JP6607792B2 - Heat spreader - Google Patents

Description

  The present invention relates to a heat spreader.

  In Patent Document 1, four copper plates are arranged so as to surround a side surface of a graphite structure formed by laminating a plurality of graphene sheets, and these copper plates and the graphite structure are joined by an insert material (brazing material). A (brazed) graphite composite is disclosed.

JP 2012-238733 A

  By the way, in the structure of the graphite complex disclosed in Patent Document 1, when the graphite structure and the copper plate are brazed, there is a possibility that the brazing material heated and melted from between the graphite structure and the copper plate. When the brazing material flows out, the gap between the graphite structure and the copper plate increases.

  An object of this invention is to provide the heat spreader by which the outflow of the brazing material at the time of manufacture was suppressed.

The heat spreader according to claim 1 of the present invention is formed by laminating a plurality of heat conductive layers, and is composed of a laminated body in which the heat conductive layers adjacent in the stacking direction are joined together by a brazing material, and a metal material. And a box shape in which one side is opened, the casing in which the stacked body is accommodated and joined by a brazing material and the stacked body, and a metal material, with closing have a, a closing member joined by a brazing material to each of the housing and the laminate, the edges of the closing member, the side wall portion is provided, the side wall portion, of the housing Surrounds the peripheral wall .

  In the heat spreader according to claim 1, since the laminated body is accommodated in the housing and the opening portion of the housing is closed with a closing member, for example, only the outer periphery of the laminated body is covered with a cylindrical housing. Compared to the enclosing structure, the brazing material heated and melted at the time of brazing (in other words, at the time of joining using the brazing material) (the brazing material heated and melted) is less likely to flow out from the inside of the housing. That is, in the heat spreader, the outflow of the brazing material at the time of manufacture (at the time of brazing) is suppressed.

Further, in the heat spreader according to claim 1 , since the side wall portion of the closing member surrounds the peripheral wall portion of the housing, for example, the side wall portion of the closing member does not surround the peripheral wall portion of the housing. The deformation in which the peripheral wall portion is inclined so as to increase the open area of the body can be suppressed. For this reason, in the said heat spreader, the thermal expansion of each heat conductive layer at the time of brazing is suppressed by suppressing the said deformation | transformation of the surrounding wall part of a housing | casing by the side wall part of a closure member. As a result, in the heat spreader, an increase in the gap between the peripheral wall portion of the housing and the laminated body due to a difference in thermal expansion direction and a difference in thermal expansion coefficient of each heat conductive layer is suppressed.

The heat spreader according to claim 2 of the present invention is the heat spreader according to claim 1 , wherein the heat conductive layer is made of a carbon-based material, and the orientations of the heat conductive layers adjacent to each other in the stacking direction are different. .

In the heat spreader according to claim 2 , since the heat conductive layer is made of a carbon-based material and the orientation of the heat conductive layers adjacent to each other in the stacking direction is different, for example, between the heat conductive layers adjacent to each other in the stacking direction. Compared with the same orientation, the effect of suppressing the thermal expansion of each heat conductive layer during brazing is improved. Moreover, the heat conductivity of the laminated body formed with the said heat conductive layer improves.

The heat spreader according to claim 3 of the present invention is the heat spreader according to claim 1 or 2 , wherein the inner surface of the side wall portion is joined to the outer surface of the peripheral wall portion by a brazing material.

In the heat spreader according to claim 3 , since the inner surface of the side wall portion of the closing member is joined (brazed) to the outer surface of the peripheral wall portion of the housing by a brazing material, for example, the inner surface of the side wall portion is connected to the outer surface of the peripheral wall portion. Compared with a structure that is not brazed, the bonding force between the closing member and the housing is improved.

The heat spreader according to a fourth aspect of the present invention is the heat spreader according to any one of the first to third aspects, wherein the tip of the side wall portion has the one surface of the casing more than the root of the peripheral wall portion. It is located on the other surface side on the opposite side.

In the heat spreader according to claim 4 , since the tip of the side wall portion of the closing member is positioned on the other surface side of the housing from the base of the peripheral wall portion of the housing, for example, the tip of the side wall portion is the peripheral wall portion. The effect of suppressing the thermal expansion of each heat conductive layer during brazing is improved as compared with the structure positioned on the tip side of the peripheral wall portion with respect to the base of the metal.

