Composite structure, and heat dissipation structure

Abstract

To provide a composite structure that is a composite of metal and graphite capable of improving heat transfer performance.SOLUTION: The composite structure includes a graphite laminate and a metal body. The graphite laminate has a structure in which multiple graphite plates are stacked, and has a first end and a second end opposite to the first end in the longitudinal direction. The metal body has an internal space extending longitudinally, and at least between the first end and the second end, a graphite laminate is accommodated in the internal space enclosing the outer periphery of the graphite laminate. The graphite laminate has a rectangular cross-section defined by four sides that are inclined relative to the stacking direction of the graphite plates, as a cross-section that intersects the longitudinal direction. The metal body is in contact with the four sides of the rectangular cross-section of the graphite laminate on its inner surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a composite structure and a heat dissipation structure that efficiently diffuses and dissipates heat generated from semiconductor devices, in-vehicle devices, electronic devices, etc., suppresses the occurrence of malfunctions in the devices due to heat generation, and maintains and improves the functionality of the devices. [Background technology]

[0002] With the recent demand for high-volume and high-speed communications, semiconductor devices, in-vehicle devices, electronic devices, etc., are required to avoid performance degradation or shutdown caused by high temperatures in parts of the device or its surroundings due to their high output. Conventionally, copper heat spreaders and aluminum heat dissipation fins have been used to transfer and dissipate generated heat from the device to the board or housing. Materials with high thermal conductivity, such as metals and carbides, are used for heat transfer and dissipation.

[0003] Crystalline graphite has a high thermal conductivity compared to metals, making it a promising heat transport material. However, crystalline graphite exhibits strong anisotropy in both the plane direction (basal plane direction) and the thickness direction, resulting in a difference in thermal conductivity and strength of several tens of times between the plane direction and the thickness direction, making it difficult to use crystalline graphite alone. To utilize crystalline graphite as a heat transport material, it is necessary to combine it with a metal that has a high thermal conductivity so as not to impair the thermal conductivity of the crystalline graphite.

[0004] For example, Patent Document 1 discloses a production method for obtaining a metal-carbon particle composite material by applying a slurry containing carbon particles to a metal foil such as aluminum or copper, drying the coated foil, preparing a laminate of the metal foil containing the carbon particles, winding the laminate into a roll, and then extruding the roll using an extruder. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6821409 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the composite of Patent Document 1, the carbon material with high thermal conductivity is used in particulate form, and it is difficult to arrange the carbon particles inside the composite so that adjacent carbon particles are in contact with each other. Therefore, the composite of Patent Document 1 does not achieve an improvement in thermal conductivity in the intended direction.

[0007] Therefore, an object of the present disclosure is to provide a composite structure and a heat dissipation structure that can improve heat transfer performance in a composite structure that combines a metal material and graphite. [Means for solving the problem]

[0008] A composite structure according to one embodiment of the present disclosure includes a graphite laminate and a metal body. The graphite laminate has a structure in which a plurality of graphite plates are stacked, and has a first end in a longitudinal direction and a second end opposite the first end. The metal body has an internal space extending in the longitudinal direction and accommodates the graphite laminate in the internal space so as to surround the outer periphery of the graphite laminate at least between the first end and the second end. The graphite laminate has a rectangular cross section that intersects with the longitudinal direction and is defined by four sides that are inclined with respect to the stacking direction of the graphite plates. The metal body contacts the four sides of the rectangular cross section of the graphite laminate on its inner surface.

