Thermally conductive materials and electronic components

Abstract

The present disclosure addresses the problem of providing a thermoconductive material that can achieve sufficient close contact with the center part of a heat-generating element where there is a large amount of heat generated, that provides improved cooling performance, and that has excellent reliability. A thermoconductive material (1) is provided between a heat-generating element (20) and a heat-dissipating element (30), and is fastened with a plurality of screws together with the heat-generating element (20) and the heat-dissipating element (30). The thermoconductive material (1) is mainly constituted by a carbon material and has a plurality of screw holes (13) through which the plurality of screws respectively pass in the thickness direction. Included are an inward region which is more toward the center part of the thermoconductive material (1) than are the plurality of screw holes (13), and an outward region which is more toward the outer periphery of the thermoconductive material (1) than is the inward region. The outward region includes a support part as at least a part thereof. Upon application of 500k Pa of pressure in the thickness direction, the outward thickness, which is the thickness at the support part, is greater than the inward thickness, which is the maximum thickness in the inward region.

Description

[Technical Field]

[0001] The present disclosure relates to a thermally conductive material and an electronic component, and more particularly to a thermally conductive material and an electronic component that are interposed between a heat generating body and a heat dissipating body. [Background technology]

[0002] In recent years, the number of electric vehicles and hybrid vehicles that use electric motors as the main or auxiliary drive sources for running has been increasing. The inverters that control these vehicles use insulated gate bipolar transistors (IGBTs), and these IGBTs are attached to a heat sink with screws or other means to dissipate the heat they generate.

[0003] Regarding such a technique, Patent Document 1 discloses a power module with a heat dissipation component, which includes a power module including a base plate, a ceramic insulating substrate bonded onto the base plate, and a semiconductor element bonded onto the ceramic insulating substrate, and a heat dissipation component attached to the base plate side of the power module via a heat dissipation sheet, in which the flatness of the surface of the base plate opposite to the ceramic insulating substrate is set to 20 μm or less.

[0004] In addition to this method, grease or other materials are used between the IGBT and the heat sink to smoothly transfer heat. However, when grease is used, the thermal conductivity is insufficient. In addition, when the IGBT repeatedly heats up and cools down, the grease expands and gradually pushes outward, which can cause a deterioration in thermal conductivity. Another method involves transferring heat by sandwiching a solid thermal conductive sheet such as a graphite sheet, but when tightened with screws, more force is applied to the periphery, preventing sufficient adhesion to the center of the heat sink, where the heat generation is greatest, and therefore, insufficient cooling effect can be achieved. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-067801 Summary of the Invention

[0006] The object of the present disclosure is to provide a thermally conductive material and an electronic component that can be sufficiently adhered to a heat-generating element even in the central portion where the amount of heat generated is large, can improve cooling performance, and are highly reliable.

[0007] A thermally conductive material according to one aspect of the present disclosure is a thermally conductive material interposed between a heat generating element and a heat dissipating element and fastened together with the heat generating element and the heat dissipating element by a plurality of screws. The thermally conductive material is primarily made of carbonaceous material and has a plurality of threaded portions through which the plurality of screws pass in the thickness direction. The thermally conductive material includes an inner region that is a region closer to the center of the thermally conductive material than the plurality of threaded portions, and an outer region that is a region closer to the outer edge of the thermally conductive material than the inner region, and the outer region includes a support portion that is at least a part of the inner region. When a pressure of 500 kPa is applied in the thickness direction, the outer thickness, which is the thickness at the support portion, is greater than the inner thickness, which is the maximum thickness of the inner region.

