WO2019159776A1

WO2019159776A1 - Cooling device

Info

Publication number: WO2019159776A1
Application number: PCT/JP2019/004174
Authority: WO
Inventors: 駿介倉橋; 克樹奥野; 好成奥野; 南　和彦; 誠二松島
Original assignee: 昭和電工株式会社
Priority date: 2018-02-16
Filing date: 2019-02-06
Publication date: 2019-08-22
Also published as: CN111480228A; JP7201658B2; JPWO2019159776A1

Abstract

This cooling device (1) is equipped with a plurality of cooling device components that are integrally joined in a laminated state, wherein the plurality of components comprise an electric insulation layer (3), an upper heat conduction member (11) disposed on the upper side of the electric insulation layer (3), and a lower heat conduction member (12) disposed on the lower side of the electric insulation layer (3). In the upper heat conduction member (11), the thermal conductivity in the thickness direction Z and the thermal conductivity in a first direction parallel to the flat surface are higher than the thermal conductivity in a second direction perpendicular to the thickness direction and the first direction. In the lower heat conduction member (12), the thermal conductivity in the thickness direction Z and the thermal conductivity in a first direction parallel to the flat surface are higher than the thermal conductivity in a second direction perpendicular to the thickness direction Z and the first direction. The upper heat conduction member (11) and the lower heat conduction member (12) are arranged in such a manner that the first direction of the upper heat conduction member (11) intersects with the first direction of the lower heat conduction member (12) in a plan view.

Description

Cooling system

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

Here, although the vertical direction of the cooling device according to the present invention is not limited, in the present specification and claims, in order to facilitate understanding of the configuration of the cooling device, a heat generating element in the cooling device is mounted. The side to be applied is defined as the upper side of the cooling device and the opposite side is defined as the lower side of the cooling device.

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

In this specification, unless otherwise specified in the text, the term “aluminum” is used to include both pure aluminum and aluminum alloys, and the term “copper” refers to both pure copper and copper alloys. Used to mean including.

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 stacked. A metal-carbon fiber composite material is known which is bonded and integrated in a state of being formed, and International Publication No. 2009/051094 (Patent Document 3) describes a metal-scale piece using scaly graphite particles as carbon particles. A graphite particle composite is disclosed.

As other patent documents disclosing metal-carbon particle composite materials, JP-A-2015-25158 (Patent Document 4), JP-A-2015-217655 (Patent Document 5), JP-A-2017-88913 (Patent Document) Reference 6).

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.

Incidentally, for example, a cooling device that cools a semiconductor element as a heat generating element is required to have high thermal conductivity in order to obtain high cooling performance. Therefore, it is possible to use a metal-carbon particle composite material as a material of a member constituting the cooling device, as disclosed in JP-A-2016-132113 (Patent Document 7), JP-A-2016-152241 (Patent Document 8), No. 2016-207799 (Patent Document 9) and the like.

Japanese Patent Laying-Open No. 2012-222160 (Patent Document 10) discloses a material for a heat diffusion plate of a heating element module that has high thermal conductivity in two of three directions orthogonal to each other and low heat in the other direction. It discloses that a carbon-based material having conductivity and high orientation is used.

Such a cooling device includes a plurality of cooling device constituent members joined and integrated in a stacked manner, and is arranged as an insulating layer made of a ceramic material or the like as the plurality of constituent members. An upper heat conductive member (for example, an upper wiring layer) and a lower heat conductive member (for example, a lower wiring layer, a buffer layer, and a cooling member) disposed below the insulating layer are included. That is, the insulating layer is disposed between the upper heat conductive member and the lower heat conductive member. The exothermic element is mounted on the upper heat conductive member.

Japanese Patent No. 5150905 Japanese Patent No. 5145591 International Publication No. 2009/051094 Japanese Patent Laying-Open No. 2015-25158 JP2015-217655A JP 2017-88913 JP 2016-132113 A Japanese Unexamined Patent Publication No. 2016-152241 Japanese Unexamined Patent Publication No. 2016-207799 JP 2012-222160 A

In recent years, cooling devices having such a laminated structure have been required to have higher cooling performance as the heat generating elements have higher performance and heat generation.

Therefore, an object of the present invention is to provide a cooling device having high cooling performance. Other objects and advantages of the present invention will become apparent from the following preferred embodiments.

The present invention provides the following means.

[1] A cooling device for cooling an exothermic element,
A plurality of cooling device components that are joined and integrated in a stacked manner,
As the plurality of constituent members, including an insulating layer, an upper heat conductive member disposed on the upper side of the insulating layer, and a lower heat conductive member disposed on the lower side of the insulating layer,
The upper heat conductive member has a heat conductivity in the thickness direction and a heat conductivity in the first direction along the plane higher than the heat conductivity in the second direction perpendicular to the thickness direction and the first direction. And
The lower heat conductive member has a heat conductivity in the thickness direction and a heat conductivity in the first direction along the plane higher than the heat conductivity in the second direction perpendicular to the thickness direction and the first direction. And
The cooling device, wherein the upper heat conducting member and the lower heat conducting member are arranged such that the first direction of the upper heat conducting member and the first direction of the lower heat conducting member intersect in plan view .

[2] The thickness of the upper heat conducting member is different from the thickness of the lower heat conducting member,
At least the thicker heat conducting member of the upper heat conducting member and the lower heat conducting member has a longitudinal direction and a short side direction, and the first direction of the thicker heat conducting member is the thicker heat conducting member. 2. The cooling device according to item 1, wherein the cooling device is oriented in the longitudinal direction of the member.

[3] The cooling device according to item 2, wherein the thicker heat conduction member is the lower heat conduction member.

[4] The cooling device according to item 1, wherein the lower heat conductive member has a longitudinal direction and a short side direction, and the first direction of the lower heat conductive member faces the longitudinal direction of the lower heat conductive member.

[5] At least one of the upper heat conductive member and the lower heat conductive member is formed of a metal-anisotropic particle composite material including a metal matrix and anisotropic particles dispersed in the metal matrix. ,
5. The cooling device according to any one of items 1 to 4, wherein the anisotropic particles include both scaly graphite particles and carbon fibers.

