Immersion cooling device

Abstract

To provide an immersion cooling device capable of improving cooling performance.SOLUTION: An immersion cooling device 1 includes: a circuit board 11; a heating element 12 implemented on the circuit board 11; a heat sink 13; an electronic device 10 having a thermal conductive sheet 14 arranged between the heating element 12 and the heat sink 13; and a coolant 20 for immersing at least a part of the electronic device 10. At least a part of the thermal conductive sheet 14 is composed of a porous body.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an immersion cooling apparatus, and more particularly to an immersion cooling apparatus including an electronic device and a cooling medium. [Background technology]

[0002] Patent Document 1 discloses an immersion cooling device that is used to cool a heat sink and includes a heat transfer fluid contained in a sealed volume. In this immersion cooling device, a thermal interface material is disposed between the heat generating body and the heat sink, and an indium sheet or the like is used as the thermal interface material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2006 / 049768 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conventional liquid immersion cooling apparatus still has room for improvement in terms of cooling performance.

[0005] An object of the present disclosure is to provide an immersion cooling device that can improve cooling performance. [Means for solving the problem]

[0006] An immersion cooling apparatus according to an aspect of the present disclosure includes an electronic device having a circuit board, a heat generating element mounted on the circuit board, a heat sink, and a thermally conductive sheet disposed between the heat generating element and the heat sink, and a cooling medium in which at least a portion of the electronic device is immersed. At least a portion of the thermally conductive sheet is made of a porous material.

[0007] An immersion cooling apparatus according to another aspect of the present disclosure includes an electronic device having a circuit board, a heat generating element mounted on the circuit board, a heat sink, and a thermally conductive sheet disposed between the heat generating element and the heat sink, and a coolant in which at least a portion of the electronic device is immersed. The thermally conductive sheet has at least one selected from irregularities, slits, grooves, and holes.

[0008] According to yet another aspect of the present disclosure, there is provided an immersion cooling apparatus including an electronic device having a circuit board, a heat generating element mounted on the circuit board, a heat sink, and a thermally conductive sheet disposed between the heat generating element and the heat sink, and a cooling medium in which at least a portion of the electronic device is immersed. The thermally conductive sheet is made of graphite. Effect of the Invention

[0009] According to the present disclosure, it is possible to improve the cooling performance of an immersion cooling device. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating an immersion cooling apparatus according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram illustrating an immersion cooling apparatus according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 1. Overview An immersion cooling apparatus 1 according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the following embodiment is merely one example of various embodiments of the present disclosure. The following embodiment can be modified in various ways depending on the design, etc., as long as it does not deviate from the technical concept of the present disclosure. Also, each figure described in the following embodiment is a schematic diagram, and the size and thickness ratios of each component in each figure do not necessarily reflect the actual dimensional ratios.

[0012] In the above-mentioned conventional immersion cooling apparatus, an indium sheet or the like is used as a thermal interface material disposed between the heating element and the heat sink. Since the indium sheet is not compressible, it is considered that the gap between the heating element and the heat sink cannot be sufficiently filled. In order to solve the above-mentioned problem, the inventors have conducted extensive research and found that the cooling performance of the immersion cooling apparatus can be improved by using a thermally conductive sheet 14 having specific physical properties as the thermally conductive sheet 14 disposed between the heating element 12 and the heat sink 13 in the immersion cooling apparatus 1, and have completed the present disclosure.

[0013] Fig. 1 is a cross-sectional view showing an example of an immersion cooling apparatus 1 of the present embodiment. The immersion cooling apparatus 1 of Fig. 1 includes an electronic device 10 and a coolant 20. The electronic device 10 has a circuit board 11, a heat generating element 12 mounted on the circuit board 11, a heat sink 13, and a thermally conductive sheet 14 disposed between the heat generating element 12 and the heat sink 13. At least a portion of the electronic device 10 is immersed in the coolant 20.

[0014] The immersion cooling apparatus 1 in Fig. 2 includes a plurality (five pieces) of electronic devices 10, which are immersed in a cooling medium 20. The immersion cooling apparatus 1 in Fig. 2 also includes a heat exchanger 30, and the cooling medium 20 is sent to the heat exchanger 30 by a pump (not shown) and cooled, and then returns to its original state.

