Development Of A Prototype System For Electrogenerated Chemical Polishing

In recent years,with the development of ultra-precision technology,ultra-smooth surfaces occupy a prominent position in the optical field,functional components and the growth of functional film materials.The quality of ultra-smooth surfaces is the key to their performance.Therefore,the processing method for ultra-smooth surfaces is in urgent need.Conventional ultra-smooth surface processing methods often impose limitations on the processing of high-quality ultra-smooth surfaces due to problems such as processing stress,thermal deformation,low efficiency,and expensive equipment.Electrogenerated Chemical Polishing(EGCP),as a new stress-free ultra-smooth surfaces processing method,has achieved good results in small-area copper material polishing.But it is a challenge for the processing on a large-area copper workpiece.Therefore,the processing system for a large-area copper workpiece is of great significance for solving this critical problem.EGCP is essentially a chemical reaction to remove materials.The etchant is generated by the working electrode,and diffused to the surface of the workpiece.The material removal is achieved by atomic reaction of the etchant with the surface of the workpiece.EGCP is sensitive to processing gap,therefore,the most critical technology of the processing system is how to achieve the uniformity of the gap between the working electrode and the workpiece during large-area processing.In this paper,a processing system for workpieces with a diameter of 50 mm has been developed based on the technical requirements of EGCP.The stability,the accuracy of the system and the processing efficiency have been studied.Finally,the pure copper workpiece with a diameter of 50 mm has been processed by the processing system.The main research contents of this paper are as the following:(1)Design and development of EGCP prototype system.The key technical requirements and implementation methods of EGCP processing system were studied and analyzed.Based on the key technology and process requirements,the EGCP processing system with gap controlling uniformity based on hydrostatic support was designed systematically.The system has the following functions: a.stable controlling of processing gap uniformity,b.automatic leveling and liquid film thickness detection,c.automatic circulation of polishing solution,and d.automatic lifting and lowering of the working electrode.(2)Study on the stability of ultra-smooth electrodes.The factors affecting the stability of the electrode were studied.The stability control method of the processing gap was obtained by analytical simulation.It can be known that increasing the number of hydraulic cavity support of the electrode can improve the normal stiffness and anti-overturning ability of the electrode.The relationship between the processing gap and the supply pressure was calibrated by experiments.The processing gap was in the range of 0-11 ?m.The adjustment of the gap was adjusted by adjusting the supply pressure to have an adjustment capacity of 0.2 ?m/kPa.(3)Experimental study on dynamic and static processing of EGCP.The static-dynamic processing of pure copper with a diameter of 50 mm and a thickness of 2 mm was polished by the gold sputter electrode.The processing efficiency and precision of the processing system were analyzed.In static processing,the planarization is better and the material removal rate(MRR)is higher,which is up to 0.107 ?m/h.The relationship between depth and MRR is in line with the theory;during dynamic processing,the MRR of the material remains basically unchanged with the increase of the rotational speed,which is about 0.618-0.756 ?m/h.It is lower than the MRR during static polishing,and is easier due to dynamic polishing.The reduction of copper ions in the gap leads to slower etching efficiency.The surface flatness improves from 3.859 ?m to 2.410 ?m at a speed of 0.4 r/min.