Synthesis and characterization of borosilicate glass/beta-spodumene/Al2O3 composites with low CTE value for LTCC applications

Glass + ceramic composites based on low-softening-point borosilicate (BS) glass, beta-spodumene and Al2O3 were produced in this work. The influence of ceramic filler composition on the microstructure, sintering quality, mechanical properties, thermal properties and dielectric properties of composites were studied. XRD and DSC indicated that both kinds of ceramic filler as well as the BS glass maintained their characteristics after sintering. The addition of beta-spodumene would decrease the coefficient of thermal expansion (CTE) value of composites to match with silicon well. The better wetting behavior between beta-spodumene and BS glass would lead to better sintering quality, microstructure and dielectric properties for composites containing more beta-spodumene. With appropriate Al2O3 content, the flexural strength of composites could be enhanced. Composite with 45 wt% BS glass, 30 wt% beta-spodumene and 25 wt% Al2O3 sintered at 875 degrees C showed good properties which meet the requirements of low temperature co-fired ceramic applications: dense microstructure with high relative density of 96.27%, proper CTE value of 3.57 ppm/degrees C, high flexural strength of 156 MPa, low dielectric constant of 6.20 and low dielectric loss of 1.9 x 10(-3).