[0008] An electronic component according to one aspect of the present disclosure includes a heat generating element, a heat sink, a thermally conductive material interposed between the heat generating element and the heat sink, and a plurality of screws fastening the heat generating element, the thermally conductive material, and the heat sink. The thermally conductive material is primarily carbonaceous and has the plurality of screws passing through it in its thickness direction. The thermally conductive material includes an inner region that is closer to the center of the thermally conductive material than the central axes of the plurality of screws, and an outer region that is closer to the outer edge of the thermally conductive material than the inner region, and the outer region includes a support portion that is at least a part of the outer region. When a pressure of 500 kPa is applied in the thickness direction, the outer thickness, which is the thickness at the support portion, is greater than the inner thickness, which is the maximum thickness of the inner region. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a schematic top view showing an example of the thermally conductive material according to this embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view of the thermally conductive material of FIG. [Figure 3] FIG. 3 is a schematic cross-sectional view showing an example of an electronic component according to this embodiment. [Figure 4] 4A to 4D are schematic top views showing other examples of the thermally conductive material according to this embodiment. [Figure 5] 5A and 5B are schematic top views showing other examples of the thermally conductive material according to this embodiment. [Figure 6] 6A to 6D are schematic cross-sectional views showing other examples of the thermally conductive material according to this embodiment. [Figure 7] 7A to 7C are schematic perspective views showing the thermally conductive materials used in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1. Overview A thermally conductive material and an electronic component according to an embodiment of the present disclosure will be described. Note that the following embodiment is merely one of various embodiments of the present disclosure. The following embodiment can be modified in various ways depending on the design as long as the object of the present disclosure can be achieved.

[0011] A thermal interface material (TIM) is a material that mediates the transfer of heat between two components when placed between them.

[0012] The thermally conductive material 1 according to this embodiment is a thermally conductive material that is interposed between a heat generating element and a heat dissipating element and fastened together with the heat generating element and the heat dissipating element with a plurality of screws. The thermally conductive material 1 is mainly made of carbonaceous material and has a plurality of threaded portions through which a plurality of screws are respectively passed in the thickness direction. The thermally conductive material 1 includes an inner region that is a region closer to the center of the thermally conductive material 1 than the plurality of threaded portions, and an outer region that is a region closer to the outer edge of the thermally conductive material 1 than the inner region, and the outer region includes a support portion that is at least a part of the outer region. When a pressure of 500 kPa is applied in the thickness direction, the outer thickness, which is the thickness at the support portion, is greater than the inner thickness, which is the maximum thickness of the inner region.

[0013] Conventional thermally conductive materials are, for example, rectangular graphite sheets with screw holes or the like near the corners, and screws are passed through these screw holes to fasten the heat generating element and the heat dissipating element, compressing and adhering the thermally conductive material. Normally, with such thermally conductive materials, a greater force is applied to the periphery, which is more compressed, resulting in poor adhesion in the center, increased thermal resistance, and making it difficult to achieve a sufficient cooling effect.

[0014] In contrast, when a pressure of 500 kPa is applied in the thickness direction, the thermally conductive material 1 of this embodiment has a larger outer thickness, which is the thickness of the support portion that is at least a part of the outer region that is closer to the outer edge than the inner region, than the inner thickness, which is the maximum thickness in the inner region that is closer to the center than the screw-through portion. The support portion in the outer region provides support, allowing sufficient adhesion even in the center, where the heat generation of the heat-generating element is high, when fastened with a screw. This reduces the thermal resistance in the inner region and improves cooling performance. As a result, the reliability of the thermally conductive material and electronic components that use this thermally conductive material can be improved.

[0015] The electronic component 100 according to this embodiment includes a heat generating element, a heat sink, a thermally conductive material 1 interposed between the heat generating element and the heat sink, and a plurality of screws for fastening the heat generating element, the thermally conductive material, and the heat sink. The plurality of screws pass through the thermally conductive material 1 in the thickness direction thereof, and the thermally conductive material 1 is primarily composed of carbonaceous material. The thermally conductive material 1 includes an inner region that is closer to the center of the thermally conductive material 1 than the central axes of the plurality of screws, and an outer region that is closer to the outer edge of the thermally conductive material 1 than the inner region, and the outer region includes a support portion that is at least a part of the outer region. When a pressure of 500 kPa is applied in the thickness direction, the outer thickness, which is the thickness at the support portion, is greater than the inner thickness, which is the maximum thickness of the inner region.

[0016] In the electronic component 100 of this embodiment, the thermally conductive material 1 has an outer thickness, which is the thickness of a support portion that is at least a part of the outer region that is closer to the outer edge than the inner region, greater than the inner thickness, which is the maximum thickness in the inner region that is closer to the center than the central axis of the screw. The support portion in the outer region provides support, allowing the heat-generating element to be sufficiently tightly attached even in the center, where heat generation is high, when fastened with a screw. This reduces thermal resistance in the inner region and improves cooling performance. As a result, the reliability of the electronic component 100 can be improved.

