JP7182403B2 - Cooling system - Google Patents

Description

The present invention relates to a cooling device for cooling heat-generating elements such as electronic elements (eg, semiconductor elements).

Here, the vertical direction of the cooling device according to the present invention is not limited. We define the top side of the cooling device as the side to be cooled and the bottom side of the cooling device as the opposite side.

Furthermore, in the cooling device according to the present invention, a plane perpendicular to the thickness direction of each structural member of the cooling device is referred to as a plane of each structural member, and a direction parallel to the plane of each structural member is referred to as a planar direction of each structural member. .

In addition, in this specification, unless otherwise specified, the term "plate" is used to include foil, and the term "aluminum" is used to include both pure aluminum and aluminum alloy. , the term "copper" is used to include both pure copper and copper alloys.

As a metal-carbon particle composite material, for example, as described in Japanese Patent No. 5150905 (Patent Document 1) and (Patent No. 5145591 (Patent Document 2), a plurality of metal layers and carbon fiber layers are alternately laminated. A metal-carbon fiber composite material that is bonded and integrated in a state of being made is known.In addition, International Publication No. 2009/051094 (Patent Document 3) discloses a metal-carbon fiber composite material using scaly graphite particles as carbon particles. A flake graphite particle composite is disclosed.

Other patent documents that disclose metal-carbon particle composites include JP 2015-25158 (Patent Document 4), JP 2015-217655 (Patent Document 5), JP 2017-88913 (Patent Reference 6), etc.

The metal-carbon particle composite material described above has anisotropy in thermal conductivity, and is expected to be used as a material for members that require high thermal conductivity.

By the way, a cooling device for cooling a heat-generating element such as a semiconductor element is required to have high thermal conductivity in order to obtain high cooling performance. Therefore, the use of a metal-carbon particle composite material as a material for a constituent member of a cooling device has been proposed in JP-A-2016-132113 (Patent Document 7), JP-A-2016-152241 (Patent Document 8), and the like. ing.

In addition, Japanese Patent Application Laid-Open No. 2016-207799 (Patent Document 9) discloses that a material for a heat diffusion plate of a heating element module has high thermal conductivity in two directions perpendicular to each other and low thermal conductivity in the remaining one direction. It discloses using a highly oriented carbonaceous material.

Japanese Patent No. 5150905 Japanese Patent No. 5145591 WO2009/051094 JP 2015-25158 A JP 2015-217655 A JP 2017-88913 A JP 2016-132113 A JP 2016-152241 A JP 2016-207799 A

In recent years, as the performance of heat-generating elements has improved and the amount of heat generated has increased, more and more high cooling performance has been required for such cooling devices.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the cooling performance of a cooling device that cools a heat-generating element.

The present invention provides the following means.

1) A cooling device for cooling an exothermic element, comprising:
A wiring layer having an upper surface including an element mounting region on which a heat-generating element is mounted; and a cooling member disposed below the wiring layer,
The wiring layer is formed of an aluminum-carbon particle composite material,
The composite material has, in orthogonal coordinates, a direction with the highest thermal conductivity, a b direction with the highest thermal conductivity, and a thermal conductivity higher than the thermal conductivity in the a direction and the thermal conductivity in the b direction. having a low c-direction and
When the thermal conductivities in the a-direction, b-direction, and c-direction are ka, kb, and kc, respectively, ka, kb, and kc satisfy the following formula 1,
ka≧kb>kc (Formula 1)
Further, the wiring layer is composed of a plurality of segments divided by a dividing plane passing through the element mounting region on the upper surface of the wiring layer,
In each of the segments of the wiring layer, the a direction is a direction inclined downward toward the outer edge of the segment in the wiring layer, and the b direction is a direction along the upper surface of the wiring layer. Cooling system.

2) the wiring layer has a longitudinal direction and a lateral direction;
the plurality of segments includes a first segment and a second segment;
The first segment and the second segment are joined to each other at the dividing surface,
2. The cooling device according to the preceding item 1, wherein the dividing surface passes through the element mounting region on the upper surface of the wiring layer in the longitudinal direction of the wiring layer.

3) The cooling device according to the preceding item 1 or 2, wherein, in each of the segments of the wiring layer, an acute angle between the upper surface and the direction a is 25° or more and less than 90°.

4) The cooling device according to the preceding item 1 or 2, wherein in each segment of the wiring layer, an acute angle formed between the upper surface and the direction a is 35° or more and 70° or less.

5) the plurality of segments includes a first segment and a second segment;
In the first segment, an acute angle formed by the upper surface and the direction a is θ1,
In the second segment, when the acute angle formed by the upper surface and the direction a is θ2,
5. The cooling device according to any one of the preceding items 1 to 4, wherein the difference θ1-θ2 between θ1 and θ2 is within a range of ±10°.

6) The cooling device according to item 1, wherein the plurality of segments includes at least three segments.

The present invention has the following effects.

In the preceding item 1, when the heat-generating element is cooled by the cooling device, heat diffusion in the direction from the position of the element mounting region on the upper surface of the wiring layer toward the cooling member and heat diffusion in the planar direction within the wiring layer. both occur. As a result, it is possible to improve the cooling performance of the cooling device.

In the above item 2, thermal diffusion in the planar direction within the wiring layer occurs particularly effectively. This makes it possible to further improve the cooling performance of the cooling device.