The heat spreader according to claim 5 of the present invention is the heat spreader according to any one of claims 1 to 4 , wherein at least a part of the inner surface of the side wall portion has a thickness of the side wall portion from the root side to the tip side. The outer wall of the peripheral wall portion is inclined so that the thickness of the peripheral wall portion gradually decreases from the base side toward the distal end side.

In the heat spreader according to claim 5 , at least a part of the inner surface of the side wall portion of the closing member is inclined so that the thickness of the side wall portion gradually decreases from the root side toward the tip side, and the outer surface of the peripheral wall portion of the housing At least a part is inclined so that the thickness of the peripheral wall portion gradually decreases from the base side toward the tip side. With this structure, in the heat spreader, it is possible to reduce the thickness of the side wall portion of the closing member and the peripheral wall portion of the housing while ensuring the effect of suppressing the thermal expansion of each heat conductive layer during brazing. Reduction and weight reduction can be achieved.

The heat spreader of claim 6 of the present invention, in the heat spreader according to any one of claims 3-5 quoting claims 2 and 2, the carbonaceous material comprises graphite.

  In the heat spreader according to the sixth aspect, graphite is included in the carbon-based material constituting the heat conductive layer. Since graphite has high thermal conductivity, the thermal conductivity of the laminate is improved. Furthermore, since graphite has a low coefficient of thermal expansion, the thermal expansion of each heat conductive layer during brazing can be suppressed.

  As described above, the present invention can provide a heat spreader in which the outflow of the brazing material during production is suppressed.

It is sectional drawing of the heat spreader which concerns on 1st Embodiment of this invention. It is an enlarged view of the part pointed by the arrow 2 of FIG. It is sectional drawing of the heat spreader which concerns on 2nd Embodiment of this invention. FIG. 4 is an enlarged view of a portion indicated by an arrow 4 in FIG. 3. It is sectional drawing of the heat spreader which concerns on 3rd Embodiment of this invention. FIG. 6 is an enlarged view of a portion indicated by an arrow 6 in FIG. 5. It is sectional drawing of the heat spreader which concerns on 4th Embodiment of this invention. FIG. 8 is an enlarged view of a portion indicated by an arrow 8 in FIG. 7. It is sectional drawing of the heat spreader of a comparative example. FIG. 10 is an enlarged view of a portion indicated by an arrow 10 in FIG. 9.

(First embodiment)
A heat spreader 20 according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the heat spreader 20 has a flat plate shape, and a semiconductor element 90 (indicated by a two-dot chain line in FIG. 1) that is a heating element and a heat sink 92 (indicated by a two-dot chain line in FIG. 1). ) To transfer heat from the semiconductor element 90 to the heat sink 92. The semiconductor element 90 is disposed on a substrate (not shown), and a power module is configured by the substrate, the semiconductor element 90, the heat spreader 20, and the heat sink 92.

  The heat spreader 20 has a laminated body 22, a box shape in which one surface (the upper surface in the present embodiment) is opened, a housing 24 in which the laminated body 22 is accommodated, and an open portion 25 of the housing 24. And a closing member 26 for closing. In the heat spreader 20 of the present embodiment, the closing member 26 is disposed on one side (the upper side in the present embodiment) in the thickness direction (arrow H direction), and the other side in the thickness direction (the lower side in the present embodiment). ) Is provided with a casing 24.

  The laminate 22 is formed by laminating a plurality (two in this embodiment) of heat conductive layers 28 and 30 that are made of a carbon-based material and have different orientations. Specifically, the laminate 22 is formed by laminating two thermal conductive layers 28 and 30 made of a carbon-based material having a high thermal conductivity and a low thermal expansion coefficient so that the orientations are orthogonal to each other. . In this laminated body 22, the heat conduction layer 28 and the heat conduction layer 30 adjacent in the lamination direction are joined (so-called brazing) by a brazing material 32 (see FIG. 2).

  Examples of the carbon-based material constituting the heat conductive layers 28 and 30 include graphite, diamond, carbon nanofiber, and carbon nanotube. In the present embodiment, the graphite layers formed by stacking a plurality of graphene sheets are used as the heat conductive layers 28 and 30.

