JP2014001439A - Composite member, method for manufacturing composite member and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite member which has a metal layer usable for a substrate for soldering and can construct a heat dissipation structure excellent in heat dissipation properties, a method for manufacturing a composite member capable of manufacturing the composite member with high productivity and a semiconductor device having the composite member.SOLUTION: The composite member comprises: a substrate composed of a composite material that combines 50 vol.% or more of SiC, magnesium or a magnesium alloy; and a metal layer provided on at least a part of a surface of the substrate. The metal layer is formed in direct contact with at least a metal composition of the substrate and has a thickness of 0.001 mm or more and less than 0.5 mm and a surface roughness Ra of 10 μm or less. A metal layer that is thin and has a smooth surface can be directly and easily formed on the substrate by using a cold spray method. The composite material has a smooth metal layer and can bond a semiconductor element or the like by uniformly disposing a solder, and further can construct a heat dissipation structure excellent in heat dissipation properties because the metal layer is thin.

Description

  The present invention relates to a composite member comprising a substrate made of a composite material in which a non-metallic inorganic material such as SiC and magnesium (so-called pure magnesium) or a magnesium alloy are combined, and a metal layer that functions as a solder base, and a method for manufacturing the same The present invention relates to a semiconductor device including a heat radiating member made of this composite member. In particular, the present invention relates to a composite member excellent in heat dissipation and productivity, and a method for manufacturing the same.

  A composite material such as Al-SiC is used as a constituent material of a heat radiating member of a semiconductor element such as a power device. Patent Document 1 discloses a composite material of SiC, which is lighter than aluminum or magnesium alloy (hereinafter referred to as Mg or the like) and SiC. The Mg-SiC composite material is lightweight as described above, has high thermal conductivity, and is excellent in consistency with the thermal expansion coefficient of the heat generation target (typically a semiconductor element) and its peripheral components (difference). Therefore, it can be suitably used as a material for a heat dissipation member of a semiconductor element.

  In a case where the semiconductor element is sufficiently cooled, the heat radiating member and the semiconductor element, or the heat radiating member and the cooling device are joined together by solder. Since the composite material is inferior in wettability with solder, in Patent Document 1, a metal layer made of metal having high wettability with solder, such as Ni or Cu, is formed on a substrate made of composite material. Has proposed.

  As a method for forming the metal layer such as Ni or Cu, Patent Document 1 mentions, for example, an electroplating method. Patent Document 1 proposes to simultaneously form an Mg equivalent layer that covers the surface of the substrate with molten Mg or the like when forming the composite material, and to use this Mg equivalent layer as a conductive portion of electroplating. Yes. Usually, when electroplating is performed on Mg or the like, a zincate treatment is performed as a pretreatment. In this case, there is a Mg layer, a zincate layer, and a metal layer such as Ni or Cu between the substrate made of the composite material and the solder.

  As another forming method, Patent Document 1 mentions a method of joining plate materials made of Ni or Cu by casting or hot pressing. In this case, since the plate material can be directly bonded to the substrate made of a composite material, the above-mentioned Mg layer or zincate layer can be omitted.

JP 2010-106362 A

  The demand for larger capacity and smaller power modules to which power devices can be assembled is increasing year by year. Therefore, it is desired to develop a material that can construct a heat dissipation structure that excels in heat dissipation and that is also excellent in productivity.

  In the form in which the above-described zincate layer is interposed, there are many processes, and since the process uses a solution, management of the concentration and temperature of the solution is complicated, and improvement in productivity is desired. Further, in this embodiment, there is a risk that Zn constituting the zincate layer and Mg constituting the Mg equivalent layer form an alloy. Since the zincate layer is very thin, even if the above alloy is produced, it is considered that the amount of the zincate layer is extremely small. However, this alloy has low thermal conductivity. Therefore, in consideration of further improvement in heat dissipation and productivity, a configuration in which a zincate layer is not provided is desired.

