JP5388654B2 - High thermal conductive composite material and manufacturing method thereof - Google Patents

Description

  The present invention relates to a high thermal conductive composite material in which a fibrous carbon material such as vapor grown carbon fiber (VGCF) is mixed in an Al-based material made of pure aluminum or an aluminum alloy, and more specifically, cooling of a semiconductor element or the like. The present invention relates to a plate-like high thermal conductive composite material that is particularly suitable as a thermal diffusion plate.

  As the fibrous carbon material, carbon nanotube (CNT) and vapor grown carbon fiber (VGCF) are well known. Both carbon nanotubes and vapor-grown carbon fibers are ultra-thin tube-like structures made of graphene, and are distinguished by a laminated structure and a difference in fiber diameter associated therewith as described below.

  Graphene is a honeycomb-structured net consisting of six carbon atoms arranged two-dimensionally regularly, and is also called a carbon hexagonal mesh surface. Called. A single-layer or multi-layered and ultrafine tube-like structure made of this graphene is a fibrous carbon material, and includes carbon nanotubes and vapor-grown carbon fibers.

  That is, the carbon nanotube is a seamless tube in which graphene is rounded into a cylindrical shape, and there are a single-walled tube and a multi-walled tube that is concentrically stacked. Single-walled ones are called single-walled nanotubes, and multiple-walled ones are called multi-walled nanotubes.

  In addition, the vapor grown carbon fiber has a single-layer or multiple-layer graphene tube in which graphene is rounded into a cylindrical shape, that is, a carbon nanotube in the core, and surrounds the core in multiple and polygonal shapes. Graphite is laminated in the radial direction of the graphene tube, and it is also called ultra-multi-walled carbon nanotube due to its structure.

  In other words, the single-layer or multi-layer carbon tube present at the center of the vapor-grown carbon fiber is a carbon nanotube.

  Many composite materials have been proposed in which such a fibrous carbon material is incorporated into metals and ceramics, and also a mixture thereof, and the thermal conductivity is improved by the fibrous carbon material while taking advantage of the characteristics of the metal and ceramics. One of them is a high thermal conductive composite material described in Patent Document 1.

  Among the high thermal conductive composite materials described in Patent Document 1, an aluminum powder layer and a fiber carbon material sheet are alternately laminated with fiber orientation sheets in which the fiber direction is oriented in a specific direction parallel to the sheet surface The composite material obtained by pressurizing the laminated body in the laminating direction and subjecting the aluminum powder in the laminated body to discharge plasma sintering has excellent thermal conductivity in the fiber orientation direction, and the fibrous carbon material is vapor-grown carbon fiber. In the case of, particularly excellent thermal conductivity is exhibited.

  By the way, as one application of the high thermal conductive composite material, there is a heat diffusion plate used for cooling a semiconductor element. More specifically, the heat diffusion plate is also used as an element mounting portion connected to the fin portion. However, since the composite material described in Patent Document 1 is a laminated body in which aluminum powder sintered bodies and sheets made of fibrous carbon materials are alternately laminated, it is mechanical compared to an aluminum powder sintered body alone. Low strength. For this reason, this composite material has a restriction that it cannot be used directly as an element cooling heat diffusion plate that also serves as an element mounting portion.

International Publication WO2006 / 120803 Pamphlet

  The object of the present invention is to have mechanical strength that can be used as an element cooling heat diffusion plate that also serves as an element mounting portion, and has excellent thermal conductivity equivalent to a laminated composite material using a fibrous carbon material. In addition, another object of the present invention is to provide a highly thermally conductive composite material that can reduce the manufacturing cost by suppressing the amount of fibrous carbon material used from the composite material, and a method for manufacturing the same.

  In order to achieve the above object, the present inventors sandwiched the composite material 2 having the above-described laminated structure between a pair of plate-like base materials 1 and 1 made of an aluminum powder sintered body, as shown in FIG. The composite sintered plate 3 having a sandwich structure was considered as the heat diffusion plate. The manufacturing method is as follows. In this specification, aluminum means both pure aluminum and aluminum alloy, and has the same meaning as Al-based metal.

  Since the composite material 2 is a sintered body, as shown in FIG. 6A, the first aluminum powder layer 1a is formed on the lower punch 7 in the die 6, and the composite material 2 is formed thereon. The fiber orientation sheet 2a and the aluminum powder layer 2b are alternately stacked, and a second aluminum powder layer 1b is formed on the laminate. In a state where the thus obtained laminate is pressed in the layer thickness direction between the lower punch 7 and the upper punch 8, the aluminum powder in the laminate is subjected to discharge plasma sintering. The fiber orientation sheet 2a is made of, for example, vapor-grown carbon fibers oriented in a specific direction X parallel to the sheet surface. By this method, the composite sintered plate 3 having a sandwich structure shown in FIG. 5 and having high strength and high thermal conductivity is manufactured by one-time sintering.