[6] The plurality of constituent members further includes an upper buffer layer disposed on an upper side of the upper heat conducting member,
The linear expansion coefficient in the same direction as the direction of the minimum linear expansion coefficient of the upper thermal conductive member in the upper buffer layer is smaller than the minimum linear expansion coefficient of the linear thermal expansion coefficient in the planar direction of the upper thermal conductive member. 6. The cooling device according to any one of items 1 to 5, wherein the is small.

The present invention has the following effects.

In the preceding paragraph 1, the upper heat conducting member and the lower heat conducting member are arranged so that the first direction of the upper heat conducting member and the first direction of the lower heat conducting member intersect in plan view, thereby generating a heat generating element. The thermal conductivity of the cooling device in the direction from the position toward the cooling member increases. Thereby, a cooling device having high cooling performance can be provided. Further, it is not always necessary to perform complicated processing on the heat conducting member, and therefore the cooling device can be manufactured at low cost.

In any of the preceding items 2 to 4, the cooling performance of the cooling device can be improved.

In the preceding

paragraphs

5 and 6, both the cooling performance of the cooling device can be improved, and further, the stress such as the thermal stress generated in the cooling device can be relaxed, so that the reliability of the cooling device can be improved.

FIG. 1 is a schematic perspective view of a cooling device according to a first embodiment of the present invention. FIG. 2 is a schematic front view of the cooling device. FIG. 3 is a schematic perspective view for explaining the orientation of the anisotropic material. FIG. 4 is a schematic perspective view of a cooling device according to the second embodiment of the present invention. FIG. 5 is a schematic perspective view of a cooling device according to a third embodiment of the present invention. FIG. 6 is a schematic perspective view of a cooling device according to a fourth embodiment of the present invention. FIG. 7 is a schematic front view of the cooling device used for evaluating the cooling performance of the cooling device by simulation. FIG. 8 is a schematic plan view of the cooling device.

Next, some embodiments of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, the cooling device 1 according to the first embodiment of the present invention is for the exothermic element 8, that is, for cooling the exothermic element 8. Examples of the exothermic element 8 include semiconductor elements such as power semiconductor elements (eg, IGBT elements).

The cooling device 1 includes a plurality of cooling device constituent members that are joined and integrated in a stacked manner. Specifically, as the plurality of constituent members, the insulating layer 3 and an upper side of the insulating layer 3 are arranged. And at least one lower heat conductive member 12 disposed on the lower side of the insulating layer 3.

In the first embodiment, the number of the upper heat conducting members 11 is one, which is the upper wiring layer 2. There are a plurality of lower heat conducting members 12, specifically three. For convenience of explanation, when the three lower heat conductive members 12 are first to third lower heat conductive members in order from top to bottom, the first lower heat conductive members 12 are the lower wiring layer 4 and the second lower heat conductive members 12. The buffer layer 5 and the third lower heat conducting member 12 are plate-like cooling members 6. The upper wiring layer 2, the insulating layer 3, the lower wiring layer 4, the buffer layer 5 and the cooling member 6 are joined and integrated by a predetermined joining means in a state where they are laminated in this order from top to bottom. Thus, the cooling device 1 is formed.

The joining means is not limited, and brazing, clad rolling, sintering (eg, discharge plasma sintering) or the like is used.

The upper wiring layer 2 (upper heat conducting member 11) is also called an upper circuit layer, and has a flat mounting surface 1a composed of the upper surface thereof. The heat generating element 8 is joined to the substantially central portion of the mounting surface 1a with a solder layer 9. The solder layer 9 is made of a tin alloy (Sn alloy) or the like. If the exothermic element 8 is a semiconductor element, the semiconductor element is bonded to the mounting surface 1a of the upper wiring layer 2 to form the semiconductor element module 10.

The insulating layer 3 has electrical insulation and is made of a ceramic material such as aluminum nitride (AlN), silicon nitride, or alumina. The upper wiring layer 2 is bonded to the upper surface of the insulating layer 3.

The lower wiring layer 4 (first lower heat conducting member 12) is also called a lower circuit layer, and is joined to the lower surface of the insulating layer 3.

The buffer layer 5 (second lower heat conducting member 12) is a layer for relieving stress such as thermal stress generated in the cooling device 1.

The cooling member 6 (third lower heat conducting member 12) cools the heat-generating element 8, and in the first embodiment, the cooling member 6 is a cooling plate.

In the present invention, the cooling member 6 is not limited to being a cooling plate. In addition, for example, a heat radiating member that cools the heat generating element 8 by radiating the heat of the heat generating element 8 (e.g., a heat sink). , A heat radiating plate) or a heat diffusing member (eg, heat diffusing plate). Further, in the present invention, the cooling member 6 is of a liquid cooling type or an air cooling type that cools the heat generating element 8 by transferring the heat conducted from the heat generating element 8 to the cooling member 6 to the cooling medium. Also good. When the cooling member 6 is, for example, a liquid cooling type, generally, a flow path (not shown) through which a cooling liquid as a cooling medium flows is provided inside the cooling member 6.

In the cooling device 1, heat generated in the heat generating element 8 is sequentially conducted from the heat generating element 8 to the solder layer 9, the upper wiring layer 2, the insulating layer 3, the lower wiring layer 4, the buffer layer 5 and the cooling member 6. As a result, the exothermic element 8 is cooled and its temperature decreases.

The arrows X, Y, and Z in FIGS. 1 and 2 respectively indicate the longitudinal direction X of each component of the cooling device 1 (upper wiring layer 2, insulating layer 3, lower wiring layer 4, buffer layer 5 and cooling member 6). The lateral direction Y and the thickness direction Z are shown. The longitudinal direction X, the lateral direction Y, and the thickness direction Z are orthogonal to each other, for example. In addition, the longitudinal direction X, the lateral direction Y, and the thickness direction of each constituent member coincide with 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 short direction Y. In detail, the shape of the upper wiring layer 2 in plan view is a substantially rectangular shape. Further, the upper wiring layer 2 is formed of an anisotropic material having anisotropy in thermal conductivity.