  In the form using the above-described cast-hole or hot press method, although it is excellent in productivity, by heating, a metamorphic phase due to heat may be generated at the interface between the metal plate made of Ni or Cu and the composite material. There is. This metamorphic phase also has a low thermal conductivity and may cause a reduction in heat dissipation. Here, the thinner the metal plate, the shorter the distance between the semiconductor element and the heat radiating member (composite material), so it is expected that a heat radiating structure with excellent heat radiating properties can be constructed. However, in this method, it is necessary to use a metal plate that is thick to some extent, and there is a limit to making it thin. In addition, by using a thick metal plate, the total thickness with the composite material is increased, leading to an increase in the size (thickening) and an increase in weight of the heat radiating member, which is contrary to the demand for thickness reduction and size reduction.

  For example, consider a case in which a thick metal plate is joined and then subjected to cutting such as polishing to reduce the thickness of the plate portion. However, in this case, the thickness to be removed by polishing, that is, the amount of polishing is increased, and frictional heat during polishing and internal stress of the bonded metal plates are released during polishing, so that the composite material portion is warped. There is a risk. Here, the Mg—SiC composite material has a small difference from the thermal expansion coefficient of the metal plate because the thermal expansion coefficient is small due to the inclusion of a nonmetallic inorganic material such as SiC. Therefore, when a metal plate provided on the surface of a composite material (particularly a thin material (10 mm or less, further 5 mm or less)) is polished, warping may occur due to release of frictional heat or internal stress during polishing. If such a warped member is used for a heat dissipation member of a semiconductor element, the solder is not uniformly placed on the surface of the heat dissipation member, and the semiconductor element and the heat dissipation member cannot be sufficiently adhered to each other. There is a risk that a sufficient storage area cannot be secured. Further, when the polishing amount is large, the yield is lowered and the productivity is lowered due to the lengthening of the polishing time.

  On the other hand, the smoother the surface on which the solder is placed in the heat radiating member (hereinafter referred to as the coated surface), the more uniform the solder can be placed on the coated surface and the more uniform melting can be performed. As a result, the semiconductor element and the heat dissipation member can be satisfactorily adhered to each other. Therefore, it can be said that the coated surface is preferably smoothed by polishing. However, considering the solder application state, securing the mounting area for semiconductor elements, etc., and productivity, the polishing should be as little as possible, specifically, the thickness removed by polishing should be about 0.3 mm or less. Is preferred.

  Therefore, one of the objects of the present invention is to provide a composite member having a metal layer that functions as a solder base, and having excellent heat dissipation and productivity. Another object of the present invention is to provide a composite member manufacturing method capable of manufacturing the composite member with high productivity.

  In order to further improve the heat dissipation of the composite member comprising the Mg-SiC composite material and the metal layer used for the solder base, there is no alloy or metamorphic phase that causes a decrease in the heat dissipation described above. In addition, it can be said that it is desirable to have a smooth and thin metal layer that requires as little polishing as possible. Therefore, as a method for forming such a metal layer, as a result of examining a method in which the above-described alloy or metamorphic phase is not generated, the inventors have found that a cold spray method capable of solid-phase film formation of the metal layer is preferable.

  In the cold spray method, a metal powder is introduced into a spray gun by a carrier gas heated to a temperature below its melting point or softening point, and the metal powder is discharged from the spray gun and sprayed onto an object to be coated. In this film forming method, a metal layer is formed by depositing on a coating target. Each metal particle constituting the metal powder by the heated gas is improved in plastic deformability, and a metal layer is formed by depositing the metal particles plastically deformed on the object to be coated.

  In the cold spray method, a thin metal layer of less than 0.5 mm can be formed by adjusting the size of the metal powder and the film formation time. In addition, the metal layer formed by the cold spray method is configured by depositing plastically deformed metal particles, so it is configured by an isotropic structure, and rolling is a typical form of a metal plate. There is no orientation like a board. Therefore, it can be said that this metal layer is easy to polish and is less likely to be warped due to the above-described polishing. Furthermore, the metal layer formed by the cold spray method is composed of a uniform metal surface with metal particles whose surface is plastically deformed, and is smooth (the surface roughness of the metal layer is plastically deformed at most. Just below the particle size of the previous metal particles). Therefore, it has been found that this metal layer can be made very smooth even when the amount of polishing is small when it is polished, specifically, even when the thickness to be removed is 0.3 mm or less. The present invention is based on the above findings.