  The heat diffusion portion 4 having a fin structure is joined to the end portion of the composite material 2 in the manufactured composite sintered plate 3 in the fiber orientation direction X, and the semiconductor element 5 is brought into contact with the surface of the composite sintered plate 3. The heat generated in the semiconductor element 5 is transmitted to the heat diffusion part 4 through the fiber orientation sheet layer in the composite material 2, and the semiconductor element 5 is efficiently cooled.

  The composite sintered plate 3 is used as an element cooling heat diffusion plate that also serves as an element mounting portion, and there is no problem in terms of mechanical strength and thermal conductivity. However, what contributes particularly to the diffusion of the heat generated in the semiconductor element 5 is from the mounting position of the semiconductor element 5 in the composite material 2 sandwiched between the plate-like base materials 1 and 1 made of an aluminum powder sintered body. It is a part of the belt-like region shown by hatching in FIG. 5 that reaches the thermal diffusion part 4, and the other part does not substantially contribute to thermal diffusion. In that case, it is a good idea to eliminate the composite material 2 in a portion other than the band-shaped region indicated by hatching, but this is difficult with the current manufacturing method.

  This is because it is difficult in the manufacturing method to partially dispose the composite material 2 in a part of the aluminum powder sintered plate, that is, in the intermediate portion of the sintered plate in the plate thickness direction. The reason will be described with reference to FIG. In order to manufacture a composite sintered plate in which the composite material 2 is disposed in a part of the aluminum powder sintered plate, first, the first aluminum powder layer 1c is formed on the lower punch 7 in the die 6 and the center thereof is formed. A laminated body of the fiber orientation sheet 2a and the aluminum powder layer 2b is formed on the part as a constituent material of the composite material 2. Thereafter, a second aluminum powder layer 1d is formed around the laminate. Finally, a third aluminum powder layer 1e is formed on the laminate and the surrounding second aluminum powder layer 1d. In a state where the thus obtained laminate is pressed in the layer thickness direction between the lower punch 7 and the upper punch 8, the aluminum powder in the laminate is subjected to discharge plasma sintering.

  In the pressurization between the lower punch 7 and the upper punch 8, only aluminum powder is present around the laminate that is a constituent material of the composite material 2, so that a sufficient pressing force is ensured and the density is also ensured. Further, in this portion, the final interval between the lower punch 7 and the upper punch 8 is defined. However, in the portion where the constituent material of the composite material 2 exists, the bulk density of the laminated body which is the constituent material is small, so that a height higher than that of the portion containing only the aluminum powder is required. As a result, the height of the component part of the composite material 2 is insufficient, and the composite material 2 having a predetermined performance is not formed.

  If it demonstrates in more detail, the laminated body which laminated | stacked the fiber orientation sheet | seat 2a and the aluminum powder layer 2b which are the components of the composite material 2 by turns will normally be manufactured as follows. Vapor-grown carbon fibers having excellent thermal conductivity are produced by simultaneously vapor-growing a large number of fibers from the substrate surface using a catalyst. As a result, the vapor-grown carbon fiber is produced in a form in which a large number of fibers are two-dimensionally packed on the substrate. A large number of two-dimensionally dense fibers are often tilted in one direction due to a gas flow in the production process, and a fiber sheet oriented in one direction can be obtained simply by separating the dense fibers from the substrate. This can be used as it is as a fiber-oriented sheet, or it can be used by lightly pressing it. If not tilted, a fiber sheet that is one-dimensionally oriented in one direction can be obtained by pushing it down in one direction with a roller or the like.

  Aluminum powder is made to adhere to both surfaces of the fiber orientation sheet 2a manufactured in this way. A laminated body of the fiber orientation sheet 2a and the aluminum powder layer 2b is produced by superimposing the fiber orientation sheets having the aluminum powder adhered on both surfaces.

  In the produced laminated body, the fiber orientation sheet | seat which the aluminum powder adhered to both surfaces is not flat, and has uneven | corrugated deformation | transformation considerably. For this reason, the height of the laminated body which laminated | stacked the fiber orientation sheet | seat which the aluminum powder adhered on both surfaces becomes markedly larger than the height of the composite material 2 after sintering. When the composite material 2 after sintering has a height of 1 mm, the height of the laminate reaches 10 mm. That is, in order to make the laminated body of the fiber orientation sheet 2a and the aluminum powder layer 2b which are the constituent materials of the composite material 2 into the composite material 2 which is a product, it is necessary to reduce the height to 1/10. It is. On the other hand, the reduction rate of the height accompanying the sintering of the aluminum powder is about 1/2 to 1/3. This difference in the reduction rate makes it difficult to manufacture the composite sintered plate 3 in which the composite material 2 is partially arranged at a predetermined location in the aluminum powder sintered plate.

