Research On The Key Technology Of Preparing Comb-type High Aspect Ratio Micro Electrostatic Motor

Aiming at the problems of high driving voltage,small driving displacement and nonlinear electrostatic force,this thesis designs the model of comb-type micro electrostatic motor by calculation and simulation,and concludes that the comb structure with high aspect ratio can effectively improve the output energy and efficiency of micro electrostatic motor.Thus,the comb-type high aspect ratio nanostructures were designed and fabricated based on the LIGA process.The preparation process was also optimized to effectively improve the hardness of the devices and provide theoretical guidance and technical support for the large-scale production.The main researches of this thesis are as follows:(1)According to the structural characteristics and working principle of comb-type micro electrostatic motor,the corresponding simulation model is designed.The electrostatic field of the electrostatic comb capacitor structure is analyzed and simulated by finite element simulation,and the relationship between its driving voltage and the generated electrostatic force and driving displacement at different depth-to-width ratios is analyzed.Through the simulation,it is concluded that when the driving displacement reaches the theoretical minimum displacement,the higher the aspect ratio,the smaller the driving voltage required,emphasizing the importance of improving the aspect ratio of the device.(2)To improve the aspect ratio of electrostatic comb structures,the preparation of combtype high aspect ratio microstructures was completed based on the LIGA process.Poly(methyl methacrylate)(PMMA)was selected as the photoresist,and the optimized experimental parameters were found by characterizing the pre-experiments.After the optimization,a combtooth microstructure with a depth-to-width ratio of 8.28 was obtained at a mask-to-PMMA pitch of 20 μm and a development and drying temperature of 23℃.And the rectangularization of comb teeth is better at this time.(3)In order to enhance the wear resistance and strength of the device,a nickel-based composite plating with 100 nm diamond particles was prepared by electrodeposition,and a pure nickel plating and a plating with 500 nm embedded particles were set as the control group.The Vickers hardness(HV)test showed that the HV of the composite plated layer with 100 nm diamond particles could reach 403,which is 70.76% higher than that of the pure nickel plated layer and 59.29% higher than that of the plated layer embedded with 500 nm diamond particles.In order to achieve low-cost,high-efficiency and large-scale production of microstructures,we have designed and developed a small anti-shaking thermal imprinting device,which has effectively improved the positioning offset,uneven imprinting pressure and sticking during the demolding process of the conventional thermal imprinting device,and the minimum size of the prepared microstructures can reach 3 μm.