The insulating layer 3 has a longitudinal direction X and a short direction Y. In detail, the shape of the insulating layer 3 in plan view is a substantially rectangular shape. Furthermore, the insulating layer 3 is made of a ceramic material as described above, and has no anisotropy in thermal conductivity.

The lower wiring layer 4 has a longitudinal direction X and a short direction Y. Specifically, the shape of the lower wiring layer 4 in plan view is substantially the same as the shape of the upper wiring layer 2 in plan view, that is, substantially rectangular. is there. Further, the lower wiring layer 4 is formed of an anisotropic material having anisotropy in thermal conductivity.

The buffer layer 5 has a longitudinal direction X and a short direction Y. In detail, the shape of the buffer layer 5 in plan view is substantially the same as the shape of the upper wiring layer 2 in plan view, that is, substantially rectangular. Furthermore, in the first embodiment, the buffer layer 5 is made of a metal material such as aluminum or copper, and has no anisotropy in thermal conductivity.

The cooling member 6 has a longitudinal direction X and a short direction Y. In detail, the shape of the cooling member 6 in plan view is substantially the same as the shape of the upper wiring layer 2 in plan view, that is, substantially rectangular. Furthermore, in the first embodiment, the cooling member 6 is formed of a metal material such as aluminum or copper, and has no anisotropy in thermal conductivity.

The length (that is, the length in the longitudinal direction X of the upper wiring layer 2) and the width (that is, the length in the short direction Y of the upper wiring layer 2) of the upper wiring layer 2 are larger than the length and width of the insulating layer 3, respectively. small. The length and width of the lower wiring layer 4 are substantially equal to the length and width of the upper wiring layer 2, respectively. The length and width of the buffer layer 5 are substantially equal to the length and width of the upper wiring layer 2, respectively. The length and width of the cooling member 6 are larger than the length and width of the upper wiring layer 2, respectively.

In the cooling device 1, the upper wiring layer 2, the insulating layer 3, the lower wiring layer 4, the buffer layer 5, and the cooling member 6 have a longitudinal direction X and a lateral direction Y that coincide with each other in a plan view. Are stacked so that their center positions coincide 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 3 is not limited and is, for example, in the range of 0.1 to 2 mm. The thickness of the lower wiring layer 4 is not limited and is preferably in the range of 0.1 to 2 mm. The thickness of the buffer layer 5 is not limited and is preferably in the range of 0.1 to 3 mm. The thickness of the cooling member 6 is not limited and is preferably in the range of 0.2 to 3 mm.

The exothermic element 8 has a substantially rectangular shape in plan view. For example, in the plan view, the longitudinal direction X and the short direction Y of the exothermic element 8 are the same as the longitudinal direction X and the short direction Y of the upper wiring layer 2. In addition, the heat generating element 8 is joined by the solder layer 9 so that the center position of the heat generating element 8 coincides with the center position of the mounting surface 1a of the upper wiring layer 2.

Next, the anisotropic material for forming the upper wiring layer 2 and the lower wiring layer 4 will be described below with reference to FIG.

Arrows a, b, and c in the figure indicate three axial directions in the anisotropic material 20 that intersect each other. In the first embodiment, the a-axis direction, the b-axis direction, and the c-axis direction are orthogonal to each other.

As shown in the figure, the anisotropic material 20 has two directions of the a-axis direction, the b-axis direction, and the c-axis direction, and the c-axis direction in which the thermal conductivity in the a-axis direction and the b-axis direction is the other direction. It has an anisotropy of higher than the thermal conductivity.

That is, when the thermal conductivity in the a-axis direction, the b-axis direction, and the c-axis direction of the anisotropic material 20 is ka, kb, and kc, respectively, the thermal conductivity of the anisotropic material 20 is “ka> kc” and “kb> kc”. Is satisfied. Further, ka and kb are equal (that is, “ka = kb”). However, in the present invention, ka and kb are not limited to being equal and may be different.

Accordingly, in the anisotropic material 20, the surface formed by the a-axis direction and the b-axis direction is the high heat conduction surface (indicated by dot hatching) AB of the anisotropic material 20, and the direction parallel to the high heat conduction surface AB (a axis direction and b). (Including the axial direction) is the high heat conduction direction of the anisotropic material 20, and the c-axis direction, which is the direction perpendicular to the high heat conduction surface AB, is the low heat conduction direction of the anisotropic material 20.

In the figure, the symbol “BC” is a surface formed by the b-axis direction and the c-axis direction in the anisotropic material 20, and the symbol “CA” is a surface formed by the c-axis direction and the a-axis direction in the anisotropic material 20.

The thermal conductivity (ka, kb) in the direction parallel to the high thermal conductivity surface AB of the anisotropic material 20 is not limited, and is preferably 400 W / (m · K) or more. Further, the thermal conductivity kc in the c-axis direction of the anisotropic material 20 is not limited and is preferably 30 W / (m · K) or more.

The anisotropic material 20 is not limited as long as it has the above-described anisotropy in thermal conductivity, and preferably a metal matrix (not shown) and a number of anisotropic materials dispersed in the metal matrix. It is preferable that it is made of a metal-anisotropic particle composite material containing conductive particles (not shown). In this case, the thermal conductivity of the

heat conducting members

11 and 12 can be reliably increased.

Anisotropic particles have anisotropy in thermal conductivity. In detail, for example, the thermal conductivity in the planar direction of the particle is higher than the thermal conductivity in the thickness direction of the particle. It has directionality. The plane of the particle means a plane perpendicular to the thickness direction of the particle, and the plane direction of the particle means a direction parallel to the plane of the particle.

As anisotropic particles, carbon particles, hexagonal boron nitride particles (h-BN particles) and the like are used. As the carbon particles, scaly graphite particles, carbon fibers and the like are used. As the metal of the metal matrix, aluminum, copper or the like is used. In the metal-anisotropic particle composite material, generally, a large number of anisotropic particles are dispersed in the metal matrix in a state of being oriented in the direction of the high heat conduction surface of the anisotropic material 20. When the anisotropic particles are carbon particles, the metal-anisotropic particle composite material is also called a metal-carbon particle composite material.