[0017] 2.Details <Thermal conductive materials> The thermally conductive material 1 according to this embodiment is primarily carbonaceous. "Carbonaceous" refers to a substance that is primarily composed of carbon and is composed solely of carbon, excluding atoms or molecules that are unavoidably mixed in as impurities. "Mainly composed of carbonaceous" means that the proportion of carbonaceous material in the substances that make up the thermally conductive material 1 is, for example, 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more.

[0018] Examples of substances made of carbonaceous materials include sheet-like carbonaceous materials such as graphite and graphene, particulate carbonaceous materials such as carbon black, ketjen black, and acetylene black, and fibrous carbonaceous materials such as carbon nanotubes, carbon nanohorns, and vapor-grown carbon fibers.

[0019] The thermally conductive material 1 has a plurality of screw-through portions. The screw-through portions are portions through which screws are passed in the thickness direction of the thermally conductive material 1. The screw-through portions are preferably hole-shaped or notched. In this case, the screws can be more firmly fixed, thereby improving adhesion, further improving cooling performance, and providing greater reliability.

[0020] The thermally conductive material 1 preferably has four or more threaded portions. Furthermore, it is preferable that four of these threaded portions are arranged at the vertices of a rectangle. In this case, the thermally conductive material 1 can be more firmly fixed, thereby improving adhesion, cooling performance, and reliability. It is more preferable that the four threaded portions are arranged at the vertices of a rectangle or square.

[0021] The thermally conductive material 1 includes an inner region (hereinafter also referred to as inner region A) and an outer region (hereinafter also referred to as outer region A).

[0022] The inner region A is a region closer to the center of the thermally conductive material 1 than the multiple threading portions. More specifically, the inner region A is a region closer to the center than the most central portion of the threading portions. When there are two threading portions, the inner region A is a region closer to the center than the most central portion of each of the two threading portions. When there are four or more threading portions, and these four are arranged at the vertices of a rectangle, the inner region A is a quadrilateral region whose vertices are the most central portions of the thermally conductive material 1 at each of the four threading portions. In this case, adhesion can be further improved, cooling performance can be further improved, and reliability can be further enhanced.

[0023] The outer region A is a region closer to the outer edge of the thermally conductive material 1 than the inner region A. In other words, the outer region A is a region outside the inner region A. The outer region A includes a support portion (hereinafter also referred to as support portion A) that is at least a part of the outer region A.

[0024] In the thermally conductive material 1, the outer thickness (hereinafter also referred to as the outer thickness A) is greater than the inner thickness (hereinafter also referred to as the inner thickness A). The inner thickness A is the maximum thickness in the inner region A when a pressure of 500 kPa is applied in the thickness direction. The outer thickness A is the thickness of the supporting portion A when a pressure of 500 kPa is applied in the thickness direction. By making the outer thickness A greater than the inner thickness A, the supporting portion A present in the outer region A provides support, allowing the thermally conductive material 1 to be sufficiently tightly attached even in the central portion where the heat generation of the heat-generating element is large when fastened with a screw. This reduces the thermal resistance in the inner region A and improves cooling performance. As a result, the reliability of the thermally conductive material 1 and the electronic component 100 using the thermally conductive material 1 can be improved.

[0025] The shape of the thermally conductive material 1 is not particularly limited, but may be, for example, a sheet shape that is rectangular in plan view.

[0026] FIG. 1 is a top view showing an example of a thermally conductive material 1 of this embodiment. FIG. 2 is a cross-sectional view showing the thermally conductive material 1 of FIG. 1. The thermally conductive material 1 shown in FIGS. 1 and 2 includes a carbonaceous sheet 11, a screw-through portion 13, and an overlapping portion 12 that overlaps the carbonaceous sheet 11 in an outer region A. The thermally conductive material 1 of FIGS. 1 and 2 has the overlapping portion 12 disposed in the outer region A, forming a laminated structure in the outer region A, so that the outer thickness A is greater than the inner thickness A. In this case, adhesion can be further improved, cooling performance can be further improved, and reliability can be further enhanced.

