Patent ID: 9630846
Date: 2017-04-25
CPC Classifications: B32B,C01B,C01P,C04B,H01L,H05K

Claim:
1. A silicon nitride substrate comprising silicon nitride crystal grains and a grain boundary phase and having a thermal conductivity of 50W/m·K or more, wherein, in a sectional structure of the silicon nitride substrate, a ratio, T 2 /T 1 , of a total length T 2 of the grain boundary phase in a thickness direction with respect to a thickness T 1 of the silicon nitride substrate is 0.01 to 0.30, an average grain diameter with respect to a long diameter of the silicon nitride crystal grains is between 1.5 and 10 μm, and a variation from a dielectric strength mean value when measured by a four-terminal method in which electrodes are brought into contact with front and rear surfaces of the substrate is 20% or less.