[0015] In the immersion cooling apparatus 1 of the present embodiment, the thermally conductive sheet 14 has the following characteristics: (1) at least a portion of the thermally conductive sheet 14 is made of a porous material; (2) the thermally conductive sheet 14 has at least one selected from the group consisting of irregularities, slits, grooves, and holes; or (3) the thermally conductive sheet 14 is made of graphite.

[0016] According to the immersion cooling apparatus 1 of the present embodiment, the cooling performance can be improved. The reason why the immersion cooling apparatus 1 having the above-mentioned configuration produces the above-mentioned effect can be inferred as follows, for example. Since the thermally conductive sheet 14 has the above-mentioned characteristics (1) to (3), the thermally conductive sheet 14 is easily crushed due to its specific shape, and can fill the gap between the heat generating body 12 and the heat dissipating body 13. In addition, the cooling medium 20 permeates the thermally conductive sheet 14, thereby filling the gap in the thermally conductive sheet 14. Furthermore, the permeated cooling medium 20 moves to the inside and surface of the thermally conductive sheet 14, improving the contact state between the thermally conductive sheet 14 and the heat generating body 12 and the heat dissipating body 13. As a result, the thermal resistance between the heat generating body 12 and the heat dissipating body 13 can be reduced. Furthermore, when the heat generating body 12 repeats heating and cooling, the cooling medium 20 can enter and exit the thermally conductive sheet 14. As a result of these, it is considered that the cooling performance of the immersion cooling apparatus 1 can be improved.

[0017] 2.Details <Liquid immersion cooling device> The immersion cooling apparatus 1 of the present embodiment will be described in detail below. [First embodiment] The immersion cooling apparatus 1 includes an electronic device 10 and a coolant 20. In the immersion cooling apparatus 1 of the first embodiment, at least a portion of the thermally conductive sheet 14 is made of a porous material. Each component of the immersion cooling apparatus 1 will be described below.

[0018] [Electronic equipment] The electronic device 10 has a circuit board 11, a heat generating element 12, a heat sink 13, and a thermally conductive sheet 14. The immersion cooling apparatus 1 may include one or more electronic devices 10.

[0019] Examples of electronic devices 10 include HDDs, DVDs, mobile phones, smartphones, tablet terminals, automobile electronic control units (ECUs), power control units (PCUs), display devices such as LCD displays, organic EL lighting, solar cells, touch panels, camera modules, inverters, converters, etc., as well as blade servers that incorporate these together with components such as memory and a CPU (central processing unit) in a small housing.

[0020] (Circuit board) The circuit board 11 is a board including circuits such as an inverter circuit and a motor drive circuit for operating the electronic device 10. The electronic device 10 may have one or more circuit boards. The circuit board 11 may be a single-layer board or a multi-layer board.

[0021] (heating element) The heating element 12 is a member that generates heat and is mounted on the circuit board 11. The heating element 12 is, for example, a semiconductor component. Examples of the semiconductor components include, but are not limited to, a transistor, a CPU (central processing unit), an MPU (microprocessing unit), a driver IC, and a memory. The heating element 12 may be composed of, for example, a heat spreader and a chip portion fixed on the heat spreader. The heat spreader is a plate-like member made of metal or the like, and the chip portion is, for example, a semiconductor package. In this case, the chip portion is disposed on a portion of the heat spreader excluding the outer edge portion, and a plurality of screw holes or the like may be formed on the outer edge portion at positions corresponding to a plurality of screw holes or the like penetrating the heat spreader.

[0022] (Heat sink) The heat sink 13 is a member to which heat generated by the heat generating body 12 is transferred. Heat can be released from the heat sink 13. The heat sink 13 is, for example, a heat sink. When the heat sink 13 is a plate-shaped heat sink, the heat sink 13 may further include a heat dissipation fin. The heat sink 13 may have a plurality of screw holes or the like formed at positions corresponding to the plurality of screw holes or the like in the heat generating body 12 described above.

