JP2012117085A - Aluminum-diamond composite and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum-diamond composite having both high thermal conductivity and a coefficient of thermal expansion near that of a semiconductor element and further improved in surface roughness of a surface and flatness so as to be suitable for use in a heat sink of a semiconductor element or the like.SOLUTION: The aluminum-diamond composite contains an aluminum-diamond composite material which includes metal containing 40-70 vol.% of a diamond particle and the remainder of aluminum, and is formed in a plate with a thickness of 0.4-6 mm or a plate having a recessed and projecting portion. Both main surfaces of the aluminum-diamond composite are coated with an aluminum-ceramic composite with a thickness of 0.05-0.5 mm, and the aluminum-diamond composite has a structure where the aluminum-diamond composite is exposed at a side face and a hole.

Description

The present invention relates to an aluminum-diamond composite and a method for producing the same.

In general, in semiconductor elements such as semiconductor laser elements and high-frequency elements used for optical communications, how to efficiently release the heat generated from the elements is very important to prevent malfunction. is there. In recent years, with the advancement of semiconductor device technology, higher output, higher speed, and higher integration of devices have progressed, and the demand for heat dissipation has become increasingly severe. For this reason, generally, high heat conductivity is also required for heat dissipation components such as heat sinks, and copper (Cu) having a high heat conductivity of 390 W / mK is used.

On the other hand, the size of each semiconductor element has increased with the increase in output, and the problem of thermal expansion mismatch between the semiconductor element and the heat sink used for heat dissipation has become apparent. In order to solve these problems, development of a heat sink material that satisfies both the characteristics of high thermal conductivity and the matching of the thermal expansion coefficient with the semiconductor element is required. As such a material, a composite of metal and ceramic, for example, a composite of aluminum (Al) and silicon carbide (SiC) has been proposed. (Patent Document 1)

However, in Al-SiC composites, no matter how the conditions are optimized, the thermal conductivity is 300 W / mK or less, and development of a heat sink material having a higher thermal conductivity than that of copper has been developed. It has been demanded. As such a material, a metal-diamond composite having a high thermal conductivity and a thermal expansion coefficient close to that of a semiconductor element material has been proposed by combining the high thermal conductivity of diamond and the large thermal expansion coefficient of metal. Yes. (Patent Document 2)

Further, in Patent Document 3, by forming a β-type SiC layer on the surface of diamond particles, the formation of low-conductivity metal carbide formed at the time of compounding is suppressed, and wettability with molten metal is improved. Thus, the thermal conductivity of the metal-diamond composite obtained is improved.

Furthermore, since diamond is a very hard material, a metal-diamond composite obtained by compounding with a metal is also very hard and difficult to process. For this reason, metal-diamond composites can hardly be processed with ordinary diamond tools, and how low the cost is to use metal-diamond composites as heat sinks that are small and have various shapes. The problem is whether to perform shape processing. With respect to such problems, the metal-ceramic composite can be energized, and a processing method using electric discharge machining or the like has been studied.

JP-A-9-157773 JP 2000-303126 A Special table 2007-518875 gazette

However, as a usage form of the heat sink material as described above, in order to efficiently dissipate heat generated from the semiconductor element, the heat sink is usually placed in contact with the semiconductor element in a form of being joined by a brazing material or the like. . In the case of the conventional metal-diamond composite, since the diamond particles are exposed on the joint surface, the surface roughness of the joint surface is rough. As a result, the thermal resistance of the contact interface increases, which is not preferable. For this reason, as a characteristic required for the heat sink material, there is a problem of how to reduce the surface roughness.

  As a means for solving this problem, it has been proposed to form an aluminum alloy layer on the surface of an aluminum-diamond composite. By this method, the surface roughness can be improved. However, the aluminum alloy layer has a coefficient of thermal expansion that is about three times that of the aluminum-diamond composite, and this heat expansion coefficient causes a problem that the heat sink itself warps and flatness decreases. Therefore, there is a demand for a composite material having improved surface roughness and flatness while having a high thermal conductivity and a thermal expansion coefficient close to that of a semiconductor element.

  That is, the object of the present invention is to improve the surface roughness flatness so that it has high thermal conductivity and thermal expansion coefficient close to that of semiconductor elements, and is suitable for use as a heat sink for semiconductor elements. An aluminum-diamond composite.

  That is, the aluminum-diamond composite according to the present invention is a plate-like aluminum-diamond composite having a plate-like or uneven portion containing diamond particles and a metal containing aluminum, and the aluminum-diamond composite The composite is composed of a composite part and a surface layer provided on both surfaces of the composite part, the surface layer is made of an aluminum-ceramic composite having a thickness of 0.05 to 0.5 mm, and the content of the diamond particles Is 40% by volume to 70% by volume of the entire aluminum-diamond composite.

  The aluminum-diamond composite having the above structure has a high thermal conductivity and a thermal expansion coefficient close to that of a semiconductor element, and further has a small surface roughness and flatness.

The aluminum-diamond composite according to the present invention has high thermal conductivity and a coefficient of thermal expansion close to that of a semiconductor element, and furthermore, since the surface roughness and flatness of the surface are small, it is preferable as a heat sink for heat dissipation of a semiconductor element. Used.

Structure diagram of aluminum-diamond composite according to Embodiment 1 Sectional drawing of the structure layer body before complex | conjugation of the aluminum-diamond type composite_body | complex concerning Embodiment 1. FIG. Structural diagram of composite aluminum-diamond composite according to Embodiment 1 Structural diagram of an aluminum-diamond composite after grinding according to Embodiment 1 1 is a perspective view of an aluminum-diamond composite according to Embodiment 1. FIG. Sectional drawing of the structure layer body before complex | conjugation of the aluminum-diamond type composite based on Embodiment 2 Structural diagram of aluminum-diamond composite according to Embodiment 2

[Explanation of terms]
In this specification, the symbol “to” means “above” and “below”. For example, “A to B” means not less than A and not more than B.

  In this specification, “both surfaces” means both the upper and lower surfaces of an aluminum-diamond composite formed in a flat plate shape. Further, in the present specification, the “side surface portion” means a side surface of the aluminum-diamond based composite formed in a flat plate shape, that is, a portion substantially perpendicular to the both surfaces.

