Heat sink device

Abstract

A heat radiator 1 includes an insulating substrate 3 whose first side serves as a heat-generating-element-mounting side, and a heat sink 5 fixed to a second side of the insulating substrate 3. A metal layer 7 is formed on a side of the insulating substrate 3 opposite the heat-generating-element-mounting side. A stress relaxation member 4 intervenes between the metal layer 7 of the insulating substrate 3 and the heat sink 5. The stress relaxation member 4 is formed of an aluminum plate 10 having a plurality of through holes 9 formed therein, and the through holes 9 serve as stress-absorbing spaces. The stress relaxation member 4 is brazed to the metal layer 7 of the insulating substrate 3 and to the heat sink 5. This heat radiator 1 is low in material cost and exhibits excellent heat radiation performance.

1 . A heat radiator comprising an insulating substrate whose first side serves as a heat-generating-element-mounting side, and a heat sink fixed to a second side of the insulating substrate;
 wherein a stress relaxation member formed of a high-thermal-conduction material and having a stress-absorbing space intervenes between the insulating substrate and the heat sink, and the stress relaxation member is metal-bonded to the insulating substrate and to the heat sink.   
   
   
       2 . A heat radiator according to  claim 1 , wherein the stress relaxation member is brazed to the insulating substrate and to the heat sink. 
   
   
       3 . A heat radiator comprising an insulating substrate whose first side serves as a heat-generating-element-mounting side, and a heat sink fixed to a second side of the insulating substrate;
 wherein a metal layer is formed on a side of the insulating substrate opposite the heat-generating-element-mounting side; a stress relaxation member formed of a high-thermal-conduction material and having a stress-absorbing space intervenes between the metal layer and the heat sink; and the stress relaxation member is metal-bonded to the metal layer of the insulating substrate and to the heat sink.   
   
   
       4 . A heat radiator according to  claim 3 , wherein the stress relaxation member is brazed to the metal layer of the insulating substrate and to the heat sink. 
   
   
       5 . A heat radiator according to  claim 1 , wherein the insulating substrate is formed of a ceramic. 
   
   
       6 . A heat radiator according to  claim 1 , wherein the stress relaxation member is formed of an aluminum plate having a plurality of through holes formed therein, and the through holes serve as the stress-absorbing spaces. 
   
   
       7 . A heat radiator according to  claim 6 , wherein the through holes are formed in at least a portion of the aluminum plate which corresponds to a perimetric portion of the insulating substrate. 
   
   
       8 . A heat radiator according to  claim 6 , wherein the through holes are of a non-angular shape and have a circle-equivalent diameter of 1 mm to 4 mm. 
   
   
       9 . A heat radiator according to  claim 6 , wherein a percentage of a total area of all of the through holes to an area of one side of the aluminum plate is 3% to 50%. 
   
   
       10 . A heat radiator according to  claim 3 , wherein the stress relaxation member is formed of an aluminum plate having a plurality of recesses formed on at least either side, and the recesses serve as the stress-absorbing spaces. 
   
   
       11 . A heat radiator according to  claim 10 , wherein the recesses are formed on at least a portion of the aluminum plate which corresponds to a perimetric portion of the insulating substrate. 
   
   
       12 . A heat radiator according to  claim 10 , wherein openings of the recesses are of a non-angular shape and have a circle-equivalent diameter of 1 mm to 4 mm. 
   
   
       13 . A heat radiator according to  claim 10 , wherein a percentage of a total area of openings of all of the recesses to an area of a side of the aluminum plate on which the recesses are formed is 3% to 50%. 
   
   
       14 . A heat radiator according to  claim 1 , wherein the stress relaxation member is formed of an aluminum plate having a plurality of recesses formed on at least either side and a plurality of through holes formed therein, and the recesses and through holes serve as the stress-absorbing spaces. 
   
   
       15 . A heat radiator according to  claim 6 , wherein a thickness of the aluminum plate used to form the stress relaxation member is 0.3 mm to 3 mm. 
   
   
       16 . A heat radiator according to  claim 1 , wherein the stress relaxation member is formed of a corrugate aluminum plate comprising wave crest portions, wave trough portions, and connection portions each connecting the wave crest portion and the wave trough portion, and spaces present between the adjacent connection portions serve as the stress-absorbing spaces. 
   
   
       17 . A heat radiator according to  claim 16 , wherein a thickness of the corrugate aluminum plate is 0.05 mm to 1 mm. 
   
   
       18 . A heat radiator according to  claim 16 , wherein at least one cutout portion extending in a direction perpendicular to a longitudinal direction of the wave crest portions and the wave trough portions is formed at the wave crest portions, the wave trough portions, and the connection portions of the corrugate aluminum plate. 
   
   
       19 . A heat radiator according to  claim 16 , wherein a plurality of the corrugate aluminum plates are disposed in a longitudinal direction of the wave crest portions and the wave trough portions while being spaced apart from one another. 
   
   
       20 . A heat radiator according to  claim 19 , wherein the adjacent corrugate aluminum plates are disposed such that the wave crest portions and the wave trough portions of one corrugate aluminum plate are shifted from those of the other corrugate aluminum plate in a lateral direction of the wave crest portions and the wave trough portions. 
   
   
       21 . A heat radiator according to  claim 6 , wherein the aluminum plate is formed of pure aluminum having a purity of 99% or higher. 
   
   
       22 . A heat radiator according to  claim 6 , wherein the stress relaxation member is formed of a brazing sheet which comprises a core, and brazing-material layers covering respective opposite sides of the core, and the stress relaxation member is brazed to the insulating substrate or the metal layer of the insulating substrate and to the heat sink by use of the brazing-material layers of the brazing sheet. 
   
   
       23 . A heat radiator according to  claim 6 , wherein the stress relaxation member is brazed to the insulating substrate or the metal layer of the insulating substrate and to the heat sink by use of a sheetlike brazing material. 
   
   
       24 . A power module comprising a heat radiator according to  claim 1 , and a semiconductor device mounted on the insulating substrate of the heat radiator.