[0023] (Thermal Conduction Sheet) The heat conductive sheet 14 is a member for transferring heat from the heat generating body 12 to the heat dissipating body 13. At least a part of the heat conductive sheet 14 in the immersion cooling apparatus 1 of the first embodiment is made of a porous body. The term "porous body" refers to a solid having holes (voids) therein. The term "voids" refers to a portion of the heat conductive sheet 14 where the material constituting the heat conductive sheet does not exist. The pores in the porous body may be interconnected pores or independent pores, and may or may not be connected to the surface of the heat conductive sheet 14, but are preferably interconnected pores connected to the surface. In this case, the coolant 20 is more likely to permeate the heat conductive sheet 14. The porosity of the heat conductive sheet 14 is preferably 30% by volume or more and 95% by volume or less, and more preferably 50% by volume or more and 90% by volume or less. The "porosity" (volume %) is a value calculated by [1-(apparent specific gravity of the heat conductive sheet / true specific gravity of the material constituting the heat conductive sheet)]×100. The apparent specific gravity of the thermally conductive sheet can be calculated from the volume and mass obtained from the outer dimensions of the thermally conductive sheet. The thermally conductive sheet 14 is preferably composed of 50% by mass or more of a porous material, more preferably 90% by mass or more of a porous material, and may be composed of 100% by mass or more of a porous material.

[0024] Thus, the thermally conductive sheet 14 has voids. In the immersion cooling apparatus 1, it is preferable that the coolant 20 permeates at least a portion of the voids. In this case, the thermal resistance of the thermally conductive sheet 14 can be further reduced by the permeated coolant 20.

[0025] The shape of the thermally conductive sheet 14 is preferably at least one selected from a sponge shape, a honeycomb shape, a fiber shape, and a laminate shape. The sponge shape refers to a shape having numerous holes inside, which may be interconnected or independent. The honeycomb shape refers to a shape in which a plurality of linear holes are bundled together and separated by thin partitions, and the cross section of the linear holes may be hexagonal or of other shapes. "Fibrous" means that each material constituting the thermally conductive sheet has a fiber-like shape (for example, the ratio of length to diameter is 3 or more). The laminate shape refers to a shape in which layered structures are stacked.

[0026] By having such a shape, the thermally conductive sheet 14 becomes easily crushed by compression, and can fill the gap between the heat generating body 12 and the heat dissipating body 13, thereby making it possible to further reduce the thermal resistance.

[0027] It is preferable that the thermally conductive sheet 14 does not react with the coolant 20 and does not dissolve in the coolant 20 .

[0028] The compression ratio of the thermally conductive sheet 14 when compressed in the thickness direction at 200 kPa is preferably 5% or more and 95% or less. In this case, the gap between the thermally conductive sheet 14 and the heating element 12 and the heat sink 13 can be more effectively filled, and the thermal resistance can be further reduced. The compression ratio of the thermally conductive sheet 14 is more preferably 20% or more and 95% or less, and even more preferably 30% or more and 95% or less. The "compression ratio" of the thermally conductive sheet 14 is the value of 1-T1 / T0 expressed as a percentage, where T0 is the initial thickness of the thermally conductive sheet 14 and T1 is the thickness after applying a pressure of 200 kPa.

[0029] The average thickness of the thermally conductive sheet 14 is, for example, from 30 μm to 500 μm, and preferably from 50 μm to 200 μm. The "average thickness" refers to the arithmetic mean value of thicknesses measured at multiple points (for example, any 10 points) on the thermally conductive sheet 14.

[0030] [Cooling medium] The coolant 20 is a medium used to cool the electronic device 10, particularly the heat sink 13. The coolant 20 is usually placed in a container or the like, and the electronic device 10 is used by immersing it in the coolant 20. As the coolant 20, for example, an insulating liquid having high electrical insulation properties can be used.

[0031] Examples of the cooling medium 20 include hydrocarbon oils such as hydrocarbons and polyalphaolefins (PAOs), fluorine-containing oils such as perfluorocarbons, hydrofluorocarbons, hydrofluoroethers, and perfluoroketones, silicone oils, hydrocarbon compounds such as alkylbenzenes, alkylnaphthalenes, and alkyldiphenylalkanes, and mineral oils. The cooling medium 20 preferably contains at least one of a hydrocarbon oil and a fluorine-containing oil.

[0032] [Heat exchanger] The immersion cooling apparatus 1 typically includes a heat exchanger 30. The heat exchanger 30 exchanges heat between the coolant 20 supplied by a pump (not shown), for example, and cooling water supplied from a cooling unit (not shown). This makes it possible to control the temperature of the coolant 20, and further improve the cooling performance of the immersion cooling apparatus 1.

