Thermal diffuser and cooling apparatus for cooling heat source using the same

Abstract

A thermal diffuser includes a plurality of thermally-conductive plates, each of which has a strip-like shape. The plurality of thermally-conductive plates is laminated onto one another in a plate-thickness direction of the strip-like shape to form a laminated body. Each of the plurality of thermally-conductive plates has thermal conductivities in a longitudinal direction and in a width direction of the strip-like shape better than a thermal conductivity in the plate-thickness direction. The thermally-conductive plates has sides, each of which extends in the longitudinal direction. The laminated body is formed such that the sides of the thermally-conductive plates form a plate surface of the laminated body, which surface extends in the plate-thickness direction that serves as a lamination direction, in which the thermally-conductive plates of the laminated body are laminated. A direction perpendicular to the plate surface corresponds to a thickness direction of the laminated body.

1 . A thermal diffuser comprising:
 a plurality of thermally-conductive plates, each of which has a strip-like shape, wherein:   the plurality of thermally-conductive plates is laminated onto one another in a plate-thickness direction of the strip-like shape to form a laminated body;   each of the plurality of thermally-conductive plates has thermal conductivities in a longitudinal direction and in a width direction of the strip-like shape better than a thermal conductivity in the plate-thickness direction;   the thermally-conductive plates has sides, each of which extends in the longitudinal direction;   the laminated body is formed such that the sides of the thermally-conductive plates form a plate surface of the laminated body, which surface extends in the plate-thickness direction that serves as a lamination direction, in which the thermally-conductive plates of the laminated body are laminated; and   a direction perpendicular to the plate surface corresponds to a thickness direction of the laminated body.   
     
     
         2 . The thermal diffuser according to  claim 1 , wherein the laminated body is one of a plurality of laminated bodies and the plurality of laminated bodies is laminated in the thickness direction,
 the thermal diffuser further comprising:   an inorganic layer that is provided between the plurality of laminated bodies to bond the plurality of laminated bodies with each other; and   adjacent ones of the plurality of laminated bodies have the respective lamination directions of the plurality of thermally-conductive plates different from each other.   
     
     
         3 . The thermal diffuser according to  claim 2 , wherein:
 the lamination directions of the plurality of thermally-conductive plates define therebetween an angle in a range from 85 to 90 degrees.   
     
     
         4 . The thermal diffuser according to  claim 2 , wherein:
 the inorganic layer includes at least one of titanium, nickel, tin, lead, and gold.   
     
     
         5 . The thermal diffuser according to  claim 1 , wherein:
 the laminated body is one of a plurality of laminated bodies that is arranged in a direction, in which the plate surface extends;   a part of the plate surface of each of the plurality of laminated bodies is included in a connecting region that is connected with a heat source;   each of the plurality of laminated bodies has an outer peripheral section that forms an outer periphery of an entirety of the plurality of laminated bodies;   any point within the connecting region and any point on the outer peripheral section of each of the plurality of laminated bodies defines an imaginary line therebetween; and   the respective longitudinal direction of the thermally-conductive plates of each of the plurality of laminated bodies is parallel to the imaginary line.   
     
     
         6 . The thermal diffuser according to  claim 5 , wherein:
 the plurality of laminated bodies includes four laminated bodies, the plate surface of which has a rectangular shape; and   the rectangular shape of each of the laminated body has one corner portion that is included in the connecting region.   
     
     
         7 . The thermal diffuser according to  claim 1 , wherein:
 the laminated body has a thermal conductivity in the thickness direction equal to or greater than 600 W/mK.   
     
     
         8 . The thermal diffuser according to  claim 1 , wherein:
 the thermally-conductive plate is made of one of a graphite material and a composite material, which has graphite and metal.   
     
     
         9 . A cooling apparatus for a heat source comprising:
 a thermal diffuser according to  claim 1 , wherein the plate surface of the thermal diffuser is one of a plurality of plate surfaces;   a heat source provided to one of the plurality of plate surfaces of the thermal diffuser;   an insulating plate provided to the other one of the plurality of plate surfaces of the thermal diffuser; and   a cooling unit provided to a surface of the insulating plate opposite from the thermal diffuser.   
     