The composite member of the present invention comprises a nonmetallic inorganic material, a substrate made of a composite material in which magnesium or a magnesium alloy is combined as a metal component, and a metal layer provided on at least a part of the surface of the substrate. . The composite material contains 50% by volume or more of SiC as the non-metallic inorganic material. The metal layer satisfies the following (1) to (4).
(1) It is made of a metal different from the metal component in the composite material.
(2) Of the material constituting the surface of the substrate, it is formed in direct contact with at least the metal component.
(3) The metal layer has a thickness of 0.001 mm or more and less than 0.5 mm.
(4) The surface roughness of the metal layer is 10 μm or less in terms of Ra.

The composite member of the present invention in which the above-described thin and smooth metal layer is directly formed on the surface of the substrate can be produced, for example, by the following method for producing a composite member of the present invention. The method for producing a composite member of the present invention comprises forming a metal layer on at least a part of a surface of a substrate made of a composite material in which a nonmetallic inorganic material and magnesium or a magnesium alloy are combined as a metal component, And the following preparation process and covering process.
Preparatory step: A step of preparing a substrate made of a composite material containing 50% by volume or more of SiC as the non-metallic inorganic material.
Coating step: a step of preparing a powder made of a metal different from the metal component in the composite material and forming the following metal layer on at least a part of the surface of the substrate by a cold spray method.
The metal layer has a thickness of 0.001 mm or more and less than 0.5 mm, and a surface roughness Ra of 10 μm or less.

In the composite member of the present invention, a thin and smooth metal layer is provided in contact with the surface of a substrate made of a composite material, and this metal layer can be used as a solder base. Therefore, when the composite member of the present invention is used as a material for a heat dissipation member of a semiconductor element, the following effects are obtained.
(1) By providing the metal layer directly on the substrate, inclusions between the substrate and the solder can be reduced and the interval can be narrowed compared to the case where a zincate layer or the like is interposed.
(2) The substrate has a metal layer directly, and there is no Mg-Zn alloy or heat metamorphic phase between the substrate and the solder.
(3) Since the metal layer itself is thin, the space between the heat dissipation member and the solder can be made small (thin).
(4) Since the metal layer itself is smooth, the solder can be uniformly placed and can be melted uniformly, so that the heat dissipation member and the semiconductor element or the cooling device can be in close contact via the solder.
From the above points, the composite member of the present invention can construct a heat dissipation structure with excellent heat dissipation.

  Moreover, since the metal layer is in direct contact with the substrate, the composite member of the present invention does not require a zincate treatment or the like, and the metal layer itself is thin and smooth. Even if it performs, it may be light polishing with a small polishing amount. Therefore, the composite member of the present invention is excellent in productivity. In addition, since the light polishing with a small amount of polishing may be used, the composite member of the present invention is substantially free of solder application due to warpage or the like and a reduction in the mounting area of a semiconductor element, etc. even when polishing is performed. Does not occur. Furthermore, the composite member of the present invention has a smoother surface by performing light polishing, and since the solder is placed and melted better and can be in close contact with a semiconductor element or the like, a heat dissipation structure with better heat dissipation is provided. Expected to build.

  Furthermore, the composite member of the present invention includes a substrate made of an Mg-SiC composite material, thereby increasing the SiC content as described in Patent Document 1 (for example, 70% by volume or more). Excellent heat dissipation. In particular, when the SiC has a SiC sintered body in which SiCs are connected by SiC, the thermal conductivity is 180 W / m · K or more, more than 250 W / m · K, especially about 300 W / m · K. It has a high thermal conductivity and is excellent in heat dissipation. In addition, when the SiC content is higher (preferably with a SiC sintered body), the coefficient of thermal expansion is small and it is difficult to be thermally deformed, and it is excellent in consistency with the coefficient of thermal expansion of the semiconductor element and its peripheral devices. . Therefore, the composite member of the present invention has preferable thermal characteristics as a material for the heat dissipation member of the semiconductor element.