[0033] [Second embodiment] In the immersion cooling apparatus 1 of the second embodiment, the heat conductive sheet 14 has at least one selected from unevenness, slits, grooves, and holes. The immersion cooling apparatus 1 of the second embodiment is similar to the first embodiment except for the heat conductive sheet 14.

[0034] The thermally conductive sheet 14 in the second embodiment has at least one selected from unevenness, slits, grooves, and holes. "Having unevenness" includes not only the case where both recesses and protrusions are provided, but also the case where only recesses or only protrusions are provided. A slit refers to a narrow cut or gap that penetrates the thermally conductive sheet. A groove refers to a linear or curved opening that does not penetrate the thermally conductive sheet. A hole includes both a hole that does not penetrate the thermally conductive sheet, and a through hole that penetrates the thermally conductive sheet.

[0035] Because the thermally conductive sheet 14 in the immersion cooling apparatus 1 has such a structure, it can be appropriately compressed and the thermal resistance between the heating element 12 and the heat sink 13 can be further reduced, thereby further improving the cooling performance of the immersion cooling apparatus 1.

[0036] [Third embodiment] In the immersion cooling apparatus 1 of the third embodiment, the heat conductive sheet 14 is made of graphite. The immersion cooling apparatus 1 of the third embodiment is similar to the first and second embodiments except for the heat conductive sheet 14.

[0037] The heat conductive sheet 14 in the third embodiment is made of graphite. "Graphite" is a type of carbon allotrope, and is also called graphite. Graphite is a material in which the carbon atoms are sp 2 The graphene layer is arranged in a hexagonal honeycomb lattice shape by bonding, and the layers are laminated in the thickness direction by van der Waals forces. Examples of graphite include a laminate of multiple graphite layers.

[0038] In the immersion cooling apparatus 1, since the thermally conductive sheet 14 is made of graphite having such a structure, it has an appropriate amount of voids and can be compressed appropriately, thereby enabling the thermal resistance between the heating element 12 and the heat sink 13 to be further reduced, and thereby enabling the cooling performance of the immersion cooling apparatus 1 to be further improved.

[0039] (summary) As is apparent from the above-described embodiment, the present disclosure includes the following aspects. In the following, reference symbols are given in parentheses only to clarify the correspondence with the embodiment.

[0040] The immersion cooling apparatus (1) of the first embodiment includes an electronic device (10) and a coolant (20). The electronic device (10) has a circuit board (11), a heat generating element (12) mounted on the circuit board (11), a heat sink (13), and a heat conductive sheet (14) disposed between the heat generating element (12) and the heat sink (13). At least a portion of the electronic device (10) is immersed in the coolant (20). At least a portion of the heat conductive sheet (14) is made of a porous material.

[0041] The immersion cooling apparatus (1) of the second embodiment includes an electronic device (10) and a coolant (20). The electronic device (10) includes a circuit board (11), a heat generating element (12) mounted on the circuit board (11), a heat sink (13), and a thermally conductive sheet (14) disposed between the heat generating element (12) and the heat sink (13). At least a portion of the electronic device (10) is immersed in the coolant (20). The thermally conductive sheet (14) has at least one type selected from unevenness, slits, grooves, and holes.

[0042] The immersion cooling apparatus (1) of the third embodiment includes an electronic device (10) and a coolant (20). The electronic device (10) has a circuit board (11), a heat generating element (12) mounted on the circuit board (11), a heat sink (13), and a heat conductive sheet (14) disposed between the heat generating element (12) and the heat sink (13). At least a portion of the electronic device (10) is immersed in the coolant (20). The heat conductive sheet (14) is made of graphite.

[0043] According to the first to third aspects, it is possible to reduce the thermal resistance between the heat generating body (12) and the heat dissipating body (13), thereby improving the cooling performance of the immersion cooling apparatus (1).

[0044] In the immersion cooling apparatus (1) of a fourth aspect, in any one of the first to third aspects, the thermally conductive sheet (14) has voids, and the cooling medium (20) permeates at least a portion of the voids.