  In the present embodiment, the thickness direction of the heat spreader 20 (hereinafter referred to as “spreader thickness direction” as appropriate) and the stacking direction of the stacked body 22 are the same.

  The casing 24 is made of a metal material, and a portion opened to one side in the spreader thickness direction is the opening portion 25. A heat sink 92 is attached to the other surface (lower surface in the present embodiment) 24A in the spreader thickness direction of the casing 24.

The laminated body 22 is accommodated inside the housing 24, and the other surface (lower surface in the present embodiment) 22 </ b> A in the laminating direction of the laminated body 22 faces the bottom surface 24 </ b> B of the housing 24. The bottom surface 24B and the surface 22A are joined by a brazing material 32. Specifically, the other side surface (part constituting the surface 22A) and the bottom surface 24B in the stacking direction of the heat conducting layer 30 located on the other side (the lower side in the present embodiment) of the stack 22 in the stacking direction. It is brazed.
Further, a surface (in this embodiment, a side surface) 22C in a direction orthogonal to the stacking direction of the stacked body 22 is disposed on the inner wall surface 24C of the casing 24 so as to face the inner wall surface 24C. Joined by a brazing material 32. Specifically, each side surface (part constituting the side surface 22C) and the inner wall surface 24C of the heat conductive layers 28 and 30 constituting the laminated body 22 are brazed.

  Examples of the metal material constituting the casing 24 include copper, bronze, silver, gold, titanium, nickel, iron (steel), and aluminum. In the present embodiment, copper is used as the metal material constituting the housing 24.

  The closing member 26 is made of a metal material and is formed in a flat plate shape. A semiconductor element 90 is attached to the surface 26 </ b> A (the surface on one side in the spreader thickness direction (the upper surface in the present embodiment)) 26 </ b> A of the closing member 26. The present invention is not limited to the above configuration, and the heat sink 92 may be attached to the surface 26A of the closing member 26, and the semiconductor element 90 may be attached to the surface 24A of the housing 24.

  Further, the back surface (the other surface in the spreader thickness direction (the lower surface in this embodiment)) 26B of the closing member 26 has an edge portion 26C that is an edge portion of the open portion 25 of the housing 24 (the spreader thickness direction of the housing 24). Are joined by brazing material 32 to one end 24D). Further, the back surface 26B has a central portion 26D of the closing member 26 (a portion inside the edge portion 26C of the closing member 26) on one side surface (upper surface in the present embodiment) 22B in the stacking direction of the stacked body 22. It arrange | positions facing and the center part 26D and the surface 22B are joined by the brazing material 32. FIG. Specifically, the one side surface (site forming the surface 22B) and the back surface 26B in the laminating direction of the heat conducting layer 28 located on one side (in the present embodiment, the upper side) of the laminated body 22 are stacked. The central portion 26D is brazed.

  Examples of the metal material constituting the closing member 26 include the same material as that of the housing 24. In the present embodiment, copper is used as the metal material constituting the closing member 26.

  As shown in FIG. 2, the brazing material 32 includes the heat conductive layer 28 and the heat conductive layer 30 adjacent to each other in the stacking direction, the stack 22 and the housing 24, and the stack 22 and the closing member 26. Between the casing 24 and the closing member 26. The brazing material 32 is interposed between the heat conductive layer 28 and the heat conductive layer 30 to join the heat conductive layer 28 and the heat conductive layer 30, the surface 22 A of the laminate 22, and the housing. A brazing filler metal layer 32B which is interposed between the bottom surface 24B of 24 and joins the surface 22A and the bottom surface 24B, and is interposed between the surface 22B of the laminate 22 and the central portion 26D of the closing member 26; A brazing filler metal layer 32C that joins the central portion 26D, a brazing filler metal layer 32D that is interposed between the side face 22C of the laminate 22 and the inner wall face 24C of the housing 24, and joins the side face 22C and the inner wall face 24C; The edge part (end part 24D) of the opening part 25 and the edge part 26C of the closing member 26 are joined between the edge part of the opening part 25 of the housing 24 and the edge part 26C of the back surface 26B of the closing member 26. And a brazing filler metal layer 32E.

