Chemical Mechanical Polishing Of Pure Lead

In order to obtain ideal ultra-smooth pure lead surface,improve the processing rate and reduce surface defects,based on self-made polishing slurries,the influence of shape,particle size and concentration of colloidal silica polishing particles,down force,the rotation speed and direction of polishing head/disc and the slurry flow rate,as well as the types and concentrations of additives such as oxidizer,complexing agent,and lubricant on the surface material removal rate and roughness of lead sheet were investigated by chemical mechanical polishing（CMP）.The results reveal that:（1）Compared with the larger spherical colloidal silica polishing particles,the smaller particle with brow-shaped are more beneficial to the polishing of lead sheet.The influence of particle size and concentration of polishing particles on the polishing performance of pure lead mainly depends on the coupling relationship among lead sheet surface,colloidal silica particles and the lint on polishing pad surface.（2）With the change of down force,the rotation speed and direction of polishing head/disc as well as the slurry flow rate,the thickness and status of polishing slurries vary at the lead sheet/polishing pad interface,which will directly affect the fluidity,lubricity and dispersion of polishing slurries and the chemical-mechanical interaction between polishing particles,chemical reagent and lead sheet surface,thereby affecting the polishing quality and the material removal rate.（3）Among the effects of additives on the polishing performance of pure lead,the effects of oxidizer mainly depend on the strength of oxidability and self-decomposability;the effects of complexing agent mainly depend on the type and number of functional groups,as well as its own acid-base property and activity in the pH range;the effects of the lubricant mainly depend on water solubility,decomposability and its own viscosity and molecular size..（4）With the change of the hydrogen peroxide concentration,the resulting lead（hydrated）oxide films vary at it’s uniformity,hardness and brittleness;With the change of the EDTA concentration,the resulting PbY^2-complex vary the surface solubility;With the change of glycerol concentration,the lubricity and decomposability of the polishing slurries vary,which will directly affect the surface material removal rate and roughness.By the investigation of the influence of process parameters and additives,optimization of process parameters,and the selection of types and the optimization of concentrations of the different additives,this work finally obtained an ideal high-quality pure lead surface with surface roughness of Ra⁰.5 nm,where the material removal rate was¹000?/min.