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Nano-cutting is an important development direction of the modern manufacturing technology. However, the research on the mechanism underlying nano-cutting lags far behind the practical application, which restricts the development of this advanced manufacturing technology. The chip formation process is the basic process of nano-cutting, and it is of key importance for the mechanism research of nano-cutting. In this paper, the nano-tensile behavior of single crystal copper was studied based on the molecular dynamics simulations. The toughness and brittleness characteristics of the copper at different temperatures were analyzed. Then, the molecular dynamics simulations of nano-cutting for single crystal copper with different toughness and brittleness were studied. The crystal structure, cutting force, stress–strain distribution and atomic motion characteristics were systematically investigated. The nano-chip formation mechanism of single crystal copper was revealed. The results show that the chip is formed through two ways, namely the shear and extrusion. The material near the free surface of the workpiece undergoes continuous shear slip and periodic long-distance slippage along the primary shear direction, forming the block chip in which the FCC and HCP structures are orderly distributed. The material near the tool-chip interface is extruded by the tool, block chip and stagnation zone to form the flowing chip with amorphous structure. As the temperature increases, the occurrence frequency of long-distance slippage in the block chip increases, while the slippage degree decreases. Besides, with the increase in temperature, the thickness of block chip formed by shear slip decreases, while the thickness of flowing chip formed by extrusion increases.

In this paper, we presented several practical aspects for building robust and reliable finite element models in thermomechanical modeling in electronics packaging using finite element analysis. Firstly, for layered or patterned structures, a homogenized equivalent model, with equivalent orthotropic material properties, gives excellent agreement with the exact finite element model solutions. Such a simplified finite element model provides an efficient way for structural parameter optimization. Secondly, the finite element mesh should keep the fixed size and shape at the location of interest where the singular point exists. This approach provides a simple way for relative stress comparison in different designs, although the absolute value of stress components has no actual meaning. Thirdly, to further eliminate the mesh dependency, the volume averaging method can be used. We extended the local volume averaging method for large-area die attach problems. Fourthly, in this paper, we presented a comparison study between linear elastic and nonlinear viscoplastic analysis, and demonstrated that in some cases, two different types of analysis give opposite trend results. Lastly, we demonstrated that with the use of different stress components, the conclusions may be different. We also provided an ANSYS APDL script in the supplemental material as a benchmark example.