[0009] A heat dissipation structure according to one aspect of the present disclosure includes a heat source object, a substrate on which the heat source object is disposed, and a plurality of composite structures having the features of the above-described aspect. The plurality of composite structures are arranged with their respective longitudinal directions intersecting the substrate and supporting the substrate. The plurality of composite structures dissipate thermal energy conducted from the heat source object via the substrate. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a composite structure and a heat dissipation structure that can improve heat transfer performance in a composite structure in which a metal material and graphite are combined. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an external view of a composite structure according to a first embodiment of the present disclosure; [Figure 2] X-Z cross section of the composite structure in Figure 1 [Figure 3] Y-Z cross section of the composite structure in Figure 1 [Figure 4] Manufacturing flow of the composite structure of the first embodiment [Figure 5a] Schematic explanatory diagram of the manufacturing process of the composite structure of the embodiment (step a) [Figure 5b] Schematic explanatory diagram of the manufacturing process of the composite structure of the embodiment (process b) [Figure 5c] Schematic explanatory diagram of the manufacturing process of the composite structure of the embodiment (step c) [Figure 5d] Schematic explanatory diagram of the manufacturing process of the composite structure of the embodiment (step d) [Figure 5e] Schematic explanatory diagram of the manufacturing process of the composite structure of the embodiment (step e) [Figure 5f] Schematic explanatory diagram of the manufacturing process of the composite structure of the embodiment (process f) [Figure 5g] Schematic explanatory diagram of the manufacturing process of the composite structure of the embodiment (step g) [Figure 5h] Schematic explanatory diagram of the manufacturing process of the composite structure of the embodiment (step h) [Figure 6] FIG. 1 is a diagram illustrating the state of a connection interface between a metal body and a graphite laminate in the composite structure of the first embodiment. [Figure 7] FIG. 10 is a diagram illustrating the state of the connection interface between the metal body and the graphite laminate in the composite structure according to the comparative example. [Figure 8] FIG. 10 is an external view of a heat dissipation structure according to a second embodiment of the present disclosure. [Figure 9]XZ cross section of the heat dissipation structure in Figure 8 [Figure 10] FIG. 9 is a diagram showing the heat transfer path of the composite structure of the heat dissipation structure of FIG. 8. [Figure 11] Cross-sectional view of a heat dissipation structure according to a modified example (XZ cross-sectional view: rectangular cross-section) [Figure 12] Cross-sectional view of a heat dissipation structure according to a modified example (XZ cross-sectional view: trapezoidal cross-section) [Figure 13] Cross-sectional view of a heat dissipation structure according to a modified example (XZ cross-sectional view: polygonal cross-section) [Figure 14] Cross-sectional view of a heat dissipation structure according to a modified example (XZ cross-sectional view: rectangular cross-section) DETAILED DESCRIPTION OF THE INVENTION

[0012] A composite structure according to a first aspect of the present disclosure includes a graphite stack having a structure in which a plurality of graphite plates are stacked, the graphite stack having a first end and a second end opposite the first end in a longitudinal direction, and a metal body having an internal space extending in the longitudinal direction and accommodating the graphite stack in the internal space so as to surround the outer periphery of the graphite stack at least between the first end and the second end. The graphite stack has a rectangular cross section defined by four sides inclined with respect to the stacking direction of the graphite plates, as a cross section intersecting the longitudinal direction. The metal body has an inner surface in contact with the four sides of the rectangular cross section of the graphite stack.

[0013] A composite structure according to a second embodiment of the present disclosure is the composite structure according to the first embodiment, wherein four sides of the rectangular cross section of the graphite laminate are inclined at an angle in the range of 30° to 60° with respect to the stacking direction.

[0014] A composite structure according to a third embodiment of the present disclosure is the composite structure according to the second embodiment, wherein four sides of the rectangular cross section of the graphite laminate are inclined at 45° with respect to the lamination direction.

[0015] A composite structure according to a fourth aspect of the present disclosure is the composite structure of any one of the first to third aspects, wherein the quadrangular cross section of the graphite laminate has a square cross section.

[0016] A composite structure of a fifth aspect of the present disclosure is a composite structure of any one of the first to fourth aspects, wherein the metal body has a rectangular frame-shaped cross section intersecting the longitudinal direction and having a thickness of 1 mm or more and 20 mm or less.

[0017] A composite structure according to a sixth aspect of the present disclosure is the composite structure according to any one of the first to fifth aspects, wherein the metal body is aluminum or an aluminum alloy.

[0018] A composite structure according to a seventh aspect of the present disclosure is the composite structure of any one of the first to sixth aspects, wherein the graphite laminate has a structure in which a plurality of graphite plates, each having a thickness of 0.01 mm or more and 0.5 mm or less, are stacked such that their basal surfaces are in contact with each other.

[0019] A composite structure according to an eighth aspect of the present disclosure is the composite structure according to any one of the first to seventh aspects, wherein the graphite plate has a density of 1.8 g / cm 3 More than 2.2g / cm 3 The thermal conductivity in the basal plane direction is 1000 W / m K or more and 1500 W / m K or less.

[0020] A composite structure according to a ninth aspect of the present disclosure is the composite structure according to any one of the first to eighth aspects, wherein the density is 3 g / cm 3 and the thermal conductivity in at least the longitudinal direction is 400 W / m·K or more.

