An improved unified creep-plasticity model for SnAgCu solder under a wide range of strain rates
An improved unified creep-plasticity model for SnAgCu solder under a wide range of strain rates
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宽应变率范围内 SnAgCu 焊料改进的统一蠕变塑性模型
DOI：
10.1007/s10853-017-0851-x
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发表时间：
2017-05-01
影响因子：
4.5
通讯作者：
Yao, Yao
中科院分区：
文献类型：
--
作者：
Long, Xu;He, Xu;Yao, Yao
基于统一蠕变和塑性理论，本研究提出了一种改进的本构模型来描述 Sn3.0Ag0.5Cu (SAC305) 焊料合金在宽范围应变率下的单轴力学行为。在电子器件的通常使用条件下，焊料材料的应变率远小于1.0 s(-1)，此时蠕变变形占主导地位，特别是在较高的工作温度下。然而，电子封装结构在跌落冲击下的应变率范围可能为1.0至300 s(-1)，由于缺乏实验数据，尤其是无铅焊料合金的动态力学性能，这一问题引起了更多关注。在极端冲击条件下，焊接材料可能会经历更高的应变率。由于不同的机制主导着各自的应变率范围，通过适当考虑蠕变和塑性的耦合效应，所开发的本构模型被校准为适用于大多数应变率范围。此外，该模型中的参数定义具有明确的物理意义，并通过对已发表的实验研究的回归合理确定。最后，将所开发的模型与文献中的其他本构模型进行了比较，包括低应变率下蠕变变形的幂律方程和高应变率下塑性变形的 Johnson-Cook 模型。结论是，所提出的模型更加通用，能够以合理的精度预测 SAC305 焊料在低、中和高应变率下的单轴力学行为。
Based on the unified creep and plasticity theory, an improved constitutive model is proposed in this study to describe the uniaxial mechanical behaviour of Sn3.0Ag0.5Cu (SAC305) solder alloy subjected to a wide range of strain rates. In the usual service condition of electronic devices, the strain rates of solder material are far less than 1.0 s(-1) at which the creep deformation is dominant, especially at higher working temperatures. However, the strain rate could range from 1.0 to 300 s(-1) under drop impact in electronic packaging structures, which is drawing more attention due to lack of experimental data, especially on dynamic mechanical properties of lead-free solder alloys. In extreme impact conditions, the solder material may experience even higher strain rates. As different mechanisms dominate the respective regime of strain rates, the developed constitutive model is calibrated to be applicable to most of the strain rate regimes by properly considering the coupled effect of creep and plasticity. Moreover, the parameters in the proposed model are defined with clear physical meanings and reasonably determined by regression to the published experimental studies. Lastly, the developed model is compared with other constitutive models from the literature, including the power-law equation for creep deformation at low strain rates and the Johnson-Cook model for plastic deformation at high strain rates. It is concluded that the proposed model is more generalized and capable of predicting uniaxial mechanical behaviour of SAC305 solder at low, medium and high strain rates with reasonable accuracy.