As the carbon fiber, fibrous carbon particles (eg, short carbon fiber) can be used. Specifically, one or two or more selected from the group consisting of pitch-based carbon fiber, PAN-based carbon fiber, vapor-grown carbon fiber, and carbon nanotube are used as the carbon fiber. When 2 or more types are used, it is preferable that the 2 or more types are mixed and used.

The size of the anisotropic particles is not limited. For example, the average length of the anisotropic particles in the longest axial direction is 0.1 μm to 2 mm.

The method for producing the metal-anisotropic particle 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 + sintering method.

The molten metal stirring method is a method in which an anisotropic powder (eg, scaly graphite powder) as anisotropic particles is placed in a molten metal (eg, aluminum molten metal), mixed with stirring, and cooled and solidified. The powder sintering method is a method of pressure-sintering a mixture of metal powder (eg, aluminum powder) and anisotropic powder (eg, scaly graphite powder) as anisotropic particles. The powder extrusion method is a method of extruding a mixture of metal powder (eg, aluminum powder) and anisotropic powder (eg, scaly graphite powder) as anisotropic particles. The coating + sintering method refers to a plurality of coating foils obtained by coating anisotropic powder (eg, scaly graphite powder) as anisotropic particles on metal foil (eg, aluminum foil). It is a method of laminating and integrating by sintering.

As shown in FIG. 1, in the first embodiment, the upper wiring layer 2 has a high thermal conductive surface AB (indicated by a two-dot chain line) AB of the anisotropic material 20 in the short direction Y and the thickness direction Z of the upper wiring layer 2. Is formed of an anisotropic material 20 so as to be substantially parallel to the line. Accordingly, the thermal conductivity in the thickness direction Z and the thermal conductivity in the short direction Y of the upper wiring layer 2 are higher than the thermal conductivity in the longitudinal direction X of the upper wiring layer 2.

Here, the short direction Y of the upper wiring layer 2 corresponds to the first direction along the plane of the upper heat conductive member described in the claims, and the longitudinal direction X of the upper wiring layer 2 is , Corresponding to the thickness direction of the upper heat conducting member and the second direction perpendicular to the first direction.

Accordingly, the first direction of the upper wiring layer 2 is directed to the short direction Y of the upper wiring layer 2. More specifically, the first direction of the upper wiring layer 2 coincides with the short direction Y of the upper wiring layer 2. Yes. The second direction of the upper wiring layer 2 faces the longitudinal direction X of the upper wiring layer 2. More specifically, the second direction of the upper wiring layer 2 coincides with the longitudinal direction X of the upper wiring layer 2.

The lower wiring layer 4 is formed of the anisotropic material 20 so that the high thermal conductivity surface (indicated by a two-dot chain line) AB of the anisotropic material 20 is substantially parallel to the thickness direction Z and the longitudinal direction X of the lower wiring layer 4. . Therefore, the thermal conductivity in the thickness direction Z and the thermal conductivity in the longitudinal direction X of the lower wiring layer 4 are higher than the thermal conductivity in the short direction Y of the lower wiring layer 4.

Here, the longitudinal direction X of the lower wiring layer 4 corresponds to the first direction along the plane of the lower heat conducting member described in the claims, and the short direction Y of the lower wiring layer 4 is , Corresponding to the thickness direction of the lower heat conducting member and the second direction perpendicular to the first direction.

Therefore, the first direction of the lower wiring layer 4 is directed to the longitudinal direction X of the lower wiring layer 4. More specifically, the first direction of the lower wiring layer 4 coincides with the longitudinal direction X of the lower wiring layer 4. The second direction of the lower wiring layer 4 faces the short direction Y of the lower wiring layer 4. More specifically, the second direction of the lower wiring layer 4 coincides with the short direction Y of the lower wiring layer 4.

Furthermore, as described above, the first direction of the upper wiring layer 2 faces the short direction Y of the upper wiring layer 2 and the first direction of the lower wiring layer 4 faces the longitudinal direction X of the lower wiring layer 4. The upper wiring layer 2 and the lower wiring layer 4 are insulating layers such that the first direction of the upper wiring layer 2 and the first direction of the lower wiring layer 4 intersect (in detail, orthogonal) in a plan view of the cooling device 1. 3 are arranged on both upper and lower sides.

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

Since both the thermal conductivity in the thickness direction Z of the upper wiring layer 2 and the thermal conductivity in the thickness direction Z of the lower wiring layer 4 are both high, the heat of the heat generating element 8 is rapidly conducted toward the cooling member 6. . Thereby, the cooling performance of the cooling device 1 is enhanced.

Further, the upper wiring layer 2 and the lower wiring layer are 4, and the first direction (short direction Y) of the upper wiring layer 2 and the first direction (longitudinal direction X) of the lower wiring layer 4 intersect in plan view (details). Then, when the heat of the heat generating element 8 is conducted from the heat generating element 8 to the cooling member 6, the heat diffusion direction changes. Therefore, heat is effectively diffused in the plane direction of the cooling device 1. Thereby, the cooling performance of the cooling device 1 is improved.

Furthermore, since the first direction of one of the upper wiring layer 2 and the lower wiring layer 4 is directed in the longitudinal direction X, the heat of the heat generating element 8 is widely spread in the plane direction of the one wiring layer. Diffused. Thereby, the cooling performance of the cooling device 1 is improved.

Further, of the upper wiring layer 2 and the lower wiring layer 4, the heat conductive member disposed at a position farther from the position of the exothermic element 8 in the heat conduction direction of the exothermic element 8 in the cooling device 1 is the lower wiring layer. 4, the first direction of the lower wiring layer 4 is oriented in the longitudinal direction X, so that the cooling device 1 is compared with the case where the first direction of the upper wiring layer 2 is oriented in the longitudinal direction X. The cooling performance is improved.

Therefore, the cooling device 1 has high cooling performance.

Further, it is not always necessary to perform complicated processing on the upper wiring layer 2 and the lower wiring layer 4, and therefore the cooling device 1 can be manufactured at low cost.

