A method for determining elastic properties of micron-sized polymer particles by using flat punch test
A method for determining elastic properties of micron-sized polymer particles by using flat punch test
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DOI：
10.1016/j.commatsci.2006.06.009
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发表时间：
2007-04
影响因子：
3.3
通讯作者：
Zhiliang Zhang;H. Kristiansen;Johan Liu
中科院分区：
文献类型：
--
作者：
Zhiliang Zhang;H. Kristiansen;Johan Liu
微米级金属包覆聚合物颗粒被用于开发各向异性导电胶(ACA)。聚合物颗粒的力学性能对ACA的可靠性和设计至关重要。本文提出了一种用平面冲压试验--软弹性球面撞击刚性平板来确定聚合物球体在大变形下的力学性能的方法。对大变形接触进行了有限元分析。结果表明，经典的Hertz解只适用于非常小的球体变形(小于1%的压缩应变)，而Tatara解对于高达20%的球体压缩效果很好，超过20%则应考虑大应变效应。当压缩比小于20%时，压缩应力-应变曲线和侧向膨胀应变-压缩应变曲线均可用泊松比进行归一化。基于有限元计算结果，给出了描述这些关系的显式方程，用于确定聚合物颗粒在大变形时的杨氏模数和泊松比。将该方法应用于电容式平板冲压实验，分析了用于导电胶粘剂的典型聚合物粒子的实验结果。
Micron-sized metal coated polymer particles are used in developing anisotropic conductive adhesives (ACA). The mechanical properties of polymer particles are of crucial importance for the reliability and design of ACA. In this paper we present a method to determine the mechanical properties of polymer sphere particles under large deformation by using a flat punch test-soft elastic sphere against a rigid flat. Finite element analyses have been carried out to study large deformation contacts. It has been shown that the classical Hertz solution works only for very small sphere deformation (less than 1% compression strain) and Tatara’s solution works well for sphere compression up to 20%, beyond that large strain effect should be considered. For compression less than 20%, both the compression stress–strain curves and lateral expansion strain–compression strain curves can be normalized by a function of the Poisson ratio. Based on the finite element results, explicit equations describing these relations are presented for determining the Young’s modulus and Poisson ratio of polymer particles at large deformation. The proposed method has been applied to analyze the experimental results of typical polymer particles used for conductive adhesives from a specially built capacitance-based flat punch test.