In the above items 3 and 4, both heat diffusion in the direction from the position of the element mounting region on the upper surface of the wiring layer toward the cooling member and heat diffusion in the planar direction within the wiring layer occur more effectively. This makes it possible to further improve the cooling performance of the cooling device.

In the above item 5, the heat of the exothermic element is diffused substantially uniformly to the first segment and the second segment of the wiring layer. This makes it possible to further improve the cooling performance of the cooling device.

In the above item 6, both heat diffusion in the direction from the position of the element mounting region on the upper surface of the wiring layer toward the cooling member and heat diffusion in the planar direction within the wiring layer occur more effectively. As a result, it is possible to improve the cooling performance of the cooling device.

FIG. 1 is a schematic front view showing a cooling device according to a first embodiment of the present invention with a heat-generating element mounted thereon. FIG. 2 is a schematic perspective view of the same cooling device. FIG. 3 is a schematic front view of the upper wiring layer and its vicinity of the cooling device. FIG. 4 is a schematic plan view of the same cooling device. FIG. 5 is a schematic perspective view of an aluminum-carbon particle composite material used as a material for segments constituting the same wiring layer. FIG. 6 is a schematic perspective view of a cooling device according to a second embodiment of the invention. FIG. 7 is a schematic side view of the upper wiring layer and its vicinity of the cooling device. FIG. 8 is a schematic plan view of the same cooling device. FIG. 9 is a schematic perspective view of a cooling device according to a third embodiment of the invention. FIG. 10 is a schematic plan view of the cooling device. FIG. 11 is a schematic perspective view showing an upper wiring layer of the cooling device and four segments forming the upper wiring layer. FIG. 12 is a schematic perspective view of an aluminum-carbon particle composite material used as a material for segments constituting the same wiring layer. 13 is a schematic plan view of the cooling device of the first embodiment used in Simulation Example 1. FIG. 14 is a graph showing the maximum temperature of the exothermic element in Simulation Example 1. FIG. 15 is a schematic plan view of the cooling device of the second embodiment used in Simulation Example 2. FIG. 16 is a graph showing the maximum temperature of the exoergic element in Simulation Example 2. FIG.

Several embodiments of the invention are described below with reference to the drawings.

1 to 5 are diagrams for explaining a cooling device according to a first embodiment of the present invention.

A cooling device 1 of the first embodiment is for cooling a heat-generating element 11, as shown in FIGS. Examples of the exothermic element 11 include semiconductor elements such as power semiconductor elements (eg, IGBT elements).

The cooling device 1 is provided with a plurality of cooling device constituent members joined and integrated in a laminated manner. 6, a buffer layer 7 and a cooling member 8; Then, these are laminated in the order described above from top to bottom and joined together by a predetermined joining means, whereby the cooling device 1 is formed.

Note that the cooling member 8 is not shown in FIG. Cooling members are not shown in FIGS. 8 and 10, which will be described later.

The predetermined joining means mentioned above is not limited, and examples thereof include brazing, clad rolling, and sintering (eg, discharge plasma sintering).

The upper wiring layer 2 is also called an upper circuit layer, and has a flat upper surface 3 including an element mounting area (shown by cross-hatching in FIG. 2) 3a on which the exothermic element 11 is mounted. . The element mounting region 3 a is located substantially at the center of the upper surface 3 of the upper wiring layer 2 . As shown in FIG. 1, the heat-generating element 11 is mounted on the element-mounting region 3a by bonding with a solder layer 12. As shown in FIG. The solder layer 12 is made of tin alloy (Sn alloy) or the like.

If the exothermic element 11 is a semiconductor element, the semiconductor element module is formed by mounting the semiconductor element on the element mounting region 3a on the upper surface 3 of the upper wiring layer 2. FIG.

A detailed configuration of the upper wiring layer 2 will be described later.

The insulating layer 5 has electrical insulating properties and is made of _a ceramic material such as aluminum nitride (AlN), silicon nitride ( _Si3N4 ), alumina ( _Al2O3 ), or the _like . The upper wiring layer 2 is bonded to the upper surface of the insulating layer 5 .

The lower wiring layer 6 is also called a lower circuit layer, and is made of a metal material (eg, aluminum, copper) or the like. Furthermore, the lower wiring layer 6 is bonded to the lower surface of the insulating layer 5 .

The buffer layer 7 is a layer for relaxing stress such as thermal stress generated in the cooling device 1, and is made of a metal material (eg, aluminum, copper) or the like. Furthermore, the buffer layer 7 is bonded to the lower surface of the lower wiring layer 6 .

The cooling member 8 is a plate-like member for cooling the exothermic element 11, and a cooling plate is used as the cooling member 8 in the first embodiment. The cooling member 8 is made of a metal material (eg, aluminum, copper) or the like, and is joined to the lower surface of the buffer layer 7 .

In addition, in the present invention, the cooling member 8 is not limited to being a cooling plate. Alternatively, for example, a heat dissipation member (eg, a heat sink, heat dissipation plate) that dissipates the heat of the exothermic element 11 may be used, or a liquid cooling type may be used. When the cooling member 8 is of a liquid-cooling type, the cooling member 8 is generally provided with a flow path through which a cooling liquid (for example, cooling water) as a cooling medium flows.

In the cooling device 1, the heat generated in the exothermic element 11 is conducted from the exothermic element 11 to the solder layer 12, the upper wiring layer 2, the insulating layer 5, the lower wiring layer 6, the buffer layer 7 and the cooling member 8 in order. As a result, the exothermic element 11 is cooled and its temperature is lowered.

