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The effect of firing temperature on microstructure and dielectric properties of ceramic substrate was studied. The substrate which consists mostly of Al2O3 was fabricated using tape casting technique. Three ceramic substrate samples were fired at different temperatures of 1100, 1300 and 1500°C. All samples were characterised for dielectric properties. Pore characterisation was carried out using small angle neutron scattering technique, and X-ray diffraction was used to determine grain growth. The present investigation shows that pore/grain boundary relaxation is the foremost reason of dielectric loss in this Al2O3 substrate in the low frequency region and grain size effect (interfacial grain boundary) was concluded to be less significant. This pore/boundary relaxation is found mostly originated from intragranular pore.

This paper reports the effect of firing temperature on the physical properties of the Al2O3-SiO2 based LTCC materials for RF applications. Al2O3-SiO2 material in the form of tape was prepared using mixed oxide method. The prepared tape was than laminated and fired at different firing temperatures in the range of 840 to 960degC. The physical properties of all samples were fully characterized, such as density, crystalline phase, dielectric and thermal expansion properties. It was found that the firing temperature influences the dielectric properties of the developed tape. In this study, the sample sintered at 880degC has the best dielectric property with dielectric constant, (epsivr) of 5.65 and dielectric loss, (tan delta) of 0.003 and this is suitable for RF applications. The CTE value of this sample is 2.63, which is close to that of Si (3.0-3.5).