The nucleation and growth of A6M tape, a crystallisable CaO-B2O3-SiO2 glass for low temperature of co-fired ceramics (LTCCs) produced by Ferro, was investigated. The crystalline phases wollastonite and calciborite formed from the glass at heat treatment temperatures of 830, 850 and 870 deg C. The nucleation rate was found to be a function of temperature with a maximum at 850 deg C; as the temperature increases or decreases from 850 deg C, the nucleation rate reduces. A high nucleation rate is found to be crucial to generate a fine and uniform microstructure. The fine scale microstructure generated at 850 deg C led to LTCCs with high fracture strengths experimentally, which is consistent with fracture analysis of ceramics.