Arrows X, Y, and Z in the drawing indicate the longitudinal direction X and the lateral direction of each component (upper wiring layer 2, insulating layer 5, lower wiring layer 6, buffer layer 7, and cooling member 8) of cooling device 1, respectively. Direction Y and thickness direction Z are indicated. The longitudinal direction X, the transverse direction Y and the thickness direction Z are, for example, orthogonal to each other. In addition, the longitudinal direction X, the lateral direction Y and the thickness direction Z of each structural member match the longitudinal direction, the lateral direction and the thickness direction of the cooling device 1 .

The upper wiring layer 2 has a longitudinal direction X and a transverse direction Y, and as shown in FIG. 4, the upper wiring layer 2 has a substantially rectangular shape in plan view.

The insulating layer 5 has a longitudinal direction X and a lateral direction Y, and the shape of the insulating layer 5 in plan view is substantially rectangular.

The lower wiring layer 6 has a longitudinal direction X and a lateral direction Y, and the shape of the lower wiring layer 6 in plan view is substantially rectangular.

The buffer layer 7 has a longitudinal direction X and a lateral direction Y, and the shape of the buffer layer 7 in plan view is substantially rectangular.

The cooling member 8 has a longitudinal direction X and a lateral direction Y, and the shape of the cooling member 8 in plan view is substantially rectangular.

The length of the upper wiring layer 2 (that is, the length in the longitudinal direction X of the upper wiring layer 2) and the width (that is, the length of the upper wiring layer 2 in the transverse direction Y) are longer than the length and width of the insulating layer 5, respectively. small. The length and width of the lower wiring layer 6 are substantially equal to the length and width of the upper wiring layer 2, respectively. The length and width of the buffer layer 7 are substantially equal to the length and width of the upper wiring layer 2, respectively. The length and width of the cooling member 8 are greater than the length and width of the upper wiring layer 2, respectively.

In the cooling device 1, the longitudinal direction X and the lateral direction Y of the upper wiring layer 2, the insulating layer 5, the lower wiring layer 6, the buffer layer 7, and the cooling member 8 are aligned with each other in plan view. are stacked so that their centers are also aligned with each other.

The thickness of the upper wiring layer 2 is not limited, and is preferably in the range of 0.1 to 2 mm. The thickness of the insulating layer 5 is not limited, and is preferably in the range of 0.1 to 2 mm, for example. The thickness of the lower wiring layer 6 is not limited, and preferably ranges from 0.1 to 2 mm. The thickness of the buffer layer 7 is not limited, and preferably ranges from 0.1 to 3 mm. The thickness of the cooling member 8 is not limited, and preferably ranges from 0.2 to 3 mm.

In addition, in the present invention, the shape of each structural member of the cooling device 1 in a plan view is not limited to a substantially rectangular shape, and may be, for example, a substantially square shape.

The heat-generating element 11 has a substantially square shape in plan view, and the heat-generating element 11 is positioned upward so that the center position of the heat-generating element 11 coincides with the center position of the upper surface 3 of the upper wiring layer 2 in plan view. It is mounted on the element mounting area 3a on the upper surface 3 of the wiring layer 2 by bonding with the solder layer 12. As shown in FIG.

In the present invention, the planar shape of the exothermic element 11 is not limited to a substantially square shape, and may be, for example, a substantially rectangular shape.

A detailed configuration of the upper wiring layer 2 will be described below.

As shown in FIG. 2, the upper wiring layer 2 is composed of a plurality of segments divided by a dividing plane 4 passing through an element mounting region 3a on the upper surface 3 of the upper wiring layer 2. As shown in FIG. In the first embodiment, the dividing surface 4 passes straight through the element mounting region 3 a on the upper surface 3 of the upper wiring layer 2 in the lateral direction Y of the upper wiring layer 2 . Therefore, the upper wiring layer 2 is composed of two segments 2A and 2B as the plurality of segments described above.

Here, for convenience of explanation, one of the two segments 2A and 2B is called "first segment 2A" and the other is called "second segment 2B".

The first segment 2A and the second segment 2B are adjacent to each other in the longitudinal direction X of the upper wiring layer 2, and are integrally joined to each other at the dividing surface 4 by a predetermined joining means (eg, brazing). there is

Further, the upper wiring layer 2 is made of an aluminum-carbon particle composite material (21, see FIG. 5). Therefore, the first segment 2A and the second segment 2B are each made of an aluminum-carbon particle composite material.

A composite material has an anisotropic thermal conductivity. The arrows a, b and c in FIGS. 2 and 3 indicate the three orthogonal directions of the Cartesian coordinates defined for the composite. The a-direction indicates the direction in which the composite has the highest thermal conductivity. The direction b indicates the direction in which the composite material has a high thermal conductivity. The c-direction indicates the direction in which the thermal conductivity of the composite material is lower than the thermal conductivity in the a-direction and the thermal conductivity in the b-direction.

That is, in the thermal conductivity of the composite, the thermal conductivity in the a direction of the composite is "ka", the thermal conductivity in the b direction of the composite is "kb", and the thermal conductivity in the c direction of the composite is When "kc", ka, kb and kc satisfy the following formula 1.

ka≧kb>kc (Formula 1).