[0027] The dimensions of the thermally conductive material 1 can be selected appropriately according to the size of the IGBT to be mounted, but for example, it is a rectangle of approximately 60 mm x 120 mm with a central thickness of approximately 0.2 mm. The overlapping portion 12 can be formed, for example, by attaching polyethylene terephthalate (PET) tape with a thickness of approximately 10 μm to both short sides of the rectangular shape of the carbonaceous sheet 11. This thermally conductive material 1 is designed so that when a pressure of 500 kPa is applied to the inner region A, the thickness is, for example, approximately 0.125 mm, and when a pressure of 500 kPa is applied to the outer region A, the thickness is, for example, approximately 0.135 mm.

[0028] The carbonaceous sheet 11 is a sheet containing carbonaceous material. Examples of the carbonaceous sheet 11 include a graphite sheet and a graphene sheet. The carbonaceous sheet 11 may be, for example, a graphite sheet or the like impregnated with a resin, or a mixture of carbonaceous material and a resin or the like formed into a sheet.

[0029] The overlapping portion 12 is a portion that overlaps the carbonaceous sheet 11 in the outer region A. In the outer region A, the overlapping portion 12 and the carbonaceous sheet 11 form a laminated structure.

[0030] The shape of the overlapping portion 12 is not particularly limited, and may be, for example, a sheet shape, a protrusion shape, or the like. The material constituting the overlapping portion 12 is not particularly limited, and may be the same material as the carbonaceous sheet 11, or may be a resin, a metal, or the like. An example of a resin is PET. PET is hardly compressed at a pressure of about 500 kPa, and therefore is preferably used as a material constituting the overlapping portion 12. The overlapping portion 12 may be formed of one layer or member, or two or more layers or members.

[0031] When the screw-through portion 13 is hole-shaped, the overlapping portion 12 in the outer region A is formed over both short sides of the rectangular shape in the thermally conductive material 1 of FIG. 1 . This positioning of the overlapping portion 12 is preferable because it facilitates longitudinal deflection when the thermally conductive material 1 is rectangular. The positioning of the overlapping portion 12 in the outer region A is not limited thereto, and may be, for example, part of both short sides of the rectangle ( FIG. 4A ), all of both long and short sides of the rectangle ( FIG. 4B ), scattered on both short sides of the rectangle ( FIG. 4C ), or at the four corners of the rectangle ( FIG. 4D ). Furthermore, when the screw-through portion 13 is cutout-shaped, the positioning of the overlapping portion 12 in the outer region A is not particularly limited, and may be, for example, all of both long and short sides of the rectangle other than the screw-through portion 13 ( FIG. 5A ), or part of both short sides of the rectangle ( FIG. 5B ).

[0032] The laminated structure formed by the carbonaceous sheet 11 and the overlapping portion 12 may be, for example, a structure formed by the carbonaceous sheet 11 and the protrusion-shaped overlapping portion 12 (FIG. 6A), or a structure formed by providing the sheet-shaped overlapping portion 12 on both sides of the carbonaceous sheet 11 (FIG. 6B).

[0033] The laminated structure may also be formed by folding back at least a portion of the outer region A (FIG. 6C). In this case, the thermally conductive material 1 can be produced more easily.

[0034] The thermally conductive material 1 may be formed by removing the inner region A so that the inner thickness A is smaller than the outer thickness A, as shown in FIG. 6D.

[0035] The difference between the outer thickness A and the inner thickness A, i.e., the value obtained by subtracting the inner thickness A from the outer thickness A, is preferably 10 μm or more. In this case, stable contact can be achieved even at the center of the thermally conductive material 1, further reducing the temperature of the heating element. This difference can be achieved, for example, by making the thickness of the overlapping portion 12 forming the laminated structure 10 μm or more. This difference is more preferably 20 μm or more, and even more preferably 30 μm or more. There is no particular upper limit to this difference, but it is, for example, 1500 μm or less.

[0036] The ratio of the outer thickness A to the inner thickness A (outer thickness A / inner thickness A) is preferably 1.05 or more. In this case, stable contact can be achieved even at the center of the thermally conductive material 1, further reducing the temperature of the heating element. This ratio is more preferably 1.1 or more, and even more preferably 1.2 or more. There is no particular upper limit to this ratio, but it is, for example, 10 or less.

