| abstract |
Disclosure of the Invention An object of the present invention is to provide a silicon nitride sintered body and a circuit substrate having a high thermal conductivity and high mechanical strength, a silicon nitride powder as a raw material thereof, and a method of manufacturing the same. In the present invention, the frequency of the particle size distribution obtained by the volume-based particle size distribution measurement by the laser diffraction scattering method, which has a specific surface area of 4.0 to 9.0 m 2 / g, a β phase ratio of less than 40%, an oxygen content of 0.20 to 0.95 mass% The distribution curve has two peaks, the peak top of the peak is in the range of 0.4 to 0.7 mu m and the range of 1.5 to 3.0 mu m, and the ratio of the frequency of the peak top (the peak top of the peak top in the range of 0.4 to 0.7 mu m in particle diameter (Frequency of peak / frequency of peak top in particle diameter of 1.5 to 3.0 mu m) is 0.5 to 1.5, and the median diameter D50 (mu m) obtained by the particle size distribution measurement and the specific surface area equivalent diameter D BET ) Having a D50 / D BET (mu m / mu m) of 3.5 or more, a silicon nitride sintered body obtained from the silicon nitride powder and a circuit board, and a process for producing the silicon nitride powder. |