In the composite material, the plane AB formed by the a direction and the b direction is the high thermal conductivity plane (indicated by the two-dot chain line) of the composite material, and the c direction, which is perpendicular to the high thermal conductivity plane AB, is the low thermal conductivity direction of the composite material. is.

ka and kb are not limited, and each is preferably 400 W/(m·K) or more. kc is not limited and is preferably 30 W/(m·K) or more.

The composite material is not limited as long as it has anisotropy in thermal conductivity as described above, and preferably includes an aluminum matrix and carbon particles (including carbon powder) dispersed in the aluminum matrix. It should contain In this case, the thermal conductivity of the upper wiring layer 2 can be reliably increased.

Carbon particles have an anisotropic thermal conductivity. It has The plane of the carbon particles means a plane perpendicular to the thickness direction of the carbon particles, and the plane direction of the carbon particles means a direction parallel to the plane of the carbon particles.

As the carbon particles, flake graphite particles (including flake graphite powder) and the like are used.

The carbon particles in the composite material are dispersed in the aluminum matrix while being oriented in the AB direction of the high thermal conductivity plane of the composite material.

The method for producing the composite material is not limited, and examples thereof include a molten metal stirring method, a powder sintering method, a powder extrusion method, and a coating and sintering method.

The molten metal stirring method is a method in which carbon particles are put into molten aluminum, stirred and mixed, and cooled to solidify. The powder sintering method is a method of pressurizing and sintering a mixture of aluminum powder and carbon particles. The powder extrusion method is a method of extruding a mixture of aluminum powder and carbon particles. The coating and sintering method is a method of stacking a plurality of coated plates obtained by coating carbon particles on an aluminum plate and sintering and integrating them.

In the first embodiment, the composite material is manufactured by the coating and sintering method, and FIG. 5 shows a schematic perspective view of this composite material 21. As shown in FIG.

Composite material 21 includes an aluminum matrix and carbon particles dispersed in the aluminum matrix. For example, scale-like graphite particles are used as the carbon particles.

Arrows L, M and N in FIG. 5 indicate the length direction, width direction and thickness direction of the composite material 21, respectively. In this composite material 21, when the carbon particles are coated on the aluminum plate, the carbon particles are oriented in the surface direction of the aluminum plate. 21 in the direction parallel to the plane perpendicular to the thickness direction N). Therefore, the a-direction and b-direction of the composite material 21 are aligned with the length direction L and width direction M of the composite material 21, and therefore the high thermal conductivity surface AB of the composite material 21 is parallel to the plane direction of the composite material 21. be.

The first segment 2A and the second segment 2B of the upper wiring layer 2 are formed as follows.

A cut piece 21a is obtained by cutting the composite material 21 to a predetermined thickness along a cutting plane S which is inclined with respect to the thickness direction N of the composite material 21 and parallel to the width direction M of the composite material 21 . α in FIG. 5 is the complementary angle of the inclination angle of the cut surface S with respect to the thickness direction N of the composite material 21, that is, the acute angle formed by the high thermal conductivity surface AB of the composite material 21 and the cut surface S. . This α is greater than 0° and less than 90° (ie 0°<α<90°).

Then, the cut piece 21a is formed into the first segment 2A and the second segment 2B so that both sides (that is, the cut surfaces S and S) in the thickness direction of the cut piece 21a are the upper surface 3 and the lower surface of the upper wiring layer 2, respectively. . Thereby, in each of the first segment 2A and the second segment 2B, the high thermal conductivity surface AB of the composite material 21 is inclined with respect to the downward direction d. Then, the first segment 2A and the second segment 2B are joined together at the dividing surface 4, whereby the upper wiring layer 2 is obtained.

As shown in FIGS. 2 and 3, the direction a of the composite material in the first segment 2A of the upper wiring layer 2 is a direction inclined toward the outer edge 2a of the first segment 2A in the upper wiring layer 2 with respect to the downward direction d. is. The b direction of the composite material in the first segment 2A is the direction along the upper surface 3 of the upper wiring layer 2 (that is, the upper surface 3 of the first segment 2A). It is a direction parallel to the Y direction.

The direction a of the composite material in the second segment 2B of the upper wiring layer 2 is a direction inclined toward the outer edge portion 2a of the second segment 2B in the upper wiring layer 2 with respect to the downward direction d. The inclination direction of the first segment 2A with respect to the downward direction in the a direction and the inclination direction of the second segment 2B with respect to the downward direction in the a direction are different, and in the first embodiment, they are opposite to each other. The b direction of the composite material in the second segment 2B is the direction along the upper surface 3 of the upper wiring layer 2 (that is, the upper surface 3 of the second segment 2B). It is a direction parallel to the Y direction.

In each of the first segment 2A and the second segment 2B, the downward direction d coincides with the direction from the position of the element mounting region 3a on the upper surface 3 of the upper wiring layer 2 toward the cooling member 8. FIG.

The cooling device 1 of the first embodiment has the following advantages.

In the first segment 2A of the upper wiring layer 2, the direction a is inclined with respect to the downward direction d toward the outer edge 2a of the first segment 2A in the upper wiring layer 2, and the second segment of the upper wiring layer 2 In 2B, the direction a is inclined toward the outer edge portion 2a of the second segment 2B in the upper wiring layer 2 with respect to the downward direction d. Therefore, the heat of the exothermic element 11 is conducted in the downward direction d and the plane direction in the entire upper wiring layer 2 . Therefore, both heat diffusion from the position of the element mounting region 3a on the upper surface 3 of the upper wiring layer 2 toward the cooling member 8 and heat diffusion in the planar direction within the upper wiring layer 2 occur. Thereby, the cooling performance of the cooling device 1 is improved.