  Examples of the brazing material 32 include materials mainly composed of copper, silver, titanium, zinc, phosphorus, gold, and the like. In the present embodiment, the brazing material 32 is made of an alloy mainly composed of copper, silver, titanium, or the like. Moreover, when the metal material which comprises the housing | casing 24 and the closure member 26 is aluminum, it is good also as brazing (soldering) using the alloy (soft brazing) which has aluminum as a main component.

  In the heat spreader 20 of the present embodiment, the brazing filler metal 32 is formed between the heat conductive layer 28 and the heat conductive layer 30, between the stacked body 22 and the housing 24, and between the stacked body 22 and the closing member 26. And between the casing 24 and the closing member 26, and each component is assembled, and the brazing material 32 is heated and melted while pressing the casing 24 and the closing member 26 in the assembled state. The constituent members (the casing 24, the closing member 26, and the heat conductive layers 28 and 30) constituting the heat spreader 20 are brazed (joined by a brazing material 32).

Next, the operation and effect of the heat spreader 20 will be described.
In the heat spreader 20, heat from the semiconductor element 90 is input to the closing member 26. The heat input to the closing member 26 is transmitted to the casing 24 through the stacked body 22 and is radiated from the heat sink 92. Thereby, the semiconductor element 90 is cooled.

Since the heat spreader 20 has a structure in which the laminated body 22 is accommodated in the housing 24 and the open portion 25 of the housing 24 is closed by the closing member 26, for example, the outer periphery of the laminated body 22 is formed by a rectangular cylindrical housing. Compared with the structure that surrounds only the brazing material (in other words, at the time of joining using the brazing material 32), the brazing material (the brazing material that has been heated and melted) 28 is heated from the inside of the housing 24 to the outside. Difficult to leak. That is, in the heat spreader 20, the outflow of the brazing material 32 at the time of manufacture (at the time of brazing) is suppressed.
Thereby, the increase in the space | gap between each structural member which comprises the heat spreader 20 is suppressed, and the manufactured heat spreader 20 becomes difficult to become a defective product, ie, the incidence rate of a defective product falls.

  Further, in the heat spreader 20, graphite is included in the carbon-based material constituting the heat conductive layers 28 and 30. Since graphite has high thermal conductivity, the thermal conductivity of the laminate 22 formed by the thermal conductive layers 28 and 30 is improved. Furthermore, since graphite has a low coefficient of thermal expansion, the thermal expansion of the heat conductive layers 28 and 30 during brazing can be suppressed.

(Second Embodiment)
Next, the heat spreader 40 which concerns on 2nd Embodiment of this invention is demonstrated using FIG.3 and FIG.4. In addition, the same code | symbol is attached | subjected about the structure similar to 1st Embodiment, and description is abbreviate | omitted suitably.

  As shown in FIGS. 3 and 4, the heat spreader 40 includes the same laminate 22 and casing 24 as in the first embodiment, and a closing member 42. Since this heat spreader 40 has the same configuration as that of the first embodiment except for the configuration of the closing member 42, the configuration of the closing member 42 will be described below.

  The closing member 42 is made of a metal material, and includes a closing portion 44 formed in a flat plate shape, and a side wall portion 46 provided at an edge of the closing portion 44.

A semiconductor element 90 is attached to the surface 44 </ b> A (a surface on one side in the spreader thickness direction (an upper surface in the present embodiment)) 44 </ b> A of the blocking portion 44.
Further, the back surface (the other surface in the spreader thickness direction (the lower surface in the present embodiment)) 44B of the closing portion 44 is joined to the edge portion (end portion 24D) of the open portion 25 of the housing 24 by the brazing material 32. That is, it is brazed. Further, the back surface 44B of the closing portion 44 is disposed to face the surface 22B of the stacked body 22, and is joined to the surface 22B by the brazing material 32. Specifically, the surface on the one side in the stacking direction of the heat conductive layer 28 of the stacked body 22 and the back surface 44B of the closing portion 44 are brazed.