[0021] A heat dissipation structure of a tenth aspect of the present disclosure comprises a heat source object, a substrate on which the heat source object is arranged, and a composite structure of any one of the first to ninth aspects, the composite structure having its longitudinal direction aligned in a direction intersecting the substrate and supporting the substrate, and the multiple composite structures dissipate thermal energy conducted from the heat source object via the substrate.

[0022] A composite structure according to an eleventh aspect of the present disclosure is the heat dissipation structure according to the tenth aspect, wherein the plurality of composite structures are arranged such that the stacking direction of each of the composite structures faces the center of the substrate.

[0023] (Embodiment 1) Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In each drawing, elements are exaggerated for ease of explanation.

[0024] <Overall structure> Fig. 1 is an external view of a composite structure 1 according to a first embodiment of the present disclosure, Fig. 2 is an XZ cross-sectional view of the composite structure 1, and Fig. 3 is a YZ cross-sectional view of the composite structure 1.

[0025] 1 to 3, composite structure 1 includes metal body 2 and graphite laminated body 3, and graphite laminated body 3 is enclosed within metal body 2. In Fig. 1, the longitudinal direction of metal body 2 and graphite laminated body 3 is the Y direction, the X direction is a direction perpendicular to the Y direction, and the Z direction is a direction perpendicular to the X and Y directions.

[0026] Graphite laminate 3 has a first end 31 in the longitudinal direction and a second end 32 opposite to first end 31. Graphite laminate 3 has a structure in which a plurality of graphite plates 4 are stacked. Graphite plate 4 has a structure in which planes formed by condensed benzene rings are stacked in layers, with the benzene ring condensed planes forming basal planes 5 and planes intersecting with basal planes 5 forming edge planes (non-basal planes) 6.

[0027] Graphite laminate 3 is formed by stacking a plurality of graphite plates 4 such that the basal surfaces 5 of the graphite plates 4 face each other. Graphite laminate 3 has a characteristic that its thermal conductivity in a direction along basal surfaces 5 is significantly higher than its thermal conductivity in a direction intersecting basal surfaces 5. First end 31 and second end 32 of graphite laminate 3 form edge surfaces 6. In the example shown in FIGS. 1 to 3 , the cross section of graphite laminate 3 perpendicular to the longitudinal direction (Y direction) is square, and graphite laminate 3 has a square prism shape. Alternatively, the cross section of graphite laminate 3 perpendicular to the longitudinal direction (Y direction) may be rectangular, and graphite laminate 3 may have a square prism shape.

[0028] The graphite plate 4 is a plate-shaped member obtained by sintering one or more polymer films under controlled pressure to produce highly oriented graphite. The graphite plate 4 may have a thickness of 0.01 mm or more and a specific gravity of 1.0 to 2.2. The graphite plate 4 may have a thermal conductivity in the basal plane direction of 1000 W / m·K or more and 1500 W / m·K or less. A thickness of 0.01 mm or more ensures the necessary rigidity and ease of handling, while a thickness of 0.5 mm or less prevents economical degradation. A specific gravity of 1.0 or more of the graphite plate 4 increases crystallinity and thermal conductivity, while a specific gravity of 2.2 or less prevents increases in manufacturing costs. If the thermal conductivity of the graphite plate 4 in the basal plane direction is less than 1000 W / m·K, the thermal conductivity as a heat transport structure will be low, and if the thermal conductivity exceeds 1500 W / m·K, the manufacturing cost may increase.

[0029] The polymer film may be at least one member of the group consisting of, for example, polyimide, polyamideimide, polyoxadiazole, polybenzothiazole, polybenzobisthiazole, polybenzoxazole, polybenzobisoxazole, polypyromellitimide, aromatic polyamide, polyphenylenebenzimidazole, polyphenylenebenzobisimidazole, polythiazole, and polyparaphenylenevinylene.

[0030] When graphite plate 4 is made by compressing graphite powder, a dense graphite structure is not formed in the plane direction. In other words, the six-membered rings made of carbon atoms are torn and scattered and compressed together, resulting in a weak strength and poor heat transport performance. As a result, the intended high heat transport performance cannot be achieved. In contrast, graphite plate 4 made using the above-mentioned polymer film has a highly crystalline state in which the six-membered rings made of carbon atoms are uniformly aligned in the plane direction, resulting in improved heat transport performance.

[0031] 1 to 3, metal body 2 has internal space 20 extending in the longitudinal direction (Y direction) and has a rectangular frame-like cross section in the longitudinal direction. Metal body 2 accommodates graphite laminates 3 in internal space 20 so as to surround at least graphite laminates 3 between first end 31 and second end 32 of graphite laminates 3.

