Refiring performance of calcium aluminoborosilicate-based dielectrics

Two dielectric materials consisting of a zinc calcium aluminoborosilicate glass with either an Al₂O₃ or a CaTiO₃ filler were selected to investigate the sensitivity of refirings at a fixed temperature of 850°C to the final physical and dielectric performance. The property changes with refirings depended on the type of filler material and the number of refirings. For example, crystallization of the unexpected ZnAl ₂O₄ phase was found to progress further on increasing the number of refirings in the case of the Al₂O₃ filler sample. The five refirings of the sample resulted in a decrease of the dielectric constant from 8.46 to 8.06 at 1 MHz. The case of the CaTiO ₃ filler can be highlighted with the opposite increasing effect of the dielectric constant as the crystalline CaTiSiO₅ phase evolved further with refirings.