  The side wall portion 46 protrudes from the edge of the closing portion 44 to the other side in the spreader thickness direction (downward in the present embodiment), and surrounds the peripheral wall portion 24E of the housing 24. Specifically, the side wall portion 46 is formed continuously along the edge portion of the closing portion 44, and surrounds the peripheral wall portion 24E from the outside. In addition, this invention is not limited to the said structure, The side wall part 46 may be formed intermittently along the edge part of the obstruction | occlusion part 44. FIG.

  The tip 46A of the side wall 46 is located on the surface 24A side of the casing 24 with respect to the root 24F of the peripheral wall 24E in the spreader thickness direction. In the present embodiment, the front end surface forming the front end 46A of the side wall portion 46 is flush with the surface 24A of the housing 24 in the horizontal direction.

  The inner surface 46B of the side wall 46 is joined to the outer surface 24G of the peripheral wall 24E of the housing 24 (same as the outer surface of the housing 24) by the brazing material 32, that is, brazed. The brazing material 32 of the present embodiment has a layered brazing material layer 32F disposed between the inner surface 46B of the side wall portion 46 and the outer surface 24G of the peripheral wall portion 24E. 46B and the outer surface 24G are joined.

  Examples of the metal material constituting the closing member 42 include the same materials as the closing member 26 of the first embodiment. In the present embodiment, copper is used as the metal material constituting the closing member 42.

  Next, the operation and effect of the heat spreader 40 of this embodiment will be described. In addition, description is abbreviate | omitted about the effect | action and effect obtained by the structure similar to the heat spreader 20 of 1st Embodiment.

In the heat spreader 40, since the side wall portion 46 of the closing member 42 surrounds the peripheral wall portion 24E of the housing 24, for example, the open area of the open portion 25 of the housing 24 is larger than that of the heat spreader 20 of the first embodiment. Thus, the deformation in which the peripheral wall portion 24E is inclined can be suppressed. Specifically, in the heat spreader 40, since the tip (end portion 24D) of the peripheral wall portion 24E is supported by the base 46C of the side wall portion 46, the peripheral wall portion 24E is supported at both ends by the root 24F and the tip. As compared to the structure of the one-end support of only the root 24F of the peripheral wall 24E as in the heat spreader 20 of the embodiment, the above-described deformation in which the peripheral wall 24E tilts so that the open area of the open portion 25 of the housing 24 can be suppressed.
Thereby, in the heat spreader 40, the thermal expansion of the heat conductive layers 28 and 30 at the time of brazing is suppressed by suppressing the deformation of the peripheral wall portion 24E of the casing 24 by the side wall portion 46 of the closing member 42. . As a result, in the heat spreader 40, there is a gap between the peripheral wall portion 24E and the laminated body 22 due to a difference in thermal expansion direction (direction orthogonal to the stacking direction) of the thermally conductive layers 28 and 30 having different orientations or a difference in thermal expansion coefficient. The increase is suppressed.

  Moreover, since the heat spreader 40 can suppress the thermal expansion of the heat conductive layers 28 and 30 during brazing, the dimensional accuracy after manufacture can be ensured. As a result, for example, a structure that hardly suppresses thermal expansion of the heat conductive layers 28 and 30 at the time of brazing is employed, and it is not necessary to adjust the dimensions by scraping the outer surface of the housing deformed by thermal expansion. Can be improved.

  In the heat spreader 40, since the inner surface 46B of the side wall portion 46 of the closing member 42 is brazed to the outer surface 24G of the peripheral wall portion 24E of the housing 24, for example, the inner surface 46B of the side wall portion 46 is brazed to the outer surface 24G of the peripheral wall portion 24E. Compared with a structure that is not attached, the bonding force between the closing member 42 and the housing 24 is improved.

  In the heat spreader 40, the distal end 46A of the side wall 46 of the closing member 42 is positioned closer to the surface 24A of the casing 24 than the root 24F of the peripheral wall 24E of the casing 24. As compared with the structure in which the peripheral wall portion 24E is positioned closer to the tip (end portion 24D) side than the root 24F, the effect of suppressing the thermal expansion of the heat conductive layers 28 and 30 during brazing is improved.