  Further, in this specification, the “hole” is processed so as to penetrate the upper and lower surfaces of a flat plate-like aluminum-diamond composite provided for screwing the component of the present invention to another heat radiating member. It means a through hole.

  Hereinafter, embodiments of an aluminum-diamond composite and a method for manufacturing the same according to the present invention will be described with reference to the drawings.

  An aluminum-diamond composite according to the present embodiment (1 in FIG. 1) is a plate-like aluminum-diamond composite including diamond particles and a metal containing aluminum, and the aluminum-diamond composite described above. 1 comprises a composite part (2 in FIG. 1) and a surface layer (3 in FIG. 1) provided on both surfaces of the composite part 2, and the surface layer 3 comprises an aluminum-ceramic composite, and the diamond Content of particle | grains is 40 volume%-70 volume% of the said aluminum-diamond type complex 1 whole, It is characterized by the above-mentioned.

  The aluminum-diamond composite having the above structure has a high thermal conductivity and a thermal expansion coefficient close to that of a semiconductor element, and further has a small surface roughness and flatness.

  Hereinafter, the manufacturing method by the molten metal forging method is demonstrated about the aluminum-diamond type composite_body | complex which concerns on this embodiment.

Here, the manufacturing method of the aluminum-diamond composite can be roughly classified into two types: an impregnation method and a powder metallurgy method. Of these, many are actually commercialized by impregnation methods from the viewpoint of characteristics such as thermal conductivity. There are various impregnation methods, and there are a method performed at normal pressure and a high-pressure forging method performed under high pressure. High pressure forging methods include a molten metal forging method and a die casting method. A method suitable for the present invention is a high-pressure forging method in which impregnation is performed under high pressure, and a molten forging method is preferable to obtain a dense composite having excellent characteristics such as thermal conductivity. The molten metal forging method is generally a method in which a high pressure vessel is filled with a powder or compact such as diamond and impregnated with a molten metal such as an aluminum alloy at high temperature and high pressure to obtain a composite material.

[Diamond powder]
As the raw material diamond powder, either natural diamond powder or artificial diamond powder can be used. Moreover, you may add binders, such as a silica, to this diamond powder as needed. By adding the binder, an effect that a molded body can be formed can be obtained.

  Regarding the particle size of the diamond powder, from the viewpoint of thermal conductivity, a powder having an average particle size of 50 μm or more is preferable, and an average particle size is more preferably 100 μm or more. The upper limit of the particle diameter of the diamond particles is not limited as long as it is equal to or less than the thickness of the obtained composite, but is preferably 500 μm or less because the composite can be obtained at a stable cost. In order to increase the filling rate of diamond particles, 60% by volume to 80% by volume of diamond powder having an average particle size of 100 μm or more and 20% by volume to 40% by volume of diamond powder having an average particle size of 30 μm or less are mixed. More preferably, it is used.

The content of diamond particles in the aluminum-diamond composite is preferably 40% by volume or more and 70% by volume or less. When the content of the diamond particles is 40% by volume or more, the thermal conductivity of the obtained aluminum-diamond composite can be sufficiently ensured. Moreover, it is preferable that content of a diamond particle is 70 volume% or less from the surface of a filling property. If it is 70 volume% or less, it is not necessary to process the shape of diamond particles into a spherical shape or the like, and an aluminum-diamond composite can be obtained at a stable cost.

  In the composite obtained by the molten metal forging method, the molten metal spreads between the gaps between the powders under appropriate conditions. Therefore, the ratio of the volume of the powder to the filling volume is the volume of the powder material relative to the total volume of the obtained composite ( Particle content).

Furthermore, the use of diamond powder having a β-type silicon carbide layer formed on the surface of the diamond particles can suppress the formation of low thermal conductivity metal carbide (Al ₄ C ₃ ) formed at the time of compounding. And wettability with molten aluminum can be improved. As a result, it is possible to obtain an effect that the thermal conductivity of the obtained aluminum-diamond composite is improved.

  As a preparation for molten metal forging, a mold material (4 in FIG. 2) made of a porous body that can be impregnated with an aluminum alloy, a ceramic porous body (5 in FIG. 2), and a dense mold release plate (FIG. 2) coated with a release agent. 6) and the diamond powder (7 in FIG. 2) are arranged as shown in FIG. 2, thereby forging a molten metal consisting of the mold material 4, the release plate 6, the ceramic porous body 5 and the filled diamond powder 7. A structure.

  Here, FIG. 2 is a cross-sectional view of a structure for molten metal forging, and is a cross-sectional view of a portion filled with the diamond powder. When the aluminum alloy and the diamond powder are combined by the molten metal forging method, the aluminum alloy reaches a portion where the diamond powder is filled through the porous mold and the ceramic porous body.

[Mold made of porous material]
Here, the material of the mold 4 made of a porous body that can be impregnated with the aluminum alloy by the molten metal forging method is not particularly limited as long as it is a porous material that can be impregnated with the aluminum alloy by the molten metal forging method. However, as the porous body, porous bodies such as graphite, boron nitride, and alumina fiber that are excellent in heat resistance and can supply a stable molten metal are preferably used.

[Ceramic porous body]
Moreover, the ceramic porous body is a porous body that can be impregnated with an aluminum alloy by a molten metal forging method, and is a porous body containing at least one of silicon carbide, silicon nitride, and aluminum nitride, and the resulting aluminum- Silicon carbide is more preferable from the viewpoint of the thermal conductivity of the ceramic composite. The porosity of the ceramic porous body is 20 to 60% by volume, which requires pores that can be impregnated with an aluminum alloy by a molten metal forging method. On the other hand, the ceramic content in the aluminum-ceramic composite is preferably adjusted so that the difference in coefficient of thermal expansion between the aluminum-diamond composite and the aluminum-ceramic composite is small. When the difference in coefficient of thermal expansion between the aluminum-diamond composite and the aluminum-ceramic composite is large, warpage or the like occurs in the subsequent processing step, which is not preferable. Further, by using a ceramic porous body having a concave surface as shown in FIG. 6, a plate-like aluminum-diamond composite having an uneven portion as shown in FIG. 7 can be produced.