     
         10 . The cooling apparatus according to  claim 9 , wherein the heat source is a semiconductor device,
 the cooling apparatus further comprising:   a metal plate that is provided between the thermal diffuser and the insulating plate.   
     
     
         11 . The cooling apparatus according to  claim 9 , wherein the heat source is a semiconductor device,
 the cooling apparatus further comprising:   a metal plate that is provided between the heat source and the thermal diffuser.   
     
     
         12 . A cooling apparatus for a heat source, comprising:
 a thermal diffuser according to  claim 3 , wherein the thermal diffuser includes two laminated bodies, wherein the plate surface of the thermal diffuser is one of a plurality of plate surfaces;   a heat source provided to one of the plurality of plate surfaces of the thermal diffuser;   an insulating plate provided to the other one of the plurality of plate surfaces of the thermal diffuser; and   a cooling unit provided to a surface of the insulating plate remote from the thermal diffuser,   wherein:   one of the two laminated bodies of the thermal diffuser has a thickness dimension of t 1 ;   the other one of the two laminated bodies has a thickness dimension of t 2 ;   a distance, which is measured from a center position of the heat source to an end of the thermal diffuser in a longitudinal direction of the thermally-conductive plates of the one of the laminated bodies, is defined as r 1 ;   a distance, which is measured from the center position of the heat source to another end of the thermal diffuser in the longitudinal direction of the thermally-conductive plates of the other one of the laminated bodies, is defined as r 2 ; and   the dimensions t 1 , t 2 , and the distances r 1 , r 2  satisfy the following equation:
   0.5≦( t 1/ t 2)/( r 1/ r 2)≦2.
 
   
     
     
         13 . A method of manufacturing a thermal diffuser, the method comprising:
 forming a laminated body by laminating a plurality of thermally-conductive plates, each of which has a plate shape, in a plate-thickness direction of the plate shape,
 wherein each of the plurality of thermally-conductive plates has a thermal conductivity in a plane direction of the plate shape better than a thermal conductivity in the plate-thickness direction; and 
   forming a plate member by cutting the laminated body in a lamination direction, in which the thermally-conductive plates are laminated, along one sides of the thermally-conductive plates such that the plate member has a plate shape,
 wherein the plate member is formed such that one sides of the thermally-conductive plate form a plate surface that extends in the lamination direction, 
 wherein a direction perpendicular to the plate surface corresponds to a thickness direction of the plate member. 
   
     
     
         14 . A method for manufacturing a thermal diffuser, the method comprising:
 forming a laminated body by laminating a plurality of thermally-conductive plates, each of which has a plate shape, in a plate-thickness direction of the plate shape,
 wherein each of the plurality of thermally-conductive plates has a thermal conductivity in a plane direction of the plate shape better than a thermal conductivity in the plate-thickness direction; 
   forming a primary plate member by cutting the laminated body in the lamination direction along one sides of the thermally-conductive plates such that the primary plate member has a plate shape,
 wherein the primary plate member is formed such that the one sides of the thermally-conductive plates form a plate surface that extends in a lamination direction, in which the plurality of thermally-conductive plates is laminated, 
 wherein a direction perpendicular to the plate surface corresponds to a thickness direction of the primary plate member; 
   forming a secondary plate member by cutting off four corners of the primary plate member such that the secondary plate member has a rectangular shape,
 wherein a direction, in which the one sides of the thermally-conductive plates extend, is angled relative to each side of the secondary plate member, 
 wherein the forming of the secondary plate member includes forming a plurality of secondary plate members; and 
   arranging the plurality of secondary plate members in a direction, in which the plate surface extends,
 wherein a part of the plate surface of each of the plurality of secondary plate members is included in a connecting region that is connected with a heat source, 
 wherein each of the plurality of secondary plate members has an outer peripheral section that forms an outer periphery of an entirety of the plurality of secondary plate members, 
 wherein any point within the connecting region and any point on the outer peripheral section of each of the plurality of secondary plate members define an imaginary line therebetween, 
 wherein a direction of the one sides of the thermally-conductive plates of each of the plurality of secondary plate members is parallel to the imaginary line.