  In order to solve this problem, as shown in FIG. 6 (c), it is conceivable to thicken the aluminum powder layer 1e at the portion where the composite material 2 is embedded. Since the difference in compressibility is too large and there are many uncertain factors, it is difficult to partially form the composite material 2 having a predetermined performance at a predetermined location in the aluminum powder sintered plate. Therefore, a composite sintered plate 3 having a sandwich structure in which the composite material 2 is evenly sandwiched between a pair of plate-shaped base materials 1 and 1 made of an aluminum powder sintered body is used as the heat diffusion plate. That is why. For this reason, the composite material 2, especially a fibrous carbon material will be used in the area | region beyond necessity, and a manufacturing cost will become very high.

  Under such circumstances, the present inventors diligently studied a method of partially embedding the composite material 2 in the aluminum powder sintered plate. As a result, a powder sheet formed by mixing aluminum powder with a binder is used as a constituent material of the composite material 2, particularly the aluminum powder layer 2b, and a compression process when the composite material 2 is sealed in an aluminum powder sintered plate Thus, it was proved that the combined use of an aluminum plate bulk body instead of a part of the aluminum powder was effective.

  More specifically, in order to manufacture a composite sintered plate in which the composite material 2 is disposed in a part of the aluminum powder sintered plate, first, the first aluminum powder layer 1c is formed on the lower punch 7 in the die 6. Then, a laminated body of the fiber orientation sheet 2a and the aluminum powder layer 2b is formed as a constituent material of the composite material 2 on the central portion, but at this time, instead of the aluminum powder layer 2b, aluminum powder is mixed with a binder. The formed powder sheet is used. Since this powder sheet can be freely deformed, in a laminate in which the fiber orientation sheet 2a and the powder sheet are stacked and pressed in the laminating direction, it is not necessary to attach aluminum powder to the fiber orientation sheet 2a. In addition, since the fiber orientation sheet 2a is absorbed by the deformation of the powder sheet, the height of the laminate before sintering can be reduced.

  Then, after the second aluminum powder layer 1d is formed around the laminated body, the third aluminum powder layer 1e is formed on the laminated body and the second aluminum powder layer 1d and pressed in the laminating direction. At this time, if the third aluminum powder layer 1e is replaced with a plate-like bulk body made of aluminum, the contraction of the plate-like bulk body in the sintering process is much smaller than that of the powder layer. The body becomes an effective push plate for the laminate, and combined with the high initial compression degree of the laminate, the laminate can be compressed to a predetermined density in the sintering process.

  About the 1st aluminum powder layer 1c used as the laying board of the said laminated body, an aluminum powder layer may be used as it is, and you may change into the plate-shaped bulk body of aluminum. In any case, the aluminum plate-like bulk body is integrated with the laminate and the aluminum powder layer in the sintering process.

  The high thermal conductive composite material of the present invention has been completed on the basis of such knowledge, and fibrous carbon is contained in a plate-like base material made of pure aluminum or aluminum alloy, and a powder sintered body of pure aluminum or aluminum alloy. A plate-like composite material containing a material, and comprising a plate-like heat conduction promoting portion embedded in a part of a plane region perpendicular to the plate thickness direction in the plate thickness direction intermediate portion of the plate-like base material, In the plate-like base material, one side or both sides of the plate-like heat conduction promoting portion is made of a plate-like bulk body of pure aluminum or aluminum alloy, and the other portion is made of a powder sintered body of pure aluminum or aluminum alloy.

  In the high thermal conductive composite material of the present invention, a plate-like high heat conductive portion having a required width and shape is embedded and arranged only in a required portion in the plate-like base material.

  The plate-like high heat conduction part may be one in which the fibrous carbon material is uniformly dispersed in the aluminum powder sintered body, but the direction of the fibers is a sintered body layer of aluminum powder and a sheet made of the fibrous carbon material. A laminate with a fiber orientation sheet oriented in a direction parallel to the sheet surface is preferable from the viewpoint of thermal conductivity, and the one-dimensional orientation sheet in which the fiber direction in the fiber orientation sheet is oriented in a specific direction parallel to the sheet surface Is particularly preferred.