Here, in the cooling device 1, at least one of the upper wiring layer 2 and the lower wiring layer 4 is formed of a metal-anisotropic particle composite material including a metal matrix and anisotropic particles dispersed in the metal matrix. The anisotropic particles preferably contain both flaky graphite particles and carbon fibers. The reason is as follows.

That is, when the scaly graphite particles are dispersed in the metal matrix of the metal-anisotropic particle composite material, the composite material has a high thermal conductivity. Furthermore, when not only scaly graphite particles but also carbon fibers are dispersed in the metal matrix of the composite material, the composite material can reduce the linear expansion coefficient of the composite material while maintaining high thermal conductivity.

Therefore, when both the scaly graphite particles and the carbon fibers are dispersed in the metal matrix of the composite material, the cooling performance of the cooling device 1 can be improved, and further, the thermal stress generated in the cooling device 1 can be improved. The stress can be relaxed, and therefore the reliability (eg, bonding reliability) of the cooling device 1 can be improved.

FIG. 4 is a view for explaining a cooling device 101 according to the second embodiment of the present invention. In the figure, elements having the same action as the elements of the cooling device 1 of the first embodiment are denoted by reference numerals obtained by adding 100 to the reference numerals assigned to the elements of the cooling apparatus 1. Hereinafter, the second embodiment will be described below with a focus on differences from the first embodiment.

In the cooling device 101 of the second embodiment, the lower wiring layer 104 is made of a metal material such as aluminum or copper, and has no anisotropy in thermal conductivity.

The buffer layer 105 is formed of an anisotropic material having anisotropy in thermal conductivity. More specifically, the buffer layer 105 is formed of the anisotropic material 20 so that the high heat conduction surface AB of the anisotropic material (see FIG. 3, reference numeral 20) is substantially parallel to the thickness direction Z and the longitudinal direction X of the buffer layer 105. ing. Therefore, the thermal conductivity in the thickness direction Z and the thermal conductivity in the longitudinal direction X of the buffer layer 105 are higher than the thermal conductivity in the short direction Y of the buffer layer 105.

Further, the thickness of the buffer layer 105 is larger than the thickness of the upper wiring layer 102.

Here, the longitudinal direction X of the buffer layer 105 corresponds to the first direction along the plane of the lower heat conducting member described in the claims, and the short direction Y of the buffer layer 105 is the patent. This corresponds to the thickness direction of the lower heat conducting member and the second direction perpendicular to the first direction described in the claims.

Therefore, the first direction of the buffer layer 105 faces the longitudinal direction X of the buffer layer 105, and in detail, the first direction of the buffer layer 105 coincides with the longitudinal direction X of the buffer layer 105. The second direction of the buffer layer 105 faces the short direction Y of the buffer layer 105, and in detail, the second direction of the buffer layer 105 coincides with the short direction Y of the buffer layer 105.

Furthermore, the upper wiring layer 102 and the buffer layer 105 are crossed in the plan view (the orthogonal direction, in detail, the first direction (short direction Y) of the upper wiring layer 102 and the first direction (longitudinal direction X) of the buffer layer 105). The insulating layer 103 is disposed on both upper and lower sides.

According to the cooling device 101 of the second embodiment, since the thickness of the buffer layer 105 is larger than the thickness of the upper wiring layer 102, the heat of the heat generating element 8 is diffused more widely in the planar direction of the buffer layer 105. . Thereby, the cooling performance of the cooling device 101 is improved.

Therefore, the cooling device 101 has high cooling performance.

Here, in the cooling device 101, at least one of the upper wiring layer 102 and the buffer layer 105 is formed of a metal-anisotropic particle composite material including a metal matrix and anisotropic particles dispersed in the metal matrix. The anisotropic particles preferably contain both flaky graphite particles and carbon fibers. The reason is as described above.

FIG. 5 is a view for explaining a cooling device 201 according to the third embodiment of the present invention. In the same figure, the element which has the same effect | action as the element of the cooling device 1 of the said 1st Embodiment is attached | subjected the code | symbol which added 200 to the code | symbol attached | subjected to the element of the cooling device 1. FIG. Hereinafter, the third embodiment will be described below with a focus on differences from the first embodiment.

In the cooling device 201 of the third embodiment, the lower wiring layer 204 is formed of a metal material such as aluminum or copper and has no anisotropy in thermal conductivity.

The cooling member 206 is formed of an anisotropic material having anisotropy in thermal conductivity. More specifically, the cooling member 206 is formed of the anisotropic material 20 so that the high heat conduction surface AB of the anisotropic material (see FIG. 3, reference numeral 20) is substantially parallel to the thickness direction Z and the longitudinal direction X of the cooling member 206. ing. Therefore, the thermal conductivity in the thickness direction Z and the thermal conductivity in the longitudinal direction X of the cooling member 206 are higher than the thermal conductivity in the short direction Y of the cooling member 206.

Further, the thickness of the cooling member 206 is larger than the thickness of the upper wiring layer 202.

Here, the longitudinal direction X of the cooling member 206 corresponds to the first direction along the plane of the lower heat conducting member described in the claims, and the short direction Y of the cooling member 206 is the patent. This corresponds to the thickness direction of the lower heat conducting member and the second direction perpendicular to the first direction described in the claims.

Therefore, the first direction of the cooling member 206 is directed to the longitudinal direction X of the cooling member 206. More specifically, the first direction of the cooling member 206 coincides with the longitudinal direction X of the cooling member 206. The second direction of the cooling member 206 faces the short direction Y of the cooling member 206. Specifically, the second direction of the cooling member 206 coincides with the short direction Y of the cooling member 206.

Further, in the upper wiring layer 202 and the cooling member 206, the first direction (short direction Y) of the upper wiring layer 202 and the first direction (longitudinal direction X) of the cooling member 206 intersect each other in plan view. The insulating layer 203 is disposed on both upper and lower sides.

According to the cooling device 201 of the third embodiment, since the thickness of the cooling member 206 is thicker than the thickness of the upper wiring layer 202, the heat of the heat generating element 8 is diffused more widely in the planar direction of the cooling member 206. . Thereby, the cooling performance of the cooling device 201 is improved.

Therefore, the cooling device 201 has high cooling performance.

