Tape casting of low permittivity Wesselsite-Glass composite for LTCC based microwave applications

Strontium copper silicate (SrCuSi4O10:SCS)-Lithium magnesium boro silicate (LMZBS) glass composite has been developed for low temperature cofired ceramic (LTCC) applications. The SCS ceramic with 5 wt% LMZBS glass sintered at 900 °C had εr=5.0 and tan δ=1.9×10−3 at 5 GHz. The tape casting slurry of SCS+5 wt% LMZBS glass with typical pseudo-plastic behavior has been prepared by optimizing different organic additives. The slurry was cast into thin tapes of thickness 90 µm. The green tape had εr of 2.2 and tan δ of 1.8×10−2 at 5 GHz. The thermo-laminated tape sintered at 900 °C showed εr=4.8 and tan δ=1.6×10−3 at 5 GHz and 4.7 and 1.9×10−3 at 15 GHz respectively. The composite showed chemical compatibility with the silver electrode material and showed nearly zero coefficient of linear thermal expansion (CTE).