  Fibrous carbon materials include both vapor-grown carbon fibers and carbon nanotubes. From the viewpoint of thermal conductivity, they are thick, long, and straight vapor-grown carbon fibers, or a mixture of a small amount of carbon nanotubes. preferable. The mixing amount of carbon nanotubes is preferably 0.01 to 5%, particularly preferably 0.2 to 2%, expressed as a volume ratio when the specific gravity is 1.4. Carbon nanotubes are thin and basically non-oriented. By mixing a small amount of carbon nanotubes with oriented large-diameter vapor-grown carbon fibers, thin non-oriented carbon nanotubes are entangled with vapor-grown carbon fibers and function as a thermally conductive cross-linking material. A high-performance thermal network that is developed three-dimensionally is constructed.

  In addition, the plate-like high heat conducting portion preferably has a structure in which at least one end surface is exposed on the end surface of the plate-like base material as the element cooling heat diffusion plate that also serves as the element mounting portion. By exposing at least one end surface of the plate-like high heat conducting portion to the end surface of the plate-like base material, heat is efficiently applied to fins and the like that are mechanically connected to the end of the plate-like base material. Can be communicated.

  The manufacturing method of the high thermal conductive composite material of the present invention is the following two, and the first is made of pure aluminum or aluminum alloy on a partial surface of the first aluminum powder layer made of pure aluminum or aluminum alloy. A step of forming a first laminate of a powder sheet formed by mixing powder with a binder and a sheet made of a fibrous carbon material, and a first laminate around the first laminate on the first aluminum powder layer Forming a second aluminum powder layer made of pure aluminum or an aluminum alloy with the same thickness as the plate, and a plate-like bulk body made of pure aluminum or an aluminum alloy on the first laminate and the second aluminum powder layer A step of forming a second laminated body and pressing the second laminated body in the laminating direction to simultaneously sinter the aluminum powder in the first laminated body and the second laminated body. It includes a step.

  In the second method for producing a high thermal conductivity composite material, a powder made of pure aluminum or an aluminum alloy is mixed with a binder on a partial surface of the first plate-like bulk body made of pure aluminum or an aluminum alloy. A step of forming a first laminated body of a powder sheet and a sheet made of a fibrous carbon material, and a pure aluminum having a thickness equivalent to that of the first laminated body around the first laminated body on the first plate-like bulk body; A step of forming an aluminum powder layer made of an aluminum alloy; a step of forming a second laminate by placing a second plate-like bulk body made of pure aluminum or an aluminum alloy on the first laminate and the aluminum powder layer; And the step of pressing the second laminated body in the laminating direction and simultaneously sintering the aluminum powder in the first laminated body and the second laminated body.

  According to the first manufacturing method, a plate-like base material is formed in which one side of the plate-like high heat conducting portion is made of an aluminum plate-like bulk body and the other portion is made of an aluminum powder sintered body. According to the second manufacturing method, a plate-like base material is formed in which both side surfaces of the plate-like high heat conducting part are made of an aluminum plate-like bulk body and the other part is made of an aluminum powder sintered body. In any of the methods, the plate-shaped base material includes a plate-shaped high heat conduction portion made of a plate-shaped composite material in which a fibrous carbon material is contained in an aluminum powder sintered body. A highly heat-conductive composite material embedded in a portion of a plane region perpendicular to the plate thickness direction at the middle in the thickness direction is manufactured.

  The plate-like high thermal conductive part in the manufactured high thermal conductive composite material uses a powder sheet using a binder for the aluminum powder layer portion of the first laminated body that is the constituent material, and the uppermost part of the second laminated body. Since aluminum plate-like bulk material is used for the aluminum layer part, it is strongly pressed in the laminating direction and hard-baked and laminated despite being simultaneously sintered with the plate-like base metal part. Become a unity. The binder in the powder sheet disappears during the sintering process.

  The sheet made of fibrous carbon material laminated with the powder sheet is preferably a fiber orientation sheet in which the fiber direction is oriented in a direction parallel to the sheet surface, and a fiber orientation sheet oriented in a specific direction parallel to the sheet surface. Particularly preferred.

  As the sintering method, a discharge plasma sintering method is preferable. The discharge plasma sintering method is also called a pulsed current method or a pulsed current pressure sintering method. By using high-temperature plasma generated between powder particles, the adhesion between adjacent powder particles is improved, and a sintered body is obtained. In addition to making the porosity in the interior as close as possible to 0, the oxide on the particle surface disappears, the thermal conductivity of the aluminum powder itself as a matrix is improved, and the thermal conductivity between the matrix and the fibrous carbon material is improved. Contribute.

  The fibrous carbon material in the plate-like high heat conduction part needs to ensure a suitable content in order to ensure heat conductivity. However, if the content is too large, characteristics such as excellent workability and ductility inherently possessed by the aluminum powder sintered body as the matrix cannot be sufficiently obtained. In either case, the merit as a composite material cannot be obtained sufficiently. In this respect, the content ratio of the fibrous carbon material is preferably 1 to 65%, and particularly preferably 5 to 60%, by volume.