Here, as shown in FIGS. 2 and 3, in the first segment 2A, the acute angle between the upper surface 3 of the upper wiring layer 2 (that is, the upper surface 3 of the first segment 2A) and the direction a is defined as θ1. In the second segment 2B, the acute angle formed by the upper surface 3 of the upper wiring layer 2 (that is, the upper surface 3 of the second segment 2B) and the direction a is assumed to be θ2.

Both θ1 and θ2 are preferably 25° or more and less than 90°. That is, it is desirable that θ1 and θ2 satisfy the following equations 2a and 2b, respectively.

25°≦θ1<90° (Formula 2a)
25°≦θ2<90° (Formula 2b).

In this case, both the heat diffusion in the direction from the position of the element mounting region 3a on the upper surface 3 of the upper wiring layer 2 toward the cooling member 8 and the heat diffusion in the planar direction within the upper wiring layer 2 are more effective. occur. Thereby, the cooling performance of the cooling device 1 is further improved.

In particular, both θ1 and θ2 are preferably 35° or more and 70° or less. That is, it is particularly desirable that .theta.1 and .theta.2 satisfy the following equations 3a and 3b, respectively.

35°≦θ1≦70° (Formula 3a)
35°≦θ2≦70° (Formula 3b).

In this case, the cooling performance of the cooling device 1 is further improved.

Furthermore, it is desirable that the difference θ1−θ2 between θ1 and θ2 is in the range of ±10°. In this case, the heat of the exothermic element 11 is diffused substantially uniformly to the first segment 2A and the second segment 2B of the upper wiring layer 2. FIG. Thereby, the cooling performance of the cooling device 1 is further improved.

6 to 8 are diagrams illustrating a cooling device 101 according to a second embodiment of the invention. In these figures, elements having the same functions as the elements of the cooling device 1 of the first embodiment are assigned reference numerals with 100 added. The second embodiment will be described below, focusing on the differences from the first embodiment.

As shown in FIGS. 6 and 8, in the cooling device 101 of the second embodiment, the dividing surface 104 of the upper wiring layer 102 is arranged such that the element mounting region 103a of the upper surface 103 of the upper wiring layer 102 is aligned with the longitudinal direction of the upper wiring layer 102 . It passes straight through X. Therefore, the first segment 102A and the second segment 102B of the upper wiring layer 102 are adjacent to each other in the lateral direction Y of the upper wiring layer 102 and are joined together at the dividing surface 104. As shown in FIG.

As shown in FIGS. 6 and 7, the direction a of the composite material in the first segment 102A of the upper wiring layer 102 is a direction inclined toward the outer edge 102a of the first segment 102A in the upper wiring layer 102 with respect to the downward direction d. is. The b direction of the composite material in the first segment 102A is the direction along the upper surface 103 of the upper wiring layer 102 (that is, the upper surface 103 of the first segment 102A). It is a direction parallel to X.

The direction a of the composite material in the second segment 102B of the upper wiring layer 102 is a direction inclined toward the outer edge portion 102a of the second segment 102B in the upper wiring layer 102 with respect to the downward direction d. The direction in which the first segment 102A is inclined downward in the direction a and the direction in which the second segment 102B is inclined downward in the direction a are different and opposite to each other in the second embodiment. The b direction of the composite material in the second segment 102B is the direction along the upper surface 103 of the upper wiring layer 102 (that is, the upper surface 103 of the second segment 102B). It is a direction parallel to X.

In the cooling device 101, both θ1 and θ2 are preferably 25° or more and less than 90° for the same reason as the cooling device 1 of the first embodiment, and in particular, θ1 and θ2 are both 35° or more and 70° or less. Further, it is desirable that the difference θ1-θ2 between θ1 and θ2 is in the range of ±10°.

Furthermore, in the cooling device 101, the dividing surface 104 of the upper wiring layer 102 passes through the element mounting region 103a of the upper surface 103 of the upper wiring layer 102 in the longitudinal direction X of the upper wiring layer 102. The thermal diffusion in the planar direction of is particularly effective. As a result, the dividing surface 4 of the upper wiring layer 2 passes through the element mounting region 3a on the upper surface 3 of the upper wiring layer 2 in the lateral direction Y of the upper wiring layer 2 as in the cooling device 1 of the first embodiment. The cooling performance of the cooling device 101 is improved compared to the case where the cooling device 101 is provided.

9 to 12 are diagrams illustrating a cooling device 201 according to a third embodiment of the invention. In these figures, the elements having the same function as the elements of the cooling device 1 of the first embodiment are assigned reference numerals with 200 added. The third embodiment will be described below, focusing on the differences from the first embodiment.

As shown in FIGS. 9 to 11, in the cooling device 201 of the third embodiment, the upper wiring layer 202 passes through the element mounting region 203a of the upper surface 203 of the upper wiring layer 202 in the longitudinal direction X of the upper wiring layer 202. It is composed of four segments 202A, 202B, 202C and 202D divided by a first dividing surface 204a and a second dividing surface 204b passing through the element mounting region 203a in the lateral direction Y of the upper wiring layer 202. FIG.

