Study On Metallization And Densification Of Al₂O₃Ceramic Packaging Substrate For High-power LED

The metallization of Al2O3ceramic packaging substrate was realized by thick film technology. With acopper thick film electronic paste without glass phase as the optimized electronic slurry, the deposition ofcopper on Al2O3ceramic substrate was prepared after sintering and reduction process. The effects ofcarbon reduction process on the metallization behavior were emphatically studied. In order to improve theperformance of Al2O3ceramic packaging substrate, the electroless plating and high temperature heattreatment methods were used to densify the metallized substrates. And the infulence of the electrolessplating adding different complexing agent, heat treatment temperature and holding time was mainlyresearched on the performance of the subatrate. The surface morphology of the metallized or densifiedsamples was examined by the scanning electron microscopy (SEM). And the surface porosity wascalculated roughly. The electrical and mechnical properties were also tested and analyzed. Finally, on thebasis of densified optimal Al2O3ceramic packaging substrate, a new packaging structure for LED waspresented, in which the substrate and heat dissipation fin were jointed by soldering technology. And thecomputer simulation and experiments were carried to compare the heat dissipation performance of this newpackaging structure with the ordinary structure. The experimental results show:1) The carbon reductionprocess was best when the temperature was950°C, and the porosity was16.2%, the surface resistance was3m, the bond strength was230N/cm2.2) Compared with the single complesing angent, electrolessplating with composite complexing agents had better densification effect for the substrate. The optimumcomposite complexing agents were sodium oxalate and sodium potassium tartrate. And the porosity was8.78%, surface resistance decreased by0.8m, the bond strength was310N/cm2.3) Upon heat treatmentat950°C for15min, the substrates had the best properties, and the porosity was17.6%, susface resistancedecreased by0.22m, the bond strength reached290N/cm2.4) Under different thermal simulationconditions with constant temperature thermal load and different power thermal load, compared to ordinarypackaging structure, the new packaging structure with soldering jointing had better heat dissipationperformance. And with the increase of thermal power, this performance of new packaging structure wasmore outstanding and it was more suitable for applications in high power LED.5) The thermalexperimental results showed that the temperature differential of packaging structure with soldering joiningwas3°C while that of ordinary packaging structure was4.5°C. No matter in heating state or steady state,the new packaging structure always had better heat dissipation capability.