[0032] Metal body 2 has first opening 21 and second opening 22 that are connected to each other by internal space 20. First end 31 of graphite laminate 3 is exposed from first opening 21, and second end 32 of graphite laminate 3 is exposed from second opening 22. Note that metal body 2 may not have both first opening 21 and second opening 22, and graphite laminate 3 may be completely enclosed within metal body 2. Alternatively, only one of first opening 21 or second opening 22 may be provided, and only one end of graphite laminate 3 may be exposed from this opening. In the example shown in FIGS. 1 to 3 , internal space 20 of metal body 2 has a square pillar shape similar to the outer shape of graphite laminate 3.

[0033] The metal body 2 is made of aluminum or an aluminum alloy. The thickness of the metal body 2 (the distance from the inner surface defining the internal space 20 of the metal body 2 to the outer surface) surrounding the graphite laminate 3 may be 1 mm or more and 50 mm or less. Aluminum or an aluminum alloy has the advantages of being relatively lightweight among metals, having high thermal conductivity, and being a commonly used structural material and relatively inexpensive. A similar configuration to the heat transport structure 1 can be achieved even when a metal such as copper is used as the metal body 2. However, copper has a significantly higher specific gravity than aluminum, and aluminum is preferred from the perspective of lightness. Furthermore, if the thickness of the metal body 2 is less than 1 mm, manufacturing may be difficult and the rigidity of the heat transport structure 1 may be insufficient. If the thickness exceeds 50 mm, the weight of the heat transport structure 1 increases, which may result in poor productivity and economic efficiency and reduce the work efficiency when assembling multiple structures. However, the thickness of the metal body 2 is not limited to the preferred range described above and can be set to various specifications depending on the application and usage environment of the heat transport structure 1.

[0034] In the portion where the metal body 2 surrounds the graphite laminate 3, the inner surface 23 of the metal body 2, which defines the internal space 20, and the outer peripheral surface of the graphite laminate 3 constitute an interface between the metal body 2 and the graphite laminate 3. That is, the inner surface 23 of the metal body 2 and the outer peripheral surface of the graphite laminate 3 are in direct contact with each other without any other layer interposed between them. Direct contact without any other layer intervening means that there are no voids that hinder heat conduction. When observed from any cross section, it is preferable that the voids at the contact portion between the metal body and the graphite laminate are 10% or less of the contact length. By enveloping the graphite laminate 3 in contact with the metal body 2 in this manner, heat conduction loss between the materials can be reduced and the thermal conductivity of the heat transport structure 1 can be increased.

[0035] Here, the interface between metal body 2 and graphite laminate 3 will be described. As shown in Fig. 2, graphite laminate 3 has a square cross section, as a cross section orthogonal to the longitudinal direction (XZ cross section), defined by four sides inclined with respect to the stacking direction of graphite plates 4. Specifically, each of the four sides of the square cross section is inclined at 45° with respect to the stacking direction D of graphite laminate 3 (i.e., direction orthogonal to basal plane 5). In other words, the four sides of the square cross section are inclined at 45° with respect to basal plane 5 of graphite laminate 3.

[0036] As a result, substantially the entire outer peripheral surface of graphite laminate 3 becomes edge surface 6, and graphite laminate 3 comes into contact with inner surface 23 of metal body 2 at edge surface 6. Note that edge surface 6 of graphite laminate 3 refers to a surface formed by connecting edge surfaces 6 of each of stacked graphite plates 4. Composite structure 1 of the present embodiment 1 employs a structure in which metal body 2 covers four surfaces formed by edge surfaces 6 extending from first end 31 to second end 32 of graphite laminate 3.

[0037] <Features of the heat transfer structure> Next, the characteristics of the composite structure 1 including the graphite laminate 3 and the metal body 2 containing it will be described. The composite structure 1 has a specific gravity of 2.7 or less and a thermal conductivity of 400 W / m·K or more in the basal plane direction. If the metal body 2 is made of aluminum or an aluminum alloy, the specific gravity of the composite structure 1 will be 2.7 or less. Furthermore, by increasing the graphite ratio in the composite of aluminum or an aluminum alloy and highly crystalline graphite to a volume ratio of 8:2 or more, preferably 7:3 or more, the thermal conductivity of the composite structure 1 in the basal plane direction will be 400 W / m·K or more. On the other hand, if the graphite ratio is lower than a volume ratio of 8:2, the thermal conductivity of the composite structure 1 will not exceed 400 W / m·K. Therefore, it is preferable that the volume ratio of the graphite laminate 3 in the composite structure 1 be 20% or more.