  The manufacturing method in particular of a fibrous carbon material is not ask | required. Although any of an arc discharge method, a laser evaporation method, a thermal decomposition method, a chemical vapor deposition method, and the like may be used, the vapor grown carbon fiber is manufactured by a chemical vapor deposition method. VGCF, which represents vapor grown carbon fiber, is an abbreviation for Vapor Grown Carbon Fiber.

  The high thermal conductive composite material of the present invention comprises an aluminum powder in an intermediate portion in the plate thickness direction of a plate-like base material composed of a composite of an aluminum powder sintered body and a bulk body and in a part of a plane region perpendicular to the plate thickness direction. Since a configuration in which a plate-like high heat conductive portion made of a plate-like composite material containing a fibrous carbon material is embedded in the sintered body is employed, it has mechanical strength that can withstand mounting of a semiconductor element. In addition, a high-performance plate-like high heat conduction part can be arranged only at a necessary location in the plate-like base material. Therefore, the amount of the fibrous carbon material used can be reduced while maintaining the mechanical strength and excellent thermal conductivity of the high thermal conductive composite material having a sandwich structure, which is excellent in economic efficiency.

  Moreover, the manufacturing method of the highly heat conductive composite material of this invention uses the powder sheet which uses the binder for the aluminum powder layer part of the 1st laminated body used as a plate-shaped highly heat-conductive part, and contains the 1st laminated body. Since an aluminum plate-like bulk body is used for the uppermost aluminum layer of the laminated body, the second laminated body in the first laminated body is strongly pressed in the laminating direction together with the first laminated body by one sintering. be able to. For this reason, a highly heat conductive composite material in which a plate-shaped base material composed of a composite of an aluminum powder sintered body and a bulk body is partially embedded with a hard heat-bonded plate-shaped high heat conductivity portion is used. Can be manufactured. Therefore, the amount of the fibrous carbon material used can be reduced while maintaining the mechanical strength and excellent thermal conductivity of the sandwich structure high thermal conductive composite material, and the manufacturing cost can be greatly reduced.

It is a perspective view which shows an example of the semiconductor element cooling device using the high heat conductive composite material of this invention. It is a perspective view of the high heat conductive composite material currently used for the semiconductor element cooling device. (A) (b) is sectional drawing of the same high heat conductive composite material, and is an AA line arrow figure in FIG. (A) is a schematic cross-sectional view showing the first manufacturing method of the high thermal conductive composite material stepwise, (b) is a schematic cross-sectional view showing the second manufacturing method of the high thermal conductive composite material stepwise. is there. It is a perspective view which shows schematic structure of the high heat conductive composite material used as the premise of the high heat conductive composite material of this invention. (A) is a schematic cross-sectional view showing a method for producing the same highly heat conductive composite material, (b) is a schematic cross-sectional view showing another method for producing a high heat conductive composite material, and (c) is still another high heat conductive composite material. It is a schematic cross section which shows the manufacturing method of material.

  Embodiments of the present invention will be described below with reference to the drawings.

  The high thermal conductive composite material of the present embodiment is a thermal diffusion plate that also serves as an element mounting portion in the semiconductor element cooling apparatus. As shown in FIG. 1, the semiconductor element cooling device includes a rectangular frame-shaped casing 10 and a heat diffusion plate 20 that also serves as a plurality of element mounting portions arranged in a predetermined interval in the casing 10. ing. The plurality of heat diffusion plates 20 are held in parallel at predetermined intervals between the side plates 13 on both sides of the housing 10. In the following description, the arrangement direction of the heat diffusion plates 20 in the housing 10 is referred to as a depth direction, and the insertion direction of the heat diffusion plates 20 is referred to as a depth direction.

  The housing 10 has fin portions 11 at both ends. The fin portions 11 are arranged at predetermined intervals in the depth direction of the housing 10 and each include a plurality of rib-like protrusions extending in the depth direction. Square grooves 12 extending in the depth direction of the housing 10 are formed at predetermined intervals in the depth direction of the housing 10 so that the end portions of the heat diffusing plate 20 are fitted to the inner surface of the fin portion 11. Has been. The material of the housing 10 is aluminum.

  As shown in FIG. 2, the heat diffusing plate 20 has convex portions 21 formed integrally at both ends so as to be inserted into the square grooves 12 of the housing 10. As shown in FIG. 3, the heat diffusion plate 20 is also a composite material in which plate-like high heat conducting portions 23 reaching from one end to the other end are embedded in two stages in a plate-like base material 22 made of an aluminum powder sintered body. It is.