[Release board]
Further, as the dense release plate 6, a stainless plate or a ceramic plate can be used, and there is no particular limitation as long as it is a dense body that is not impregnated with an aluminum alloy by a molten metal forging method. Moreover, about the mold release agent apply | coated to a mold release plate, mold release agents, such as graphite, boron nitride, and alumina which are excellent in heat resistance, can be used preferably. Furthermore, after the surface of the release plate is coated with alumina sol or the like, a release plate capable of more stable release can be obtained by applying the release agent.

[Aluminum alloy]
The aluminum alloy (aluminum-containing metal) in the aluminum-diamond composite according to the present embodiment has a melting point as low as possible in order to sufficiently penetrate into the voids of the diamond powder (between the diamond particles) during impregnation. preferable. Examples of such an aluminum alloy include an aluminum alloy containing 5 to 25% by mass of silicon. By using an aluminum alloy containing 5 to 25% by mass of silicon, an effect of promoting densification of the aluminum-diamond composite can be obtained.

  Furthermore, inclusion of magnesium in the aluminum alloy is preferable because the bond between diamond particles and ceramic particles and the metal portion becomes stronger. The metal components other than aluminum, silicon, and magnesium in the aluminum alloy are not particularly limited as long as the characteristics of the aluminum alloy do not change extremely. For example, copper or the like may be included.

The thickness of the aluminum-diamond composite according to the present embodiment can be adjusted by the filling amount of diamond powder at the time of compounding, and the thickness is preferably 0.4 to 6 mm. When the thickness is less than 0.4 mm, it is not preferable because sufficient strength for use as a heat sink or the like cannot be obtained. When the thickness exceeds 6 mm, the material itself is expensive, and the effect of high heat conduction of the present invention cannot be sufficiently obtained, which is not preferable.

  The obtained structure is further laminated to form a block, and the block is heated to about 600 to 750 ° C. Then, one or two or more blocks are arranged in the high-pressure vessel, and a molten aluminum alloy heated to the melting point or higher is supplied as quickly as possible in order to prevent a temperature drop of the block, and the pressure is increased to 20 MPa or higher. .

Here, if the heating temperature of the block is 600 ° C. or higher, the composite of the aluminum alloy is stable, and an aluminum-diamond composite having a sufficient thermal conductivity can be obtained. Further, when the heating temperature is 750 ° C. or lower, an aluminum-diamond composite having a sufficient thermal conductivity can be suppressed when aluminum carbide (Al ₄ C ₃ ) is formed on the surface of the diamond particles when composited with an aluminum alloy. You can get a body.

  Moreover, regarding the pressure at the time of impregnation, if it is 20 MPa or more, the composite of the aluminum alloy is stable, and an aluminum-diamond composite having a sufficient thermal conductivity can be obtained. More preferably, the impregnation pressure is 50 MPa or more. If it is 50 MPa or more, an aluminum-diamond composite having more stable thermal conductivity characteristics can be obtained.

[Annealing treatment]
In addition, you may anneal-treat to the aluminum-diamond type molded object obtained by the said operation. By performing the annealing treatment, distortion in the aluminum-diamond-based molded body is removed, and an aluminum-diamond-based composite having more stable thermal conductivity characteristics can be obtained.

  In order to remove only the strain in the molded body without affecting the surface of the obtained aluminum-diamond-based molded body, the annealing treatment is performed at a temperature of 400 ° C. to 550 ° C. for 10 minutes or more. preferable.

[Processing method]
Next, an example of a method for processing an aluminum-diamond composite according to this embodiment will be described. The aluminum-diamond composite is a very hard and difficult-to-work material. Therefore, the aluminum-ceramic composite (3 in FIG. 3) present on the outer periphery of the composite aluminum-diamond composite of FIG. 3 is ground using a diamond tool, diamond abrasive grains, etc. A structure in which both surfaces of a diamond composite (2 in FIG. 4) are covered with a surface layer (3 in FIG. 4) made of an aluminum-ceramic composite having a thickness of 0.05 to 0.5 mm is prepared. To do.

Next, the outer peripheral portion (side surface portion) (8 in FIG. 5) and the hole portion (9 in FIG. 5) are processed on the aluminum-diamond composite of FIG. 4 using a water jet processing machine or a laser processing machine. It can be processed into an aluminum-diamond composite. As a result, the obtained aluminum-diamond composite has a structure in which the composite part 2 is exposed in the outer peripheral part 8 and the hole part 9 as shown in FIG.

Here, as shown in FIG. 5, the hole 9 may be provided so as to penetrate the upper and lower surfaces so that it can be screwed to another heat radiating component. In addition, the processing cost can be reduced by processing into a shape like a U-shape connected to the outer peripheral portion.

  Moreover, since the aluminum-diamond type molded object which concerns on this embodiment is an electroconductive material, even if it uses an electric discharge machine, the outer peripheral part 8 and the hole part 9 can be processed. The obtained aluminum-diamond composite has a structure in which the composite part 2 is exposed in the outer peripheral part 8 and the hole part 9.

  Although the aluminum-diamond-based molded body according to the present embodiment can be processed using a normal diamond tool or the like, it is a very hard and difficult-to-process material, so that the durability and processing cost of the tool are reduced. Therefore, processing by a water jet processing machine, a laser processing machine or an electric discharge machine is preferable.

[Surface layer]
In the aluminum-diamond composite according to the present embodiment, a surface layer (FIG. 1) made of an aluminum-ceramic composite having both surfaces of the composite portion (2 in FIG. 1) having a thickness of 0.05 to 0.5 mm on the surface. 3).

This aluminum-ceramic composite can be impregnated with an aluminum alloy by a molten metal forging method into a ceramic porous body containing at least one of silicon carbide, silicon nitride, and aluminum nitride. From the viewpoint of the thermal conductivity of the obtained aluminum-ceramic composite, the ceramic is more preferably silicon carbide. The ceramic content of the aluminum-ceramic composite is 40% by volume to 80% by volume, and is preferably adjusted so that the difference in thermal expansion coefficient between the aluminum-diamond composite and the aluminum-ceramic composite is small. When the difference in coefficient of thermal expansion between the aluminum-diamond composite and the aluminum-ceramic composite is large, warpage or the like occurs in the subsequent processing step, which is not preferable.