[0038] <Method of manufacturing a composite structure> 4 shows a manufacturing flow (steps a to h) of the manufacturing method of the composite structure 1 of the present embodiment 1, and the manufacturing method of the composite structure 1 will be described along the manufacturing flow. Schematic explanatory diagrams including presses, dies, etc. used in each manufacturing step are shown in FIGS. 5a to 5h.

[0039] (Step a: Setting the graphite laminate) As shown in Figure 5a, graphite plate 4 having a thickness of 0.01 mm to 0.5 mm is set in a mold or the like, either one piece or multiple pieces stacked depending on the application. Graphite plate 4 is held in place by holding it on one or more sides with holding tool 7 having a split mold or other structure.

[0040] (Process b: Crimping) As shown in Figure 5b, stacked graphite plates 4 are compressed in stacking direction D using a press 8 or the like to produce stack 3A of graphite plates 4. One or more sides of graphite plate 4 are held with holding tool 7 having a split mold or other structure, and pressure is applied to graphite plates 4 so as not to damage them, thereby crimping basal surfaces 5 of graphite plates 4 together.

[0041] (Step c: Forming): A laminate 3A of graphite plates 4 is formed using a processing machine 9 such as a cutting machine. The laminate 3A is held by a jig 10 having a concave holding portion. Specifically, as shown in FIG. 5c, the laminate 3A is held by the jig 10 so that the stacking direction D of the laminate 3A is inclined (for example, at an angle of 45°) relative to a cutting surface 9a of the processing machine 9 (a surface arranged horizontally in FIG. 5c).

[0042] While held in this manner, laminate 3A is cut and shaped using cutting surface 9a of processing machine 9. This forms graphite laminate 3 having a square cross section defined by four sides, with each of the four sides inclined at 45° with respect to stacking direction D of graphite plates 4. During the shaping process, stacking direction D of laminate 3A of graphite plates 4 can be set at any angle with respect to cutting surface 9a of processing machine 9 depending on the shape of the concave holding portion of jig 10.

[0043] (Step d: Heating) 5d, a heat source such as heater 11 is provided on at least one outer peripheral surface of graphite laminate 3 having a square cross section to heat graphite laminate 3. Heating may be performed by bringing the heat source into direct contact with graphite laminate 3, or by heating graphite laminate 3 via another member such as a holder that holds graphite laminate 3. Preferably, the heat source is brought into contact with the outer peripheral surface of graphite laminate 3 and the holder for graphite laminate 3, and both are heated.

[0044] When graphite and a metal body are combined, it is preferable to use aluminum or an aluminum alloy as the metal body. In this case, the heating temperature is preferably 330°C or higher, more preferably 360°C or higher. If the heating temperature is lower than 330°C, unfilled portions of the metal material may be formed inside the composite structure 1, and if the heating temperature is lower than 360°C, small bubbles may remain inside the composite structure 1. This is because the thermal conductivity of the highly crystalline graphite used in the graphite plate 4 is between 1000 W / m·K and 1500 W / m·K. Therefore, if the graphite plate 4 is not continuously heated above the above-mentioned temperature range, the heat of the graphite plate 4 will be dissipated through the holder or mold.

[0045] (Process e: Pouring molten metal) As shown in FIG. 5e, heated graphite laminate 3 is placed in a metal mold (casting die) 14. At this time, graphite laminate 3 is positioned and placed so that a cavity 15, which is a predetermined space corresponding to metal body 2, is formed between the outer peripheral surface of graphite laminate 3 and the inner peripheral surface of metal mold 14. Thereafter, a metal material serving as a raw material for metal body 2, specifically aluminum or an aluminum alloy, is placed in a crucible 12 or the like and heated to 700°C or higher, and is poured into metal mold 14 as molten metal 13.

[0046] The molten metal 13 passes through a gate and a sprue in the mold 14 and flows into a cavity 15, which will become the metal body 2 in the composite structure 1. By providing an overflow shape at the end of the filling of the molten metal 13 in advance, it is possible to prevent improper filling of the molten metal 13. Furthermore, by providing a mesh-like flow plate at the sprue, it is possible to prevent air bubbles from flowing into the cavity 15. Furthermore, by applying pressure to the sprue after pouring the molten metal 13 or by making the volume of the sprue sufficiently large relative to the cavity 15, it is possible to increase the pressure in the cavity 15 and prevent improper filling. During the pouring of the molten metal 13, it is preferable to continue the heating of step d (i.e., heating of the graphite laminate 3 by the heater 11).

