Sintering behaviors and thermal properties of Li2SiO3-based ceramics for LTCC applications

A series of new Li2SiO3+4 wt% Al2O3-xK2O–B2O3–SiO2 (x = 1–4 wt%) LTCC materials were prepared by standard traditional solid-state method and their bulk density, microstructure and crystalline phase composition were shown in detail. The sintering behavior, heat conduction and thermal expansion of the samples were all thoroughly studied. And their microwave dielectric properties were also demonstrated. The bulk density of the samples was enhanced with the addition of 3 wt% KBS glass, and the sintering temperature was reduced from 1020 °C to 900 °C. Meanwhile, the thermal diffusivity of the samples was determined using the LFA447 laser flash apparatus and the specific heat was calculated, according to the results of thermal diffusivity and specific heat, all samples possessed high thermal conductivity ranging from 5.5 ± 0.02 W/mK to 8.6 ± 0.08 W/mK. Furthermore, the attractive flexural strength and average coefficient of thermal expansion reach to 270 MPa and 15.7 × 10−6/K (at 100 °C), respectively. The reduction of the sintering temperature is attributed to the addition of KBS glass which reduces the crystallization activation energy of the samples. Besides, increasing bulk density can substantially reduce pores in the grain boundary, which has great effects on phonon scattering, improving the thermal conductivity.