Patent ID: 8476756

Claim:
A semiconductor device, comprising: a semiconductor element having a rectangular two-dimensional geometry and serving as a heat source; a first heat sink section comprising said semiconductor element mounted thereon; and a second heat sink section joined to an opposite side of said first heat sink section that comprises said semiconductor element, wherein a relation among directional components of a thermal conductivity of said first heat sink section is: K 1 yy ≧K 1 xx >K 1 zz, wherein the thermal conductivity of said first heat sink section is defined as K 1 , and directional components of a three-dimensional thermal conductivity of said first heat sink section in X, Y, and Z directions are determined as K 1 xx , K 1 yy , and K 1 zz , and wherein a relation among directional components of a thermal conductivity of said second heat sink section is: K 2 zz ≧K 2 yy >K 2 xx or K 2 yy ≧K 2 zz >K 2 xx, wherein the thermal conductivity of said second heat sink section is defined as K 2 , and the directional components of the thermal conductivity of said second heat sink section in X, Y, and Z directions are determined as K 2 xx , K 2 yy , and K 2 zz.