关键词: 移动阴极, 微沟槽结构, 掩膜电解加工, 刻蚀均匀性

Abstract:

As a typical surface texture, microgrooves have broad prospects in the fields of mechanical engineering, bio-medicine, new energy and efficient heat dissipation of electronic products. Through-mask electrochemical micromachining (TMEMM) is widely used in the fabrication of micro-structures because of high processing efficiency and no residual stress. However, due to the edge effect of current distribution, there is often a serious dimension discrepancy problem in electrochemical machining of micro-structures. In order to weaken the influence of edge effect on the uniformity of microgrooves, the method that TMEMM with a moving cathode is presented. The current distribution in the electrochemical machining is constantly changed by the movement of the cathode. Thus, the uniformity of the micro-structure is improved. The method is studied through the combination of simulation and experimental verification. Firstly, the electrochemical machining process of TMEMM was analyzed theoretically. The theoretical analysis results show that the depth of electrolytic etching is proportional to the current density of electrolytic machining. To change the uniformity of the electrochemical machining, the most important thing is to improve the uniformity of the current distribution. On this theoretical basis, the current distribution and anodic contour of microgroove array during TMEMM are simulated by using the COMSOL finite element analysis software. The simulation results indicate that, compared with the conventional TMEMM, the TMEMM with moving cathode can obtain the microgrooves array with more uniform size. Secondly, on the basis of numerical simulation, the TMEMM experiment was carried out. The experimental results indicate that the TMEMM method of moving cathode can effectively improve the size uniformity of microgroove array. It can be observed by microscope that the microgroove array obtained by TMEMM with a moving cathode had good structural morphology and higher uniformity. Compared with conventional TMEMM, the uniformity of TMEMM with moving cathode has been improved by 68.3%. At the same time, under different experimental conditions, the trend of unevenness of microgroove array was calculated. With the increase of the distance between the cathode and anode, the microgroove depth heterogeneity showed a tendency of first decreasing and then increasing, when the distance between anode and cathode is about 1.3 mm, the unevenness of microgroove array reaches the minimum point. With the increases of cathode width and cathode speed, the depth inhomogeneities of microgroove increase and decrease gradually, respectively. The simulation results are basically consistent with the experimental results. It can be seen that the TMEMM with the moving cathode method can greatly improve the size uniformity.

Key words: moving cathode, microgroove structure, through-mask electrochemical micromachining, etching uniformity