Preparation And Properties Of AlN Ceramic Substrate For High-Power LED

In this paper, the metallized AlN substrate was realised by a reactively thick film method after learning the package substrate and it's metallization for the high-power LED. Thick film copper is deposited on the surface of AlN substrate through the processes of printing, heat treatment and reduction respectively. On the basis of this research, several kinds of metal oxide(MgO, Co3O4, and Fe2O3) were mixed into Cu slurry. Through the same processes, metallized AlN substrate with excellent properties was prepared by reaction between AlN and metal oxides. Finally, considering the properties of this AlN substrate, the new method of soldering for the high-power LED was present. The phase compositions and morphologies were examined by XRD and SEM. The adhesion strenghth of bonded samples was evaluated by the tensile test. The electrical property was studied by four-probe method. In order to realize the application of this substrate, thermal simulation and experiment were used to analisys the heat dissipation performance.The main work and achievements can be summarized as the following:(1) The optimally metallized process was heat treatment at 1075°C for 30 min and reduction at 400°C for 120 min. After treated in this process, the sheet resisitivity and adhesion strength was 2.2 m?/? and 11.9MPa respectively.(2) The intermediate phases were detected at the interface layer between copper film and AlN substrate. Spinel CuAl2O4 and isolated CuAlO2 laminate can increase the donding strength becasuse of the modest CTE and strongly chemical bonding. However, the presence of Cu2 O and continuous CuAlO2 were detrimental to adhesion strength.(3) Adding matal oxides(MgO, Co3O4, and Fe2O3) into slurry was benefited for increase the compactness of Cu film on the surface of AlN. As a result of it, the electrical property of Cu film was affected. In asddition, some of metal oxides(Co3O4, Fe2O3) can react with AlN and generate the intermediate phases in the interface layer, which can increase the adhesion strength of metallized substrate.(4) After comparison the influence of metal oxides, the optimal mixing quantity was 8% wt Fe2O3. The adhesion strength and sheet resisitivity of sample treated through this process was 20.6MPa and 5.6m?/?, respectively.(5) The heat dissipation performance was evaluated by transient analysis on the condition of constant temperature thermal load and steady-state analysis on the condition of varied power load. Contrasting the results of thermal simulation and experiment, we consider that soldering has the better property of heat dissipation. Therefore, soldering is a method which can use in high-power LED package.