Here, in the cooling device 201, at least one of the upper wiring layer 202 and the cooling member 206 is formed of a metal-anisotropic particle composite material including a metal matrix and anisotropic particles dispersed in the metal matrix. The anisotropic particles preferably contain both flaky graphite particles and carbon fibers. The reason is as described above.

FIG. 6 is a view for explaining a cooling device 301 according to the fourth embodiment of the present invention. In the same figure, the element which has the same effect | action as the element of the cooling device 1 of the said 1st Embodiment is attached | subjected the code | symbol which added 300 to the code | symbol attached | subjected to the element of the cooling device 1. FIG. Hereinafter, the fourth embodiment will be described below with a focus on differences from the first embodiment.

The cooling device 301 according to the fourth embodiment further includes an upper buffer layer 307 disposed on the upper side of the upper wiring layer 302 as a plurality of cooling device constituent members.

The upper buffer layer 307 is a layer for relieving stress such as thermal stress generated in the cooling device 301, and is bonded to the upper wiring layer 302 in a state of being laminated on the upper wiring layer 302.

The thickness of the upper buffer layer 307 is thinner than the thickness of the lower wiring layer 302. The upper buffer layer 307 has a mounting surface 301a formed from the upper surface thereof.

Furthermore, the linear expansion coefficient in the same direction as the direction of the minimum linear expansion coefficient of the upper wiring layer 302 in the upper buffer layer 307 is more than the minimum linear expansion coefficient among the linear expansion coefficients in the planar direction of the upper wiring layer 302. It is getting smaller.

Here, the above-mentioned linear expansion coefficient means an average linear expansion coefficient in the range of 25 to 300 ° C.

According to the cooling device 301 of the fourth embodiment, since the upper buffer layer 307 is disposed on the upper side of the upper wiring layer 302, stress such as thermal stress generated in the cooling device 301 can be relieved. The reliability (eg, bonding reliability) of the cooling device 301 can be improved.

The material of the upper buffer layer 307 is not limited, and is particularly preferably a metal-carbon fiber composite material including a metal matrix and carbon fibers dispersed in the metal matrix. In this case, the linear expansion coefficient of the upper buffer layer 307 can be reliably reduced.

Here, in the cooling device according to the present invention, the upper buffer layer 307 may be disposed above the upper wiring layer 102 of the cooling device 101 of the second embodiment, or the cooling device of the third embodiment. 201 may be disposed on the upper side of the upper wiring layer 202.

Although several embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

In the first to fourth embodiments, the lower wiring layer, the buffer layer, and the cooling member are disposed below the insulating layer. In the present invention, for example, the buffer layer is provided below the insulating layer. May not be disposed, and the lower wiring layer may not be disposed below the insulating layer.

Furthermore, in the present invention, there are a plurality of upper heat conductive members, and two or more of the plurality of upper heat conductive members are the heat conductivity in the thickness direction and the heat conductivity in the first direction along the plane. Is higher than the thermal conductivity in the thickness direction and in the second direction perpendicular to the first direction, and these upper heat conductive member and lower heat conductive member are in the first direction and lower direction of these upper heat conductive members. You may arrange | position so that the 1st direction of a heat conductive member may cross | intersect in planar view.

Furthermore, in the present invention, the number of lower heat conductive members is plural, and two or more of the plurality of lower heat conductive members are heat conductivity in the thickness direction and heat conductivity in the first direction along the plane. Is higher than the thermal conductivity in the thickness direction and the second direction perpendicular to the first direction, and the upper heat conducting member and the lower heat conducting member are You may arrange | position so that the 1st direction of a heat conductive member may cross | intersect in planar view.

[Evaluation of cooling performance of cooling device]
Next, in order to evaluate the cooling performance of the cooling device according to the present invention, the maximum temperature of the exothermic element mounted on the mounting surface of the upper wiring layer of the cooling device was examined by simulation under various conditions.

The software used for the simulation is thermal fluid analysis software “FloTHERM” manufactured by Mentor Graphics Corporation.

7 and 8 show a cooling device 501 used as a model in this simulation. As shown in these drawings, the cooling device 501 is formed by joining and integrating the upper wiring layer 502, the insulating layer 503, the lower wiring layer 504, the buffer layer 505, and the cooling member 506 in order from the top to the bottom. Is formed. Specifically, the cooling member 506 is a cooling plate. The upper wiring layer 502 corresponds to the upper heat conductive member 511, and the lower wiring layer 504, the buffer layer 505, and the cooling member 506 all correspond to the lower heat conductive member 512.

In the cooling device 501, the upper wiring layer 502, the insulating layer 503, the lower wiring layer 504, the buffer layer 505, and the cooling member 506 are each substantially rectangular in plan view, and as shown in FIG. The layers are stacked such that the longitudinal direction X and the lateral direction Y coincide with each other and the center positions thereof also coincide with each other. In FIG. 8, the cooling member 506 is not shown.

The exothermic element 508 has a substantially rectangular shape in plan view. In the plan view, the longitudinal direction X and the short direction Y of the exothermic element 508 coincide with the longitudinal direction X and the short direction Y of the upper wiring layer 502 and The heat generating element 508 is joined by the solder layer 509 so that the center position of the heat generating element 508 coincides with the center position of the mounting surface 501 a of the upper wiring layer 502.

Table 1 shows the conditions of each component of the cooling device 501 applied to the simulation.

As shown in Table 1, the thermal conductivity of the exothermic element 508 was set to depend on the temperature t (unit: ° C.). Moreover, the thickness of the upper wiring layer 502 was set to three types of 0.4, 0.6, and 1.0 mm.

In the thermal conductivity column of the upper wiring layer 502, the lower wiring layer 504, and the buffer layer 505, “kab” is the thermal conductivity in the direction parallel to the high thermal conductive surface AB of the anisotropic material (see FIG. 3, reference numeral 20). “Kc” is the thermal conductivity in the c-axis direction, which is the low thermal conduction direction of the anisotropic material 20. The high thermal conductivity surface AB of the anisotropic material is a surface formed by the a-axis direction and the b-axis direction of the anisotropic material as described above, and the thermal conductivity ka in the a-axis direction is equal to the thermal conductivity kb in the b-axis direction. Set.