The first divided surface 204 a passes straight through the element mounting region 203 a on the upper surface 203 of the upper wiring layer 202 in the longitudinal direction X of the upper wiring layer 202 . The second dividing surface 204b passes straight through the element mounting region 203a of the upper surface 203 of the upper wiring layer 202 in the lateral direction Y of the upper wiring layer 202. As shown in FIG.

Here, for convenience of explanation, the four segments are respectively called "first segment 202A", "second segment 202B", "third segment 202C" and "fourth segment 202D".

The first segment 202 A and the second segment 202 B are adjacent to each other in the longitudinal direction X of the upper wiring layer 202 . The third segment 202</b>C and the fourth segment 202</b>D are adjacent to each other in the longitudinal direction X of the upper wiring layer 202 . The first segment 202A and the third segment 202C are adjacent to each other in the lateral direction Y of the upper wiring layer 202. As shown in FIG. The second segment 202B and the fourth segment 202D are adjacent to each other in the lateral direction Y of the upper wiring layer 202. As shown in FIG. Then, as shown in FIG. 11, the first to fourth segments 202A to 202D are joined and integrated with each other at the first split surface 204a and the second split surface 204b by a predetermined joining means (eg, brazing). .

As shown in FIG. 12, the aluminum-carbon particle composite material 221 used as the material of the upper wiring layer 202 is manufactured by the coating and sintering method, like the aluminum-carbon particle composite material 21 of the first embodiment. It is what was done. Each segment of the upper wiring layer 202 is formed as follows.

A cut piece 221a is obtained by cutting the composite material 221 to a predetermined thickness along a cutting plane S inclined with respect to the thickness direction N of the composite material 221 and with respect to the width direction M of the composite material 221. . α in FIG. 12 is the complementary angle of the inclination angle of the cut surface S with respect to the thickness direction N of the composite material 221 . This α is greater than 0° and less than 90° (ie 0°<α<90°). β in the figure is the complementary angle of the inclination angle of the cut surface S with respect to the width direction M of the composite material 221 . This β is greater than 0° and less than 90° (ie 0°<β<90°).

Then, the first to fourth segments 202A to 202D are formed from the cut piece 221a so that both sides (that is, the cut surfaces S and S) in the thickness direction of the cut piece 221a correspond to the upper surface 203 and the lower surface of the upper wiring layer 202, respectively. . Accordingly, in each of the first to fourth segments 202A to 202D, the high thermal conductivity surface AB of the composite material 221 is inclined with respect to the downward direction d. Then, as shown in FIG. 11, the first to fourth segments 202A to 202D are joined together at the first dividing surface 204a and the second dividing surface 204b, whereby the upper wiring layer 202 is obtained.

As shown in FIG. 9, the a direction of the composite material in the first segment 202A of the upper wiring layer 202 is a direction inclined toward the outer edge portion 202a of the first segment 202A in the upper wiring layer 202 with respect to the downward direction d. . The b direction of the composite material in the first segment 202A is the direction along the upper surface 203 of the upper wiring layer 202 (that is, the upper surface 203 of the first segment 202A). , and is inclined with respect to the lateral direction Y of the upper wiring layer 202 .

The direction a of the composite material in the second segment 202B of the upper wiring layer 202 is a direction inclined toward the outer edge portion 202a of the second segment 202B in the upper wiring layer 202 with respect to the downward direction d. The b direction of the composite material in the second segment 202B is the direction along the upper surface 203 of the upper wiring layer 202 (that is, the upper surface 203 of the second segment 202B). , and is inclined with respect to the lateral direction Y of the upper wiring layer 202 .

The direction a (not shown) of the composite material in the third segment 202C of the upper wiring layer 202 is a direction inclined toward the outer edge 202a of the third segment 202C in the upper wiring layer 202 with respect to the downward direction d. The b direction of the composite material in the third segment 202C is a direction along the upper surface 203 of the upper wiring layer 202 (that is, the upper surface 203 of the third segment 202C). , and is inclined with respect to the lateral direction Y of the upper wiring layer 202 .

The direction a (not shown) of the composite material in the fourth segment 202D of the upper wiring layer 202 is a direction inclined toward the outer edge 202a of the fourth segment 202D in the upper wiring layer 202 with respect to the downward direction d. The inclination direction of the first segment 202A downward in the a direction, the inclination direction of the second segment 202B downward in the a direction, the inclination direction of the third segment 202C downward in the a direction, and the inclination direction of the fourth segment 202D in the a direction It is different from the tilt direction with respect to the downward direction. The b direction of the composite material in the fourth segment 202D is the direction along the upper surface 203 of the upper wiring layer 202 (that is, the upper surface 203 of the fourth segment 202D). , and is inclined with respect to the lateral direction Y of the upper wiring layer 202 .

Here, although not shown, in the first segment 202A, the acute angle formed by the upper surface 203 of the upper wiring layer 202 (that is, the upper surface 203 of the first segment 202A) and the direction a is defined as θ1, and the second segment 202B , the acute angle formed by the upper surface 203 of the upper wiring layer 202 (that is, the upper surface 203 of the second segment 202B) and the direction a is defined as θ2. Let θ3 be the acute angle between the upper surface 203 of the segment 202C and the direction a. The side angle is θ4.

In the cooling device 201, for the same reason as the cooling device 1 of the first embodiment, θ1 to θ4 are preferably 25° or more and less than 90°, and in particular, θ1 to θ4 are all 35° or more and 70° or less. Further, the difference between the two angles selected from θ1 to θ4 (that is, θ1-θ2, θ1-θ3, θ1-θ4, θ2-θ3, θ2-θ4, θ3-θ4) is ± A range of 10° is desirable.