  The plate-like base material 22 employs either the first laminated structure shown in FIG. 3A or the second laminated structure shown in FIG. In the first laminated structure shown in FIG. 3A, one surface side of the plate-like high heat conduction portion 23 is made of an aluminum plate-like bulk body 22a, and the other surface, that is, the other surface of the plate-like high heat conduction portion 23. The side and the layer at the same level as the plate-like high heat conduction portion 23 are made of an aluminum powder sintered body 22b. Moreover, in the 2nd laminated structure shown in FIG.3 (b), both the surface sides of the plate-shaped high heat conductive part 23 consist of the plate-shaped bulk bodies 22a and 22a of aluminum, and other parts, ie, the plate-shaped high heat conductive part 23, are shown. The layer of the same level is made of an aluminum powder sintered body 22b. In any laminated structure, the plate-like bulk body 22a, the powder sintered body 22b, and the plate-like high heat conduction portion 23 are integrated.

  Each of the plate-like high heat conduction portions 23 is a thin flat plate disposed in the central portion of the heat diffusion plate 20 in the plate thickness direction. More specifically, the fiber orientation sheet and the aluminum powder sintered body layer are arranged in the plate thickness direction. It is the plate-shaped composite material of the laminated structure laminated | stacked alternately. The fiber-oriented sheet is a thin sheet of vapor-grown carbon fiber, in which the fiber direction is oriented in the longitudinal direction.

  Both end portions of the plate-like high heat conducting portion 23 are exposed at both end portions of the heat diffusion plate 20. Specifically, the end portions of the plate-like high heat conduction portion 23 are exposed on the top surface and both side surfaces of the convex portion 21 of the heat diffusion plate 20. And in the area | region where the plate-shaped high heat conduction part 23 is arrange | positioned, the semiconductor element 40 is contacting the surface of the thermal diffusion board 20. As shown in FIG. An arrangement region of the plate-like high heat conduction portion 23 on the surface of the heat diffusion plate 20 is indicated by hatching in FIG.

  The heat generated from the semiconductor element 40 is mainly transmitted to the plate-like high heat conduction portion 23 in the heat diffusion plate 20 arranged on the back side. Since the fiber orientation sheet in the plate-like high heat conduction portion 23 has the fiber direction oriented in the longitudinal direction, the heat is transferred to the end of the heat diffusion plate 20 via the plate-like high heat conduction portion 23, and the housing 10 fins 11 are discharged. At both ends of the heat diffusing plate 20, the ends of the plate-like high heat conducting portion 23 are exposed on the top surface and both side surfaces of the convex portion 21 of the heat diffusing plate 20, and the convex portions 21 are fitted into the square grooves 12. Therefore, the contact area of the plate-like high heat conduction part 23 with respect to the fin part 11 is large, and the heat conductivity at the contact part is also good.

  The thermal diffusion plate 20 which is a high thermal conductive composite material of the present embodiment has a high strength because the composite body of aluminum powder sintered body and bulk body is the plate-like base material 22, and the semiconductor element 40 is mounted. But it doesn't cause any problems. Since the plate-like high heat conduction portion 23 oriented toward both ends is partially disposed on the back side of the semiconductor element 40, the thermal resistance to the fin portion 11 is small. Even if the plate-like high heat conducting portion 23 is disposed over the entire surface, the heat resistance in the direction perpendicular to the orientation direction is large, so that only the band-like portion located on the back side of the semiconductor element 40 contributes to heat conduction. Therefore, although the plate-like high heat conducting portion 23 is partially arranged in a band shape, a cooling ability substantially equal to that in the case where it is arranged over the entire surface is ensured.

  On the other hand, since the portion where the plate-like high heat conduction portion 23 is arranged is limited to the band-like region on the back side of the semiconductor element 40, the arrangement area becomes smaller than in the case of the entire arrangement, and accordingly, an expensive fibrous shape The amount of carbon material used is reduced.

  Next, the manufacturing method of the thermal diffusion plate 20 which is the high thermal conductive composite material of the present embodiment will be described with reference to FIGS. FIG. 4A shows an example of the first manufacturing method of the present invention stepwise and schematically, and FIG. 4B shows an example of the second manufacturing method of the present invention stepwise and schematically. Is shown.

  In the first manufacturing method, first, a fiber orientation sheet is produced. Specifically, a fiber-oriented sheet in which vapor-grown carbon fibers are one-dimensionally oriented in one direction (sheet longitudinal direction) parallel to the sheet surface is produced. As this fiber orientation sheet, a sheet naturally produced in the vapor phase growth process can be used. The details of the sheet manufacturing method are as described above.