  In the heat spreader 40, the heat conductive layers 28 and 30 are made of a carbon-based material containing graphite, and the orientation of the heat conductive layers 28 and 30 adjacent to each other in the stacking direction is made different. , 30 have different thermal expansion directions. For this reason, the effect which suppresses the thermal expansion of the heat conductive layers 28 and 30 at the time of brazing improves compared with the thing with the same orientation of the heat conductive layers 28 and 30 adjacent to the lamination direction, for example. In addition, the thermal conductivity of the laminate 22 formed by the heat conductive layers 28 and 30 is improved.

(Third embodiment)
Next, a heat spreader 50 according to a third embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected about the structure similar to 2nd Embodiment, and description is abbreviate | omitted suitably.

  As shown in FIGS. 5 and 6, the heat spreader 50 includes the stacked body 22, the casing 24, and the closing member 42 similar to the heat spreader 40 of the second embodiment. The heat spreader 50 has the same configuration as that of the second embodiment except that the positional relationship between the casing 24 and the closing member 42 is turned upside down with respect to the heat spreader 40 of the second embodiment. In the present embodiment, the semiconductor element 90 is attached to the surface 22A of the housing 24, and the heat sink 92 is attached to the surface 44A of the closing member 42.

  Next, the operation and effect of the heat spreader 50 of this embodiment will be described. In addition, description is abbreviate | omitted about the effect | action and effect obtained by the structure similar to the heat spreader 40 of 2nd Embodiment.

  In the heat spreader 50, since the positional relationship between the casing 24 and the closing member 42 is upside down with respect to the heat spreader 40 of the second embodiment, the brazing material 32 that is heated and melted during brazing is connected to the inner surface 46B of the side wall portion 46 and the peripheral wall portion. It is difficult to flow out from between the outer surface 24G of 24E. Specifically, since the space between the inner surface 46B of the side wall portion 46 and the outer surface 24G of the peripheral wall portion 24E is opened upward, for example, compared with a case where the space is opened downward. Thus, the heated and melted brazing material 32 is unlikely to flow out. This improves the reliability of the heat spreader 50 against external contamination and the like.

(Fourth embodiment)
Next, the heat spreader 60 which concerns on 4th Embodiment of this invention is demonstrated using FIG.7 and FIG.8. In addition, the same code | symbol is attached | subjected about the structure similar to 2nd Embodiment, and description is abbreviate | omitted suitably.

  As shown in FIGS. 7 and 8, the heat spreader 60 includes the same laminate 22 as that of the second embodiment, a housing 62 and a closing member 64. Since the heat spreader 60 has the same configuration as that of the second embodiment except for the configuration of the housing 62 and the closing member 64, the configuration of the housing 62 and the closing member 64 will be described below.

  The casing 62 has the same configuration as that of the casing 24 of the second embodiment except for the configuration of the peripheral wall 62A and the outer surface 62B of the peripheral wall 62A (the outer surface of the casing 62). The outer surface 62B of the peripheral wall portion 62A is inclined so that the thickness T1 of the peripheral wall portion 62A gradually decreases from the root side toward the tip (upper end) side.

  The closing member 64 has the same configuration as the closing member 42 of the second embodiment except for the configuration of the side wall portion 64A and the inner surface 64B of the side wall portion 64A. The inner surface 64B of the side wall portion 64A is inclined so that the thickness T2 of the side wall portion 64A gradually decreases from the root side toward the tip (lower end) side.

  Further, the outer surface 62B of the peripheral wall portion 62A of the housing 62 and the inner surface 64B of the side wall portion 64A of the closing member 64 are opposed to each other. A brazing material layer 32E is disposed between the outer surface 62B and the inner surface 64B, and the outer surface 62B and the inner surface 64B are joined by the brazing material layer 32E.

  Next, the operation and effect of the heat spreader 60 of this embodiment will be described. In addition, description is abbreviate | omitted about the effect | action and effect obtained by the structure similar to the heat spreader 40 of 2nd Embodiment.

