Microwave dielectric characterization and thermal analysis of B2O3-La2O3-ZnO glass-ceramic/Al2O3 composites for LTCC applications

High frequency performance and the content of glass are the direct factors affecting the performance of LTCC. In order to reduce the content of glass and improve the performance, we conducted a systematic study on the composition regulation of B2O3-La2O3-ZnO (BLZ) glass. Glass with low softening point is helpful for LTCC to achieve compact structure. DSC shows that the softening point of BLZ glass can be reduced from 580 ℃ to 537 ℃ by adjusting the composition. XRD analysis indicate that the glass and Al2O3 formed ZnAl2O4 interfacial phases. Combined with the thermal shrinkage curve, it can be proved that the softening of glass and the formation of interfacial phases are the reasons for the shrinkage and densification of LTCC. The lowest coefficient of thermal expansion of 2.878 ppm/℃ was obtained, and the minimum loss of LTCC is 0.00277 at 15 Ghz. These properties are making LTCC more suitable for high-frequency applications.