| In order to meet the demand of high density packaging, extensive studies on low temperature co-fired ceramics (LTCC) have been carried out worldwide. In this work, glass/ceramics composites for LTCC using SiO2-B2O3-PbO glass andα-Al2O3 were investigated. After glass composition design, glass powder and glass/ceramics preparation, etc., the glass/alumina composites were sintered at 800～975°C. The densification behavior and properties of glass/Al2O3 composites was analyzed by differential scanning calorimetry, scanning electron microscopy, X-ray diffraction analysis and other testing methods.SiO2-B2O3-PbO glass was designed and prepared for LTCC substrate materials. It was found that dielectric constant and dielectric loss of the designed glass were 6 and 20～50×10-4 at 1MHz, respectively. The softening temperature was lower than 800°C, which could be sintered at low temperature.The shrinkage behavior of glass/alumina composites was tested by dilatometer and shrinkage characteristics were studied. It showed that sintering rate was not monotone relative to glass content, and there was a maximum value. According to the sintering shrinkage curves, the sintering process could be established reasonably. The sintering kinetics of composites was studied by the method of isothermal sintering. The results indicated that the sintering activation energy of composites was 184.3～248.6kJ /mol and sintering process was controlled by the diffusion.Effects of some factors on densification of glass/alumina composites were studied. The densification of composites was influenced by the size and specific area of alumina particles, glass content, density of green body and sintering process. It was found that using larger specific area Al2O3 particles with particles size 1μm, the relative density of composites could reach 98%. The relative density of composites increased with the increasing of glass content. The density reached the maximum value when the relative density of green body was 60%. The densification temperature decreased with the increasing glass content of composites.The influences of some factors on dielectric properties, coefficient of thermal expansion, thermal conductivity, and flexural strength of composites were investigated. The obtained substrate materials exhibited properties such as dielectric constant (7～8), dielectric loss (20×10-4), coefficient of thermal expansion (5～7×10-6/°C), thermal conductivity (3～4W/m·K) and flexural strength (>200MPa). Therefore, the sintered glass/Al2O3 composites with excellent combination properties could meet the requirements of LTCC substrate materials. |
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