基于LIGA技术的微细电火花加工优化研究

比较了活动掩膜法与固定掩膜法得到的PMMA胶结构,实验表明固定掩膜法更适合于多次曝光.结合LIGA技术和微细电火花加工的优点,用LIGA技术制备出具有复杂形状的铜微细工具电极,再用该工具电极进行微细电火花加工,在不锈钢上加工出异形微细孔.并通过进一步调整电火花加工工艺参数,优化了加工尺寸精度和表面粗糙度.     

飞秒激光在6H-SiC表面诱导偏振依赖纳米结构特性研究

激光诱导偏振依赖纳米结构是一种有效实现纳米图案化的技术,并且一直备受研究者的青睐。利用飞秒激光微加工技术,对6H-SiC晶体表面激光诱导偏振依赖纳米结构特性进行了研究。通过改变入射激光加工偏振态和延迟时间样品表面诱导产生了直径约为150 nm的球形纳米颗粒、椭圆形纳米颗粒和空间周期约为150 nm的高空间频率表面条纹结构。实验结果表明,入射激光偏振特性会直接影响诱导产生的微结构形貌,并且优先入射的飞秒激光对最终产生的表面微结构形貌有决定性作用。初步探讨了偏振依赖纳米结构形成的物理机制,表面等离激元(surface plasmon polariton, SPP)在表面微纳米结构的产生过程中扮演着重要角色,研究结果对激光诱导表面周期结构(laser-induced periodic surface structures, LIPSS)可控制备具有重要意义。     

Cutting force and hole quality analysis in micro-drilling of CFRP

Micro-drilling in carbon fiber reinforced plastic (CFRP) composite material is challenging because this material machining is difficult due to anisotropic, abrasive and non-homogeneous properties and also downscaling of cutting process parameters affect the cutting forces and micro-drilled hole quality extensively. In this work, experimental results based statistical analysis is applied to investigate feed and cutting speed effect on cutting force components and hole quality. Analysis of variance based regression equation is used to predict cutting forces and hole quality and their trend are described by response surface methodology. Results show that roundness error and delamination factor have similar trends to those of radial forces and thrust force, respectively. Non-linear trends of cutting forces and hole quality errors are observed during downscaling of the micro-drill feed value. Optimization results show that cutting forces and hole quality errors are minimum at a feed value which is almost equal to the tool edge radius rather than at the lowest feed value. Therefore, the presented results clearly show the influences of size effects on cutting forces and hole quality parameters in micro-drilling of CFRP composite material.     

Bulk micromachining of silicon in TMAH-based etchants for aluminum passivation and smooth surface

The fabrication of silicon based micromechanical sensors often requires bulk silicon etching after aluminum metallization. All wet silicon etchants including ordinary undoped tetramethyl ammonium hydroxide (TMAH)-water solution attack the overlaying aluminum metal interconnect during the anisotropic etching of (100) silicon. This paper presents a TMAH-water based etching recipe to achieve high silicon etch rate, a smooth etched surface and almost total protection of the exposed aluminum metallization. The etch rate measurements of (100) silicon, silicon dioxide and aluminum along with the morphology studies of etched surfaces are performed on both n-type and p-type silicon wafers at different concentrations (2, 5, 10 and 15%) for undoped TMAH treated at various temperatures as well as for TMAH solution doped separately and simultaneously with silicic acid and ammonium peroxodisulphate (AP). It is established through a detailed study that 5% TMAH-water solution dual doped with 38 gm/l silicic acid and 7 gm/l AP yields a reasonably high (100) silicon etch rate of 70 μm/h at 80 °C, very small etch rates of SiO₂ and pure aluminum (around 80 Å/h and 50 Å/h, respectively), and a smooth surface (±7 nm) at a bath temperature of 80 °C. The etchant has been successfully used for fabricating several MEMS structures like piezoresistive accelerometer, vaporizing liquid micro-thruster and flow sensor. In all cases, the bulk micromachining is carried out after the formation of aluminum interconnects which is found to remain unaffected during the prolonged etching process at 80 °C. The TMAH based etchant may be attractive in industry due to its compatibility with standard CMOS process.     

一种扭摆式硅微机械加速度传感器

介绍了一种基于体硅微机电系统(MEMS)工艺制作的扭摆式硅微机械加速度传感器,对制作过程的一些工艺问题进行探讨,并提出相应的解决办法,主要涉及到硅-玻璃阳极键合、结构释放等关键工艺。对测试结果进行了初步分析,分辨力可以达到1mgn,测试±1gn范围内线性度可以达到99.99%。     

纳焦飞秒激光在有机材料表面刻划微结构光栅的研究

使用振荡器产生的飞秒激光在透明有机材料PMMA表面进行了刻划微结构光栅的研究．通过理论分析得到了飞秒激光参数和平台移动速度对线宽的影响，进行了系统的加工实验，加工结果与理论分析基本吻合．在透明有机材料PMMA表面进行了多种光栅的刻划，并对刻划的光栅进行了衍射和色散测试，调整光栅的尺寸和排列方式，得到了形状各异的衍射图案。     

元胞自动机方法在MEMS工艺模拟中的应用

随着计算机技术的发展和MEMS(micro-electro-mechanical system)自身发展的需要,应用元胞自动机方法模拟MEMS加工工艺的研究发展迅速.首先,简要介绍了元胞自动机原理,然后,综述了元胞自动机方法在MEMS工艺模拟中的应用现状,分析了应用元胞自动机方法模拟MEMS加工工艺的前景和方向.     

铜基正弦波微通道内流动沸腾传热特性试验研究

基于超快激光技术加工铜基正弦波弯曲型微通道,以去离子水为流动工质,在不同质量流量和热通量条件下,对弯曲型微通道内流动沸腾特性进行试验研究。基于温度/压力数据和流动可视化结果,发现通道传热系数随出口干度增大,呈迅速增大后减小并趋于稳定趋势,正弦波微通道相较直微通道具有更好的换热性能,传热系数最大提高127.7%,压降仅增加14.4%。波状通道结构能明显抑制流动沸腾中不稳定现象发生。通过可视化试验发现,随热通量增大,流型经历泡状流-弹状流-环状流的转变,换热主导机制由核态沸腾逐渐过渡到薄液膜蒸发。     

A novel tuning fork gyroscope with high Q-factors working at atmospheric pressure

In this paper, we report the design and fabrication of a novel micromachined electro-magnetically driven tuning fork type gyroscope with bar structure proof masses working at atmospheric pressure. The applied angular rate is sensed by detecting the differential change of capacitance between the bar structure electrodes and the fixed electrodes on the glass substrate. Instead of common squeeze-film damping, slide-film damping in the gap between proof masses and glass substrate plays a dominant role, which enables it to achieve high Q-factors and thus eliminate vacuum packaging. The measured Q-factors for driving and sensing modes are 965 and 716, respectively. The sensor obtained a sensitivity of 6 mV/°/s and a non-linearity of less than 0.5%.The work is sponsored by the Major State Basic Research and Development Program Integrated Micro-Optical-Electro-Mechanical System (G1999033101).