  The method for producing a composite member of the present invention can produce a composite member having a thin and smooth metal layer as described above, and this composite member is excellent in heat dissipation from the above points (1) to (4). . Also, the composite member manufacturing method of the present invention does not require a zincate treatment, etc., compared to the case of forming a metal layer by electroplating or the like, and can reduce the number of processes and produce an Mg-Zn alloy. There is nothing to do. Furthermore, the method for producing a composite member of the present invention differs from the case of casting or hot pressing in that a substrate made of a composite material forms a metal layer in a state maintained at a temperature of about room temperature. The metal layer can be formed with little or substantially no formation. In addition, the method for producing a composite member of the present invention can form a thin and smooth metal layer, so that polishing in a subsequent step can be dispensed with, or light polishing with a small polishing amount can be performed even when polishing is performed. In addition, the composite member manufacturing method of the present invention is a metal layer having a higher purity than a case where a plating layer such as Cu or Ni is formed by an electroplating method, that is, a metal layer that is superior in thermal conductivity. It can be formed. From the above points, it can be said that the composite member manufacturing method of the present invention can manufacture a composite member capable of constructing a heat dissipation structure excellent in heat dissipation with high productivity.

  As one form of the composite member of the present invention, there is a form in which the metal layer is composed of one kind of metal selected from nickel, nickel alloy, copper, copper alloy, gold, gold alloy, silver and silver alloy. .

  All of the listed metals are familiar with solder, and a metal layer made of each metal can function well as a solder base.

  As one form of the composite member of the present invention, the metal layer may be formed in direct contact with both the non-metallic inorganic material and the metal component constituting the surface of the substrate.

  The substrate provided in the composite member of the present invention has a form in which the entire surface is composed of both a non-metallic inorganic material and a metal component, and at least a part of two opposite surfaces (front and back surfaces) of the surface. A form constituted only by a metal component, typically a form provided with a surface layer made of a metal component, as described in Patent Document 1. In the former form, the metal layer is in direct contact with both the non-metallic inorganic material and the metal component as described above. In this form, the thermal conductivity of the entire substrate tends to be higher than that of the latter form with the surface layer, and the thermal expansion coefficient of the entire substrate can be easily reduced. In addition, this form does not require the formation of a surface layer, so that the productivity of the substrate is excellent, and the thickness and weight can be reduced. On the other hand, in the form including the surface layer, since the metal component in the composite material and the metal constituting the surface layer are the same type of metal, there is little or substantially no dissimilar metal bonding between the composite material and the surface layer. Therefore, it is difficult for different metal corrosion to occur at the interface between the composite material and the surface layer. Moreover, this form is excellent in smoothness by having the uniform surface which consists of Mg etc.

  As one form of the composite member of the present invention, there is a form in which the thermal conductivity of the substrate is 180 W / m · K or more and the thermal expansion coefficient of the substrate is 10 ppm / K or less.

  The above form is excellent in thermal conductivity, has a small coefficient of thermal expansion and is difficult to thermally deform, and is excellent in consistency with the coefficient of thermal expansion of the semiconductor element and its peripheral components. Therefore, the said form has a more preferable thermal characteristic as a raw material of the thermal radiation member of a semiconductor element. This thermal characteristic depends on the material of the non-metallic inorganic material, but for any of the above-listed materials, the higher the content, the more preferable the material as the material for the heat dissipation member of the semiconductor element.

  Examples of the semiconductor device of the present invention include a device having a heat radiating member constituted by the composite member of the present invention and a semiconductor element placed on the heat radiating member.

