Ultra-low temperature co-fired CaV₂O₆-glass composite ceramic substrate for microelectronics

Bivalent calcium metavanadate (CaV₂O₆) ceramic-glass composite substrates were fabricated using non-aqueous environmental friendly tape casting formulation. 3 wt% of commercial glass was added to the calcined powder of CaV₂O₆ to achieve a sintering temperature of 650 °C which enables ultra-low temperature co-firing with aluminum electrode. An environmentally benign binder/solvent (Polypropylene carbonate/dimethyl carbonate) system was adopted to prepare the well dispersed slurry for tape casting. The crystal structure and co-fireability of the sintered substrate with Al was verified by X-ray diffraction technique. Thermal, dielectric and morphological analysis of the multilayer were analyzed. The room temperature thermal conductivity of CaV₂O₆-glass composite sintered at 650 °C is about 2.8 W/m K. Sintered ceramics shows a relatively high linear coefficient of thermal expansion (CTE) of 11.46 ppm/°C, which is favorable for co-firing with high CTE metallic materials. Microwave dielectric properties of CaV₂O₆-glass composite multilayer fired at 650 °C are ε_r = 10.6 and tanδ = 3.19 × 10⁻⁴ at 15 GHz.