[0047] (Process f: Cure) 5f, the heating in step d is continued until the molten metal 13 poured in step e is completely solidified. If the heating is stopped before the molten metal 13 is completely solidified, the temperature of the core of the composite structure 1 (near the graphite laminates 3) will be dissipated to the holding member or mold 14 through the graphite plate, which may deteriorate the adhesion between the graphite laminates 3 and the metal body 2.

[0048] (Process g: Removal) As shown in Fig. 5g, after the molten metal 13 has completely solidified into the metal body 2 in step f, the heater 11 is turned off, the mold 14 is opened, and the composite structure 1 is removed. At this time, since the composite structure 1 has a sprue, gate, and overflow portion attached, the sprue, gate, and overflow portion are cut off, leaving the composite structure 1.

[0049] (Process h: Outer shape processing) As shown in Fig. 5h, the outer peripheral surface of the composite structure 1 separated in step g may be smoothed by machining or the like as necessary. Holes may be drilled to fasten the composite structure 1 to other components. Also, a structure for connecting the composite structure 1 to other components using only the metal body 2 may be provided in advance in the mold 14.

[0050] A cross section in the extension direction of composite structure 1 according to the first embodiment is shown in Fig. 6, and a cross section in the extension direction of composite structure 100 according to a comparative example is shown in Fig. 7. As shown in Fig. 7, composite structure 100 of the comparative example is similar to composite structure 1 of the present embodiment in that it has a structure in which the outer peripheral surface of graphite laminate 103 having a square cross section is surrounded by metal body 102. Composite structure 1 differs from composite structure 1 in that stacking direction D of graphite laminate 3 is inclined at 45° with respect to each of the four sides of graphite laminate 3, whereas composite structure 100 differs in that stacking direction D of graphite laminate 103 is perpendicular to or parallel to two opposing sides.

[0051] Consider the case where thermal energy is input from the outer surface of the metal body 102 to the composite structure 100 of the comparative example shown in FIG. 7 . The thermal energy input to the metal body 102 is transferred to the inner surface of the metal body 102 and then transferred from the inner surface of the metal body 102 to the graphite laminate 103. The inner surfaces of the metal body 102 on the left and right sides in the figure are in contact with the edge surfaces of the graphite laminate 103, so heat transfer from the metal body 102 to the graphite laminate 103 is relatively efficient in these areas. On the other hand, the inner surfaces of the top and bottom sides in the figure are in contact with the basal surfaces of the graphite laminate 103, so the heat transfer efficiency is lower than in the areas in contact with the edge surfaces. Therefore, in the composite thermal structure 100 of the comparative example, the transfer efficiency of the thermal energy input from the outer peripheral surface varies. This variation in heat transfer efficiency also occurs in the heat transfer from the graphite laminate 103 to the metal body 102.

[0052] In composite structure 1 of the present embodiment 1 shown in Fig. 6, the inner surfaces of metal body 2 on the left and right sides and the inner surfaces of the upper and lower sides are in contact with the edge faces of graphite laminates 3. This reduces the variation in heat transferability from metal body 2 to graphite laminates 3 depending on the location. Furthermore, the number of locations where metal body 2 is in contact with the basal surface can be reduced or substantially eliminated, thereby maintaining good heat transferability from metal body 2 to graphite laminates 3.

[0053] In particular, composite structure 1 employs a structure in which the lamination direction is inclined at 45° with respect to each of the four sides of graphite laminates 3, so that the connection state between the graphite laminates 3 and the inner surfaces of the left and right sides of metal body 2 in the figure is the same as that between the graphite laminates 3 and the inner surfaces of the top and bottom sides in the figure. This allows the heat transferability between metal body 2 and graphite laminates 3 to be the same on the top, bottom, left, and right sides in the figure.

[0054] Furthermore, the edge surfaces of the graphite laminates 3 have exposed terminals of the covalent bonds of carbon atoms, and therefore have stronger adhesion and bonding strength with the metal material than the basal surface. In the composite laminate 1, all of the inner surfaces of the metal body 2 are connected to the edge surfaces of the graphite laminates 3. Therefore, compared to the composite structure 100 of the comparative example, the composite structure 1 can have stronger adhesion and bonding strength between the metal body 2 and the graphite laminates 3.

[0055] Therefore, according to the first embodiment, in the composite structure 1 in which a metal material and graphite are combined, it is possible to improve the heat transfer performance.

