Ultralow-temperature sinterable alumina-45SnF(2):25SnO:30P(2)O(5) glass (Al2O3-SSP glass) composite has been developed for microelectronic applications. The 45SnF(2):25SnO:30P(2)O(5) glass prepared by melt quenching from 450 degrees C has a low T-g of about 93 degrees C. The SSP glass has epsilon(r) and tan of 20 and 0.007, respectively, at 1 MHz. In the microwave frequency range, it has epsilon(r)=16 and Q(u) x f=990 GHz with (f)=-290 ppm/degrees C at 6.2 GHz with coefficient of thermal expansion (CTE) value of 17.8 ppm/degrees C. A 30 wt.% Al2O3-70 wt.% SSP composite was prepared by sintering at different temperatures from 150 degrees C to 400 degrees C. The crystalline phases and dielectric properties vary with sintering temperature. The alumina-SSP composite sintered at 200 degrees C has epsilon(r)=5.41 with a tan of 0.01 (1 MHz) and at microwave frequencies it has epsilon(r)=5.20 at 11 GHz with Q(u) x f=5500 GHz with temperature coefficient of resonant frequency ((f))=-18 ppm/degrees C. The CTE and room-temperature thermal conductivity of the composite sintered at 200 degrees C are 8.7 ppm/degrees C and 0.47 W/m/K, respectively. The new composite has a low sintering temperature and is a possible candidate for ultralow-temperature cofired ceramics applications.