In addition, it was set that the periphery of the cooling device 501 was filled with a sealing material (not shown) having a thermal conductivity of 3 W / (m · K). Assuming that the exothermic element 508 generates heat uniformly on the upper surface of the exothermic element 508, a heat source 128.65 W was set on the upper surface of the exothermic element 508. This heat is finally radiated from the cooling member 506 through a process of conducting the solder layer 509, the upper wiring layer 502, the insulating layer 503, the lower wiring layer 504, and the buffer layer 505 in this order from the heat generating element 508. Therefore, the above-described heat conduction process was simulated by setting a heat transfer coefficient of 15000 W / (m ² · K) on the bottom surface of the cooling member 506. Then, the environmental temperature was set to 25 ° C. as the initial temperature, and the maximum temperature of the exothermic element 508 when the temperature change of the cooling device 501 reached a steady state was set as the maximum temperature of the exothermic element 508.

<Simulation example 1>
Of the plurality of heat conductive members (that is, the upper wiring layer 502, the lower wiring layer 504, the buffer layer 505, and the cooling member 506) of the cooling device 501, only the upper wiring layer 502 is set as the heat conductive member that changes the material and thickness. Further, the thickness of the lower wiring layer 504 is 0.6 mm, the material of the lower wiring layer 504 is pure aluminum (pure Al), the thickness of the buffer layer 505 is 1.2 mm, and the material of the buffer layer 505 is pure aluminum (pure Al). Moreover, when the material of the heat conductive member was pure aluminum, the heat conductive member was set to have no anisotropy in heat conductivity. The maximum temperature of the exothermic element 508 when pure aluminum and an anisotropic material were used as the material of the upper wiring layer 502 was examined by simulation. The results (maximum temperature of the heat generating element 508) are shown in Table 2.

In Table 2, “pure Al” means that the material of the upper wiring layer 502 is pure aluminum. The “anisotropic material (ZX)” is an upper wiring layer 502 so that the material of the upper wiring layer 502 is an anisotropic material and the high thermal conductivity surface of the anisotropic material is parallel to the thickness direction Z and the longitudinal direction X of the upper wiring layer 502. This means that 502 is formed of an anisotropic material, that is, the high heat conduction direction of the upper wiring layer 502 is the thickness direction Z and the longitudinal direction X. The “anisotropic material (YZ)” means that the upper wiring layer 502 is made of an anisotropic material, and the high heat conduction surface of the anisotropic material is parallel to the short direction Y and the thickness direction Z of the upper wiring layer 502. This means that the layer 502 is formed of an anisotropic material, that is, the high heat conduction direction of the upper wiring layer 502 is the short direction Y and the thickness direction Z.

The meanings of “pure Al”, “anisotropic material (ZX)” and “anisotropic material (YZ)” in the following Tables 3 to 5 are the same as described above.

Furthermore, in Table 2, “thickness 0.4 mm”, “thickness 0.6 mm”, and “thickness 1.0 mm” are the thicknesses of the upper wiring layer 502, respectively.

As can be seen from Table 2, when the upper wiring layer 502 as a heat conducting member has a thickness of 0.4, 0.6, or 1.0 mm, the upper wiring layer 502 is made of an anisotropic material. However, the maximum temperature of the heat generating element 508 was lower than that in the case where the material of the upper wiring layer 502 was pure aluminum. Further, when the high heat conduction direction of the upper wiring layer 502 is the thickness direction Z and the longitudinal direction X, the heat generation characteristics are higher than when the high heat conduction direction of the upper wiring layer 502 is the short direction Y and the thickness direction Z. The maximum temperature of the element 508 was low. Further, the maximum temperature of the heat generating element 508 was lower when the upper wiring layer 502 was thicker.

Therefore, in order to increase the cooling performance of the cooling device 501, the material of the heat conduction member is an anisotropic material, and the high heat conduction direction of the heat conduction member is the thickness direction Z and the longitudinal direction X. It turned out that a thicker member is better.

<Simulation example 2>
The upper wiring layer 502 is set to 0.6 mm, the lower wiring layer 504 is set to 0.6 mm, the buffer layer 505 is set to 1.2 mm, and the buffer layer 505 is made of pure aluminum. The maximum temperature of the exothermic element 508 when pure aluminum and an anisotropic material are used as the material of 502 and the lower wiring layer 504 was examined by simulation. The results are shown in Table 3.

As can be seen from Table 3, the maximum temperature of the heat generating element 508 is the lowest because the material of the upper wiring layer 502 is an anisotropic material, and the high heat conduction direction of the upper wiring layer 502 is the short direction Y and the thickness direction Z. And the material of the lower wiring layer 504 is an anisotropic material, and the high heat conduction direction of the lower wiring layer 504 is the thickness direction Z and the longitudinal direction X. In this case, the maximum temperature of the heat generating element 508 was 76.87 ° C.

As a result, in the plan view of the cooling device 501, the high heat conduction direction of the upper heat conduction member 511 and the high heat conduction direction of the lower heat conduction member 512 are different (crossed). The cooling performance of the cooling device 501 is improved as compared with the case where the high heat conduction direction and the high heat conduction direction of the lower heat conduction member 512 coincide (parallel), and the high heat conduction direction of the lower heat conduction member 512 is thicker. It is shown that the cooling performance of the cooling device 501 is improved in the direction Z and the longitudinal direction X than in the case where the high heat conduction direction of the upper heat conducting member 511 is the thickness direction Z and the longitudinal direction X.

<Simulation example 3>
The thickness of the upper wiring layer 502 is set to 0.6 mm, the material of the upper wiring layer 502 is set to pure aluminum, the thickness of the lower wiring layer 504 is set to 0.6 mm, and the thickness of the buffer layer 505 is set to 1.2 mm. The maximum temperature of the heat generating element 508 when pure aluminum and an anisotropic material are used as the material of the layer 504 and the buffer layer 505 was examined by simulation. The results are shown in Table 4.