[0056] In the above embodiment, a configuration has been described in which first opening 21 and second opening 22 are provided at both ends of metal body 2, and first end 31 of graphite laminate 3 is exposed from the first opening, and second end 32 is exposed from second opening 22. However, the configuration is not limited to this. For example, a configuration may be adopted in which one or more openings are provided between both longitudinal ends of metal body 2, and graphite laminate 3 is exposed from these openings. Such openings may be used to input and output heat to and from graphite laminate 3. Furthermore, such openings may be provided to reduce the weight of metal body 2.

[0057] Furthermore, although the structure in which metal body 2 covers the entire graphite laminated body 3 from first end 31 to second end 32 has been described, the present invention is not limited to this configuration. Metal body 2 may surround graphite laminated body 3 at least at any position between first end 31 and second end 32.

[0058] Although the cross-sectional shapes of the graphite laminates 3 and the composite structure 1 in a plane perpendicular to the longitudinal direction are mainly square, the present invention is not limited to such a configuration. The cross-sectional shapes of the graphite laminates 3 and the composite structure 1 may be any square shape, and may also be rectangular or trapezoidal. Various cross-sectional shapes may be adopted taking into consideration the ease of connection of the composite structure 1 and the environment in which it will be used. Furthermore, corners of the square cross-sectional shape may be provided with chamfered or rounded portions.

[0059] In addition, although the case where each of the four sides defining the rectangular cross section of graphite laminate 3 is inclined at an angle of 45° with respect to stacking direction D has been described, the inclination angle is not limited to 45° as long as the cross section is inclined. For example, the inclination angle may be in the range of 30° to 60°. By making the cross section of graphite laminate 3 square and setting the inclination angle to 45°, the heat transferability in the cross section can be made more isotropic.

[0060] (Embodiment 2) Next, a heat dissipation structure 50 according to a second embodiment of the present disclosure will be described. Fig. 8 is a diagram showing the configuration of the heat dissipation structure 50 according to the second embodiment. The heat dissipation structure 50 is an exemplary structure in which the composite structure 1 according to the first embodiment is applied to a heat source.

[0061] As shown in FIG. 8 , the heat dissipation structure 50 has four composite structures 1 arranged at intervals along the Z direction in the drawing. First ends 31 of the four composite structures 1 are connected by a rectangular top plate 55, and second ends 32 are connected by a rectangular base plate 54. A plurality of rectangular circuit boards 56 are arranged parallel to the top plate 55 between the top plate 55 and the base plate 54. Each circuit board 56 is connected to and supported by the four composite structures 1 at its four corners. The circuit boards 56 have a plurality of electronic components and electronic circuits, and the electronic components and the like serve as a heat source (heat source object) that generates thermal energy.

[0062] Fig. 9 shows a view from the Z direction of a portion of heat dissipation structure 50 that supports one circuit board 56. As shown in Fig. 9, circuit board 56 has a square shape, and the four corners of circuit board 56 are in contact with composite structure 1. Top plate 55 and base plate 54 also have a square shape, and the centers of circuit board 56, top plate 55, and base plate 54 are aligned in the Z direction.

[0063] Composite structure 1 is arranged so that the stacking direction of graphite laminates 3 is directed toward the center of circuit board 56. Heat source (electronic component or the like) 57 is arranged in the center of circuit board 56.

[0064] In this configuration, heat from heat source 57 is transferred radially from the center of circuit board 56 in the planar direction and to each composite structure 1. As shown in Fig. 10, in composite structure 1, heat from circuit board 56 is transferred to metal body 2, and then from the four inner surfaces of metal body 2 to graphite laminates 3 through edge faces. The heat transferred to graphite laminates 3 is transferred in the Z direction along the basal plane, and then transferred to metal body 2 through the edge faces after being transferred in the Z direction. In Figs. 9 and 10, arrows 58 indicate the main heat transfer path (transfer direction).

[0065] According to heat dissipation structure 50 of the second embodiment, heat from heat source 57 on circuit board 56 can be uniformly transferred to graphite laminates 3 via metal body 2. The transferred heat can also be transferred in the longitudinal direction of graphite laminates 3 and then to metal body 2. Therefore, heat can be efficiently transferred to composite structure 1, and the transferred heat can be dispersed along the longitudinal direction. Therefore, heat dissipation can be promoted using the longitudinal direction of composite structure 1, and the heat dissipation efficiency of heat dissipation structure 50 can be improved.

