Study On New Technology Of High Purity Aluminum Trioxide Material For LED Substrate

LED is recognized as the environmental lighting energy this century,is the main lighting in the 21st century.As the mature of epitaxial growth process and device fabrication process of GaN in LED main material,more and more materials can be used as LED substrate materials,including sapphire(?-Al2O3)crystal due to the nature of stability,high temperature resistant,do not absorb visible light,the manufacture technology is relatively mature and moderate price become the most widely used substrate material.There are many methods for preparing high purity alumina,in order to lower the cost of producing high-purity alumina substrate material for LED,combining with the research methods at home and abroad this paper puts forward a new preparation technology.Based on the industrial aluminum powder as raw material and the alkali soluble method,this paper analyzes the structure and properties of sodium aluminate solution,expounds the principle of sodium aluminate solution to take off the miscellaneous and carbonate decomposition.The sources of impurities in the preparation process and removal methods have been introduced as well as the transformation process of calcining aluminum hydroxide is described.Experiments using single factor experiment design,system study of the factors that affect the impurity content in alumina.The experimental process includes alkali-soluble,removal of silicon and iron,carbonate decomposition,pickling dedoping,calcined transformation,ultrasonic field pickling dedoping six main sectors.Optimal parameters for each link(1)The alkali-soluble:sodium hydroxide concentration is 112.4 g/L,the temperature is 50? to 55 ?,time of 120min?150 min,liquid to solid ratio of 20:1.(2)The depth of removal of silicon and iron:dedoping agent added is 8g/L,the temperature is 75 ??80 ?,time is 120min?140min.(3)The carbonate decomposition:CO2 flow rate of 15L/h,the concentration of sodium aluminate solution is 58g/L,the decomposition temperature is about 50 ?,stirring rate of 200 r/min.(4)The acid elution miscellaneous:hydrochloric acid concentration of 30g/L,liquid to solid ratio of 15:1,the temperature is 50 ?,time is 30min.(5)The high-temperature calcination:calcination temperature is 1450 ?,heating rate of 10 ?/min,holding time of 60min,sodium removal agent is added in an amount of 2%calcined material.(6)The ultrasonic acid elution miscellaneous:hydrochloric acid concentration of 50 g/L,liquid to solid ratio of 15:1,the temperature is 70 ?,time is 45min,ultrasonic field is selected as 20 W/cm2.Optimal parameters to experiment on the basis of the above,the purity of the ?-Al2O3 can reach 99.9975%and can meet the requirement of the LED substrate with high purity of aluminum oxide.Analysis and detection methods used in the experiment mainly ICP-OES,XRD,SEM,DSC-TG,particle size distribution,through these tests indicate that the alumina material prepared is consistent with the requirements of LED substrate material.