Abstract
Alumina ceramics have been used for insulator in electronic-power industry and in recent years, they have become main parts of microelectronic device. These ceramics usually contain 92-97w% alumina and have dielectric loss tangent of 10-3-10-4 level. In this study, above 97w% alumina ceramics were investigated with respect to dielectric loss tangent in microwave region to understand effect of accessory ingredients. Consequentry, tan 6 of single crystal level was obtained for alumina ceramics containing 0.2-0.3w% of accessory ingredients consisting of SiO2:0.68, CaO:0.16, MgO:0.16 parts by weight respectivery. As for accessory ingredients, at Cat) poor compositional region, tan 6 of 10-5 level was obtained for 0.3w% addition. Silica in accessory ingredients was expected to had principal role in reducing tang of alumina ceramic by forming homogeneous silicate in ceramic.