  In the heat spreader 60, the outer surface 62B of the peripheral wall portion 62A of the housing 62 is inclined so that the thickness T1 gradually decreases from the root side toward the tip side, and the inner surface 64B of the side wall portion 64A of the closing member 64 is inclined from the root side. It is inclined to gradually decrease toward the tip side. With this structure, in the heat spreader 60, the thicknesses T1 and T2 of the peripheral wall portion 62A of the housing 62 and the side wall portion 64A of the closing member 64 are secured while ensuring the effect of suppressing the thermal expansion of the heat conductive layers 28 and 30 during brazing. Thus, it is possible to reduce the thickness and weight of the device. In particular, in this embodiment, the entire outer surface 62B is inclined so that the thickness T1 gradually decreases from the root side toward the tip side, and the entire inner surface 64B is inclined so that the thickness T2 gradually decreases from the root side toward the tip side. Therefore, it is possible to further reduce the weight.

  In the heat spreader 60 of the fourth embodiment, the entire outer surface 62B and the entire inner surface 64B are inclined, but the present invention is not limited to this configuration, and a configuration in which a part of the outer surface 62B and a part of the inner surface 64B are inclined. It is good. Even in this case, cost reduction and weight reduction can be achieved.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above, and various modifications other than the above can be implemented without departing from the spirit of the present invention. Of course.

  Next, in order to prove the operation and effect of the present invention, three types of heat spreaders of the example according to the present invention and one type of heat spreader of the comparative example were prepared, and the following experiments 1 and 2 were performed.

(Experiment 1)
In Experiment 1, the heat spreader of Example 1 and the heat spreader of the comparative example were used.

Example 1: A heat spreader having the same structure as the heat spreader 20 of the first embodiment of the present invention.
High-temperature pyrolytic graphite was used as the heat conductive layers 28 and 30 constituting the laminate 22. This high-temperature pyrolytic graphite has a thermal conductivity in the XY plane of 1700 W / m · K and a thermal conductivity in the Z (thickness) plane of 7 W / m · K. Moreover, as for the dimension of the heat conductive layers 28 and 30, all are 19 mm in length, 19 mm in width, and 1 mm in thickness.
The case 24 is made of copper and has dimensions of 20 mm in length, 20 mm in width, 2.5 mm in height, and 0.5 mm in thickness.
The closing member 26 is made of copper and has dimensions of 20 mm in length, 20 mm in width, and 0.5 mm in thickness.
The brazing material 32 is a foil having a thickness of 50 μm mainly composed of copper, silver, and titanium, sandwiched between the constituent members, and heated at a high temperature (700 to 800 ° C.) for 1 minute to 5 minutes. Then, each component member is joined (brazed).

Comparative Example: A heat spreader in which the laminate 22 of the first embodiment is surrounded by the bottom plate 100, the four side plates 102, and the top plate 104, the brazing material 32 is sandwiched between the constituent members, and the constituent members are joined by heating at a high temperature. 106 (see FIGS. 9 and 10)
-The laminated body 22 is the same as Example 1.
The bottom plate 100 is made of copper and has dimensions of 20 mm in length, 20 mm in width, and 0.5 mm in thickness.
The side plate 102 is made of copper and has dimensions of 19 mm in length, 19.5 mm in width, and 0.5 mm in thickness. The top plate 104 is made of copper and has dimensions of 20 mm in length, 20 mm in width, and 0.5 mm in thickness.

  In Experiment 1, a plurality of heat spreaders of Example 1 and a heat spreader of a comparative example were manufactured, the gap amount of the manufactured heat spreader was measured, and the measurement results were evaluated. In addition, the thing with the void amount below fixed was evaluated as a defective product.

  As shown in Table 1, it is estimated that in the heat spreader of Comparative Example 1, the amount of voids between the constituent members increased due to the outflow of the brazing material, and as a result, the incidence of defective products was 50%. On the other hand, in the heat spreader of Example 1, since the brazing material is difficult to flow out between the constituent members, the brazing material spreads between the constituent members, and as a result, the occurrence rate of defective products was suppressed to about 10%. Guessed.

(Experiment 2)
In Experiment 2, each heat spreader of Examples 1 to 3 was used.

Example 2: A heat spreader having the same structure as the heat spreader 40 of the second embodiment of the present invention.
-The laminated body 22 is the same as Example 1.
The casing 24 is the same as that in the first embodiment.
The closing member 42 is made of copper and has dimensions of 21 mm in length, 21 mm in width, 20 mm in height, and 0.5 mm in thickness.
The brazing material 32 is the same as in the first embodiment.