In the present invention, the aluminum-ceramic composite can be produced in advance and then joined in the step of producing the aluminum-diamond composite to produce the aluminum-diamond composite shown in FIG.

  The thickness of the surface layer 3 is preferably 0.05 mm or more and 0.5 mm or less. If the thickness of the surface layer 3 (aluminum-ceramic composite) is 0.05 mm or more, it is easy to obtain the target surface accuracy (surface roughness). Moreover, if the average thickness of the surface layer 3 is 0.5 mm or less, depending on the thickness of the obtained aluminum-diamond composite 1, a sufficient thickness of the composite portion 2 occupying the composite 1 can be obtained, Sufficient thermal conductivity can be ensured.

On the other hand, when the thickness of the surface layer 3 is less than 0.05 mm, the aluminum-diamond composite is partially exposed from the surface layer 3 and the surface roughness becomes rough, which is not preferable. On the other hand, when the thickness of the surface layer 3 exceeds 0.5 mm, although it depends on the thickness of the obtained aluminum-diamond composite 1, the sufficient thickness of the composite portion 2 in the composite 1 cannot be obtained, and is sufficient. It is not preferable because a sufficient heat conductivity cannot be secured. Regarding the thickness of the surface layer 3, it is preferably as thin as possible from the viewpoint of thermal conductivity, and more preferably 0.05 to 0.20 mm.

[Surface layer processing]
Since the aluminum-diamond composite according to this embodiment has a structure in which both surfaces are coated with a surface layer 3 made of an aluminum-ceramic composite, the surface layer 3 is processed (polished). The surface accuracy (surface roughness: Ra) and flatness can be adjusted. The surface layer 3 can be processed by using a diamond abrasive or a grindstone. For example, after grinding with a grinder, the surface layer 3 is polished with a buffing machine to obtain surface roughness (Ra ) Can be 1 μm or less.

Furthermore, the average thickness of the surface layer can be adjusted by processing the surface layer 3. When the aluminum-diamond composite according to the present embodiment is used as a heat dissipation component such as a heat sink, the surface roughness is preferably a smooth surface having a small surface roughness in consideration of the thermal resistance of the bonding surface. (Ra) is preferably 1 μm or less, and more preferably 0.5 μm or less. When the surface roughness is 1 μm or less, the thickness of the bonding layer can be made uniform, and higher heat dissipation can be obtained.

  Also, the flatness of the surface layer 2 is preferably 100 μm or less, more preferably 50 μm or less, in terms of a size of 50 mm × 50 mm. When the flatness is 100 μm or less, the thickness of the solder layer can be made uniform, and higher heat dissipation can be obtained.

[Composite part]
The aluminum-diamond composite according to this embodiment has a composite part (2 in FIG. 1 and 2 in FIG. 7) of the diamond particles and the aluminum alloy.

  The boundary between the surface layer 3 and the composite portion 2 has a boundary that allows the surface layer 3 and the composite portion 2 to be visually observed when a cross section of the aluminum-diamond composite is observed with a microscope or the like. It does not have to be. In the aluminum-diamond composite having such a structure, the difference in thermal expansion coefficient between the surface layer 3 and the composite portion 2 is small, and stress is hardly generated between the surface layer 3 and the composite portion 2, and polishing or the like is performed. When the force is applied, the surface layer 3 is not damaged.

[Plating treatment]
When used as a heat sink of a semiconductor element, the aluminum-diamond composite according to the present embodiment is often used by being joined to the semiconductor element by brazing. Therefore, plating may be applied to the bonding surface of the aluminum-diamond composite.

  The method of plating treatment is not particularly limited, and any of electroless plating treatment and electroplating treatment method may be used. In the case of plating on aluminum, Ni plating or two-layer plating of Ni plating and Au plating is performed in consideration of solder wettability. In this case, the plating thickness is preferably 0.5 or more and 15 μm or less. If the plating thickness is 0.5 μm or more, the generation of plating pinholes and solder voids (voids) during soldering can be prevented, and heat dissipation characteristics from the semiconductor element can be ensured. Moreover, if the thickness of the plating is 15 μm or less, the heat dissipation characteristics from the semiconductor element can be ensured without being affected by the Ni plating film having a low thermal conductivity. The purity of the Ni plating film is not particularly limited as long as it does not hinder solder wettability, and may contain phosphorus, boron, or the like.

Furthermore, in the present invention, in order to improve the plating adhesion, after cleaning the surface of the aluminum-diamond composite, an aluminum layer having a thickness of 0.05 to 2.0 μm is formed on the surface. If the thickness of the aluminum layer is less than 0.05 μm, an unattached part of the aluminum layer is generated, or the aluminum layer reacts during plating pretreatment, etc., and an unplated part is generated due to the generation of pinholes, resulting in reduced chemical resistance. It is not preferable. On the other hand, if the aluminum layer thickness exceeds 2.0 μm, the linear thermal expansion coefficients of the aluminum layer and the metal matrix composite material are different, so that stress and peeling occur due to the difference in thermal expansion between the two materials. The aluminum layer thickness is more preferably 0.3 to 0.6 μm.

As a formation method of an aluminum layer, it forms in 0.05-2.0 micrometers in thickness by a vapor deposition method or sputtering method. The aluminum alloy constituting the aluminum layer is pure aluminum or an aluminum alloy containing 70% by mass or more of aluminum. If the aluminum content is less than 70% by mass, Ni plating with sufficient adhesion by the zincate treatment cannot be performed, which is not preferable. The metal components other than aluminum and silicon in the aluminum alloy are not particularly limited as long as the characteristics do not change extremely. For example, magnesium, copper, and the like may be included.

