Abstract: One embodiment of the present invention relates to a resin composition or a method of producing a resin composition, and the resin composition includes 100 parts by volume of a resin (A), and 230 to 640 parts by volume of a filler (B) having an average particle diameter of 5 ?m to 60 ?m, wherein the filler (B) contains a filler (B-1) having a spherical shape with an average particle diameter of 0.1 ?m or more and 0.7 ?m or less and a filler (B-2) having a peak at least in a range of 0.9 ?m to 3.0 ?m in a particle size distribution measured by a laser diffraction method, and the proportion of the filler (B-1) is from 0.2 vol % to 5.0 vol % with respect to 100 vol % of the filler (B).

Abstract: To provide an aluminum nitride particle having a hexagonal columnar barrel part and bowl-like projection parts at both ends of the columnar part, wherein the long diameter (D) of the barrel part is 10 to 250 ?m, the ratio (L1/D) of the distance (L1) between the apexes of the two projection pars to the long diameter (D) of the barrel part is 0.7 to 1.3, and the percentage of the length or thickness (L2) of the barrel part to the distance (L1) between the apexes of the two projection parts is 10 to 60%. The aluminum nitride particle can provide high heat conductivity and excellent electric insulation to a resin when it is filled into the resin.

Abstract: To provide an aluminum nitride particle having a hexagonal columnar barrel part and bowl-like projection parts at both ends of the columnar part, wherein the long diameter (D) of the barrel part is 10 to 250 ?m, the ratio (L1/D) of the distance (L1) between the apexes of the two projection pars to the long diameter (D) of the barrel part is 0.7 to 1.3, and the percentage of the length or thickness (L2) of the barrel part to the distance (L1) between the apexes of the two projection parts is 10 to 60%. The aluminum nitride particle can provide high heat conductivity and excellent electric insulation to a resin when it is filled into the resin.