Example 3: A heat spreader having the same structure as the heat spreader 60 of the fourth embodiment of the present invention.
-The laminated body 22 is the same as Example 1.
The case 62 is made of copper and has dimensions of 20 mm in length, 20 mm in width, 2.5 mm in height, and 0.5 mm in thickness.
The closing member 64 is made of copper and has dimensions of 21 mm in length, 21 mm in width, 20 mm in height, and 0.5 mm in thickness.
The brazing material 32 is the same as in the first embodiment.

  In Experiment 2, a plurality of heat spreaders of Examples 1 to 3 were manufactured, the dimensions of the manufactured heat spreaders were measured, and the results were evaluated. In addition, the thing with dimensional accuracy below fixed was evaluated as inferior goods.

  In the heat spreader of the first embodiment, the peripheral wall 24E of the housing 24 may be deformed due to thermal expansion during brazing of the heat conductive layers 28 and 30 formed of graphite. When such a deformation occurs, the heat spreader dimensions do not satisfy the reference value, and therefore, a post-process such as polishing occurs. However, if the amount of deformation of the heat spreader is too large, the graphite may be exposed by polishing, resulting in a defective product. Therefore, as shown in Table 2, in Example 1, about 10% of defective products are generated. On the other hand, in the heat spreader of the second embodiment, since the distal end of the peripheral wall portion 24E of the housing 24 is suppressed (supported) by the root 46C of the side wall portion 46 of the closing member 42, the heat conductive layer 28 during brazing, Since the deformation of the peripheral wall 24E due to the thermal expansion of 30 is suppressed, the dimensional accuracy of the heat spreader is ensured. For this reason, in the heat spreader of Example 2, the occurrence of defective products is suppressed to 5% or less.

  In the heat spreader of the third embodiment, as in the second embodiment, the dimensional accuracy of the heat spreader is ensured, and the occurrence of defective products is suppressed to 5% or less. In addition, in the heat spreader of the third embodiment, the thickness T1 of the peripheral wall portion 62A is thinned from the root toward the tip, and the thickness T2 of the side wall portion 64A is thinned from the root to the tip, so the heat spreader of the second embodiment. The weight is lighter than that. For this reason, it can be seen that the heat spreader of Example 3 has the same defective product occurrence rate as the heat spreader of Example 2, but is superior to the heat spreader of Example 2 in terms of weight reduction.

20 heat spreader 22 laminate 24 casing 24A surface (the other surface)
24E peripheral wall portion 24F root 24G outer surface 25 open portion 26 closing member 28 heat conduction layer 30 heat conduction layer 40 heat spreader 42 closing member 46 side wall portion 46B inner surface 46C root 50 heat spreader 60 heat spreader 62 housing 62A peripheral wall portion 62B outer surface 64 closing member 64A side wall Part 64B Inner surface

Claims (6)

A laminated body formed by laminating a plurality of heat conductive layers, wherein the heat conductive layers adjacent in the laminating direction are joined together by a brazing material;
It is made of a metal material and has a box shape with one side open, the housing in which the laminated body is accommodated and joined by the brazing material and the laminated body,
A closing member that is made of a metal material, closes the opening of the housing, and is joined to the housing and the laminate by a brazing material,
Have
A side wall is provided at the edge of the closing member,
The side wall portion is a heat spreader surrounding the peripheral wall portion of the housing.   The heat spreader according to claim 1, wherein the heat conductive layer is made of a carbon-based material, and the orientation of the heat conductive layers adjacent to each other in the stacking direction is different.   The heat spreader according to claim 2 or 2, wherein an inner surface of the side wall portion is joined to an outer surface of the peripheral wall portion by a brazing material.   The front end of the side wall portion is located on the other surface side opposite to the one surface of the housing from the base of the peripheral wall portion. Heat spreader. At least a part of the inner surface of the side wall portion is inclined such that the thickness of the side wall portion gradually decreases from the root side toward the tip side,
The heat spreader according to any one of claims 1 to 4, wherein at least a part of the outer surface of the peripheral wall portion is inclined so that the thickness of the peripheral wall portion gradually decreases from the root side toward the tip side.   The heat spreader according to any one of claims 3 to 5, wherein the carbon-based material includes graphite.