[0045] According to the fourth aspect, with the thermally conductive sheet (14) in the above-mentioned state, the thermal resistance can be further reduced, and the cooling performance of the immersion cooling apparatus (1) can be further reduced.

[0046] In the immersion cooling apparatus (1) of the fifth aspect, in any one of the first to fourth aspects, the shape of the heat conductive sheet (14) is at least one selected from a sponge shape, a honeycomb shape, a fiber shape, and a laminate shape.

[0047] According to the fifth aspect, since the thermally conductive sheet (14) has the above-mentioned shape, the thermal resistance can be further reduced, and the cooling performance of the immersion cooling apparatus (1) can be further reduced.

[0048] In the sixth aspect of the immersion cooling apparatus (1) of any one of the first to fifth aspects, the thermally conductive sheet (14) does not react with and does not dissolve in the cooling medium (20).

[0049] According to the sixth aspect, the cooling performance of the immersion cooling apparatus (1) can be maintained.

[0050] In the seventh aspect of the immersion cooling apparatus (1), in any one of the first to sixth aspects, the compression rate of the thermally conductive sheet (14) when compressed in the thickness direction at 200 kPa is 5% or more and 95% or less.

[0051] According to the seventh aspect, by setting the compressibility of the heat conductive sheet (14) within the above range, it is possible to further reduce the thermal resistance and further improve the cooling performance of the immersion cooling apparatus (1).

[0052] In the immersion cooling apparatus (1) of an eighth aspect, in any one of the first to seventh aspects, the heat conductive sheet (14) contains graphite.

[0053] According to the eighth aspect, the thermal resistance of the heat conductive sheet (14) can be further reduced, and the cooling performance of the immersion cooling apparatus (1) can be further improved.

[0054] The immersion cooling apparatus (1) of a ninth aspect is in any one of the first to eighth aspects, further comprising a heat exchanger (30) that cools the cooling medium (20).

[0055] According to the ninth aspect, the immersion cooling apparatus (1) includes the heat exchanger (30), and thus it is possible to control the temperature of the cooling medium (20) and further improve the cooling performance. [Explanation of symbols]

[0056] 1 Immersion cooling device 10 Electronic equipment 11 Circuit Board 12 Heating element 13 Heat sink 14 Thermal Conductive Sheet 20 Coolant 30 heat exchanger

Claims

1. An electronic device having a circuit board, a heat generating element mounted on the circuit board, a heat sink, and a thermally conductive sheet disposed between the heat generating element and the heat sink; a cooling medium in which at least a portion of the electronic device is immersed; An immersion cooling apparatus comprising: At least a part of the heat conductive sheet is made of a porous material. Immersion cooling equipment.

2. An electronic device having a circuit board, a heat generating element mounted on the circuit board, a heat sink, and a thermally conductive sheet disposed between the heat generating element and the heat sink; a cooling medium in which at least a portion of the electronic device is immersed; An immersion cooling apparatus comprising: The thermally conductive sheet has at least one selected from the group consisting of irregularities, slits, grooves, and holes. Immersion cooling equipment.

3. An electronic device having a circuit board, a heat generating element mounted on the circuit board, a heat sink, and a thermally conductive sheet disposed between the heat generating element and the heat sink; a cooling medium in which at least a portion of the electronic device is immersed; An immersion cooling apparatus comprising: The thermally conductive sheet is made of graphite. Immersion cooling equipment.

4. The thermally conductive sheet has voids, and the cooling medium is permeated into at least a portion of the voids. The immersion cooling apparatus according to any one of claims 1 to 3.

5. The shape of the thermally conductive sheet is at least one selected from a sponge shape, a honeycomb shape, a fiber shape, and a laminate shape. The immersion cooling apparatus according to any one of claims 1 to 3.

6. The thermally conductive sheet does not react with the cooling medium and is not dissolved in the cooling medium. The immersion cooling apparatus according to any one of claims 1 to 3.

7. The thermal conductive sheet has a compression rate of 5% or more and 95% or less when compressed in a thickness direction at 200 kPa. The immersion cooling apparatus according to any one of claims 1 to 3.

8. The thermally conductive sheet includes graphite. The immersion cooling apparatus according to claim 1 or 2.

9. Further comprising a heat exchanger for cooling the cooling medium. The immersion cooling apparatus according to any one of claims 1 to 3.

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