  The semiconductor device of the present invention includes a heat radiating member made of the composite member of the present invention including a metal layer that can be used as a solder base, so that the semiconductor element, the cooling device for the semiconductor element, and the heat radiating member can be soldered. The heat dissipation is excellent. Further, as described above, since the composite member of the present invention does not have an Mg-Zn alloy or a thermal metamorphic phase inferior in thermal conductivity between the substrate and the metal layer, the semiconductor device of the present invention has a heat dissipation property. Excellent.

  One embodiment of the method for producing a composite member of the present invention further includes a polishing step for polishing the surface of the metal layer, and the thickness removed by polishing in the polishing step is 0.3 mm or less.

  The said form can manufacture the composite member which has a smoother surface by providing a grinding | polishing process. In addition, the thickness removed by polishing: the amount of polishing is small, the resulting composite member is less likely to warp and remains flat (excellent flatness), and solder is uniformly applied to the surface of the composite member. In addition to being able to be mounted and melted uniformly, the mounting area of the semiconductor element can be appropriately secured, so that a desired semiconductor element can be sufficiently adhered. Furthermore, although the above-described embodiment includes a polishing step, the amount of polishing is small as described above. Therefore, it is difficult to cause a decrease in productivity by suppressing a decrease in yield and shortening a polishing time. Therefore, the said form can manufacture the composite member which can construct | assemble the heat dissipation structure which is excellent by heat dissipation with sufficient productivity.

  The composite member of the present invention is excellent in heat dissipation and productivity. The method for producing a composite member of the present invention can produce a composite member capable of constructing a heat dissipation structure excellent in heat dissipation with high productivity.

It is a microscope picture which shows the cross section (part) of the composite member which comprises the metal layer by a cold spray method on the board | substrate which consists of composite materials.

Hereinafter, the present invention will be described in more detail.
[Composite material]
The composite member of the present invention comprises Mg as a metal component, a substrate made of a composite material of this metal component and a non-metallic inorganic material, and a metal layer provided in contact with the material constituting the surface of the substrate. Have. The substrate has a form in which the entire surface is substantially composed of a nonmetallic inorganic material and a metal component (hereinafter referred to as a mixed form), a part of the surface (typically one of the front and back surfaces facing each other). Part) may be formed of only a metal component (hereinafter referred to as a coated form).

〔substrate〕
<Metal component>
The metal component in the composite material is so-called pure magnesium composed of 99.8% by mass or more of Mg and inevitable impurities, or a magnesium alloy composed of Mg and inevitable impurities with the additive element and the balance. A composite material in which the metal component is pure magnesium has high thermal conductivity, and a composite material that is a magnesium alloy is excellent in corrosion resistance and mechanical properties (for example, strength). Examples of the additive element include one or more elements selected from Li, Ag, Ni, Ca, Al, Zn, Mn, Si, Cu, Zr, and the like. Too much additive element causes a decrease in thermal conductivity, so the total content of additive elements is preferably 20% by mass or less (the metal component is 100% by mass. The same applies to the content of additive elements). . In particular, Al is more preferably 3% by mass or less, Zn is 5% by mass or less, and other elements are each preferably 10% by mass or less. When Li is contained, there is an effect of reducing the weight of the composite member and improving workability. When Al is contained, it has excellent mechanical properties and corrosion resistance. The metal component can be a known magnesium alloy, for example, AZ, AS, AM, ZK, ZC, LA, etc. in the ASTM symbol. A raw material metal is prepared so that the metal component in the composite material has a desired composition.

<Non-metallic inorganic material>
<Material>
When the non-metallic inorganic material in the composite material is SiC, an Mg-SiC composite material with excellent heat dissipation can be constructed in both the powder form and the network form described below, and in particular, the network form is more excellent in heat dissipation. . Therefore, in the present invention, the non-metallic inorganic material is SiC.