[0037] It is preferable that the compressibility of at least a portion of the internal region A when a pressure of 500 kPa is applied in the thickness direction is 30% or more. By using a thermally conductive material 1 with such high compressibility, even if the surface of a heat generating element or heat dissipating element is uneven, the thermal conductive material 1 can be deformed in accordance with the unevenness, thereby reducing thermal resistance. This compressibility is more preferably 40% or more, and even more preferably 50% or more. The upper limit of this compressibility is not particularly limited, but is, for example, 90% or less. The compressibility is the percentage of the thickness reduction of the thermally conductive material 1 when a pressure of 500 kPa is applied in the thickness direction of the thermally conductive material 1, relative to the thickness (initial thickness) of the thermally conductive material 1 when no pressure is applied. The compressibility can be measured using a method in accordance with ASTM D5470 and calculated using the formula (1-T2 / T1) × 100(%), where T1 is the initial thickness of the thermally conductive material 1 and T2 is the thickness of the thermally conductive material 1 when a compressive pressure of 500 kPa is applied.

[0038] When the screw-through portions 13 are hole-shaped and the thermally conductive material 1 has four or more screw-through portions 13, four of which are arranged at the vertices of a rectangle, the outer region A preferably has the support portions A in a region outside the rectangle whose vertices are the centers of the four screw-through portions 13. By arranging the support portions A in this region in the outer region A, the support of the support portions A is strengthened, which can improve adhesion when tightened with screws, further improve cooling performance, and provide greater reliability. Furthermore, the support portions A are preferably arranged in a region of the outer region A closer to the outer edge of the thermally conductive material 1 than the central axes of the multiple screws.

[0039] The thermally conductive material 1 described above has a laminated structure formed in the outer region A, but the thermally conductive material 1 of the present embodiment is not limited to this and may be any material as long as the outer thickness A is greater than the inner thickness A, for example, the thermally conductive material 1 may be made of different materials in the outer region A and the inner region A. Examples of such a thermally conductive material 1 include a carbonaceous sheet 11 in which the density in the outer region A is greater than the density in the inner region A, and a carbonaceous sheet 11 in which the outer region A is impregnated with a resin or the like to reduce the compressibility.

[0040] <Electronic components> 3 is a cross-sectional view showing an example of an electronic component 100 according to an embodiment of the present disclosure. The electronic component 100 in FIG. 3 includes a thermally conductive material 1, a heating element 20, a heat sink 30, and a screw 40.

[0041] The heating element 20 is a member that generates heat, such as a semiconductor component. Examples of semiconductor components include, but are not limited to, transistors, CPUs (central processing units), MPUs (microprocessing units), driver ICs, and memories. The heating element 20 may be composed of, for example, a heat spreader and a chip portion fixed on the heat spreader. The heat spreader is a plate-shaped 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 that penetrate the heat spreader may be formed in the outer edge portion.

[0042] The heat dissipator 30 is a member to which heat generated by the heat generating element 20 is transferred. Heat can be dissipated from the heat dissipator 30. The heat dissipator 30 is, for example, a heat sink. The heat dissipator 30 shown in FIG. 3 is a plate-shaped heat sink, but the heat dissipator 30 may further include heat dissipation fins. The heat dissipator 30 has a plurality of screw holes and the like formed at positions corresponding to the plurality of screw holes and the like in the heat generating element 20 described above.

[0043] 3 includes a carbonaceous sheet 11, an overlapping portion 12, and a screw-insertion portion 13. The thermally conductive material 1 in the electronic component 100 has the same configuration as the thermally conductive material 1 described above, except for the inner and outer regions.

[0044] The thermally conductive material 1 includes an inner region (hereinafter also referred to as inner region B) and an outer region (hereinafter also referred to as outer region B).

[0045] The inner region B is a region closer to the center of the thermally conductive material 1 than the central axes of the multiple screws 40. More specifically, when there are two screws 40, the inner region B is a region closer to the center than the central axes of each of the two screws 40. When there are four or more screws 40 and four of the screws 40 are arranged at the vertices of a rectangle, the inner region B is a quadrangle region whose vertices are the central axes of the four screws. In this case, it is possible to further increase adhesion, further improve cooling performance, and further enhance the reliability of the electronic component 100.

[0046] The outer region B is a region closer to the outer edge of the thermally conductive material 1 than the inner region B. In other words, the outer region B is a region outside the inner region B. The outer region B includes a support portion (hereinafter also referred to as support portion B) that is at least a part of the outer region B.

[0047] In the thermally conductive material 1 of the electronic component 100, the outer thickness (hereinafter also referred to as the outer thickness B) is greater than the inner thickness (hereinafter also referred to as the inner thickness B). The inner thickness B is the maximum thickness in the inner region B when a pressure of 500 kPa is applied in the thickness direction. The outer thickness B is the thickness of the support portion B when a pressure of 500 kPa is applied in the thickness direction. In the electronic component 100, by making the outer thickness B of the thermally conductive material 1 greater than the inner thickness B, the support portion B in the outer region B provides support, and when fastened with a screw, sufficient adhesion can be achieved even in the central portion where the heat generation of the heat-generating element is large. This reduces the thermal resistance in the inner region B and improves cooling performance. As a result, the reliability of the electronic component 100 can be improved. [Example]

[0048] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the following examples.

[0049] The thermally conductive material was evaluated in terms of the relationship between the number of overlapping sheets and the width or position of the overlapping portion.

[0050] 1. Number of layers [Comparative Example 1 and Examples 1 to 3] A 3 mm-wide overlap was created at each end of a base TIM (graphite sheet, thickness: 0.2 mm) using graphite sheets (thickness: 0.2 mm). As shown in Figure 7A, the overlap width was set to 3 mm, and the number of overlapping sheets (the number of layers stacked in the overlapping portion) was varied from 0 (Comparative Example 1), 3 (Example 1), 5 (Example 2), and 7 (Example 3) to create thermally conductive materials. The junction temperature (Tj (°C)) of these thermally conductive materials was measured using a commercially available semiconductor module. ΔTj (°C) is the difference between Tj and the heat sink temperature (25°C). (Measurement conditions) I C :220A, V GE : 15V, ON / OFF: 180 seconds / 180 seconds, heat sink temperature = 25°C, tightening torque: 4N m

[0051] In the thermally conductive material of Fig. 7A, for example, the inner region is a rectangular region whose vertices are the points closest to the center of the thermally conductive material in each of the four hole-shaped screw-through portions (hereinafter also referred to as screw holes), and the outer region is the region outside this inner region. In the thermally conductive material of Fig. 7, the inner thickness (the maximum thickness in the inner region) is, for example, the thickness at the center of the thermally conductive material when a pressure of 500 kPa is applied in the thickness direction, and the outer thickness (the thickness at the support portion which is at least a part of the outer region) is, for example, the thickness at the overlapping portion of the thermally conductive material.

[0052] The number of layers, inner thickness (mm), outer thickness (mm), ΔTj (°C), and Tj (°C) for each of Comparative Example 1 and Examples 1 to 3 are shown in Table 1 below.

[0053] [Table 1]

[0054] The results in Table 1 show that the thermally conductive material of the example, in which the outer thickness is greater than the inner thickness, has improved cooling performance compared to the thermally conductive material of the comparative example, in which the outer thickness is not greater than the inner thickness (the outer thickness is the same as the inner thickness).

[0055] 2. Position or width of overlapping part Regarding the position or width of the overlapping portion, overlapping portions were made using graphite sheets (thickness: 0.2 mm) at both ends of the base TIM (graphite sheet, thickness: 0.2 mm), and each thermally conductive material was made with three overlapping sheets, and the junction temperature (Tj (°C)) was measured using the same method as above.

[0056] [Example 1] As shown in FIG. 7A, an overlapping portion with a width of 3 mm was formed in the area outside the screw holes (partially overlapping the screw holes) (same as in Example 1 above). Comparative Example 2 As shown in FIG. 7B, an overlapping portion with a width of 10 mm was formed over the outer and inner regions of the screw hole. Comparative Example 3 As shown in FIG. 7C, a 3 mm wide overlapping portion was formed in the area inside the screw hole (partially overlapping the screw hole).

