模式下对力学特性的影响。具体地，第三章研究了热界面材料缺口处应变集中区域，发现材料的超弹特性可以显著减少缺口处的局部应变，并且发现高应变区面积可以作为表征实验中材料断裂伸长率的序参量，证明了此序参量具有普适性，为热界面材料可靠性评估提供了重要依据。在第四章的光学透明胶服役分析中，由于光学透明胶的超弹属性可以有效协调各叠层之间的不规则变形，所以主要探讨了柔性显示模组在弯折对称区域的拉压应变分布；发现光学透明胶模量的小幅变化对显示模组对称区域的拉压应变影响不大，而其厚度的变化会造成显著影响。第五章针对智能手机跌落时电池粘接胶对主板力学行为的影响开展了分析。电池粘接胶可对电池进行固定，是典型的超弹性材料。发现1米跌落情况下电池粘接胶的超弹属性对主板影响不大，可选取更大载荷的场景进行进一步探究。以上研究阐明了三种重要的电子封装应用场景中超弹性材料的行为规律，为超弹性材料在电子封装领域的应用和发展提供了重要理论指导。

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