| 摘要 |
PROBLEM TO BE SOLVED: To obtain a circuit board having both of high thermal conductivity and low dielectric property which enables fast and highly reliable signal processing by controlling the volume ratio and particle size of a particle phase in a silicon nitride sintered body to specified ranges and controlling the sum cross section of neck parts per one particle connected to other particles on the neck parts to a specified range of the surface area of the particle. SOLUTION: This silicon nitride circuit board consists of a silicon nitride sintered body having a silicon nitride particle phase and an intergranular phase of a material having a low dielectric const. The volume ratio of the particle phase in the silicon nitride sintered body is 50 to 65%, and the average primary particle size of the particles is >=1.0μm. The particles are connected to each other with a neck part in such a manner that the sum cross section of the neck parts per one particle is 30 to 70% in average of the surface area of the particle, that the diameter of the cross section of the neck is average >=0.5μm, and that the number of necks per one particle is 6 to 8 in average. The silicon nitride sintered body has <=2.10g/cm<2> apparent density, <=6.0 relative dielectric const., >=100MPa strength and >=0.20cm<2> /sec thermal diffusion ratio. |