[0057] When a pressure of 500 kPa is applied in the thickness direction of the thermally conductive material, In Example 1, the inner thickness is, for example, the thickness at the center of the thermally conductive material in FIG. 7A, and the outer thickness is, for example, the thickness at the overlapping portion of the thermally conductive material. In Comparative Example 2, the inner thickness is the thickness of the portion of the thermally conductive material closer to the center than the screw hole in the overlapping portion of the thermally conductive material in Figure 7B, and the outer thickness is the thickness of the portion of the thermally conductive material closer to the outer edge than the screw hole in the overlapping portion. In Comparative Example 3, the inner thickness is the thickness of the portion inside the screw holes (between the two screw holes) in the overlapping portion of the thermally conductive material in Figure 7C, for example, and the outer thickness is the thickness of the portion outside the screw holes in the overlapping portion, for example.

[0058] The position and width (mm) of the overlapping portion, inner thickness (mm), outer thickness (mm), ΔTj (°C), and Tj (°C) for each of Example 1 and Comparative Examples 2 and 3 are shown in Table 2 below.

[0059] [Table 2]

[0060] The results in Table 2 show that the thermally conductive materials of the examples, in which the outer thickness was greater than the inner thickness, had excellent cooling performance. On the other hand, the thermally conductive materials of the comparative examples, in which the outer thickness was not greater than the inner thickness (the outer thickness was the same as the inner thickness), had poor cooling performance.

[0061] As is clear from the above-described embodiments and examples, the thermally conductive material (1) according to the first aspect of the present disclosure is a thermally conductive material interposed between a heat generating element (20) and a heat dissipating element (30) and fastened together with the heat generating element (20) and the heat dissipating element (30) with a plurality of screws. The thermally conductive material (1) is primarily made of carbonaceous material and has a plurality of screw-through portions (13) through which a plurality of screws are respectively passed in the thickness direction. The thermally conductive material (1) includes an inner region that is a region closer to the center of the thermally conductive material (1) than the plurality of screw-through portions (13) and an outer region that is a region closer to the outer edge of the thermally conductive material (1) than the inner region, and the outer region includes a support portion that is at least a part of the outer region. When a pressure of 500 kPa is applied in the thickness direction, the outer thickness, which is the thickness at the support portion, is greater than the inner thickness, which is the maximum thickness of the inner region.

[0062] According to the first aspect, the support portion present in the outer region provides support, and when fastened with a screw, the heat generating element (20) can be sufficiently tightly attached even in the central portion where the heat generation is large, thereby reducing the thermal resistance in the inner region and improving the cooling performance. As a result, the reliability of the thermally conductive material (1) and the electronic component (100) using the thermally conductive material (1) can be improved.

[0063] In a second aspect of the present disclosure, the screw-insertion portion (13) in the first aspect has a hole shape or a notch shape.

[0064] According to the second aspect, the screw (40) can be fixed more firmly, thereby improving adhesion, improving cooling performance, and providing greater reliability.

[0065] In a third aspect of the present disclosure, in the first or second aspect, there are four or more screw-insertion portions (13), four of which are arranged at the vertices of a rectangle.

[0066] According to the third aspect, the thermally conductive material (1) can be fixed more firmly, thereby improving adhesion, cooling performance, and reliability.

[0067] In a fourth aspect of the present disclosure, in the third aspect, the inner region is a rectangular region with vertices at the points of each of the four threaded portions (13) closest to the center of the thermally conductive material (1).

[0068] According to the fourth aspect, it is possible to further increase the adhesion, to further improve the cooling performance, and to further improve the reliability.

[0069] In a fifth aspect of the present disclosure, in the third or fourth aspect, the screw-through portion (13) is hole-shaped, and has a support portion in the outer region, which is an outer region of a rectangle with vertices at the centers of the four screw-through portions (13).

[0070] According to the fifth aspect, by arranging the support part in the above-mentioned area in the external region, the support part provides stronger support, and when tightened with the screw (40), the adhesion can be improved, the cooling performance can be further improved, and the reliability can be made better.

[0071] In a sixth aspect of the present disclosure, in any one of the first to fifth aspects, the difference between the outer thickness and the inner thickness is 10 μm or more.

[0072] According to the sixth embodiment, stable contact can be achieved even at the center of the thermally conductive material (1), and the temperature of the heating element (20) can be further reduced.

[0073] In a seventh aspect of the present disclosure, in any one of the first to sixth aspects, the compressibility of at least a part of the inner region when a pressure of 500 kPa is applied in the thickness direction is 30% or more.