  Further, in the present invention, in order to improve the adhesion between the aluminum-ceramic composite on the surface of the aluminum-diamond composite and the aluminum layer, the temperature is 460 to 650 ° C. in a nitrogen, argon, hydrogen, helium or vacuum atmosphere. Heat treatment is performed for 1 minute or longer. When the treatment is performed in an oxidizing atmosphere, an oxide film is formed on the surface and subsequent plating defects occur, which is not preferable. The temperature is preferably 480-570 ° C. When the temperature is less than 460 ° C., the adhesion between the composite and the aluminum layer is deteriorated. When the temperature is higher than 650 ° C., the aluminum layer is dissolved and the surface roughness is deteriorated.

The aluminum-diamond composite according to this embodiment has a thermal conductivity of 400 W / mK or more when the temperature of the aluminum-diamond composite is 25 ° C., and a thermal expansion coefficient from 25 ° C. to 150 ° C. 5 × is preferably ^{10 -6 ~10 × 10 -6 / K} .

If the thermal conductivity at 25 ° C. is 400 W / mK or more and the thermal expansion coefficient from 25 ° C. to 150 ° C. is 5 × 10 ⁻⁶ to 10 × 10 ⁻⁶ / K, the thermal conductivity is equivalent to that of a semiconductor element. Low expansion rate of the level. Therefore, when used as a heat radiating component such as a heat sink, it has excellent heat radiating characteristics, and even when subjected to a temperature change, the difference in coefficient of thermal expansion between the semiconductor element and the heat radiating component is small, so that the destruction of the semiconductor element can be suppressed. As a result, it is preferably used as a highly reliable heat dissipation component.

<Effect>
Hereinafter, the function and effect of the aluminum-diamond composite according to the embodiment will be described.

  The aluminum-diamond composite according to the above embodiment (1 in FIG. 1 and 1 in FIG. 7) is a plate-like aluminum-diamond composite having a plate-like or uneven portion including diamond particles and a metal containing aluminum. The aluminum-diamond composite 1 is composed of a composite part (2 in FIG. 1 and 2 in FIG. 7) and a surface layer (3 in FIG. 1 and FIG. 7) provided on both sides of the composite part 2. 3), the surface layer 3 is made of an aluminum-ceramic composite, and the content of the diamond particles is 40% to 70% by volume of the entire aluminum-diamond composite 1. And

  The aluminum-diamond composite 1 having the above configuration has a high thermal conductivity and a thermal expansion coefficient close to that of a semiconductor element, and further, the surface plating property is improved, and the surface roughness and flatness of the surface are small. It is preferably used as a heat sink for heat dissipation of semiconductor elements.

  Furthermore, since the thickness of the surface layer 3 is not less than 0.05 mm and not more than 0.5 mm, it is easy to obtain the target surface accuracy, and sufficient thermal conductivity can be ensured.

  Moreover, since the surface roughness (Ra) of the surface layer 3 is 1 μm or less, the thickness of the bonding layer can be made uniform, and higher heat dissipation can be obtained.

  Moreover, since the thickness of the flat aluminum-diamond composite 1 is 0.4 to 6 mm, it is possible to obtain an effect of having sufficient strength and heat dissipation characteristics for use as a heat dissipation component such as a heat sink.

In addition, the thermal conductivity when the temperature of the aluminum-diamond composite 1 is 25 ° C. is 400 W / mK or more, and the thermal expansion coefficient of the aluminum-diamond composite 1 is 25 ° C. to 150 ° C. 5 × may be ^{10 -6 ~10 × 10 -6 / K} . In this way, when used as a heat dissipation component such as a heat sink, it has excellent heat dissipation characteristics, and even when subjected to temperature changes, the difference in thermal expansion coefficient between the semiconductor element and the heat dissipation component is small. The effect that it can suppress can be acquired.

  Further, a Ni plating layer or two plating layers of Ni plating and Au plating may be provided on the surface of the aluminum-diamond composite 1 so as to have a thickness of 0.5 to 15 μm. If it does in this way, when using it as a thermal radiation component etc., a high thermal radiation characteristic can be ensured.

  The aluminum-diamond composite 1 may be manufactured by a molten metal forging method. In this way, a dense composite having excellent characteristics such as thermal conductivity can be obtained.

  Further, the flat aluminum-diamond composite 1 has a hole 9, and the side surface 8 and the hole 9 of the flat aluminum-diamond composite 1 are exposed to the composite part 2. The structure formed may be sufficient. If it does in this way, when using as a heat dissipation component etc., it will become possible to fix with a screw etc.

  The aluminum-diamond composite is obtained by filling a mold material made of a ceramic porous body that can be impregnated with a metal containing aluminum by a molten metal forging method with diamond powder, and forming a mold material made of the porous body. And filling the diamond powder in a structure sandwiched between the release plates coated with a mold to form a structure comprising the mold material, the release plate and the filled diamond powder, and the structure at a temperature of 600 to 750 ° C. And a flat aluminum-diamond composite material in which the above-mentioned diamond powder is impregnated with a metal containing aluminum heated to a melting point or higher at a pressure of 20 MPa or more and is coated with an aluminum-ceramic composite. After the preparation, the surrounding aluminum-ceramic composite is bonded to the aluminum-ceramic composite on both main surfaces. Body thickness may be those obtained from the manufacturing method including the step of grinding so as to be 0.5mm or less.

  By such a manufacturing method, it has high thermal conductivity and a thermal expansion coefficient close to that of a semiconductor element, and further, the surface plating property is improved and the surface roughness is small, so that it is preferable as a heat sink for heat dissipation of a semiconductor element. The aluminum-diamond composite used can be obtained.

  Moreover, in the said manufacturing method, the plate-shaped aluminum-diamond type composite material which has the plate-shaped or uneven | corrugated | grooved part by which both said main surfaces were coat | covered with the 0.05-0.5-mm-thick aluminum-ceramics composite is produced. You may further include the process of processing the side part and hole part of the said flat aluminum-diamond type molded object by water jet processing, laser processing, or electric discharge processing after a process, and making it an aluminum-diamond type composite. Such a process makes it possible to fix with a screw or the like when used as a heat dissipation component or the like.

  As mentioned above, although the embodiment was mentioned and demonstrated about the aluminum-diamond type composite_body | complex which concerns on this invention, and its manufacturing method, this invention is not restrict | limited to these.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[Examples 1-7]
For 50 g of high purity diamond powder A (average particle size: 190 μm), high purity diamond powder B (average particle size: 100 μm), and high purity diamond powder C (average particle size: 20 μm), After mixing 16 g of silica powder (average particle size: 5 μm) and silicon powder (average particle size: 10 μm): 16 g, the mixture is filled in a silicon carbide crucible and heated at 1450 ° C. for 3 hours in an argon atmosphere. A diamond powder having a β-type silicon carbide layer formed on the surface of the diamond particles was produced. Thereafter, each diamond powder and aluminum powder (average particle size: 50 μm) were mixed at a blending ratio shown in Table 1.

  Next, a 60 × 60 × 1 mmt stainless steel plate (SUS430 material) was coated with alumina sol and baked at 350 ° C. for 30 minutes, and then a graphite mold release agent was applied to the surface, and the release plate (FIG. 2-6) was produced. Then, each diamond powder of Table 1 is applied to an isotropic graphite mold (4 in FIG. 2) having a porosity of 20% and having an outer shape of 60 × 60 × 8 mmt and a hole of 40 × 40 × 8 mmt in the central portion. The structure was filled by sandwiching both surfaces with a silicon carbide based porous material 5 having a porosity of 35% of 40 × 3.1 mmt.

  A plurality of the above structures are stacked with a release plate (6 in FIG. 2) coated with a 60 × 60 × 1 mmt graphite release agent interposed therebetween, and iron plates with a thickness of 12 mm are arranged on both sides, and M10 It was connected with six bolts, and was tightened with a torque wrench so that the tightening torque in the surface direction was 10 Nm, thereby forming one block.

  Next, after the obtained block was preheated to a temperature of 650 ° C. in an electric furnace, it was placed in a pre-heated press mold having an inner diameter of 300 mm, and contained 12% by mass of silicon and 1% by mass of magnesium. A molten aluminum alloy at 800 ° C. was poured and pressurized at 100 MPa for 20 minutes to impregnate the diamond powder with the aluminum alloy. And after cooling to room temperature, it cut | disconnected along the shape of the mold release plate with the wet band saw, and peeled the mold release plate pinched | interposed. Thereafter, an annealing treatment was performed at a temperature of 530 ° C. for 3 hours to remove strain at the time of impregnation to obtain an aluminum-diamond composite.

The obtained aluminum-diamond composite was subjected to buffing after both surfaces were ground to a plate thickness of 2 mm using a # 230 diamond grindstone with a surface grinder. In Example 7, both surfaces were only ground with a # 230 diamond grindstone, and no buffing was performed.

Subsequently, using a garnet having a particle size of 100 μm as abrasive grains under the conditions of a pressure of 250 MPa and a processing speed of 50 mm / min using a water jet processing machine (Abrasive Jet Cutter NC manufactured by Sugino Machine), 25 × 25 × 2 mmt An aluminum-diamond composite was processed into a shape.

The cross section of the obtained aluminum-diamond composite was observed with a factory microscope, and the average thickness of the surface layers (3 in FIG. 1) on both sides was measured. Moreover, the surface roughness (Ra) by the surface roughness meter and the flatness by the three-dimensional contour shape measurement were measured. The results are shown in Table 2.

Also, a thermal expansion coefficient measurement specimen (3 × 2 × 10 mm) and a thermal conductivity measurement specimen (25 × 25 × 2 mmt) were produced by water jet processing. Using each test piece, the thermal expansion coefficient at a temperature of 25 ° C. to 150 ° C. was measured with a thermal dilatometer (manufactured by Seiko Denshi Kogyo; TMA300), and the thermal conductivity at 25 ° C. was measured with a laser flash method (manufactured by Rigaku Corporation); LF / TCM-8510B). The results are shown in Table 2.

Further, the density of the aluminum-diamond composite of Example 1 was measured by Archimedes method and found to be 3.15 g / cm ³ . Furthermore, about Example 1, the bending strength test body (3x2x40mm) was produced, and it was 340MPa as a result of measuring 3 point | piece bending strength with a bending strength tester.

In addition, after ultrasonically cleaning the above-mentioned aluminum-diamond composite, an aluminum layer having a thickness of 0.5 μm was formed on the surface of the composite by vapor deposition, and heat treatment was performed at 500 ° C. for 30 minutes in a nitrogen atmosphere. . Next, electroless Ni—P plating and Au electroplating were performed on the aluminum-diamond composite having an aluminum layer formed on the surface, and 8 μm was formed on the surface of the aluminum-diamond composite according to Examples 1-7. A plating layer having a thickness (Ni-P: 6 μm + Au: 2 μm) was formed. As a result of measuring the solder wetting spread rate of the obtained plated product according to JIS Z3197, the solder wet spread rate was 85% or more in all plated products.

  As shown in Table 2, the aluminum-diamond composites according to Examples 1 to 7 have a very smooth surface roughness of 0.14 to 0.95 μm and a flatness of 6 to 12 μm. It has a high thermal conductivity and a thermal expansion coefficient close to that of a semiconductor element.

[Examples 8 to 19, Comparative Examples 1 to 3]
A 60 × 60 × 1 mmt stainless steel plate (SUS430 material) is coated with alumina sol and baked at a temperature of 350 ° C. for 30 minutes, and then a graphite mold release agent is applied to the surface to form a release plate (FIG. 2). 6) was produced. Then, a diamond powder A (average particle diameter) is applied to a mold (filling jig) (4 in FIG. 2) shown in Table 3 having an outer diameter of 60 × 60 × 8 mm and having a hole with an inner diameter of 40 × 40 × 8 mm in the center. : 190 μm) After mixing 70% by mass and diamond powder C (average particle size: 20 μm) 30% by mass, the porous ceramic body shown in Table 3 of 40 × 40 × mm so that the volume / filling volume = 60% by volume is obtained. 5 so as to sandwich both sides of the laminate.

  A plurality of the above laminates were laminated with a release plate (5 in FIG. 2) coated with a 60 × 60 × 1 mmt graphite release agent interposed therebetween, and 12 mm thick iron plates were arranged on both sides, and M10 It was connected with six bolts, and was tightened with a torque wrench so that the tightening torque in the surface direction was 10 Nm, thereby forming one block.

Next, the obtained block was preheated by an electric furnace at the temperature shown in Table 3, and then placed in a preheated press mold having an inner diameter of 300 mm. Silicon was 12 mass% and magnesium was 1 mass%. The molten aluminum alloy at a temperature of 800 ° C. contained was poured and pressed for 20 minutes at the pressure shown in Table 3 to impregnate the diamond powder with the aluminum alloy. And after cooling to room temperature, it cut | disconnected along the shape of the mold release plate with the wet band saw, and peeled off the sandwiched stainless steel plate. Thereafter, an annealing treatment was performed at a temperature of 530 ° C. for 3 hours to remove strain at the time of impregnation to obtain an aluminum-diamond composite.

The obtained aluminum-diamond composite was ground to a thickness of 2 mm using a # 230 and # 400 diamond grindstone on both sides with a surface grinder. In Comparative Example 1, both sides were ground to a plate thickness of 2 mm using only # 230 diamond grinding stone. Subsequently, it was processed into a 25 × 25 mm shape with a laser processing machine at a processing speed of 50 mm / min to obtain an aluminum-diamond composite. And the cross section of the obtained aluminum-diamond-type composite was observed with the factory microscope, and the presence or absence and average thickness of the surface layer of both surfaces were measured. Moreover, the surface roughness (Ra) by a surface roughness meter and the flatness by a three-dimensional shape measuring machine were measured. The results are shown in Table 4.

  In addition, a thermal expansion coefficient measurement specimen (3 mm × 10 mm × plate thickness) and a thermal conductivity measurement specimen (25 mm × 25 mm × plate thickness) were prepared by laser processing. And each Example was measured similarly to Examples 1-7, the thermal expansion coefficient in the temperature of 25 to 150 degreeC, and the thermal conductivity in 25 degreeC were measured. The results are shown in Table 4.

  In addition, after ultrasonically cleaning the aluminum-diamond composite, electroless Ni-P and electroless Au plating are performed, and the surface of the composite is 6.05 μm thick (Ni-P: 6 μm + Au: 0.05 μm). A plating layer was formed. As a result of measuring the solder wetting spread rate of the obtained plated product according to JIS Z3197, the solder wet spread rate was 85% or more in all plated products.

  As shown in Table 4, the aluminum-diamond composites according to Examples 8 to 19 have a very smooth surface roughness of 0.41 to 0.55 μm and a flatness of 2 to 25 μm. It has a high thermal conductivity and a thermal expansion coefficient close to that of a semiconductor element.

  On the other hand, the surface of the aluminum-diamond composite according to Comparative Example 1 was rough despite the same grinding process as in Example 7. Also, the desired thermal conductivity could not be obtained. This is presumably because the pressure during impregnation is less than 20 MPa.

Further, in Comparative Example 2, impregnation of the aluminum alloy diamond powder into the voids did not proceed, and the composite was incomplete. The obtained molded body had a density of 2.2 g / cm ³ , was brittle, and did not have a desired flat plate shape. This is considered to be because in Comparative Example 2, the preheating temperature is less than 600 ° C.

  In Comparative Example 3, the aluminum alloy was hardly impregnated in the voids of the diamond powder, and a molded body could not be obtained. Therefore, a flat aluminum-diamond composite could not be obtained. This is probably because non-porous stainless steel was used as the mold material.

[Example 20]
A laminate was prepared by the same method as in Example 1, and a plurality of layers were laminated with a release plate (6 in FIG. 2) coated with a 60 × 60 × 1 mmt graphite release agent interposed therebetween, and the thickness was 12 mm on both sides. The steel plates were arranged, connected with six M10 bolts, and tightened with a torque wrench so that the tightening torque in the surface direction was 10 Nm, to form one block.

Next, after the obtained block was preheated to a temperature of 700 ° C. in an electric furnace, it was placed in a pre-heated press mold having an inner diameter of 300 mm, poured with a molten pure aluminum at a temperature of 800 ° C., and a pressure of 100 MPa. For 20 minutes to impregnate the diamond powder with aluminum. And after cooling to room temperature, cut along the shape of the release plate with a wet band saw, peel off the sandwiched stainless steel plate, and then anneal for 3 hours at a temperature of 530 ° C. to remove strain during impregnation. And an aluminum-diamond molded body was obtained. The content of diamond particles in the obtained aluminum-diamond composite was 65% by volume, and the density measured by Archimedes method was 3.14 g / cm ³ .

  The obtained aluminum-diamond composite was subjected to the same grinding and polishing as in Example 1 and processed into a 25 × 25 × 2 mmt shape to obtain an aluminum-diamond composite. And as a result of observing the cross section of the obtained aluminum-diamond type composite with a factory microscope and measuring the average thickness of the surface layers (3 in FIG. 1) on both sides, the average thickness of the surface layer 3 was 0.1 mm. there were. The surface roughness (Ra) measured with a surface roughness meter was 0.18 μm, and the flatness measured with a three-dimensional shape measuring machine was 8 μm.

And the test body was processed like Example 1, and heat conductivity, a thermal expansion coefficient, and bending strength were measured. As a result, the thermal expansion coefficient at a temperature of 25 ° C. to 150 ° C. was 7.5 × 10 ⁻⁶ / K, the thermal conductivity at a temperature of 25 ° C. was 620 W / mK, and the three-point bending strength was 320 MPa.

  In Example 20, pure aluminum is used. As a result, the surface roughness is 0.18 μm and the flatness is 8 μm, which is very smooth, and has a high thermal conductivity and a thermal expansion coefficient close to that of a semiconductor element.

[Example 21]
As a ceramic porous body, a silicon carbide based porous body having a porosity of 35% having an outer shape of 40 × 40 × 4.9 mm and a groove portion of 30 × 30 × 1.8 mm and 15 × 15 × 1 mm in the central portion (5 in FIG. 6). ) And a silicon carbide based porous material having a porosity of 35% and an outer shape of 40 × 40 × 3.1 mm were produced in the same manner as in Example 1 to produce an aluminum-diamond composite.

  The obtained aluminum-diamond composite was ground to a thickness of 3 mm using a # 400 diamond grindstone on both sides with a surface grinder, and then a 17 × 17 × 1 mm protrusion shape was formed at the center in the machining center. Grinding was performed using a # 400 diamond grindstone. Next, the outer periphery was processed into a 25 × 25 mm shape with an electric discharge machine machine at a processing speed of 5 mm / min to obtain an aluminum-diamond composite. And as a result of observing the cross section of the obtained aluminum-diamond type composite with a factory microscope and measuring the average thickness of the surface layers (3 in FIG. 7) on both sides, the average thickness of the surface layer 3 is 0.1 mm. there were. The surface roughness (Ra) measured with a surface roughness meter was 0.43 μm, and the flatness measured with a three-dimensional shape measuring machine was 7 μm.

Further, the aluminum-diamond-based molded body of Example 21 was subjected to the same characteristic evaluation as that of Example 1. The density was 3.13 g / cm ³ , and the thermal expansion coefficient at a temperature of 25 ° C. to 150 ° C. was 7 The thermal conductivity at 0.0 × 10 ⁻⁶ / K and a temperature of 25 ° C. was 580 W / mK, and the three-point bending strength was 320 MPa.

  Example 21 has a shape having a protrusion at the center of the product (FIG. 7), has a very smooth surface roughness of 0.43 μm, flatness of 7 μm, high thermal conductivity, and thermal expansion close to that of a semiconductor element. Has a coefficient.

[Examples 22 to 29]
In Example 1, an aluminum-diamond composite having a shape of 25 mm × 25 mm × 2 mmt after water jet processing was ultrasonically cleaned, and then an aluminum layer having a thickness of 0.5 μm was formed on the surface of the composite by a sputtering method. Heat treatment was performed at 500 ° C. for 30 minutes in a nitrogen atmosphere. Next, the aluminum-diamond composite with the aluminum layer formed on the surface was subjected to electroless plating treatment under various conditions shown in Table 5 to form a plating layer on the surface of the composite. Table 5 shows the results of measuring the plating thickness of the obtained plated product.

  As a result of measuring the solder wetting spread rate in accordance with JIS Z3197 for each plated product, in Example 28, the surface is smooth, has both high thermal conductivity and a thermal expansion coefficient close to that of a semiconductor element, and spreads the solder wetting. Although the rate was 75%, voids were confirmed on the solder surface. As a result of confirming this solder void portion with a microscope, an unplated portion was observed at the center of the void. This is thought to be because the thickness of the plating is less than 0.5 μm.

  Further, in Example 29, the surface is smooth and has a high thermal conductivity and a thermal expansion coefficient close to that of a semiconductor element, but cracks occur in the plating layer during heating when measuring the solder wetting spread rate. did. This is probably because the thickness of the plating exceeds 15 μm.

  On the other hand, in the plated products of Examples 22 to 27, the solder wetting spread rate is 80% or more, and when used as a heat sink, higher thermal conductivity can be obtained. This is considered because the thickness of the plating is 0.5 μm or more and 15 μm or less.

DESCRIPTION OF SYMBOLS 1 Aluminum-diamond-type composite body 2 Composite part 3 Surface layer 4 Mold material which consists of porous bodies 5 Ceramic porous body 6 Release plate which applied release agent 7 Diamond powder 8 Outer peripheral part 9 Hole part

Claims (9)

It is a plate-like aluminum-diamond based composite material containing 40% to 70% by volume of diamond particles, the balance being made of a metal containing aluminum, and having a plate-like or uneven portion with a thickness of 0.4 to 6 mm. Both main surfaces are covered with an aluminum-ceramic composite having a thickness of 0.05 to 0.5 mm, and the side surface and the hole have a structure in which the aluminum-diamond composite is exposed. Aluminum-diamond composite. 2. The aluminum-diamond composite according to claim 1, wherein the surface roughness (Ra) of both main surfaces is 1 [mu] m or less. The aluminum-ceramic composite is an aluminum-silicon carbide composite comprising 40% by volume to 80% by volume of silicon carbide and the balance being made of a metal containing aluminum. 2. The aluminum-diamond composite according to 2. 4. The aluminum-diamond composite according to claim 1, wherein the diamond particles are characterized by the presence of a β-type silicon carbide layer chemically bonded to the surface thereof. The aluminum-diamond composite according to any one of claims 1 to 4, which is an aluminum-diamond composite manufactured by a molten metal forging method. The thermal conductivity at a temperature of 25 ° C. is 400 W / mK or more, and the thermal expansion coefficient from a temperature of 25 ° C. to 150 ° C. is 5 × 10 ⁻⁶ to 10 × 10 ⁻⁶ / K. The aluminum-diamond composite according to any one of the above. The surface of the aluminum-diamond composite according to any one of claims 1 to 6 is provided with a Ni plating layer having a plating thickness of 0.5 to 15 µm, or two plating layers of Ni plating and Au plating. Heat dissipation parts characterized by After forming an aluminum layer having a thickness of 0.05 to 2 μm by vapor deposition or sputtering on the surface of the aluminum-diamond composite according to claim 1, nitrogen, argon, hydrogen, helium, or After heat treatment in a vacuum atmosphere at a temperature of 460 ° C. to 650 ° C. for 1 minute or longer, an electroless plating method or an electroplating method is used to form a Ni plating layer having a plating thickness of 0.5 to 15 μm, or Ni plating and Au plating. A heat dissipating component comprising a plating layer. A metal mold containing a porous ceramic body that can be impregnated with a metal containing aluminum by a melt forging method is filled with diamond particles, heated at a temperature of 600 to 750 ° C., and then heated to a melting point or higher. After making a composite at a pressure of 20 MPa or more to produce a flat aluminum-diamond composite having the periphery coated with an aluminum-ceramic composite, the surrounding aluminum-ceramic composite was made into an aluminum-ceramic composite on both main surfaces. After grinding so that a body thickness may be 0.5 mm or less, a side surface and a hole part are cut into a predetermined shape by water jet machining, laser machining, or electric discharge machining. The manufacturing method of the aluminum-diamond type composite as described.