Synthesis and properties of borosilicate/AlN composite for low temperature co-fired ceramics application

A new glass/ceramic system of CaO-BaO-Al2O3-B2O3-SiO2/AlN was investigated for low temperature co-fired ceramics (LTCC) application. The samples with different ratio of glass/AlN were successfully prepared by ambient pressure sintering process. We characterized and analyzed the variation in bulk density, apparent porosity, microstructure, phase composition and properties of the samples along with the changes of AlN content. The results revealed that the densification process of the samples was sensitive to the AlN content, and low AlN content was a precondition for sufficient densification and excellent performance. As the composites with ⩽40 wt% AlN, well-densified samples were obtained at 775-825 °C, and the main crystalline phases were celsian (BaAl2Si2O8) and AlN. The composite with 40 wt% AlN content exhibits a thermal conductivity of 5.9 W/(m K), a dielectric constant of 6.3 and dielectric loss of 0.0049, a flexural strength of 178 MPa and a thermal expansion coefficient (TEC) of 4.7 × 10−6/K, suggesting that it is promising for LTCC application.