"shape"
Nonmetallic inorganic materials in composite materials include powder forms in which a plurality of particles are present independently, network forms in which nonmetallic inorganic materials are continuously present in a network, and mixed forms of powder forms and network forms. It is done. The material, shape, size, and content of the nonmetallic inorganic material in the composite material substantially maintain the raw material. Therefore, the powder form uses a powder of a non-metallic inorganic material as a raw material, and the network form forms a network-shaped formed body made of a non-metallic inorganic material as a raw material, that is, a porous body having open pores (preferably substantially Can be produced by using a sintered body, typically a porous body having only open pores. The powder form is (1) since powder is used as a raw material as described above, and the degree of freedom of shape is high. (2) Since the particles are dispersed in the substrate, processing such as polishing is performed. In some cases, the processability is excellent. The network form is (1) non-metallic inorganic material with excellent thermal conductivity is continuously present, which has higher thermal conductivity than the powder form and consistency with the thermal expansion coefficient of semiconductor elements, etc. (2) Since the molded body is used as a raw material as described above, there are effects such as excellent handling and easy storage in a mold.

  In the case of a powder form, the shape of each particle may be any of a spherical shape, a substantially spherical shape with some irregularities, a shape close to a cube, an elongated fiber shape, a flat flake shape, and the like. In addition, when the average particle size of the powder used as a raw material (in the case of a fiber, the average of the short diameter) is 1 μm or more and 1000 μm or less (preferably, the particle size is 5 μm or more and 200 μm or less), (1) There are effects such as easy dispersion of particles and (2) easy formation of a molded product. In particular, when a mixed powder of fine powder (preferably average particle size: 40 μm or less) and coarse powder (preferably average particle size: more than 40 μm to 200 μm or less) is used as a raw material, fine particles are obtained between coarse particles. Therefore, it is easy to increase the filling rate and to obtain a composite material having a higher content of non-metallic inorganic material.

  The shape of the non-metallic inorganic material in the composite material (the presence / absence of the network, the shape of the particle), the particle size of the particle, etc. can be determined by removing Mg, etc. (metal component) of the composite material with an acid such as hydrochloric acid. It can be confirmed and measured by extracting only the material and observing the isolated non-metallic inorganic material with a scanning electron microscope: SEM or optical microscope, or using a commercially available laser diffraction particle size distribution analyzer. In addition, the shape of the non-metallic inorganic material can be confirmed by, for example, taking a cross section of the composite material and observing the cross section with an SEM or the like.

"Content"
The content of the nonmetallic inorganic material in the composite material is 50% by volume or more. The higher the non-metallic inorganic material content, the higher the thermal conductivity and the smaller the coefficient of thermal expansion. There is a tendency for the composite material to be 55 vol% or more, 60 vol% or more, and 70 vol% or more. Can do. If it exceeds 80% by volume, the time required to fill the mold with the non-metallic inorganic material becomes long, and large-scale equipment is required. The content of the material is preferably 90% by volume or less, more preferably 85% by volume or less, and particularly preferably 80% by volume or less. The amount of the non-metallic inorganic material added as a raw material is adjusted so that a composite material having desired thermal characteristics can be obtained.

<Outline>
A typical example of the planar shape of the substrate is a rectangular shape. That is, the substrate is typically a rectangular plate, but the planar shape may be a circle, an ellipse, various polygons, or other desired shapes by cutting appropriately. When the composite member of the present invention is used as a material for a heat dissipation member, the plane area can be selected depending on the size of a target (typically a semiconductor element) to be mounted, and has at least a target mounting region. do it.

<Thickness>
The thickness of the substrate can be appropriately selected. When the composite member of the present invention is used as a heat radiating member for a semiconductor element, the distance between the semiconductor element and the cooling device can be shortened and the heat radiating structure excellent in heat radiating property can be constructed as the substrate is thinner. Therefore, the thickness of the substrate (in the covering form including the surface layer, the thickness including the surface layer) is preferably 10 mm or less, particularly preferably 5 mm or less.

<Thermal characteristics>
Although the thermal characteristics of the substrate vary depending on the material, content and form (powder or network) of the non-metallic inorganic material, and the metal component, typically, the thermal conductivity is 180 W / m Examples include those satisfying 10 ppm / K (10 × 10 ⁻⁶ / K) or less. In addition to excellent thermal conductivity, this substrate has a coefficient of thermal expansion of semiconductor elements and their peripheral components (semiconductor elements: about 4 ppm / K to 7 ppm / K (e.g., Si: 4.2 ppm / K, GaAs: 6.5 ppm / K ), Peripheral components such as packages and insulating substrates: Excellent compatibility with stainless steel (around 20 ppm / K), steel (11 ppm / K to 12 ppm / K), Al ₂ O ₃ (6.5 ppm / K), etc. Therefore, it can be suitably used as a material for a heat dissipation member of a semiconductor element. The higher the non-metallic inorganic material content, the higher the thermal conductivity and the lower the thermal expansion coefficient.For example, the thermal expansion coefficient is 3.5 ppm / K or more and 8 ppm / K or less, and the thermal conductivity is 200 W / m The form which satisfy | fills K or more is mentioned. In addition, the network form has a higher thermal conductivity and the thermal expansion coefficient tends to be smaller than the powder form. For example, the thermal expansion coefficient is 5 ppm / K or less, the thermal conductivity is 250 W / m · K or more, and further 280 W. / m · K or higher, particularly 300 W / m · K or higher.

<Surface layer>
In the covering form, at least a part of the surface of the substrate includes a surface layer made of only a metal component (Mg or the like). Typically, of the two opposing surfaces (front and back surfaces) of the substrate, the entire surface of one surface or the entire surface of the two surfaces may be formed of a surface layer. The coating form is unlikely to cause corrosion of different metals at the interface between the surface layer and the composite material, and has a good appearance with a smooth and smooth surface of the substrate. The surface layer, for example, by using a suitable spacer as described in Patent Document 1, by providing a gap in the mold, or by using a specific split type mold (described later), Can be manufactured simultaneously when compounding. Since the surface layer is a further layer of the metal layer (described later) that functions as a solder base, it may not be provided on the entire surface of the substrate as long as the formation area of the metal layer can be secured. In the case where a gap is provided in the above-described mold or a specific mold is used for manufacturing, a form having a metal layer on the entire surface can be manufactured more easily and has excellent productivity. The side surface (end surface) of the substrate may be provided with a surface layer.

  As described above, the surface layer produced at the time of compounding is composed of the same composition and the same structure (a cast structure continuous with the metal component) as the metal component compounded with the nonmetallic inorganic material. In particular, when the metal component and the surface layer are made of pure magnesium, the Young's modulus of Mg is low, so even if it has a surface layer, the thermal expansion coefficient of the entire substrate is unlikely to change, and the substrate has a low thermal expansion coefficient. It is easy to become.

  If the surface layer is too thick, the thermal conductivity of the substrate is lowered and the coefficient of thermal expansion is increased. Therefore, the thickness of the surface layer provided on one surface of the substrate is preferably 1 mm or less, more preferably 0.5 mm or less, particularly preferably 0.05 mm (50 μm) or more and 0.1 mm (100 μm) or less. In this case, the total thickness of the two layers is preferably 2 mm or less, more preferably 1 mm or less. Note that the coefficient of thermal expansion of a substrate with a surface layer can be measured with a commercially available device after preparing a test piece from the substrate, but it should be calculated according to the composite law in consideration of the rigidity of each material constituting the substrate. You can also.

<Others>
The substrate can have a groove, a through hole, a protrusion, or the like in part. Moreover, the board | substrate can have the location comprised only from a metal over the whole area of the thickness direction. Examples of the metal include different metals (for example, stainless steel) such as Mg, which is the same as the metal component of the composite material. A form in which Mg or the like and a dissimilar metal are laminated in the thickness direction of the substrate may be employed. It can be set as the form which provides the said groove | channel, a through-hole, a processus | protrusion, etc. in the location comprised only from this metal. For example, the through hole is used as a fixing bolt hole.

[Metal layer]
A metal layer is provided on at least a part of the surface of the substrate made of the composite material described above. In a mixed-type substrate in which a nonmetallic inorganic material is present on the surface, the metal layer is formed in direct contact with both the nonmetallic inorganic material constituting the surface of the substrate and Mg, etc., and has a surface layer made of a metal component. One of the features of the substrate having a coating form is that the metal layer is formed in direct contact with the surface layer, that is, in direct contact with only Mg or the like.

<Material>
The metal layer is made of a metal different from the metal component constituting the substrate. Since the metal layer is used for the base of the solder, the constituent metal is preferably excellent in adhesiveness with the solder, specifically, nickel (Ni), nickel alloy, copper (Cu), copper alloy, Examples thereof include gold (Au), gold alloy, silver (Ag), and silver alloy. In particular, nickel, copper, and alloys thereof are lighter than gold, silver, and alloys thereof, can suppress weight increase, and can be made into a lightweight composite member, and are low in cost. Although gold, silver, and alloys thereof are heavy, a composite member having high thermal conductivity and excellent heat dissipation can be obtained. Further, any of the metals listed above can be formed by the cold spray method described later. In addition, aluminum (Al) or an alloy thereof can be used as a constituent metal of the metal layer. In this case, after the zincate treatment, a metal layer made of nickel, copper, or an alloy thereof is separately provided thereon. In addition, when providing both the front and back of a board | substrate with a metal layer, respectively, the form in which all the metal layers of each surface are comprised from the same kind of metal, and the form comprised from a different kind of metal may be sufficient.

<Thickness>
One of the features of the metal layer is that the thickness is 0.001 mm (1 μm) or more and less than 0.5 mm (500 μm). When the thickness is 0.001 mm or more, it can sufficiently function as a solder base, and when it is less than 0.5 mm, it is difficult to cause deterioration of thermal characteristics due to the provision of a metal layer. The thickness of the metal layer is more preferably 0.003 mm (3 μm) or more and 0.2 mm (200 μm) or less.

<Surface roughness>
One feature of the metal layer is that the surface roughness Ra is 10 μm or less. Since the surface roughness Ra is 10 μm or less, the solder can be uniformly applied and the solder can be uniformly melted. Can adhere. Further, since the surface roughness is sufficiently small, even when further polishing is performed, the surface can be made smoother by light polishing with a small polishing amount. The metal layer is preferably as smooth as possible, and the surface roughness Ra is 3.5 μm or less, more preferably 3 μm or less, 2.5 μm or less, or 1 μm or less, and particularly preferably 0.5 μm or less.

[Production method]
The composite member of the present invention is basically a coating step in which a substrate is prepared using the infiltration method described in Patent Document 1 (preparation step), and a metal layer is formed on the substrate by a cold spray method. Can be manufactured. Then, it can grind | polish suitably.

[Preparation process]
The substrate is a step of preparing a raw material non-metallic inorganic material ⇒ a step of filling the raw material non-metallic inorganic material into a mold ⇒ a composite of infiltrating molten Mg etc. into the non-metallic inorganic material filled in the mold, It is obtained through a step of forming a plate-shaped composite material (substrate).

<Preparation of raw materials>
When producing a composite material in the form of a powder, a powder composed of particles having a desired material, shape, and size (particle size) is prepared (see the above-mentioned substrate section). When the raw material powder is a finely mixed powder as described above, it is easy to increase the filling density of the mold, and it is easy to produce a composite material having a nonmetallic inorganic material content of 50% by volume or more, and further 60% by volume or more. .

  The raw material powder may be a commercially available product of the desired material, shape and size (particle size), or after pulverizing the commercially available powder as appropriate, it is classified by a particle size distribution measuring device and has a desired size and shape. May be prepared.

  On the other hand, when manufacturing a composite material in a network form, a plate-like porous body having open pores and a porosity of 50% by volume or more as described above, typically a sintered body is prepared. For example, the SiC sintered body is produced by using a SiC powder as described in Patent Document 1, using a suitable method such as tapping, slip casting, pressure molding, and a doctor blade method, It can be manufactured by sintering this powder compact. