Silicon nitride powder, silicon nitride sintered body and a circuit board for an electronic compone

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PROBLEM TO BE SOLVED : To provide a highly heat-conductive silicon nitride sintered compact having excellent mechanical properties, no anisotropy of thermal conductivity, and an increased thermal conductivity. SOLUTION : The silicon nitride powder comprises columnar particles having a β-fraction of 30 to 100%, an oxygen content of below 0.5 wt.%, a mean particle diameter of 0.2 to 10 μm, an aspect ratio of 10 or lower, and grooves formed in the direction of a particle long axis. The sintered compact comprises 1 to 50 pts. wt. above silicon nitride powder, 99 to 50 pts. wt. α-silicon nitride powder having a mean particle diameter of 0.2 to 4 μm, and a sintering aid comprising Mg and at least one rare earth element selected from rare earth elements (RE) including La, Y, and Yb and is characterized in that when the Mg is calculated as magnesium oxide (MgO), and the at least one element selected from rare earth elements including La, Y, and Yb is calculated as an oxide (RExOy), the total of the contents of these oxides is 0.6 to 7 wt.%, and the weight ratio, (MgO/RExOy), is 1 to 70. COPYRIGHT : (C)2004, JPO&NCIPI