  Moreover, a powder sheet is produced. This is a so-called green sheet in which aluminum powder is mixed with a binder to form a sheet. As the binder, it is possible to use various resins conventionally used for preparing a brazing material for brush coating or coating in the brazing field. Specifically, polyvinyl butyral resin, vinyl acetate resin, and the like are suitable, and epoxy resin, acrylic resin, polyvinyl alcohol resin, polyethylene oxide resin, and the like can also be used. As a solvent for softening the binder resin, a commonly used solvent may be used, and isoprene alcohol (IPA) is compatible with many binder resins and has good workability.

  When a fiber orientation sheet and a powder sheet are prepared, these are alternately laminated and pressed in the laminating direction to form a first laminate.

  When the above preparation is completed, as shown in FIG. 4A, the aluminum powder is put on the lower punch 51 in the inner die 50 corresponding to the heat diffusion plate 20, and the first aluminum powder layer 52 is formed. To do. A first laminate 53 produced in advance is placed at a predetermined position on the first aluminum powder layer 52. The first laminate 53 is formed by alternately laminating vapor-grown carbon fiber orientation sheets 53a and aluminum powder sheets 53b and pressing them. Aluminum powder is charged around the first laminate 53 to form a second aluminum powder layer 54. An aluminum plate-like bulk body 55 is placed on the first laminate 53 and the second aluminum powder layer 54.

  The second laminated body 56 in the die 50 formed in this way is pressed in the layer thickness direction between the lower punch 51 and the upper punch 57, and pulsed current is applied to cause discharge plasma sintering. As a result, the aluminum powder layers 52 and 54 and the plate-like bulk body 55 are integrated to form the aluminum plate-like base material 22. In addition, a plate-like high heat conduction portion 23 in which the first laminated body 53 is sintered and integrated with the plate-like base material 22 is formed in the width-direction intermediate portion and the plate-thickness direction intermediate portion of the formed plate-like base material 22. It is formed.

  Thus, the high thermal conductivity composite material of the present embodiment, particularly the thermal diffusion plate 20 shown in FIG.

  During the sintering process, the first aluminum powder layer 52 has a layer thickness of about 1/3. Both the second aluminum powder layer 54 and the first laminated body 53 are also about 1/3. Since the first laminated body 53 is formed by alternately laminating orientation sheets 53a of vapor-grown carbon fibers and aluminum powder sheets 53b and pressurizing them in advance in the laminating direction at a pressure of 30 to 50 MPa, the bulk is considerably suppressed. In the sintering process, since pressure is applied from above by the aluminum plate-like bulk body 55, a sufficient density is ensured even if the layer thickness is reduced by 1/3.

  In the second manufacturing method, as shown in FIG. 4B, the aluminum plate-like bulk body 58 is disposed instead of the first aluminum powder layer 52. Others are the same as the first method. Even in this method, the first laminated body 53 is obtained by alternately laminating the orientation sheets 53a of vapor-grown carbon fibers and the powder sheet 53b of aluminum and pressurizing them in the laminating direction. In the sintering process, pressure is applied from above by the aluminum plate-like bulk body 55, so that a sufficient density can be ensured even if the layer thickness is reduced by 1/3, which is the same as the second aluminum powder layer 54. Thus, the thermal diffusion plate 20 shown in FIG. 3B is manufactured.

  In any method, the binder in the powder sheet 53b in the first laminate 53 disappears during the sintering process.

  A high thermal conductive composite material for the thermal diffusion plate shown in FIG. The produced high heat conductive composite material is composed of a rectangular plate-shaped base material and two plate-shaped high heat conductive portions embedded in two places in the plate width direction of the plate-shaped base material. The plate-shaped base material consists of a plate-like bulk body made of pure aluminum on one side of the plate-like high heat conducting portion, and the other portion is pure aluminum powder having an average particle size of 35 μm and Al-12Si powder having an average particle size of 40 μm. The mixed powder was sintered. The content of Al-12Si powder in the mixed powder is 10% by weight. The length of the plate-shaped base material is 450 mm, the width (height in FIGS. 2 and 3) is 290 mm, and the thickness is 6 mm.

  The plate-like high heat conduction part in the plate-like base material is a strip-like member having a thickness of 2 mm, a width of 80 mm, and a length of 450 mm, which is the same as the length of the plate-like base material. Embedded at a position of 12 mm from the distance of 20 mm.

  This plate-like high heat conduction part is a laminate in which a fiber orientation sheet and an aluminum powder sintered body layer are laminated in the thickness direction. More specifically, the fiber orientation sheet and an aluminum plastic powder sheet are laminated and sintered. Is. The fiber-oriented sheet is a dense body of vapor-grown carbon fibers having a thickness of 1 to 50 μm (average 10 μm) and a length of about 2 to 3 mm, and the direction of the fibers is parallel to the surface and oriented in the same direction. It is a vapor-grown carbon fiber oriented sheet having a thickness of the order of 100 μm. The compounding ratio of the vapor growth carbon fiber in the plate-like high heat conduction part is 60% by volume. The aluminum powder in the powder sheet is the mixed powder.