As can be seen from Table 4, the maximum temperature of the heat generating element 508 is the lowest because the material of the lower wiring layer 504 is an anisotropic material, and the high heat conduction direction of the lower wiring layer 504 is the short direction Y and the thickness direction Z. And the material of the buffer layer 505 is an anisotropic material, and the high heat conduction direction of the buffer layer 505 is the thickness direction Z and the longitudinal direction X. In this case, the maximum temperature of the heat generating element 508 was 77.73 ° C.

Furthermore, the maximum temperature of 77.73 ° C. is higher than the maximum temperature of 76.87 ° C. of the lowest exothermic element 508 in the case of the simulation example 2 described above. Therefore, in the case where anisotropic materials are used as the materials of the two heat conducting members, respectively, the case where the insulating layer 503 is disposed between the two heat conducting members (that is, in the case of the simulation example 2), the two heat conducting members. It is estimated that the cooling performance of the cooling device 501 is improved as compared with the case where the insulating layer 503 is disposed on the upper side or the lower side of the member (that is, in the case of the simulation example 3).

<Simulation example 4>
The thickness of the upper wiring layer 502 is set to 0.6 mm, the thickness of the lower wiring layer 504 is set to 0.6 mm, the material of the lower wiring layer 504 is set to pure aluminum, and the thickness of the buffer layer 505 is set to 1.2 mm. The maximum temperature of the heat generating element 508 when pure aluminum and an anisotropic material are used as the material of the layer 502 and the buffer layer 505 was examined by simulation. The results are shown in Table 5.

As can be seen from Table 5, the maximum temperature of the heat generating element 508 is the lowest because the material of the upper wiring layer 502 is an anisotropic material, and the high heat conduction direction of the upper wiring layer 502 is the short direction Y and the thickness direction Z. And the material of the buffer layer 505 is an anisotropic material, and the high heat conduction direction of the buffer layer 505 is the thickness direction Z and the longitudinal direction X. In this case, the maximum temperature of the heat generating element 508 was 76.30 ° C.

Furthermore, this maximum temperature of 76.30 ° C. is lower than the maximum temperature of 76.87 ° C. of the lowest exothermic element 508 in the case of the simulation example 2 described above. Therefore, when the anisotropic material is used as the material of the thick heat conduction member (that is, in the case of the simulation example 4), the cooling device 501 is more than when the anisotropic material is used as the material of the thin heat conduction member (ie, in the case of the simulation example 2). It is estimated that the cooling performance is improved.

This application is accompanied by the priority claim of Japanese Patent Application No. 2018-025867 filed on Feb. 16, 2018, the disclosure of which constitutes part of the present application as it is. .

The terms and expressions used herein are for illustrative purposes and are not to be construed as limiting, but represent any equivalent of the features shown and described herein. It should be recognized that various modifications within the claimed scope of the present invention are permissible.

Although several illustrated embodiments of the present invention have been described herein, the present invention is not limited to the various preferred embodiments described herein, and is equivalent to what may be recognized by those skilled in the art based on this disclosure. Any and all embodiments having various elements, modifications, deletions, combinations (eg, combinations of features across the various embodiments), improvements and / or changes are encompassed. Claim limitations should be construed broadly based on the terms used in the claims, and should not be limited to the embodiments described herein or in the process of this application, as such The examples should be construed as non-exclusive. For example, in this disclosure, the term “preferably” is non-exclusive and means “preferably but not limited to”.

The present invention can be used for a cooling device for cooling a heat-generating element such as an electronic element (eg, a semiconductor element).

1, 101, 201, 301: Cooling

device

2, 102, 202, 302:

Upper wiring layer

3, 103, 203, 303: Insulating

layer

4, 104, 204, 304:

Lower wiring layer

5, 105, 205, 305:

Buffer layer

6, 106, 206, 306: Cooling member 307:

Upper buffer layer

8, 108, 208, 308:

Exothermic element

11, 111, 211, 311: Upper heat

conductive member

12, 112, 212, 312: Lower heat Conductive member

Claims

A cooling device for cooling the exothermic element,
A plurality of cooling device components that are joined and integrated in a stacked manner,
As the plurality of constituent members, including an insulating layer, an upper heat conductive member disposed on the upper side of the insulating layer, and a lower heat conductive member disposed on the lower side of the insulating layer,
The upper heat conductive member has a heat conductivity in the thickness direction and a heat conductivity in the first direction along the plane higher than the heat conductivity in the second direction perpendicular to the thickness direction and the first direction. And
The lower heat conductive member has a heat conductivity in the thickness direction and a heat conductivity in the first direction along the plane higher than the heat conductivity in the second direction perpendicular to the thickness direction and the first direction. And
The cooling device, wherein the upper heat conducting member and the lower heat conducting member are arranged such that the first direction of the upper heat conducting member and the first direction of the lower heat conducting member intersect in plan view .
The thickness of the upper heat conductive member is different from the thickness of the lower heat conductive member,
At least the thicker heat conducting member of the upper heat conducting member and the lower heat conducting member has a longitudinal direction and a short side direction, and the first direction of the thicker heat conducting member is the thicker heat conducting member. The cooling device according to claim 1, which faces the longitudinal direction of the member.
3. The cooling device according to claim 2, wherein the thicker heat conducting member is the lower heat conducting member.
The cooling device according to claim 1, wherein the lower heat conductive member has a longitudinal direction and a short direction, and the first direction of the lower heat conductive member faces the longitudinal direction of the lower heat conductive member.
At least one of the upper heat conductive member and the lower heat conductive member is formed of a metal-anisotropic particle composite material including a metal matrix and anisotropic particles dispersed in the metal matrix,
The cooling device according to any one of claims 1 to 4, wherein the anisotropic particles include both flaky graphite particles and carbon fibers.
The plurality of constituent members further includes an upper buffer layer disposed on the upper heat conducting member,
The linear expansion coefficient in the same direction as the direction of the minimum linear expansion coefficient of the upper thermal conductive member in the upper buffer layer is smaller than the minimum linear expansion coefficient of the linear thermal expansion coefficient in the planar direction of the upper thermal conductive member. 6. The cooling device according to claim 1, wherein the cooling device is small.