Preparation Of Low Temperature Co-fired Ceramic Material And Design Of Substrate Based On The LED Backlight

In this thesis, co-fired ceramic material were synthesized by usingCaO-Al₂O₃-SiO2（CAS）, MgO-B₂O₃-SiO2（MBS）, CaO-B₂O₃-SiO2（CBS） glass andAl₂O₃as raw materials, and the effects of different glass content on the sintering,dielectrial and mechanical properties being investigated. Co-fired ceramic materialcould make the temperature of co-fired ceramic effectively drop to nearing800⁹00℃using Bi₂O₃, Li₂CO₃as additives, and then had good compatibilitywith Ag electrode. The influence of glass and ceramic powers to the thermalconductivity of low temperature co-firing ceramic device were investigated bythroughing hole and noting silver. The main research results were described asfollows:1. The sintering, dielectrial and mechanical properties of CAS/Al₂O₃,MBS/Al₂O₃, CBS/Al₂O₃glass ceramics were investigated systematically. Thedifferent content of glass were added as sintering aids to decrease the sinteringtemperature of glass ceramics by applying the principles of liquid phase sintering.The composition and thermal property of CAS, SBM, CBS glass were investigated,concluding that the glass of CBS had the lowest viscosity liquid and lowtransformation temperature and longer softening temperature（ΔT）. Therefor,CBS/Al₂O₃ceramic could be used as the material for co-fired.2. The sintering temperature of CBS/Al₂O₃（1:1） glass+ceramic using Bi₂O₃andLi₂CO₃as promoter were effectivedly decreased to900℃and830℃respecttively, which performed good sintering, dielectrial and mechanical properities.With1.5wt%Bi₂O₃addition, the density and thermal expansion coefficient ofco-fired ceramic was2.82g/cm³, and3.51×10-6/℃, with the dielectric constant anddielectric loss being7.21,1.06. With0.50wt%Li₂CO₃addition, the density andthermal expansion coefficient of co-fired ceramic was2.76g/cm³and5.91×10-6/℃,with the dielectric constant and dielectric loss being7.60, and2.43.3. The CBS/Al₂O₃-0.5%Li₂CO₃glass+ceramic tape casting slurry was prepared. The factors such as the different solvent, the content of glass, the content of binderand the content of dispersing agent were studied. The results indiacted that the slurrywith best rheological properties can gained, if the ration of the binary azeotropicsolvent is1:1, the volume content of glass+ceramic power is45%and50%, thevolume content of binder is between4%and5%and the dispersing agent is3wt%of glass+ceramic power.4. The influence of CBS/Al₂O₃-0.5%Li₂CO₃glass-ceramic green tape to theconductance properties of low temperature co-firing ceramic substrate wereinvestigated by throughing hole and noting silver. It showed that the thermalconductivity of the ceramic base performance could be improved through holing andnoting silver.