Research on the Evaluation Method and Data Analysis of the Fatigue Strength of the Micro Materials

为了设计出具有良好可靠性的MEMS，需要了解微构件的强度、断裂韧性和疲劳强度等力学性能。本研究开发了微型试件疲劳试验机。疲劳试验机和每个试件均由单晶硅制成。它们是利用基于硅半导体加工技术的微细加工技术制成的。利用该疲劳试验机对几种不同尺寸的试件进行了快速断裂强度的检测。并进行了疲劳试验。以下是结论1.成功研制了多台微型试件疲劳试验机。对每台疲劳试验机的驱动力进行了测量，确定了梳状驱动器中静电作用力F的修正系数。通过使用修正因子，可以精确地评估施加的载荷。对四种单晶硅微试件的快速断裂强度进行了评估。快速断裂强度的分布符合威布尔概率分布，说明强度的体积依赖性可以用最弱连接模型来描述。通过对几种微观试件的疲劳试验，得到了疲劳强度，其表现形式为循环次数与循环载荷幅值之间的关系。获得了铝涂层试件和氮化钛涂层试件的疲劳强度。

In order to design the MEMS having good reliability, it is necessary to know the mechanical properties such as strength, fracture toughness and fatigue strength of micro components. The fatigue testing machine for the micro specimen was developed in this research. The fatigue testing machine and each specimen are made of single crystal silicon. And they were made by using the micro fabrication technology being based on the silicon semiconductor processing technology. The examination of the fast fracture strength against the several kinds of specimens which dimensions were different each other was carried out by using that fatigue testing machine. And the fatigue tests were also carried out. Following is the conclusions.1. Several fatigue testing machine for the micro specimens were successfully made.2. The driving force of each fatigue testing machine was measured and the correction factor of static electricity force F which occurred in the comb actuator was determined.3. The precise evaluation of the applying load becomes possible by using the correction factor.4. The fast fracture strength was evaluated for four kinds of micro specimens being made of single crystal silicon.5. The distribution of the fast fracture strength was evaluated as the Weibull probabilistic distribution.It was clarified that the volme dependency of the strength could be described by the weakest linkage model.6. The fatigue strength which is shown by the relationship between the cycles to failure and the amplitude of the cyclic load was obtained against the several kinds of micro specimens.7. The fatigue strength of the aluminium coated specimens and the titan nitride coated specimens were also obtained.