Study On Lapping Process Of Sapphire Substrate And Optimization Of Grinding Equipment Structure

Sapphire has become one of the most commonly used substrate materials of the epitaxial layers for the growth of LED gallium nitride(GaN),due to the excellent optical properties,physical properties and chemical properties.To be an LED substrate material,the sapphire substrate must have the characteristics of high processing precision and ultra-smooth,damagefree surface quality is also required.As a typical hard and brittle hard-to-machine material,free abrasive processing is mainly used to grind and polish the sapphire substrate.Therefore,the grinding process is a crucial prerequisitein the processing flow.Based on the current sapphire substrate processing technology,this paper optimizes the grinding disc mechanism on the double-sided grinding machine and the sapphire substrate processing parameters,this paper also proposes a processing technology that can effectively improve the processing yield and quality parameters of large-size sapphire substrate.The specific research contents are as follows:First of all,based on the research of manufacturing and processing of sapphire doublesided grinding machinein the cooperative enterprise during intership,we analyzes the structural rationality,functional stability and substrate processing quality of the double-sided grinding machine,then proposes the optimized machine control function and the improved mechanical structure.Through the optimization design of the driving mechanism of the grinding disc on the large double-sided grinding machine,the ball hinge is used to make the upper grinding disc component in the floating state and to transmit power for it,which simplifies the driving structure,saves the manufacturing cost and avoids the error caused by the complex driving structure to reduce the grinding precision.The second,establish a trajectory model for double/single-sided grinding motion.Through the computer software simulation analysis was carried out on the abrasive particle trajectory,from the Angle of the flat surface,study the particle trajectory under different process parameters into constructing process,distribution,as to provide theoretical basis for process parameters optimization in practical processing.The simulation found processing surface grinding disc and the center gear rotating speed ratio of 4.1,better trajectory curve;The radius of the center gear and ring gear ratio 0.46,can obtain better wear particle trajectory;The grout provides the largest liquid coverage from the center area of the grinding disc.The last,experimental research on the optimization of process parameters for double/single grinding process.In the new improved double sided lapping machine tool grinding process on the basis of the experiment,through the optimization of process parameters,the sapphire substrate in the coarse grinding stage achieve better surface quality and smoothness,choose F240# boron carbide abrasive,nodular cast iron grinding plate,using two step partial pressure processing technology,substrate material always remove thickness is 65 microns,Thickness variation TTV is 3 microns,reach the surface roughness Ra 0.87 microns.The surface roughness of sapphire substrate can be further reduced to Ra 8 nm by studying the fine grinding process of sapphire substrate on one side and optimizing processing parameters such as processing pressure and grinding disc speed.