Study On The Processing Technology And Optimization Of Process Parameters In Sapphire Slicing

Sapphire,with its excellent physical and chemical properties,is widely used in LED substrate and other fields.The demand for wafers is increasing,and the quality requirements of wafers are becoming higher and higher.Slicing is the first step in sapphire machining,and its processing quality directly affects the subsequent processing efficiency.Sapphire has high hardness and brittleness,making slicing difficult.In order to ensure high efficiency and high quality in sapphire slicing,it is necessary to select appropriate slicing processing technology and process parameters.In this paper,the influence of sapphire anisotropy on the wafer surface deviation was studied.Based on the force balance of the diamond wire saw,the deflection of the diamond wire saw and material removal rate were calculated.The crack damage depth of the wafer under different slicing processing technology was analyzed.The slicing parameters were optimized considering slicing efficiency and quality.The research results can provide theoretical basis for the selection of sapphire slicing processing technology and process parameters,which of important significance for improving slicing efficiency or quality and reducing production costs.The main research work of this article is summarized as follows:Considering the anisotropy of sapphire,the expression of crystal orientation for each crystal plane was obtained by coordinate transformation,and the distribution of elastic modulus at the contact between the diamond wire saw and the workpiece was calculated.The influence of sapphire anisotropy on the surface deviation was analyzed.The formula for calculating the cutting force in C-plane sapphire slicing with a feed angle of 0° was obtained by fitting.Slicing experiments were conducted on C-plane and R-plane sapphire with a feed angle of 0°,the error between experimental results and theoretical results of surface deviation was 14%.The relative error between the experimental and theoretical results of C-plane sapphire slicing force is 1.80%～7.87%.According to the balance of the diamond wire saw in slicing,a formula for calculating the deflection of the diamond wire saw in sapphire slicing was established.The deflection of the diamond wire saw under different slicing processing technology was analyzed,and a method for determining process parameters based on the deflection of the diamond wire saw was proposed.The material removal rate was calculated by considering the influence of the deflection of the diamond wire saw in slicing on the contact length between the workpiece and the diamond wire saw,and the material removal rate was analyzed under different slicing processing technology.The material removal rate in slicing is mainly affected by the variable speed feed,while the rocking feed has a small impact on the material removal rate.Sapphire slicing experiments were conducted with different rocking angles.The error between the experimental results and theoretical results of the horizontal deflection of the diamond wire saw was 1.12%～7.69%,and the error between the experimental results and theoretical results of the rocking deflection of the diamond wire saw was 2.54%～9.66%.The crack damage depth model in sapphire slicing was established,and the crack damage depth could be evaluated by grinding time.The crack damage depth and the crack damage distribution on the subsurface of wafer under different processing technology were analyzed,and the relationship between the crack damage depth and process parameters was obtained by fitting.Sapphire slicing and grinding experiments were conducted,and the error between the experimental results and the theoretical calculation results for the crack damage depth of the wafer was 4.66～9.79%.The thickness deviation of the wafer was improved after grinding.Based on the uniform design method,a sapphire slicing experiment was designed,and the relationship between the crack damage depth and the rocking feed was obtained according to the experimental results.The process parameters were optimized under different sapphire slicing processing technology,with optimization indicators including slicing efficiency and slicing quality.Slicing time represents slicing efficiency,and the crack damage depth represents slicing quality.The crack damage depth was evaluated by grinding time,and the optimization indicator was changed to the total time in slicing and grinding.Given different weight coefficients for slicing efficiency and slicing quality,the optimal parameter combinations under different slicing processes technology were obtained.The influence of rocking feed on the total processing time is much higher than that of variable speed feed.When selecting the slicing processing technology,rocking feed should be preferred.