微电子材料在微塑成形中的尺度效应

Size effects of microelectronics materials in plastic microforming

微电子材料在微机电系统（MEMS）的发展中越来越受到青睐，但是其工艺加工的不足限制了实际应用的步伐。微塑性成形可以成形微电子器件，由于其尺寸微型化，在微塑性成形中存在一个不可避免的“尺度效应”问题，尺度效应表现在材料的流动行为、成形中摩擦效应和实验结果的分散性上。在介绍尺度效应的基础上对其进行了分类，给出了判断标准，并从流动应力、晶粒尺度、摩擦效应和温度效应等方面综述了尺度效应对微塑性成形的影响。由于基于连续介质的传统塑性力学理论无法解释微塑性成形过程中的尺度效应，因此引入了非均匀介质的塑性应变梯度理论并进行了探讨，最后指出了尺度效应的研究发展方向，从而促进微电子材料的开发应用。

The microelectronics materials receive more and more the favor in the development of MEMS, but its craft processing insufficiency has limited the practical application step. The microforming may form the micro-electron component,with the minimization of the micropart dimensions, the size effect that is an unavoidable problem in micro-forming has to be emphasized. The size effect phenomena often appear in the following aspects such as the flowing behavior of materials, friction effect in forming and the dispersion of experimental results. After introducing the definition of size effect, the classification and judging standard of the size effect are explained respectively. The influence of size effects on micro-forming aspects including flow stress, grain size, friction effect and temperature effect is summarized comprehensively. As the mechanical theory of traditional plasticity based on continuous medium is unable to explain the size effect in the micro-forming, the strain gradient plasticity theory of the nonuniform medium is introduced to solve the problem. Lastly, the development of size effect is forecasted.Thus,it promotes the practical application of microelectronics materials.