Although several embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and can be variously modified without departing from the gist of the present invention.

In the cooling devices (1, 101) of the first and second embodiments, the upper wiring layer (2, 102) is divided into two, and in the cooling device 101 of the third embodiment, the upper wiring layer 102 is divided. Although the number is four, in the cooling device according to the present invention, the number of divisions of the upper wiring layer is not limited to two or four, and may be, for example, three or five or more. may be

The cooling devices (1, 101, 201) of the first to third embodiments all have lower wiring layers (6, 106, 206), but the cooling device according to the present invention does not have lower wiring layers. may or may not be provided.

In the cooling devices (1, 101, 201) of the first to third embodiments, the plurality of segments forming the upper wiring layers (2, 102, 202) are divided at the dividing planes (4, 104, 204a, 204b). Although they are joined to each other, in the cooling device according to the present invention, the plurality of segments forming the upper wiring layer may or may not be joined to each other at the dividing surfaces. If the segments are not joined together, it is desirable that the segments are arranged in contact with each other at the parting plane.

In the cooling device (1, 101, 201) of the first to third embodiments, the lower wiring layer (6, 106, 206), the buffer layer (7, 107, 207) and the cooling member (8, 108, 208) are metal materials, but in the cooling device according to the present invention, the materials of the lower wiring layer, the buffer layer, and the cooling member are not limited to metal materials. material or other materials.

In order to evaluate the cooling performance of the cooling device according to the present invention, the maximum temperature of the exothermic element mounted in the element mounting area on the upper surface of the upper wiring layer of the cooling device was simulated under various conditions using the finite element method. Examined.

General-purpose structural analysis software "ANSYS mechanical" manufactured by ANSYS was used in the simulations shown below.

<Simulation example 1>
In Simulation Example 1, the cooling device 1 of the first embodiment was used as the model. FIG. 13 is a schematic plan view of the cooling device 1 in this case. Note that the cooling member 8 is not shown in the figure.

As shown in FIG. 13, the heat-generating element 11 has a square shape in plan view, and is arranged so that the center position of the heat-generating element 11 coincides with the center position of the upper surface 3 of the upper wiring layer 2 in plan view. A heat generating element 11 is bonded to an element mounting area 3a on the upper surface 3 of the upper wiring layer 2 with a solder layer 12 (see FIG. 1).

The dividing surface 4 that divides the upper wiring layer 2 into the first segment 2A and the second segment 2B divides the element mounting region 3a of the upper surface 3 of the upper wiring layer 2 into the upper wiring layer 2 as described in the first embodiment. 2 passes straight in the transverse direction Y.

Furthermore, in this cooling device 1, θ1 (see FIG. 3) in the first segment 2A of the upper wiring layer 2 and θ2 (see FIG. 3) in the second segment 2B of the upper wiring layer 2 are set equal, and the angle is θ. That is, θ≡θ1=θ2.

Table 1 shows the dimensions, materials, and thermal conductivity of each component of the cooling device 1, the exothermic element 11, and the solder layer 12 set in this simulation example 1. In the "material" column in the table, "Si" is silicon, "Sn alloy" is a tin alloy, "Al-C composite material" is an aluminum-carbon particle composite material, "AlN" is aluminum nitride, "Pure Al" means pure aluminum and "Al alloy" means aluminum alloy, respectively. In addition, "Si", "Sn alloy", "Al-C composite material", "AlN", "pure Al" and "Al alloy" in the "Material" column in Table 2 described later have the same meaning as above. be.

Then, the maximum temperature of the exothermic element 11 was examined by simulation when θ was changed from 0° to 90°. The results are shown in FIG. In the figure, the vertical axis represents the maximum temperature of the exothermic element 11 .

In this simulation example 1, the maximum temperature of the exothermic element 11 was calculated by performing steady heat transfer analysis. Assuming that the exothermic element 11 generates heat uniformly on the upper surface of the exothermic element 11 , a heat source of 200 W was set on the upper surface of the exothermic element 11 . This heat is mainly transmitted from the exothermic element 11 through the solder layer 12, the upper wiring layer 2, the insulating layer 5, the lower wiring layer 6, and the buffer layer 7 in order, and is finally dissipated from the cooling member 8. . Therefore, the above process was simulated by setting a heat transfer coefficient of 100000 W/(m ² ·K) on the bottom surface of the cooling member 8 . The environmental temperature was set at 25°C.

As shown in the figure, when θ is 25° or more and less than 90° (that is, when 25°≦θ<90°), the maximum temperature of the exothermic element 11 is low, and θ is 35° or more and 70° or less. (that is, 35°≦θ≦70°), the maximum temperature of the exothermic element 11 is even lower, and if θ is 49° (that is, θ=49°), the temperature of the exothermic element 11 is The maximum temperature was the lowest, and the temperature at that time was 69.234°C.

Therefore, when 25°≦θ<90°, the cooling performance of the cooling device 1 is high, when 35°≦θ≦70°, the cooling performance of the cooling device 1 is even higher, and when θ=49°, the cooling device 1 had the highest cooling performance.

<Simulation example 2>
In simulation example 2, the cooling device 101 of the second embodiment was used as the model. FIG. 15 is a schematic plan view of the cooling device 101 in this case. Note that the cooling member 108 is not shown in the figure.