[0074] According to the seventh aspect, by using a thermally conductive material (1) with high compressibility, even if the surface of the heat generating element (20) or the heat dissipating element (30) is uneven, the material can be deformed in accordance with the unevenness, thereby reducing the thermal resistance.

[0075] In an eighth aspect of the present disclosure, in any one of the first to seventh aspects, a laminated structure is formed in the outer region.

[0076] According to the eighth aspect, it is possible to further increase the adhesion, to further improve the cooling performance, and to further improve the reliability.

[0077] In a ninth aspect of the present disclosure, in the eighth aspect, the laminated structure is formed by folding back at least a portion of the outer region.

[0078] According to the ninth aspect, the thermally conductive material (1) can be produced more easily.

[0079] An electronic component (100) according to a tenth aspect of the present disclosure includes a heat generating element (20), a heat sink (30), a thermally conductive material (1) interposed between the heat generating element (20) and the heat sink (30), and a plurality of screws (40) for fastening the heat generating element (20), the thermally conductive material (1), and the heat sink (30). The thermally conductive material (1) is primarily made of carbonaceous material and has a plurality of screws (40) passing through it in its thickness direction. The thermally conductive material (1) includes an inner region that is closer to the center of the thermally conductive material (1) than the central axes of the plurality of screws (40) and an outer region that is closer to the outer edge of the thermally conductive material (1) than the inner region, and the outer region includes a support portion that is at least a part of the outer region. When a pressure of 500 kPa is applied in the thickness direction, the outer thickness, which is the thickness at the support portion, is greater than the inner thickness, which is the maximum thickness of the inner region.

[0080] According to the tenth aspect, the support portions in the outer region provide support, and when the screws are tightened, the heat generating element (20) can be tightly attached even in the central region where the heat generation is large, thereby reducing the thermal resistance in the inner region and improving the cooling performance, thereby improving the reliability of the electronic component (100). [Explanation of symbols]

[0081] 1. Thermally conductive materials 11 Carbonaceous sheet 12 Overlap 13 Threading section 20 Heating element 30 Heat sink 40 screws 100 Electronic Components

Claims

1. A thermally conductive material that is interposed between a heat generating element and a heat dissipating element and is fastened together with the heat generating element and the heat dissipating element by a plurality of screws, Mainly carbonaceous, a plurality of screw-passing portions through which the plurality of screws pass in a thickness direction; an inner region that is a region closer to a center portion of the thermally conductive material than the plurality of threading portions; and an outer region that is a region closer to an outer edge portion of the thermally conductive material than the inner region, the outer region includes a support portion that is at least a portion thereof; the screw-through portions are hole-shaped, and there are four or more of them, and the centers of the four screw-through portions are disposed at vertices of a quadrangle; The support portion is provided in an area outside the quadrangle in the outer area, A thermally conductive material in which, when a pressure of 500 kPa is applied in the thickness direction, the outer thickness, which is the thickness at the support portion, is greater than the inner thickness, which is the maximum thickness in the inner region.

2. The thermally conductive material according to claim 1 , wherein the difference between the outer thickness and the inner thickness is 10 μm or more.

3. 3. The thermally conductive material according to claim 1, wherein the compressibility of at least a portion of the inner region is 30% or more when a pressure of 500 kPa is applied in the thickness direction.

4. The thermally conductive material according to claim 1 , wherein a laminated structure is formed in the outer region.

5. The thermally conductive material according to claim 4 , wherein the laminated structure is formed by folding back at least a portion of the outer region.

6. A heating element; A heat sink; a thermally conductive material interposed between the heat generating element and the heat dissipating element; a plurality of screws for fastening the heat generating element, the thermally conductive material, and the heat dissipating element together; An electronic component comprising: The thermally conductive material is The plurality of screws are passed through the thickness direction of the Mainly carbonaceous, an inner region that is a region closer to the center of the thermally conductive material than the central axes of the plurality of screws; and an outer region that is a region closer to the outer edge of the thermally conductive material than the inner region, the outer region includes a support portion that is at least a portion thereof; There are four or more screws, and the central axes of the four screws are arranged at vertices of a quadrangle; The support portion is provided in an area outside the quadrangle in the outer area, An electronic component in which, when a pressure of 500 kPa is applied in the thickness direction, the outer thickness, which is the thickness at the support portion, is greater than the inner thickness, which is the maximum thickness in the inner region.

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