Ceramics based on eutectic of BaO-B₂O₃ -SiO₂ system and AL₂O₃ for using in the low temperature co-fired ceramics technology

The data on the preparation and study of the properties of a composite material for the technology of low-temperature co-fired ceramics (LTCC) are presented in this article. Ceramics based on glass of eutectic composition of pseudobinary system BaB₂O₄ – BaSiO₃ and Al₂O₃ filler is obtained. It is found that in the Al₂O₃ concentration range from 40 to 70 wt.% during sintering in addition to Al₂O₃ the secondary phase of hexacelzian (BaAl₂Si₂O₈) is synthesized in composites. The glass /Al2O3 ratio increasing in composites leads to the increase of the coefficient of thermal expansion (CTE) and the value of the dielectric constant. The composite ceramics with an initial glass /Al₂O₃ ratio 60/40 and sintered at 920 ℃C has ε_r value equaled to 9.13 and tg δ <10^-4 measured at a frequency of 1 MHz. The bending strength of such ceramics is 72.5 MPa (compressive strength is 165.6 MPa) and CTE = 66.5 ·10-7·K^-1. The composite is chemically compatible with silver, which indicates that it can be successfully used in low-temperature co-fired ceramic (LTCC) substrates