A dividing surface 104 obtained by dividing the upper wiring layer 102 into the first segment 102A and the second segment 102B is, as described in the second embodiment, the element mounting region 103a of the upper surface 103 of the upper wiring layer 102. 102 passes straight through in the longitudinal direction X.

Furthermore, in this cooling device 1101, as in Simulation Example 1, θ1 (see FIG. 7) in the first segment 102A of the upper wiring layer 102 and θ2 (see FIG. 7) in the second segment 102B of the upper wiring layer 102 are equal. and the angle is θ. That is, θ≡θ1=θ2.

Table 2 shows the dimensions, materials, and thermal conductivity of each component of the cooling device 101, the heat-generating element 111, and the solder layer set in this simulation example 2.

Then, under the same simulation conditions as those applied in Simulation Example 1, the maximum temperature of the exothermic element 111 was examined by simulation when θ was varied from 0° to 90°. The results are shown in FIG.

As shown in the figure, similarly to the results of Simulation Example 1, the cooling performance of the cooling device 101 is high when 25°≦θ<90°, and the cooling performance of the cooling device 101 is high when 35°≦θ≦70°. The cooling performance was even higher, and the cooling performance of the cooling device 101 was the highest when θ=49°. The maximum temperature of the exothermic element 111 was 69.185° C. when θ=49°.

Further, the maximum temperature of the exothermic element 111 of 69.185° C. when θ=49° in this simulation example 2 is the maximum temperature of the exothermic element 11 of 69.234° C. when θ=49° in the simulation example 1. lower than Therefore, the dividing surface 4 of the upper wiring layer 2 passes through the element mounting region 3a of the upper surface 3 of the upper wiring layer 2 in the lateral direction Y of the upper wiring layer 2 as in the cooling device 1 of the first embodiment. As in the cooling device 101 of the second embodiment, the dividing surface 104 of the upper wiring layer 102 passes through the element mounting region 103a of the upper surface 103 of the upper wiring layer 102 in the longitudinal direction X of the upper wiring layer 102. It could be confirmed that the cooling performance of the cooling device is higher when the

INDUSTRIAL APPLICABILITY The present invention can be applied to a cooling device for cooling exothermic elements such as electronic elements (eg, semiconductor elements).

1, 101, 201: cooling devices 2, 102, 202: upper wiring layers 2A, 102A, 202A: first segments 2B, 102B, 202B: second segments 3, 103, 203: upper wiring layer upper surfaces 3a, 103a, 203a: element mounting regions 4, 104, 204a, 204b: dividing surfaces 8, 108, 208: cooling members 11, 111, 211: exothermic element X: longitudinal direction Y of upper wiring layer (wiring layer): upper wiring layer ( wiring layer)

Claims (6)

A cooling device for cooling a heat-generating element,
A wiring layer having an upper surface including an element mounting region on which a heat-generating element is mounted; and a cooling member disposed below the wiring layer,
The wiring layer is formed of an aluminum-carbon particle composite material,
The composite material has, in orthogonal coordinates, a direction with the highest thermal conductivity, a b direction with the highest thermal conductivity, and a thermal conductivity lower than the thermal conductivity in the a direction and the thermal conductivity in the b direction. c direction and
When the thermal conductivities in the a-direction, b-direction, and c-direction are ka, kb, and kc, respectively, ka, kb, and kc satisfy the following formula 1,
ka≧kb>kc (Formula 1)
Further, the wiring layer is composed of a plurality of segments divided by a dividing plane passing through the element mounting region on the upper surface of the wiring layer,
In each of the segments of the wiring layer, the a-direction is a direction inclined downward toward the outer edge of the segment in the wiring layer, and the b-direction is a direction along the upper surface of the wiring layer. the law of nature,
Furthermore, in the two segments that are adjacent to each other via the dividing surface, the direction of inclination of one segment with respect to the downward direction of the a direction is different from the direction of inclination of the other segment with respect to the downward direction of the direction a. cooling system. the wiring layer has a longitudinal direction and a lateral direction;
The plurality of segments includes a first segment and a second segment as the two segments adjacent to each other through the dividing surface ,
The first segment and the second segment are joined to each other at the dividing surface,
the dividing surface passes through the element mounting region on the upper surface of the wiring layer in the longitudinal direction of the wiring layer;
2. The cooling device according to claim 1, wherein the inclination direction of the first segment with respect to the downward direction of the a direction and the inclination direction of the second segment with respect to the downward direction of the a direction are opposite to each other. 3. The cooling device according to claim 1, wherein in each of the segments of the wiring layer, an acute angle formed by the upper surface and the direction a is 25 degrees or more and less than 90 degrees. 3. The cooling device according to claim 1, wherein, in each of the segments of the wiring layer, an acute angle formed between the upper surface and the direction a is 35[deg.] or more and 70[deg.] or less. The plurality of segments includes a first segment and a second segment as the two segments adjacent to each other through the dividing surface ,
a direction of inclination of the first segment with respect to the downward direction of the a direction and a direction of inclination of the second segment with respect to the downward direction of the a direction are opposite to each other;
In the first segment, an acute angle formed by the upper surface and the direction a is θ1,
In the second segment, when the acute angle formed by the upper surface and the direction a is θ2,
The cooling device according to any one of claims 1 to 4, wherein the difference θ1-θ2 between θ1 and θ2 is within a range of ±10°. 2. The cooling device of claim 1, wherein said plurality of segments includes at least three segments.

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