Fabrication Of Large-area Metal Micro Mesh Plate Based On Micro-electroforming Technology

The metal micro mesh plate has been widely used in many industrial fields due to its uniform structure,large specific surface area and strong designability.The microelectroforming technology has became one of the main processing methods of metal micro mesh plate due to its high processing accuracy and mass production.However,the problems of uneven thickness of the cast layer and large residual stress of the cast layer limit its application in the fabrication of large-area,high-aspect-ratio and high-porosity metal micro-mesh plate.This paper is aimed at the production of a nickel micro mesh plate with an overall size of57.8mm×57.8mm×0.3mm,an aspect ratio of 6 and an aperture ratio of 93%.The design of lowstress mesh plate frame structure and the improvement of thickness uniformity of cast layer were studied.The specific research contents of this paper are as follows:(1)In order to reduce the residual stress of the casting layer at the frame of the mesh plate,the frame of mesh plate was improved by the method of presetting the stress relief structure..Stress simulations were carried out on the frame models of presetting circular,square and elliptical stress relief structures.The simulation results show that this method can effectively reduce the average residual stress at the frame and reduce the deformation of the frame.Among them,the improvement effect of the presetting elliptical stress relief structure is the best.Compared with the structure without presetting stress release structure,the average residual stress at the frame was reduced by 42.2%,and the maximum deformation was reduced by 56.4%.(2)In order to solve the problem of the uneven thickness of the cast layer of the large-area metal micro mesh plate,a method of adding an auxiliary cathode in the plate around the mesh plate was proposed.Taking the mesh plate as the research object,the effects of adding only square array auxiliary cathodes,adding square and frame auxiliary cathodes on the uniformity of the cast layer thickness were studied by using the Comsol simulation software.The size parameters with better improvement results were obtained from the simulation results.According to the simulation results,the micro-electroforming experiments of the mesh plate were carried out.The experimental results are in good agreement with the simulation trend.Compared with the mesh plate without auxiliary cathode,the method of adding auxiliary cathode with better size parameters improves the thickness uniformity of casting layer by 90.7%.(3)Based on the above research results,the fabrication of large-area metal micro-stencils was carried out by photolithography and micro-electroforming.Ultrasonic-assisted development and oxygen plasma bombardment were used to solve the problem of difficult development of high aspect ratio mesh.The problem of serious hydrogen evolution in the micro mesh structure during the electroforming process was solved by using the ultrasonic-assisted micro-electroforming method.During the production process of the mesh plate,there is no problem of warping and deformation at the frame,and the thickness uniformity of the cast layer of the stencil is good.Finally,a metal micro-stencil mold with an average mesh width of 48.4μm and an average height of 304.4μm was produced,and its structural accuracy and dimensional error meet the production requirements.