Aluminum nitride powder and aluminum nitride sintered compact

Abstract

The present invention relates to an aluminum nitride sintered body which satisfies both high thermal conductivity and reduction in the shrinkage factor at the time of sintering. The aluminum nitride sintered body is a sintered body of a powder mixture containing an aluminum nitride powder and a sintering aid, characterized by having a thermal conductivity of at least 190 W/m·K and a shrinkage factor represented by the percentage of {(dimensions of the molded body before sintering)-(dimensions of the sintered body after sintering)}/(dimensions of the molded body before sintering) of at most 15%.

1 . An aluminum nitride sintered body which is a sintered body of a non-fired molded body of a powder mixture comprising an aluminum nitride powder and a sintering aid, wherein the aluminum nitride sintered body has a thermal conductivity of at least 190 W/m·K and a shrinkage factor represented by the percentage of {(dimensions of the molded body before sintering)−(dimensions of the sintered body after sintering)}/(dimensions of the molded body before sintering) of at most 15%. 
     
     
         2 . The aluminum nitride sintered body according to  claim 1 , wherein the sintering aid is present in an amount of from 1 to 5 parts by mass per 100 parts by mass of the aluminum nitride powder. 
     
     
         3 . The aluminum nitride sintered body according to  claim 1 , wherein the sintering aid is a compound of an alkaline earth metal or a compound of a transition metal. 
     
     
         4 . The aluminum nitride sintered body according to  claim 1 , wherein the sintering aid is yttrium oxide or calcium oxide. 
     
     
         5 . The aluminum nitride sintered body according to  claim 1 , wherein
 the aluminum nitride powder has local maximum values in size in regions of from 3 to 15 μm, from 0.5 to 1.5 μm and 0.3 μm or less;   proportions of particles in the respective regions are from 40 to 70%, from 25 to 40% and from 0.5 to 20% on a volume basis; and   the aluminum nitride powder has an oxygen amount of from 0.5 to 1.5 mass %.   
     
     
         6 . The aluminum nitride sintered body according to  claim 5 , wherein the oxygen amount is from 0.8 to 1.3 mass %. 
     
     
         7 . The aluminum nitride sintered body according to  claim 1 , wherein the powder mixture further comprises at least one selected from the group consisting of an organic binder, a plasticizer, and a disperser. 
     
     
         8 . The aluminum nitride sintered body according to  claim 7 , wherein the organic binder is at least one selected from the group consisting of polyvinyl butyral, polyacrylate, polymethyl methacrylate, methylcellulose, polyethylene and wax. 
     
     
         9 . The aluminum nitride sintered body according to  claim 1 , wherein the powder mixture is molded by a dry press molding method or a cold isostatical press molding method. 
     
     
         10 . The aluminum nitride sintered body according to  claim 1 , wherein the aluminum nitride powder comprises a first aluminum nitride powder, a second aluminum nitride powder, and a third aluminum nitride powder in a mass ratio of 10:30:60 respectively. 
     
     
         11 . The aluminum nitride sintered body according to  claim 10 , wherein
 the first aluminum nitride powder has a BET specific surface area of 20 m 2 /g and an oxygen amount of 2.2 mass %;   the second aluminum nitride powder has a BET specific surface area of 5 m 2 /g and an oxygen amount of 0.8 mass %; and   the third aluminum nitride powder has a BET specific surface area of 1 m 2 /g and an oxygen amount of 0.6 mass %.