  The manufacturing method is the first manufacturing method shown in FIG. 4A, and the sintering is performed by discharge plasma sintering. The sintering temperature was 560 ° C. lower than the melting point of pure aluminum and higher than the melting point of Al-12Si. The heating and holding time was 60 minutes, the heating rate was 20 ° C./min, and the applied pressure was 30 MPa.

  The thickness of the plate-like high heat conductive part before sintering, that is, the thickness of the first laminate is about 6 mm, the thickness of the first aluminum powder layer is about 5.4 mm, and the thickness of the second aluminum powder layer is the first laminate. The plate thickness of the plate-like bulk body was about 3.6 mm. As described above, each thickness becomes 2 mm after sintering.

  For comparison, a conventional heat diffusion plate having a sandwich structure in which a plate-like high heat conductive portion is arranged on the entire surface of a high heat conductive composite material was produced. The same as the above embodiment, except that the plate-like high heat conduction part is arranged on the entire surface of the plate-like composite material. The semiconductor cooling performance was the same as in Example 1 above. On the other hand, the amount of vapor-grown carbon fiber used was approximately doubled in this comparative example compared to Example 1 above. The high economic efficiency of Example 1 is clear.

  A high thermal conductive composite material for the thermal diffusion plate shown in FIG. 3B was actually produced. Example 1 is the same as Example 1 except that the first aluminum powder layer (about 5.4 mm thick) is changed to a plate-like bulk body (about 3.6 mm thick). The semiconductor cooling performance was the same as in Example 1 above. The amount of vapor grown carbon fiber used was also substantially the same as in Example 1 above.

10 Housing 20 Thermal diffusion plate (high thermal conductivity composite material)
22 plate-like base material 23 plate-like high heat conduction part 40 semiconductor element 50 die 51 lower punch 52,54 aluminum powder layer 53 first laminated body 55,58 plate-like bulk body 56 second laminated body 57 upper punch

Claims (5)

A plate-like base material made of pure aluminum or aluminum alloy;
A plate-shaped composite material in which a fibrous carbon material is contained in a powder sintered body of pure aluminum or an aluminum alloy, and a part of a planar region that is an intermediate portion in the plate thickness direction of the plate-like base material and is perpendicular to the plate thickness direction And a plate-like heat conduction promoting portion embedded in
The plate-like base material has a plate-like heat conduction promoting portion on one side or both sides made of a plate-like bulk body made of pure aluminum or an aluminum alloy and the other portion made of a powder sintered body made of pure aluminum or an aluminum alloy. Composite material.   2. The high thermal conductive composite material according to claim 1, wherein the plate-like heat conduction promoting portion includes a powder sintered body layer of pure aluminum or an aluminum alloy and a sheet made of a fibrous carbon material, and a fiber direction is on the sheet surface. A high thermal conductive composite material which is a laminate of fiber orientation sheets oriented in parallel directions. A first of a powder sheet formed by mixing a powder made of pure aluminum or an aluminum alloy with a binder on a partial surface of a first aluminum powder layer made of pure aluminum or an aluminum alloy, and a sheet made of a fibrous carbon material Forming a laminate;
Forming a second aluminum powder layer made of pure aluminum or an aluminum alloy with the same thickness as the first laminate around the first laminate on the first aluminum powder layer;
Forming a second laminate by placing a plate-like bulk body made of pure aluminum or an aluminum alloy on the first laminate and the second aluminum powder layer;
Pressurizing the second laminate in the laminating direction and simultaneously sintering the aluminum powder in the first laminate and the second laminate;
A method for producing a high thermal conductive composite material. A powder sheet formed by mixing a powder made of pure aluminum or an aluminum alloy with a binder on a partial surface of a first plate-like bulk body made of pure aluminum or an aluminum alloy and a sheet made of a fibrous carbon material. Forming a laminate,
Forming an aluminum powder layer made of pure aluminum or an aluminum alloy with a thickness equivalent to that of the first laminate around the first laminate on the first plate-like bulk body;
Forming a second laminate by placing a second plate-like bulk body made of pure aluminum or an aluminum alloy on the first laminate and the aluminum powder layer;
Pressurizing the second laminate in the laminating direction and simultaneously sintering the aluminum powder in the first laminate and the second laminate;
A method for producing a high thermal conductive composite material.   5. The method for producing a high thermal conductive composite material according to claim 3, wherein the sheet made of a fibrous carbon material arranged in the first laminate is a fiber in which the direction of the fibers is oriented in a direction parallel to the sheet surface. A method for producing a highly thermally conductive composite material which is an oriented sheet.

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