[0066] (Modification of heat dissipation structure) As shown in FIG. 9 , the heat dissipation structure 50 has been described as having a generally square shape when viewed in the Z direction. However, the shape and configuration of the heat dissipation structure are not limited to this. For example, as shown in FIG. 11 , the heat dissipation structure 60 may have a rectangular shape, with composite structures 1 disposed at its four corners. As shown in FIG. 12 , the heat dissipation structure 70 may have a trapezoidal shape, with composite structures 1 disposed at its four corners. As shown in FIG. 13 , the heat dissipation structure 80 may have a polygonal shape, with composite structures 1 disposed at multiple corners. As shown in FIG. 14 , the heat dissipation structure 90 may have a circular shape, with multiple composite structures 1 disposed around the circumference of the circle. The heat dissipation structure may have an appropriate shape depending on the shape of the circuit board 56, etc.

[0067] Furthermore, the heat source is not limited to being placed at the center of the circuit board, but may be placed in a dispersed manner on the circuit board, or may be placed at a position away from the center of the circuit board.

[0068] Any of the above-described various embodiments may be combined appropriately to achieve the effects of each of them. [Industrial Applicability]

[0069] The composite structure of the present disclosure can improve heat transfer performance in a composite structure that combines a metal material and graphite. Therefore, it can be applied to heat transport members that can diffuse and dissipate heat more efficiently than conventional ones in electronic devices and semiconductor devices that have local heat sources, and is therefore industrially useful. [Explanation of symbols]

[0070] 1 Composite structure 2 Metal body 3 Graphite laminate 3A Graphite Plate Laminate 4 graphite plates 5 Basal surface 6 Edge Faces 7 Grip 8 Press Machine 9 Processing machine 9a Cutting surface 10 Jig 11 Heater 12 Crucible 13 Molten metal 14 Mold 15 Cavity 20 Interior Space 21 First Opening 22 Second opening 23 Inner surface 31 First end 32 Second end 50 Heat dissipation structure 54 Baseboard 55 Top plate 56 Circuit Board 57 Heat source (heat source object) 58 Heat transfer path D Stacking direction (Stacking direction of graphite laminate)

Claims

1. a graphite laminate having a structure in which a plurality of graphite plates are stacked, the graphite laminate having a first end and a second end opposite to the first end in a longitudinal direction; a metal body having an internal space extending in a longitudinal direction, the metal body accommodating the graphite stack in the internal space so as to surround an outer periphery of the graphite stack at least between the first end and the second end, the graphite laminate has a rectangular cross section defined by four sides inclined with respect to a stacking direction of the graphite plates as a cross section intersecting the longitudinal direction, A composite structure, wherein the metal body contacts the four sides of the rectangular cross section of the graphite laminate at its inner surface.

2. 2. The composite structure according to claim 1, wherein the four sides of the rectangular cross section of the graphite laminate are inclined at an angle in the range of 30° to 60° with respect to the lamination direction.

3. The composite structure according to claim 2 , wherein the four sides of the rectangular cross section of the graphite laminate are inclined at 45° with respect to the lamination direction.

4. The composite structure of claim 3 wherein the rectangular cross section of the graphite laminate has a square cross section.

5. The composite structure according to claim 1 , wherein the metal body has a rectangular frame-shaped cross section intersecting the longitudinal direction and having a thickness of 1 mm or more and 20 mm or less.

6. The composite structure of claim 1 , wherein the metal body is aluminum or an aluminum alloy.

7. 2. The composite structure according to claim 1, wherein the graphite laminate has a structure in which a plurality of the graphite plates, each having a thickness of 0.01 mm or more and 0.5 mm or less, are stacked such that their basal surfaces are in contact with each other.

8. The graphite plate has a density of 1.8 g / cm ３ 2.2g / cm or more ３ 2. The composite structure according to claim 1, wherein the thermal conductivity in the basal plane direction is 1000 W / m·K or more and 1500 W / m·K or less.

9. Density is 3 g / cm ３ and a thermal conductivity in at least the longitudinal direction of the composite structure is 400 W / m·K or more.

10. a heat source object; a substrate on which the heat source object is placed; a plurality of the composite structures according to any one of claims 1 to 9, the longitudinal direction of which is arranged in a direction intersecting the substrate and which support the substrate; The plurality of composite structures are heat dissipation structures that dissipate thermal energy conducted from the heat source object via the substrate.

11. The heat dissipation structure according to claim 10 , wherein the plurality of composite structures are arranged such that the lamination direction of each of the composite structures faces the center of the substrate.

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