The Establishment Of CMP Theoretical Model Of NiP Ultra-smooth Surface And Experimental Investigation

In recent years,with the increasingly widespread application of roller molds in the industrial manufacturing field,the requirements for their accuracy and surface quality have become higher,and the corresponding processing difficulties have become more difficult,mainly reflected in: Large,complex shapes;surface roughness requirements to achieve ultra-smooth levels;surface shape accuracy requirements to sub-micron level.At the same time,in order to prevent the surface of the mold from being damaged during use,the surface is usually plated with a layer of wear-resistant and corrosion-resistant nickel-phosphorus alloy(Ni P).Ultra-smooth polishing is a key step in ensuring the quality of the mold surface in the manufacturing process of high-precision roller molds.Therefore,the selected polishing method needs to consider both the material and the shape of the workpiece.There are many ultra-smooth polishing methods for nickel-phosphorus alloys,including chemical mechanical polishing,magnetic hybrid fluid polishing,and electrochemical mechanical polishing.A common method is chemical mechanical polishing(CMP),which combines mechanical,chemical,and fluid interactions to produce an ultra-smooth surface with a roughness of less than 1 nm(Ra).Because the flexible bonnet can fit well on the surface of the cylindrical part,the bonnet polishing is suitable for the polishing of the cylindrical mold.This project will study the polishing methods that combine chemical mechanical polishing with bonnet polishing to prepare for subsequent cylindrical mold polishing.The main research content as follows:The structure and properties of electroless nickel-phosphorus alloy coatings are studied.The chemical reactions of oxidant components in nickel-phosphorus alloys and polishing liquids during chemical mechanical polishing are analyzed.According to the monolayer removal mechanism and contact mechanics,Material removal model of chemical mechanical polishing is established.Based on the definition of surface roughness and the probability model of single abrasive particle removal depth,a chemical mechanical polishing surface roughness model for nickel-phosphorus alloy is established.Through the comparison of the characteristics of various polishing pads and oxidants,suitable polishing pads and polishing liquid oxidant components are selected;according to a series of experimental results,suitable polishing abrasive grains and polishing acid-base environment are determined;And through orthogonal test,the influence of the main components of the polishing solution on the roughness is analyzed.The composition and the ratio of the optimum chemical mechanical polishing solution and the ultra-smooth(Ra 0.695nm)nickel-phosphorus alloy surface are obtained.The experimental results of the main parameters are basically consistent with the theoretical analysis results of the roughness model.The difference between the two is analyzed.Through the orthogonal test,the influence of the main bonnet polishing parameters on the roughness and material removal depth is analyzed.Comprehensively evaluate the two indicators,the best polishing parameters are obtained.For the problem of polishing pattern produced in the experiment,the best precession method is obtained through experiments,and finally an ultra-smooth surface(Ra 0.540nm)is obtained.