Experimental Study On Chemical Mechanical Polishing Of Pure Copper Parts With High Radius-thickness Ratio

Extreme manufacturing refers to the manufacture of parts and functional systems with extreme dimensions or extremely high performance under extreme conditions,and the manufactured products can work in a variety of extremely hardened energy fields and active environments.Precision physics experiments require extremely high manufacturing precision and surface quality of experimental samples to study the material table/interface characteristics under extreme conditions,and the need for weak rigid parts such as thin-walled flat surfaces and curved surfaces is urgent.However,when pure copper is used as a manufacturing material for a weakly rigid member and machining is performed using a conventional processing method such as mechanical polishing,there is a problem of poor machinability and serious deformation of the workpiece.Therefore,a low-stress precision machining method is required,to make the surface fit the requirement of precision physics experiments.Among current precision machining processes,chemical mechanical polishing(CMP)is a mature processing technology capable of global planarization,but in the current research of chemical mechanical polishing of pure copper materials,the research object is limited to the IC circuit copper interconnection or low radius-thickness ratio(less than 25),If the existing CMP process is applied to pure copper parts with high radius-thickness ratio(greater than 25),the parts will suffer from problems such as deterioration of the surface accuracy,and the precision of the high surface accuracy and good surface quality of the parts cannot be satisfied by the precision physics experiments.Therefore,the CMP test of high radius-thickness ratio pure copper parts was carried out in this paper.The main research content is as follows:(1)The CMP slurry formulation for high radius-thickness pure copper parts was selected.Design and conduct orthogonal test,so as to initially select several kinds of polishing liquid formulations with good polishing effect;The selected slurry was optimized through single factor tests,so as to determine the best polishing solution:sodium hypochlorite,sodium hexametaphosphate,emulsifier OP-10,the abrasive is silica solution,and the remainder is deionized water,and its effect was verified by a repeatability test.(2)The chemical mechanical polishing process parameters of thin-walled pure copper parts were optimized.Determinate the optimal process parameters and test conditions by single factor test under no-load conditions.The high radius-thickness pure copper parts was polished under the optimized CMP process parameters,the flatness PV value was decreased from 4.813?m before polishing to 2.917?m after polishing.The surface roughness R_a was decreased from31.373 nm before polishing to 3.776 nm after polishing.(3)The removal mechanism of chemical mechanical polishing of high radius-thickness pure copper parts was studied.The elemental composition of the workpiece surface is detected by energy spectrum analysis,and the ionic parts in the polishing waste liquid are detected by spectrophotometry,the reaction equation was established.the material removal model based on the cooperation of chemical action and mechanical work was validated.Finally,the causes of corrosion defects after chemical mechanical polishing were analyzed.(4)The CMP processing residual stress of pure copper high radius-thickness pure copper parts was studied.The CMP process in this paper,general mechanical polishing and the CMP process which proposed by existing research have been used to process high radius-thickness pure copper parts respectively.The measurement results show that the residual stress generated by the CMP process proposed in this paper is less than the general mechanical polishing and the existing CMP process.Through the single factor test of CMP processing time,The influence of polishing time on the residual stress generated by the CMP process proposed in this paper was studied.