Silicon nitride powder, silicon nitride sintered body and circuit board, and method for producing silicon nitride powder

摘要

An object of the present invention is to provide a silicon nitride sintered body and a circuit board having high thermal conductivity and also high mechanical strength, a silicon nitride powder as a raw material thereof, and a method for producing the same. The specific surface area is 4.0-9.0 m2 / g, the proportion of β phase is less than 40%, the oxygen content is 0.20-0.95% by mass, and the volume-based particle size by laser diffraction scattering method. The frequency distribution curve obtained by distribution measurement has two peaks, and the peak tops of the peaks are in the range of 0.4 to 0.7 μm and in the range of 1.5 to 3.0 μm. The ratio of the frequency (frequency of peak top in the range of particle diameter 0.4 to 0.7 μm / frequency of peak top in the range of particle diameter 1.5 to 3.0 μm) is 0.5 to 1.5, Silicon nitride in which the ratio D50 / DBET (μm / μm) between the median diameter D50 (μm) obtained by the particle size distribution measurement and the specific surface area equivalent diameter DBET (μm) calculated from the specific surface area is 3.5 or more Powder, nitride nitride obtained from this silicon nitride powder An iodine sintered body, a circuit board, and a method for producing the silicon nitride powder are provided.