JP5503474B2 - Heat dissipation member, semiconductor device, and method of manufacturing heat dissipation member - Google Patents

Description

  The present invention relates to a composite member in which magnesium (so-called pure magnesium) or a magnesium alloy and a non-metallic inorganic material such as SiC are combined, a heat radiating member composed of the composite member, a semiconductor device including the heat radiating member, and a composite member It is related with the manufacturing method. In particular, the present invention relates to a composite member having excellent thermal characteristics and suitable for a heat dissipation member of a semiconductor element.

  As a constituent material of a heat dissipation member (heat spreader) of a semiconductor element, a composite material of a metal and a non-metallic inorganic material (typically ceramics) such as Al-SiC is used in addition to a material made of only a metal material such as copper . In recent years, a composite material using magnesium (Mg) or its alloy as a base material, which is lighter than aluminum (Al), has been studied mainly for the purpose of reducing the weight of the heat dissipation member (see Patent Document 1).

JP 2006-299304 A

The heat dissipation member of the semiconductor element has excellent thermal conductivity, and the coefficient of thermal expansion of the semiconductor element and its peripheral components (4 ppm / K (4 × 10 ^-6 / K) to 8 ppm / K (8 × 10 ^-6 / K) It is desirable to have excellent consistency with That is, it has a thermal conductivity equal to or higher than that of the composite material disclosed in Patent Document 1, and is closer to the thermal expansion coefficient of the semiconductor element and its peripheral components, for example, an insulating substrate: about 4.5 ppm / K Silicon package: Development of a composite material having a value close to 3.5 ppm / K is desired.

  In order to further reduce the thermal expansion coefficient of the composite material, it is effective to increase the content of the nonmetallic inorganic material in the composite material. However, for example, the powder of a nonmetallic inorganic material is put into a mold and tapped (giving vibration), or after being put into the mold and pressed to be filled and melted in the gap between the particles of the nonmetallic inorganic material. In the manufacturing method in which metal is infiltrated, there is a limit to the amount of powder that can be filled in the mold (see paragraph 0015 of the specification of Patent Document 1). Therefore, the content of the nonmetallic inorganic material in the composite material obtained by the above production method is at most 70% by volume.

  Accordingly, one of the objects of the present invention is to provide a composite member having thermal characteristics suitable for a heat dissipation member of a semiconductor element. Another object of the present invention is to provide a method for manufacturing a composite member suitable for manufacturing the composite member. Furthermore, the other object of this invention is to provide the heat radiating member which consists of the said composite member, and a semiconductor device provided with this heat radiating member.

  The present inventors use a SiC aggregate formed by a specific method to increase the content of SiC in the composite material, and use a SiC aggregate having a network part for bonding SiC to each other. As a result, it was found that the thermal characteristics of the composite material can be improved by satisfying at least one of the composite materials having the network portion. The present invention is based on the above findings.

The composite member of the present invention is a composite member in which magnesium or a magnesium alloy and SiC are combined, and the thermal expansion coefficient (linear thermal expansion coefficient) thereof is 4 ppm / K or more and 8 ppm / K or less. In particular, the composite member of the present invention satisfies at least one of the following (1) and (2).
(1) Contain more than 70% by volume of SiC.
(2) It contains 50% by volume or more of the SiC and has a network part for bonding the SiCs together.

  The composite member of the present invention contains a very large amount of SiC such as more than 70% by volume, or the SiC aggregate in the composite member has the network part, so that the thermal expansion coefficient is higher than that of a conventional composite material. It is small and can have a thermal expansion coefficient equivalent to that of the semiconductor element and its peripheral components (about 4 ppm / K to 8 ppm / K). In particular, the composite member of the present invention is mainly composed of a material having a higher thermal conductivity than Mg, such as SiC, so that the thermal conductivity is high and a continuous path for heat conduction by a metal such as magnesium ( Since a path is formed, heat dissipation is excellent. As described above, the composite member of the present invention, which is a composite of a non-metallic inorganic material such as SiC and a metal material, has excellent heat dissipation while having a low coefficient of thermal expansion suitable for a semiconductor element. It can be suitably used.

  On the other hand, in a member composed only of a nonmetallic inorganic material, there are usually pores (air) in the gaps between the nonmetallic inorganic materials, and there are few continuous paths for the heat conduction. On the other hand, in the composite member of the present invention, a metal such as magnesium having a higher thermal conductivity than air fills the gap, so that the entire composite member becomes a continuous path for heat conduction and is excellent in thermal conductivity. In addition, a dense sintered body having a relative density of about 99% exists in a member made of a nonmetallic inorganic material. However, even when such a dense sintered body is compared with the composite member of the present invention, the composite member of the present invention including a metal such as magnesium is (1) continuous for heat conduction as described above. The thermal expansion coefficient can be adjusted by adjusting the content and composition of magnesium, etc., and (3) it is easy to obtain a smooth surface. In addition, it has an advantage that it is easy to prevent chipping, and (4) the manufacturing cost is low.

  In addition, the composite member of the present invention has excellent thermal expansion coefficient consistency with the semiconductor element and its peripheral parts, so that the thermal stress generated at the joint portion with the semiconductor element or the like is small, and a predetermined bonding strength can be maintained. Therefore, the reliability of the semiconductor device including the heat dissipation member can be improved. Furthermore, since the composite member of the present invention is excellent in thermal conductivity as described above, the reliability as a heat radiating member can be improved, and the heat radiating member can be reduced in size, which in turn reduces the size of the semiconductor device. Can also contribute.

The composite member of the present invention can be manufactured, for example, by the following manufacturing method of the composite member of the present invention. The method for producing a composite member of the present invention is a method for producing a composite member in which magnesium or a magnesium alloy and SiC are composited, and includes the following forming step and composite step. Hereinafter, this manufacturing method is referred to as a SiC high filling method.
Molding step: A step of forming a SiC aggregate using any one of slip casting, pressure molding, and doctor blade method.
Compounding step: a step of infiltrating molten magnesium or a magnesium alloy into the SiC aggregate housed in a mold in an atmosphere of atmospheric pressure or lower to form a compound member containing more than 70% by volume of SiC.

Alternatively, as a method for producing a composite member of the present invention, a method for producing a composite member in which magnesium or a magnesium alloy and SiC are composited, comprising the following forming step, sintering step, and composite step A method is mentioned. Hereinafter, this manufacturing method is called a sintering method.
Molding process: A process of forming a SiC powder compact.
Sintering step: a step of sintering the above powder compact to form a SiC aggregate having a network part for bonding SiC.
Composite step: Infiltrate molten magnesium or magnesium alloy in the SiC aggregate housed in the mold in an atmosphere of atmospheric pressure or lower to form a composite member having the network part and containing 50% by volume or more of SiC. Process.

Alternatively, as a method for producing a composite member of the present invention, a method for producing a composite member in which magnesium or a magnesium alloy and SiC are composited, the method comprising the following forming step, bonding step, and composite step Is mentioned. Hereinafter, this production method is referred to as a sol-gel method.
Molding process: A process of forming a SiC powder compact.
Bonding step: The powder compact is impregnated with a solution of a precursor of a nonmetallic inorganic material and then heated to produce a nonmetallic inorganic material based on the precursor, which is composed of the produced nonmetallic inorganic material. Forming a SiC aggregate in which the SiC is bonded to each other by a network part.
Composite step: Infiltrate molten magnesium or magnesium alloy in the SiC aggregate housed in the mold in an atmosphere of atmospheric pressure or lower to form a composite member having the network part and containing 50% by volume or more of SiC. Process.

Alternatively, another method for producing the composite member is a method for producing a composite member in which magnesium or a magnesium alloy and SiC are composited, and includes the following forming step and a method including the composite step. . Hereinafter, this production method is referred to as a reaction bonding method.
Molding step: A step of forming a powder compact using a mixed powder of SiC powder and a reaction powder containing at least one of boron and oxygen.
Compounding process: Molten magnesium or magnesium alloy is infiltrated in an atmosphere of atmospheric pressure or less in the powder compact accommodated in the mold. In addition, a product made of a new nonmetallic inorganic material is generated by the reaction between the reaction powder and the molten magnesium component, and the SiC is bonded to each other. And the process of forming the composite member which has the network part comprised from this new product, and contains the said SiC 50 volume% or more.

Alternatively, as another method for producing the composite member, a method for producing a composite member in which magnesium or a magnesium alloy and SiC are composited, comprising the following forming step, sintering step, and composite step A method is mentioned. Hereinafter, this manufacturing method is referred to as a reactive sintering method.
Molding step: A step of forming a powder compact using a mixed powder of SiC powder and a precursor powder that reacts with nitrogen or oxygen to produce an oxide or nitride.
Sintering step: The powder compact is sintered in a nitrogen atmosphere or an oxygen atmosphere, and the nitride or oxide is produced by a reaction between the precursor powder and nitrogen or oxygen. And the process of forming the SiC aggregate | assembly by which said SiC was couple | bonded by the network part comprised from this product.
Composite step: Infiltrate molten magnesium or magnesium alloy in the SiC aggregate housed in the mold in an atmosphere of atmospheric pressure or lower to form a composite member having the network part and containing 50% by volume or more of SiC. Process.

  According to the above manufacturing method, a high-density SiC aggregate can be easily formed by forming a SiC aggregate by a specific method or by forming a SiC aggregate with a high SiC filling rate, for example, a sintered compact. Can be manufactured. Then, by combining such a high-density SiC aggregate and molten magnesium or a magnesium alloy (hereinafter referred to as molten Mg), the composite member of the present invention containing more than 70% by volume of SiC is easily manufactured. be able to. In addition, by forming a SiC aggregate having a network part for bonding SiC to each other or forming the network part during infiltration, the composite member of the present invention in which the network part is present in the composite member can be easily obtained. Can be manufactured. The obtained composite member satisfies a thermal expansion coefficient of 4 ppm / K to 8 ppm / K.

In particular, according to the sintering method and the sol-gel method, compared to the SiC high filling method, (1) a composite member having the network part is obtained, so that the thermal expansion coefficient is small and the thermal conductivity is low. A high composite member can be obtained, (2) a composite member having a higher SiC content can be easily manufactured, and (3) the SiC aggregate having the above network part has high strength and is easy to place in a mold, etc. And so on. Further, the formation of the powder compact in the sintering method or the sol-gel method is performed by introduction method prescribed in the SiC high filling method, a dense SiC aggregate is obtained, utilizing such a SiC aggregate Thus, a composite member having a higher SiC content and excellent thermal characteristics can be obtained.

  In particular, in the above sintering method, if the SiC is sintered so that the SiCs are directly bonded, that is, if the network part is made of SiC, the non-metallic inorganic material present in the composite member is substantially only SiC. It becomes. Since SiC has a particularly high thermal conductivity, this composite member has a high thermal conductivity.

  In particular, the sol-gel method requires a solution of the precursor, but the network portion is formed at room temperature by heating at a low temperature compared to the sintering temperature in the sintering method or without heating at all depending on the type of the solution. Can be formed. In addition, using a precursor that produces SiC having a particularly high thermal conductivity among non-metallic inorganic materials and making the network part composed of SiC, a composite member having a high thermal conductivity as described above is obtained. It is done.

  On the other hand, in the above-described reaction bonding method, the composite member having the network part can be easily manufactured without having a step of sintering or separately heating, and the network part can be generated simultaneously with the composite of the SiC aggregate and molten Mg. Therefore, it is excellent also in the productivity of a composite member. In the reaction sintering method described above, the network portion can be generated even when the sintering temperature is lowered as compared with the case of sintering so that SiCs are directly bonded together. In the reaction bonding method and reaction sintering method, the network part may be composed of a nonmetallic inorganic material having a lower thermal conductivity than SiC. Therefore, the above-described sintering method and sol-gel method are preferable in consideration of improvement in thermal conductivity.

  In addition, the composite member of the present invention can also be formed by preparing a commercially available SiC sintered body and infiltrating molten Mg into the SiC sintered body. The SiC sintered body has a SiC content in the composite member of 50% by volume or more, has a network portion that can exist in the composite member, and is open for molten Mg to infiltrate. What has a pore is good to choose suitably.

Hereinafter, the present invention will be described in more detail.
[Composite material]
As a form of the composite member of the present invention, a form of only a substrate made of a composite material in which magnesium or a magnesium alloy and a nonmetallic inorganic material (mainly SiC) are composited, the above-mentioned substrate, and a metal coating covering at least one surface of this substrate And a form having a layer. First, the substrate will be described.

<Metal component>
The metal component in the substrate is so-called pure magnesium composed of 99.8% by mass or more of Mg and impurities, or a magnesium alloy composed of additive elements and the balance Mg and impurities. When the metal component is pure magnesium, compared to the case of an alloy, (1) the thermal conductivity of the composite member can be improved, and (2) the crystallized product is deposited unevenly during solidification. Since it does not easily occur, there is an advantage that it is easy to obtain a composite member having a uniform structure. When the metal component is a magnesium alloy, the liquidus temperature is lowered, so that the temperature at the time of melting can be lowered and the corrosion resistance and mechanical properties (strength, etc.) of the composite member can be improved. Examples of the additive element include at least one of Li, Ag, Ni, Ca, Al, Zn, Mn, Si, Cu, and Zr. Since these elements cause a decrease in thermal conductivity when the content increases, the total content is preferably 20% by mass or less (the metal component is 100% by mass; the same applies to the content of the additive element). In particular, Al is preferably 3% by mass or less, Zn is 5% by mass or less, and other elements are each preferably 10% by mass or less. Addition of Li has the effect of reducing the weight of the composite member and improving the workability. Known magnesium alloys such as AZ, AS, AM, ZK, ZC, and LA may be used. A metal raw material is prepared so as to have a desired composition.

<Non-metallic inorganic material>
"composition"
Examples of the non-metallic inorganic material in the substrate include those having a thermal expansion coefficient smaller than Mg, excellent thermal conductivity, and hardly reacting with Mg. As such a non-metallic inorganic material, a ceramic such as SiC is representative. Others, Si ₃ N ₄ , Si, MgO, Mg ₃ N ₂ , Mg ₂ Si, MgB ₂ , MgCl ₂ , Al ₂ O ₃ , AlN, CaO, CaCl ₂ , ZrO ₂ , diamond, graphite, h-BN, c -At least one of BN, B ₄ C, Y ₂ O ₃ , and NaCl is included. In particular, SiC has (1) a coefficient of thermal expansion of about 3 ppm / K to 4 ppm / K, which is close to the coefficient of thermal expansion of semiconductor elements and peripheral components, and (2) has a particularly high thermal conductivity among non-metallic inorganic materials. (Single crystal: about 390W / m · K to 490W / m · K), (3) Various shapes and sizes of powders and sintered bodies are commercially available, and (4) High mechanical strength Therefore, in the present invention, SiC is employed. In the present invention, it is allowed to contain the non-metallic inorganic materials listed above other than SiC. That is, you may contain the said multiple types of nonmetallic inorganic material. Non-metallic inorganic materials other than SiC exist as a network part, for example.

"shape"
The SiC in the composite member of the present invention is typically in a form dispersed in magnesium or a magnesium alloy (hereinafter referred to as a dispersed form) or in a form joined by a network portion (hereinafter referred to as a joined form). Exists. In particular, in a bonded form having a network part, the entire SiC is continuously connected by the network part, and a form in which SiC or magnesium alloy is filled between SiC, that is, when magnesium or magnesium alloy is removed, open pores are formed. It is preferable that it is a porous body. In particular, the porous body has less closed pores, specifically, 10% by volume or less, preferably 3% by volume or less, based on the total volume of the nonmetallic inorganic material in the composite member. As the nonmetallic inorganic material in the composite member, the nonmetallic inorganic material used as a raw material is present almost as it is. Therefore, if a porous body with few closed pores as described above is used as the raw material SiC aggregate, it can have a sufficient path for impregnation with molten Mg, and the open pores are filled with molten Mg. As a result, the resulting composite member itself has fewer pores. Due to the small number of pores, this composite member has a high thermal conductivity. The shape of the mold for filling the raw material powder and the overall shape of the porous body used for the raw material may be appropriately selected so that the composite member (substrate) has a predetermined shape. The presence of the network portion and the ratio of closed pores in the composite member can be confirmed or measured by, for example, observing a cross section of the composite member with an optical microscope or a scanning electron microscope (SEM).

"Content"
The content of SiC in the substrate made of the composite material is 50% by volume or more in a bonded form having a network part when the substrate is 100% by volume, and 70% in a dispersed form having no network part. More than%. The higher the SiC content in the substrate, the higher the thermal conductivity κ, and the smaller the thermal expansion coefficient α, the semiconductor element (about 4 ppm / K to 8 ppm / K (e.g., Si: 4.2 ppm / K, GaAs: 6.5ppm / K)) and its peripheral components (insulating substrate: about 4.5ppm / K, silicon package: about 3ppm / K, alumina package: 6.5ppm / K). Accordingly, the content of SiC is preferably 75% by volume or more, particularly 80% by volume or more, and more preferably 85% by volume or more in any of the above bonded form and dispersed form, and there is no particular upper limit. If the SiC content exceeds 90% by volume, a large pressing force is required to form a high-density SiC aggregate used as a raw material, and closed pores are easily formed in subsequent processes such as sintering. There is a risk that the pores may become SiC aggregates with more than 10% by volume. Therefore, considering industrial productivity and infiltration of molten Mg, it is considered practical that the SiC content is about 80 to 90 volume%.

  A composite member (substrate) containing SiC within the above range has high thermal conductivity κ and satisfies 180 W / m · K or more. Composite with thermal conductivity κ of 200W / m · K or more, especially 250W / m · K or more, and 300W / m · K or more, depending on the SiC content, network configuration, metal composition, etc. It can be a member.

  Since the content of the nonmetallic inorganic material in the composite member is substantially equal to the amount of the raw material, the amount of the raw material may be appropriately selected so that the composite member (substrate) has desired thermal characteristics.

《Material of network part》
Examples of the constituent material of the network portion in the composite member include non-metallic inorganic materials such as SiC and metallic materials such as Mo. When the network part is also composed of SiC, this composite member is substantially composed of SiC and magnesium (or magnesium alloy), and is excellent in heat dissipation as described above. Other non-metallic inorganic materials constituting the network part are silicon nitride (Si ₃ N ₄ ), magnesium compounds (for example, MgB ₂ , MgO, Mg ₃ N ₂ ), other nitrides (for example, BN, AlN) And oxides (for example, CaO). In particular, Si ₃ N ₄ can be a composite member having a low thermal expansion coefficient and a low thermal expansion coefficient.

<< Thickness of the network part >>
When the present inventors investigated, even if the content of SiC in a composite member was equivalent, the thermal characteristics differed. When this cause was investigated, the form of the network part in the composite member was different. Specifically, a line segment of a predetermined length is arbitrarily taken in the cross-section of the composite member, and the length of the location where the outline of the SiC aggregate composed of SiC and the network part crosses the line segment, that is, The contour line has an intersection with the line segment, and the length between adjacent intersections is different. Those having a long length between the intersections, that is, those having a thick network portion are excellent in thermal characteristics, and in particular, tend to have a small coefficient of thermal expansion. The thin ones were excellent in mechanical properties, and particularly tended to have high tensile strength and bending strength. Therefore, it is defined that the network portion is thick as a configuration having excellent thermal characteristics. Specifically, when the network portion becomes thicker, the number of intersections in the line segment decreases, so in the cross section of the composite member, a line segment with a length of 1 mm is arbitrarily taken with respect to the actual size of the composite member, and the SiC and We propose that the number of intersections between the outline of the SiC aggregate composed of the network part and the line segment satisfy 50 or less. Since it is expected that the smaller the number of intersections, the better the thermal characteristics, there is no particular lower limit for the number of intersections. On the other hand, if the number of intersections is more than 50, particularly 100 or more, it is expected that the mechanical properties are further improved. In order to change the thickness of the network part, for example, adjustment of manufacturing conditions to be described later can be cited.

<Thickness of substrate>
The thickness of the substrate can be selected as appropriate, but when used as a heat dissipation member for a semiconductor element, it is preferably 10 mm or less, particularly preferably 5 mm or less. When the metal coating layer to be described later is not provided, the substrate can have a thermal expansion coefficient of about 4 ppm / K to 6 ppm / K by containing a large amount of SiC or having a network portion.

<Metal coating layer>
<Composition, organization>
The heat radiating member and the semiconductor element or a cooling device for cooling the semiconductor element may be joined by solder. A sintered body made of a non-metallic inorganic material and a substrate made of the above composite material have poor wettability with solder, and it is necessary to improve the wettability with solder by plating with Ni or the like. The plating is preferably electroplating in consideration of productivity, but it is difficult to perform electroplating because many nonmetallic inorganic materials have high electrical insulation. Therefore, by providing a metal coating layer on at least one surface of the substrate and using the metal coating layer as a base for the electroplating, the substrate made of the composite material can be easily plated with Ni or the like.

  The constituent metal of the metal coating layer may be a metal having an electrical conductivity sufficient to provide electrical conduction necessary for electroplating, and may have a composition different from or the same as the metal component of the substrate made of the composite material. In particular, when the same composition is used, when the metal coating layer is formed simultaneously with the compounding in the compounding step of the manufacturing method described above, a composite member having the metal coating layer can be manufactured with high productivity. In this case, in the obtained composite member, the metal component in the substrate and the metal constituting the metal coating layer have a continuous structure (cast structure).

  When the metal component of the substrate and the constituent metal of the metal coating layer have different compositions, the constituent metal of the metal coating layer is, for example, an Mg alloy having a composition different from the metal component of the substrate, or other than Mg and Mg alloy Selected from the group consisting of metals, for example, Al, Cu, Ni with a purity of 99% or more and alloys containing Al, Cu, Ni as the main component (alloys containing more than 50% by mass of Al, Cu, Ni) One kind of metal is mentioned.

<Formation point>
The said metal coating layer should just exist in the surface where plating is required among the surfaces which comprise the said board | substrate. Specifically, a metal coating layer is provided on at least one of the mounting surface on which the semiconductor element is mounted and the cooling surface that faces the mounting surface and contacts the cooling device. A metal coating layer may be provided on the entire surface including the end surface of the substrate (the surface connecting the mounting surface and the cooling surface). In addition to being able to perform electroplating, the composite member provided with the metal coating layer can enhance corrosion resistance and can increase the commercial value of the composite member because of its smooth surface and excellent appearance.

"thickness"
If the thickness of each metal coating layer is too thick, it causes an increase in the coefficient of thermal expansion and a decrease in the thermal conductivity of the composite member, so 2.5 mm or less, particularly 1 mm or less, more preferably 0.5 mm or less, preferably 1 μm or more In particular, if it is 0.05 mm (50 μm) or more and 0.1 mm (100 μm) or less, it will function sufficiently as a base for plating, and the metal coating layer is unlikely to be damaged during transportation or mounting of composite parts. It is done. Since the substrate provided in the composite member of the present invention has a low coefficient of thermal expansion and excellent thermal conductivity as described above, when the metal coating layer is provided on each of two opposing surfaces of the substrate, two layers of metal are provided. If the total thickness of the covering layer is 2.5 mm or less in the bonded form having the network portion and 0.5 mm or less in the dispersed form, the thermal expansion coefficient of the entire composite member including the substrate and the metal covering layer is 8 ppm / K. it can be less than or equal to. The metal coating layer may be formed thick and may have a desired thickness by polishing or the like, and the appearance of the composite member can be improved by polishing. The thermal expansion coefficient of a composite member having a metal coating layer can be easily obtained by preparing a test piece from the composite member and measuring it with a commercially available device. Alternatively, the thermal expansion coefficient of the composite member including the metal coating layer may be calculated by a composite rule in consideration of the rigidity of each material constituting the composite member.

<Application>
The said composite member can be utilized suitably for a heat radiating member. This heat dissipating member is excellent in the consistency of the thermal expansion coefficient with the semiconductor element and its peripheral components, and has high thermal conductivity, and therefore can be suitably used as a heat dissipating member for the semiconductor element. Moreover, the semiconductor device provided with the said heat radiating member and the semiconductor element mounted in this heat radiating member can be utilized suitably for the components of various electronic devices.

[Production method]
The composite member of the present invention can be manufactured by forming a SiC aggregate as described above and combining the SiC aggregate and molten Mg (infiltration → solidification). Further, when a combined composite member having a network part is manufactured, the network part is formed by an appropriate method.

"material"
SiC powder is mainly used as a raw material for the SiC aggregate. In the above-described sintering method, when silicon nitride is generated at the time of sintering, in addition to the SiC powder, it is possible to prepare a powder of Si powder or a compound containing Si, and use these mixed powders. it can. In the reaction sintering method described above, in addition to the SiC powder, the above-described precursor powder (for example, SiCl ₄ , organic Si compound) is prepared, and these mixed powders can be used. In the reaction bonding method described above, in addition to the SiC powder, the above-described reaction powder (for example, boron, BN, TiB ₂ , boric acid (B ₂ O ₃ ), sodium tetraborate (Na ₂ B ₄ O ₅ (OH ₄ ) 8H ₂ O) powders of simple elements, oxides, borides, and borate powders) are prepared, and these mixed powders can be used. These powders may be in the form of particles or fibers, and if the average particle diameter (in the case of fibers, the average short diameter) is 1 μm or more and 3000 μm or less, particularly 10 μm or more and 200 μm or less, an SiC aggregate is produced. It is easy and preferable. Further, when a plurality of types of powders having different average particle sizes are used in combination, the filling rate of SiC or the like can be further increased.

<< Molding process: Formation of powder compact >>
In the SiC high filling method described above, a powder molded body having no network part is formed by any one of slip casting, pressure molding, and doctor blade method, which will be described later. The powder compact obtained by these methods has a strength capable of handling. In the above-described sintering method, sol-gel method, reaction sintering method, and reaction bonding method, a powder compact is formed by tapping or the like in addition to the above method.

<Slip cast>
A powder compact can be formed by slip casting by preparing a slurry using the raw material powder described above, water and a dispersing agent, and drying this slurry after molding. A general surfactant can be used as the dispersant. Slip casting is a large molded body that can easily form a molded body with a complicated shape, and can obtain a molded body with a high filling rate (density) even when fine powder is used. Can be easily molded, and there is an advantage that there is little increase in equipment cost.

<Pressure molding>
Examples of pressure molding include dry press, wet press, uniaxial pressure molding, CIP (hydrostatic press), and extrusion molding. In the case of dry press molding, the above-mentioned raw material powder is pressure-molded. In the case of wet press molding, a mixed powder obtained by mixing the raw material powder and a liquid such as water is pressure-molded to extrude the liquid. A powder molded body can be formed. The pressure during molding (molding pressure) may be appropriately selected. In either case of dry type or wet type, a binder used for powder molding can be appropriately used. The pressure molding has the advantages that it is easy to make the particle size of the raw material powder uniform, and that the number of steps is small and the productivity is excellent compared to slip casting.

<Doctor blade method>
A slurry is prepared using the raw material powder described above, a solvent, an antifoaming agent, a resin, and the like, and the slurry is poured into a receptacle of a doctor blade to form a sheet-like body. Can be formed. The doctor blade method can be suitably used when forming a plate-shaped molded body.

  In the SiC high filling method described above, the powder compact formed by the above-mentioned slip cast may be used as the SiC aggregate, or the sintered compact obtained by further sintering the powder compact as the SiC aggregate, It may be combined with molten Mg. The sintering conditions at this time are, for example, (1) vacuum atmosphere, heating temperature: less than 800 to 1300 ° C, holding time: about 2 hours, (2) air atmosphere, heating temperature: 800-1500 ° C, holding time: 2 About time. By performing the sintering under the above sintering conditions, (1) the strength is higher than that of the above powder molded body, it is difficult to cause chipping and the like when stored in a mold, and (2) the porous body can be easily handled. (3) By adjusting the sintering temperature and holding time, the sintered body can be densified and the filling rate of SiC can be improved, and the SiC content is 70% by volume or more. There is an advantage that a certain composite member is easily obtained. Moreover, the binder used for producing the powder compact can be evaporated and removed by heating during sintering. The advantages of these sintered bodies are the same as those of the sintered bodies having a network portion described later. However, in the above sintering conditions (1) and (2), there is a tendency that a dispersed composite member having no network part is obtained. Therefore, when obtaining a composite member having a network portion and a low thermal expansion coefficient, it is preferable to sinter under the sintering conditions described later.

<Tapping>
By filling the above-mentioned raw material powder into a mold and applying a certain vibration, a powder compact having a shape along the mold can be easily formed. In tapping, it is difficult to form a high-density SiC aggregate, which can be used when the SiC content in the composite member is about 50 to 70% by volume. When it exceeds 70% by volume, the above-described method such as slip casting is preferred.

  In addition, the powder molded body containing components such as Si, precursor, and boric acid described above is formed by the above-described various methods using the above-mentioned mixed powder, and after producing a SiC powder molded body of only SiC powder. The SiC powder molded body was impregnated with a mixed liquid (for example, an aqueous solution) obtained by mixing the above-mentioned Si powder, precursor powder, reaction powder (boric acid or sodium tetraborate), etc. prepared in a solvent such as water. Then, it can produce by drying the said solvent. By using the above mixture, it is easy to uniformly disperse a desired substance such as Si in the powder compact, and since the powder compact other than the SiC powder is not formed, the amount of SiC powder added It is easy to increase the filling rate of SiC in the powder compact.

<< Sintering process: Formation of sintered body >>
In the above-described sintering method, an SiC aggregate (sintered body) is produced by sintering and integrating the powder compact obtained in the molding step, and a network part is generated. In particular, in the above-described sintering method, the network part in the sintered body is positively formed as the network part that can also exist in the composite member.

  The sintering conditions include a vacuum atmosphere, a heating temperature of 1300 ° C. to 2500 ° C., and a holding time of about 2 hours. When sintered under these conditions, SiC can be directly bonded together. That is, the network part can be formed of SiC. By directly bonding SiC together, the strength of the sintered body becomes higher, and when this sintered body is used, a composite member having a low thermal expansion coefficient and high thermal conductivity can be easily obtained. Further, as described above, a dense sintered body can be obtained depending on the sintering conditions, and the content (filling rate) of SiC in the composite member can be improved. In particular, when the sintering temperature is 2000 ° C. or higher, the network portion can be thickened (the number of intersections described above satisfies 50 or less), and when it is lower than 2000 ° C., the network portion tends to be thin. The heating temperature and holding time may be appropriately selected according to the form of the network unit.

When the powder compact containing the Si component described above is formed, in the sintering step, the powder compact is sintered in a nitrogen atmosphere to produce Si ₃ N ₄ , and the network portion is the Si ₃ N ₄ Can be formed. When forming the network portion in this way, even if the heating temperature during sintering is lowered to about 800 to 1800 ° C., SiC can be sufficiently bonded to each other, and the network portion is made thicker (the number of intersection points described above). Is less than 50).

The above-mentioned powder compact containing Si is formed by reducing the oxide using an additive containing Si, for example, ceramics such as SiO ₂ , H ₂ SiO ₃ , and Na ₂ SiO _3. can do. Specifically, for example, a powder compact is formed from a mixed powder of SiC powder and the oxide powder, and the powder compact is reduced using carbon powder or a carbon-containing gas, thereby containing Si. A powder compact is obtained. Alternatively, a powder molded body made of SiC powder and an aqueous solution of the oxide containing Si are prepared, and the powder molded body is impregnated with the aqueous solution and then reduced as described above to contain Si. A powder compact is obtained. In this case, it is easy to uniformly disperse Si and to increase the filling rate of SiC as in the case of using the above-described mixed solution. Commercially available carbon powder can be used for the carbon powder, and hydrocarbons such as carbon monoxide (CO) and methane (CH ₄ ) having high reducing ability can be preferably used for the carbon-containing gas.

  When a compound containing Si is used as a raw material, elements other than Si are considered to be vaporized during infiltration or remain in the composite member as a compound with Mg or other compounds.

<< Bonding process >>
In the sol-gel method described above, a non-metallic inorganic material (for example, SiC, MgO, CaO) is generated from the precursor by impregnating the powder compact obtained in the molding step with the precursor solution described above and then heating. Then, the non-metallic inorganic material forms a network part, and an integrated SiC aggregate is produced. Examples of the precursor include polycarbosilane and metal alkoxide. The heating temperature may be appropriately selected according to the precursor. The sol-gel method can form a network portion by lowering the heating temperature as compared with the case where sintering is performed, and is excellent in the productivity of the SiC aggregate. Further, when polycarbosilane is used, SiC can be born, so that the density of SiC can be increased and a composite member having a high SiC content can be obtained.

<Oxide film formation>
Further, it is preferable to use a SiC aggregate provided with an oxide film on the surface as the SiC aggregate to be used for molten Mg because wettability between the SiC aggregate and molten Mg is enhanced. By forming a SiC aggregate including an oxide film, molten Mg easily permeates due to capillary action even when the SiC content is large and the gap between SiC is very small. When obtaining a composite member having a network part, it is preferable to include an oxidation step of forming an oxide film after producing a SiC aggregate such as a sintered body. Typically, when obtaining a composite member having no network part, When the SiC powder compact is subjected to molten Mg, an oxide film is formed on a raw material powder such as SiC powder, and a SiC aggregate (powder compact) is preferably formed using powder containing the oxide film.

  The conditions for forming the oxide film are the same for powders and sintered bodies, and the heating temperature is preferably 700 ° C. or higher, particularly 750 ° C. or higher, more preferably 800 ° C. or higher, especially 850 ° C. or higher. Further, 875 ° C. or higher and 1000 ° C. or lower is preferable. Further, it is preferable to form the oxide film so that the mass ratio of the raw material to SiC is 0.4% or more and 1.5% or less (the thickness of the oxide film: about 50 nm to 300 nm), particularly 1.0% or less. When an oxide film is formed, the oxygen concentration tends to be higher in the vicinity of SiC in the composite member (region within 100 to 300 nm from the outline of the SiC aggregate) than in locations other than the vicinity.

《Composite process: substrate formation》
The composite material (substrate) is obtained by storing the SiC aggregate obtained as described above in a mold, infiltrating molten Mg, and then solidifying the molten Mg. In the reaction bonding method described above, a new product (boride) is obtained by reacting boron and oxygen in the powder molded body with molten Mg simultaneously with the composite of the SiC aggregate (powder molded body) and molten Mg. And an oxide) and a network part can be formed by this product.

When the combined process of infiltrating molten Mg into the SiC aggregate is performed in an atmosphere of atmospheric pressure (generally 0.1 MPa (1 atm)) or less, it is difficult to take in the gas in the atmosphere, and it is difficult to generate pores accompanying the gas. However, since Mg has a high vapor pressure, it becomes difficult to handle molten Mg in a high vacuum state. Therefore, 0.1 × 10 ⁻⁵ MPa or more is preferable when the atmospheric pressure in the composite process is less than atmospheric pressure. Further, when the composite process is performed in an inert atmosphere such as Ar, the reaction between the Mg component and the atmospheric gas can be prevented, and the deterioration of the thermal characteristics due to the presence of the reaction product can be suppressed. The infiltration temperature is preferably 650 ° C. or higher. Since the wettability increases as the infiltration temperature increases, 700 ° C. or higher, particularly 800 ° C. or higher, and more preferably 850 ° C. or higher is preferable. However, if the temperature exceeds 1000 ° C., defects such as shrinkage cavities and gas holes may occur, and Mg may boil. Therefore, the infiltration temperature is preferably 1000 ° C. or less. Moreover, 900 degrees C or less is preferable in order to suppress the production | generation of an excessive oxide film and the production | generation of a crystallized substance.

<Formation of metal coating layer>
When forming the metal coating layer on the surface of the substrate made of the composite material, various methods can be used. For example, a metal coating layer may be separately formed after the substrate is formed. Specifically, an appropriate metal plate is prepared, for example, at least one method of brazing, ultrasonic bonding, cast-in, rolling (clad rolling), hot press, oxide solder method, bonding with an inorganic adhesive. By using it, a metal coating layer can be formed. By using a metal plate, a metal coating layer having a composition different from that of the metal component in the substrate can be easily formed.

  As described above, the SiC aggregate having the network portion is relatively excellent in strength and can stand by itself in the mold. Therefore, maintaining a state having a predetermined gap between the SiC aggregate and the mold, and a configuration in which molten Mg flows into this gap, the thickness according to the size of the gap at the same time as the composite The metal coating layer can be easily formed. Spacers may be arranged so as to reliably maintain the gap. As the constituent material of the spacer, a material that can be removed by sublimation such as naphthalene, or a material having excellent heat resistance such as carbon, iron, and stainless steel (SUS430) can be used. In the latter case, the spacer may be left embedded in the metal coating layer, or the spacer portion may be removed by cutting or the like. Examples of the form of the spacer include a plate-like body and a linear body (wire). For example, a linear body having a slightly smaller diameter than the metal coating layer to be formed is prepared, and the SiC aggregate is fixed to the mold by the linear body, so that a gap is provided between the SiC aggregate and the mold. Also good. In this case, since most of the linear body is embedded in the metal coating layer, a composite member having a good appearance can be obtained even if the linear body remains.

  The composite member of the present invention and the heat radiating member of the present invention composed of this composite member are excellent in thermal expansion coefficient consistency with a semiconductor element and the like, and also in thermal conductivity. The manufacturing method of the composite member of the present invention can manufacture the composite member of the present invention with high productivity. The semiconductor device of the present invention has excellent thermal characteristics by including the heat dissipation member.

1 is a micrograph (50 times or 500 times) of a cross section of the composite member of Embodiment 1, FIG. 1 (I) is an example where the network part is thick (50 times), and FIG. 1 (II) is a network. An example where the part is thin (500 times) is shown. FIG. 2 is a micrograph (50 ×) of a cross section of the composite member of the second embodiment.

(Embodiment 1)
[Test Example 1]
A substrate (composite member) made of a composite material composed of pure magnesium and SiC was fabricated, and the thermal characteristics were examined.

  As raw materials, a pure magnesium ingot (commercial product) composed of 99.8% by mass or more of Mg and impurities, and a commercially available SiC sintered body (relative density 80%, length 200 mm × width 100 mm × thickness 5 mm) were prepared.

  The prepared SiC sintered body was oxidized at 875 ° C. for 2 hours to form an oxide film, and the wettability with molten pure magnesium was improved. The oxidation treatment step may be omitted.

  The SiC sintered body was housed in a mold, molten pure magnesium was infiltrated into the sintered body, and solid magnesium was solidified to form a composite member.

  The said casting_mold | template is a product made from carbon, and is a rectangular parallelepiped box which one side opened, and it is integrally formed combining several division | segmentation pieces. The internal space of the mold is used as a storage space for the sintered body. Here, the inner space of the mold is sized according to the sintered body, and when the sintered body is housed in the mold, substantially no gap is provided between the sintered body and the mold. In addition, you may utilize the casting_mold | template integrally formed without setting it as the structure which combined the division | segmentation piece.

  In addition, here, a commercially available mold release agent was applied to a portion of the inner peripheral surface of the mold that contacts the sintered body, and then the sintered body was accommodated in the mold. By applying the release agent, the composite member can be easily taken out. This step of applying the release agent may be omitted. The same applies to the second embodiment to be described later.

  The mold has an ingot mounting part connected to the periphery of the opening, the ingot prepared in the ingot mounting part is disposed, and the ingot is heated by heating the mold to a predetermined temperature. Melt. The mold is heated by inserting the mold into a heatable atmosphere furnace.

  Here, the atmosphere furnace was adjusted so that the infiltration temperature was 775 ° C., the Ar atmosphere, and the atmospheric pressure: atmospheric pressure. The molten pure magnesium flows into the inner space of the mold from the opening of the mold and is infiltrated into the sintered body arranged in the inner space. After infiltration, the mold was cooled to solidify pure magnesium. Here, the bottom side was actively cooled so as to be cooled in one direction from the bottom of the mold toward the opening. By performing such cooling, internal defects can be reduced even with a large composite member, and a high-quality composite member can be obtained. In the case of a small composite member, a high-quality composite member can be obtained without cooling in one direction as described above.

  A composite member having a length of 200 mm, a width of 100 mm, and a thickness of 5 mm was obtained using the mold. The components of the obtained composite member were examined with an EDX apparatus. As a result, Mg and SiC, and the balance: inevitable impurities, were the same as the raw materials used. Further, when the obtained composite member was subjected to CP (Cross-section Polisher) processing to obtain a cross section, and this cross section was examined by SEM observation, SiC was directly bonded to each other. That is, the network part was a porous body formed of SiC and was the same as the sintered material used. Further, when the cross section of the obtained composite member was observed with an optical microscope (50 times or 500 times), pure magnesium was infiltrated into the gaps between SiC as shown in FIGS. 1 (I) and (II). It was confirmed that In FIG. 1 (I), the part constituting the continuous network is SiC, and the part solidified in a granular form is pure magnesium. This composite member has a thick network part. In FIG. 1 (II), the light-colored portion (including a large lump) is SiC, and the dark-colored portion is pure magnesium. It can be seen that this composite member has a thin network portion.

  When the SiC content of each composite member obtained was measured, it was 80% by volume. The SiC content is determined by observing an arbitrary cross section of the composite member with an optical microscope (50 times), and processing this observation image with a commercially available image analyzer to obtain the total area of SiC in the cross section. A value obtained by converting the total area into a volume ratio was defined as a volume ratio based on this cross section (area ratio≈volume ratio), and a volume ratio of the cross section of n = 3 was obtained and averaged.

  When the thermal expansion coefficient α (ppm / K) and the thermal conductivity κ (W / m · K) were measured for each obtained composite member, the composite member with a thick network part was found to have a thermal expansion coefficient α: 4.0 ppm / K. The composite member having a thermal conductivity κ: 301 W / m · K and a thin network portion had a thermal expansion coefficient α: 4.4 ppm / K and a thermal conductivity κ: 270 W / m · K. The thermal expansion coefficient and the thermal conductivity were measured using a commercially available measuring instrument after cutting out a test piece from the obtained composite member. The thermal expansion coefficient was measured in the range of 30 ° C to 150 ° C.

  From the above, the obtained composite member is excellent in consistency with a semiconductor element having a thermal expansion coefficient of about 4 ppm / K and its peripheral components, and also has a high thermal conductivity. Therefore, it can be suitably used as a constituent material for the heat dissipation member of the semiconductor element.

[Test Example 2]
SiC aggregates were produced under various conditions, and pure magnesium was infiltrated to produce composite members. The thermal characteristics of the obtained composite members were examined.

  As raw materials, a pure magnesium ingot (commercial product) composed of 99.8% by mass or more of Mg and impurities, and a commercially available SiC powder (particle size: 10 to 170 μm, average particle size: 120 μm) were prepared. Then, SiC aggregates (length: 200 mm × width 100 mm × thickness 5 mm) were respectively produced under the conditions described in Table 1, and molten magnesium was infiltrated into the SiC aggregates under the same conditions as in Test Example 1. And then solidified.

  As a sample with a molding method of “tapping”, a powder compact was produced using the SiC powder. Among the above samples, the “oxidation treatment: present” sample was obtained by subjecting the SiC powder to an oxidation treatment at 1000 ° C. for 2 hours, and using the SiC powder having an oxide film, a SiC aggregate was produced.

  For samples whose molding methods were “CIP” and “dry press”, the above-mentioned SiC powder was used to produce a powder compact under known conditions. For samples with the “wet press” and “doctor blade” molding methods, in addition to the SiC powder, water was used for the wet press, and an organic solvent was used for the doctor blade method, and powder compacts were produced under known conditions.

  For a sample having a molding method of “slip cast”, a SiC powder, a surfactant and water were prepared, and a volume ratio of water: SiC powder≈5: 5 was added, and a surfactant was added to prepare a slurry. Here, a slurry using a 20% by mass aqueous urea solution (with the entire slurry being 100% by mass) was prepared. In addition, a slurry using a commercially available polycarboxylic acid aqueous solution may be used. The prepared slurry was poured into a mold and then air-dried to prepare a powder compact.

  For the sample whose network part was formed by “sintering”, the produced powder compact was sintered under the conditions shown in Table 1. For the sample with the network part formation method of “sintered (Si)”, a powder compact was prepared from a mixed powder of SiC powder and Si powder (average particle size: 0.1 μm). Sintered under the condition of 1.

  A sample having a network part formation method of “sol-gel” was prepared by preparing a solution of polycarbosilane, impregnating the prepared powder compact, and then heating to 800 ° C.

When the components of the obtained composite members were examined using an EDX apparatus, the samples other than Sample Nos. 16 and 17 were Mg and SiC, and the remainder: inevitable impurities, which were the same as the raw materials used. In Sample Nos. 16 and 17, Si ₄ N ₃ was interposed between SiC. Further, when the obtained composite member was observed by SEM in the same manner as in Test Example 1, a sample sintered at 1800 ° C. or higher, a sample sintered in a nitrogen atmosphere, and a sample using the sol-gel method were all made of SiC. The network part which couple | bonds is existed and it became a porous body. On the other hand, all the samples that were not sintered or did not employ the sol-gel method were in a state in which SiC particles were dispersed in a pure magnesium base material.

  For each of the obtained composite members, the SiC content, the thermal expansion coefficient α (ppm / K), and the thermal conductivity κ (W / m · K) were measured in the same manner as in Test Example 1. The results are shown in Table 1.

  As shown in Table 1, it can be seen that any sample having a SiC content exceeding 70% by volume has a small coefficient of thermal expansion and satisfies 4 ppm / K to 8 ppm / K. Moreover, even if SiC content is 50 volume%-70 volume%, it turns out that the sample which has a network part has a small thermal expansion coefficient, and satisfy | fills 4 ppm / K-8 ppm / K. Furthermore, it can be seen that the coefficient of thermal expansion decreases as the SiC content increases. In addition, it can be seen that all the samples satisfying the thermal expansion coefficient of 4 ppm / K to 8 ppm / K have high thermal conductivity and are 180 W / m · K or more.

Further, from Table 1, the following can be understood by comparing samples having the same SiC content.
(1) The sintered sample has a smaller thermal expansion coefficient and higher thermal conductivity.
(2) Thermal conductivity can be improved by using SiC aggregates with oxide films.
(3) A sample in which SiC is directly bonded, that is, a sample in which the network part is made of SiC has a higher thermal conductivity than a sample in which the network part is made of a nonmetallic inorganic material other than SiC. high.

  Moreover, it turns out that the composite member with more than 70 volume% of SiC content is obtained by using any one of slip casting, pressure molding, and a doctor blade method.

  Furthermore, as for the sample having the network part, a sample having a thick network part as shown in FIG. 1 (I) and a sample having a thin network part as shown in FIG. 1 (II) were obtained. Therefore, CP processing is performed on a sample having a network part, and a cross section is taken out. This cross section is observed with an SEM (in this case, 50 times), and a 1 mm line segment is drawn on this cross section with respect to the actual size of each sample. Arbitrarily, the number of intersections between the outline of the SiC aggregate in the composite member and the line segment is counted. Here, the average of n = 5 is taken (n: the number of line segments), the network portion is thick when the average number of intersections is 50 or less, and the network portion is thin when the average is more than 50. The results are shown in Table 1. Note that the magnification of the cross section can be appropriately adjusted so that it can be easily observed.

  As shown in Table 1, it can be seen that when the sintering temperature is 2000 ° C. or higher, the network portion tends to become thicker. For example, when comparing sample No. 5 and sample No. 7 manufactured under the same conditions except that the sintering temperature is different, in sample No. 5 where the sintering temperature is less than 2000 ° C., the number of intersection points is 224 (value of n = 1 to 5: 130 to 320), and in sample No. 7 where the sintering temperature is 2000 ° C. or more, the number of the intersections was 11 (value of n = 1 to 5: 8-14).

  In addition, as shown in Table 1, when the SiC content is about the same, the sample with a thicker network part has a smaller thermal expansion coefficient, higher thermal conductivity, and better thermal properties than the thinner sample. I understand. On the other hand, a sample with a thin network part is excellent in mechanical characteristics. For example, when comparing sample No. 5 and sample No. 7, sample No. 5 with a narrow network part has an elastic modulus of 270 GPa and a tensile strength of 180 MPa, whereas sample No. 7 with a thick network part. Had an elastic modulus of 250 GPa and a tensile strength of 60 MPa. The elastic modulus and tensile strength were measured with a commercially available measuring device.

  Furthermore, as shown in Table 1, when an SiC aggregate containing Si is prepared and sintered in a nitrogen atmosphere, it can be seen that the network part tends to be thick even if the sintering temperature is less than 2000 ° C. .

  The composite material satisfying the thermal expansion coefficient of 4ppm / K to 8ppm / K in Test Example 2 has excellent compatibility with semiconductor elements having a thermal expansion coefficient of about 4ppm / K and its peripheral components, and also has high thermal conductivity. . Therefore, it is expected that these composite members can also be suitably used as a constituent material of the heat dissipation member of the semiconductor element.

(Embodiment 2)
A composite member comprising a substrate made of a composite material in which pure magnesium and SiC were combined and a metal coating layer covering each of the two opposing surfaces of the substrate was produced, and the thermal characteristics of the obtained composite member were examined.

  The same pure magnesium ingot and SiC sintered body as those of Test Example 1 of Embodiment 1 were prepared as raw materials. The SiC sintered body was subjected to the same oxidation treatment as in Test Example 1 of Embodiment 1. Further, a pair of carbon plate-like spacers having a length of 10 mm, a width of 100 mm, and a thickness of 0.5 mm were prepared.

  Here, a mold having such a size that the spacer can be disposed between the SiC sintered body and the mold is used. A SiC sintered body and a pair of spacers are housed in a mold appropriately coated with a release agent, and the SiC sintered body is sandwiched between the pair of spacers. By being sandwiched between the spacers, the sintered body is stably disposed in the mold, and a gap according to the thickness of the spacer (here, a gap of 0.5 mm) is provided between the SiC sintered body and the mold. Provided. This mold was charged into an atmospheric furnace as in the first embodiment. Then, a SiC sintered body and molten pure magnesium were combined under the same conditions as in the first embodiment. In this composite process, the molten pure magnesium flows into the gap between the mold provided by the spacer and the SiC sintered body, so that the metal coating layers made of pure magnesium are respectively formed on the two opposing surfaces of the composite substrate. Formed.

  As described above, a composite member comprising a substrate made of a composite material in which SiC and pure magnesium were composited and a metal coating layer made of pure magnesium on two opposing surfaces of the substrate was obtained. When the cross section of the obtained composite member was observed with an optical microscope (50 ×), it was confirmed that SiC had a mesh shape as shown in FIG. 2, that is, had a network portion. Further, it was confirmed that pure magnesium was infiltrated into the gaps between the SiC, and the surface of the substrate was provided with a metal coating layer made of pure magnesium. When the composition of the constituent metals of the substrate and the metal coating layer was examined with an EDX apparatus, the same composition (pure magnesium) was obtained. Further, from the observation image of the cross section, it was confirmed that each metal coating layer had a structure continuous with pure magnesium in the substrate. Furthermore, when the thickness of each metal coating layer was measured using the observation image of the cross section, it was about 0.5 mm (500 μm), and it was confirmed that it substantially coincided with the thickness of the spacer.

  In the obtained composite member, the content of SiC in the portion where pure magnesium and SiC were combined, that is, the portion excluding the metal coating layer was measured and found to be 80% by volume. The SiC content was measured in the same manner as in the first embodiment.

  Further, when the thermal expansion coefficient α (ppm / K) and the thermal conductivity κ (W / mK) were measured for the obtained composite member, the thermal expansion coefficient α: 5.1 ppm / K, the thermal conductivity κ: It was 250 W / m · K. The thermal expansion coefficient and the thermal conductivity were measured in the same manner as in the first embodiment.

  From the above, the obtained composite member is excellent in consistency with a semiconductor element having a thermal expansion coefficient of about 4 ppm / K and its peripheral components, and also has a high thermal conductivity. Therefore, it can be suitably used as a constituent material for the heat dissipation member of the semiconductor element. Further, the composite member of Embodiment 2 can be provided with Ni plating or the like by electroplating by providing a metal coating layer on both surfaces of the substrate. By performing Ni plating or the like, wettability with solder can be improved, and even when used in a semiconductor device where solder is desired, it is possible to sufficiently cope with it. Furthermore, in the composite member of Embodiment 2, the thickness and the formation region of the metal coating layer can be easily changed by appropriately selecting the thickness and shape of the spacer.

  In the second embodiment, the configuration in which the metal coating layer is formed on both surfaces of the substrate made of the composite material has been described. However, the metal coating layer may be formed on only one surface. In this case, the spacer may be disposed only on one surface of the SiC aggregate.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention. For example, the content of SiC in the composite member, the constituent material of the network part, the composition of the metal component (for example, magnesium alloy), the size of the composite member, the thickness of the metal coating layer, the conditions at the time of composite, etc. are appropriately changed. be able to.

  The composite member of the present invention is excellent in the consistency of the thermal expansion coefficient with the semiconductor element and its peripheral components and has high thermal conductivity, and therefore can be suitably used for a heat spreader of the semiconductor element (the heat dissipation member of the present invention). . The manufacturing method of this invention composite member can be utilized suitably for manufacture of the said composite member. The semiconductor device of the present invention can be suitably used for parts of various electronic devices.

Claims (15)

A heat dissipating member composed of a composite member in which magnesium or a magnesium alloy and SiC are combined,
Containing more than 70% by volume of SiC,
The thermal expansion coefficient of the composite member is 3.7 ppm / K or more and 8 ppm / K or less ,
The thermal conductivity of the composite member is 180 W / m · K or more,
A heat dissipating member comprising plating on at least a part of the composite member . Radiating member according to claim 1, have a network portion that couples before Symbol SiC together. The network part, the heat radiating member according to 請 Motomeko 2 that is composed of a non-metal inorganic material. The network part, the heat radiating member according to 請 Motomeko 2 or 3 that is composed of SiC or Si ₃ N _4. In the cross-section of the composite member, a line segment having a length of 1 mm is arbitrarily taken with respect to the actual size of the composite member, and the intersection of the contour line of the SiC aggregate composed of the SiC and the network portion and the line segment. radiating member according to any one of 請 Motomeko 2-4 number Ru der 50 or less. In the cross-section of the composite member, a line segment having a length of 1 mm is arbitrarily taken with respect to the actual size of the composite member, and the intersection of the contour line of the SiC aggregate composed of the SiC and the network portion and the line segment. radiating member according to any one of numbers 50 super der Ru請 Motomeko 2-4. The composite member is a substrate made of a composite material in which the magnesium or the magnesium alloy and the SiC are combined;
7. The heat dissipating member according to claim 1, further comprising a metal coating layer that covers at least one surface of the substrate and is used as a base for the plating . Radiating member according to 請 Motomeko 7 ing from tissue and the metal constituting the metal coating layer and the magnesium or magnesium alloy in the substrate is continuous. A heat radiation member according to any one of claims 1-8, semiconductors devices Ru comprising a semiconductor element mounted on the heat radiation member. A heat dissipation member manufacturing method for manufacturing a heat dissipation member composed of a composite member in which magnesium or a magnesium alloy and SiC are combined,
Using any one of slip casting, pressure molding, and doctor blade method, a molding process for forming a SiC aggregate,
Incorporating molten magnesium or a magnesium alloy in the SiC aggregate housed in a mold in an atmosphere at atmospheric pressure or lower to form a composite member containing more than 70% by volume of SiC, and
Method for producing at least a portion plated plating process and a comprising Ru radiating member of the composite member. A heat dissipation member manufacturing method for manufacturing a heat dissipation member composed of a composite member in which magnesium or a magnesium alloy and SiC are combined,
A molding process for forming a powder compact of SiC;
Sintering the powder compact to form a SiC aggregate having a network part for bonding SiC, and
A composite step of infiltrating molten magnesium or a magnesium alloy in the SiC aggregate housed in a mold in an atmosphere of atmospheric pressure or less to form a composite member having the network part and containing more than 70% by volume of SiC. When,
Method for producing at least a portion plated plating process and a comprising Ru radiating member of the composite member. Wherein the network unit in the sintering step, the manufacturing method of the heat radiating member according to 請 Motomeko 11 you formed by combining the SiC together directly by sintering. In the molding step, using a mixed powder of SiC powder and powder composed of Si powder or a compound containing Si, the powder compact is formed,
In the sintering step, the powder molded body was sintered in a nitrogen atmosphere to form silicon nitride, a manufacturing method of the heat dissipating member according to the network part to 請 Motomeko 11 you formed by the silicon nitride . A heat dissipation member manufacturing method for manufacturing a heat dissipation member composed of a composite member in which magnesium or a magnesium alloy and SiC are combined,
A molding process for forming a powder compact of SiC;
The powder molded body is impregnated with a solution of a precursor of a non-metallic inorganic material and then heated to produce a non-metallic inorganic material based on the precursor, and a network portion composed of the produced non-metallic inorganic material A bonding step of forming a SiC aggregate in which the SiC is bonded to each other;
A composite step of infiltrating molten magnesium or a magnesium alloy in the SiC aggregate housed in a mold in an atmosphere of atmospheric pressure or less to form a composite member having the network part and containing more than 70% by volume of SiC. When,
Method for producing at least a portion plated plating process and a comprising Ru radiating member of the composite member. Wherein the composite process, as the SiC aggregate, a manufacturing method of the heat dissipating member according to any one of 請 Motomeko 10-14 Ru used as comprising an oxide film on the surface thereof.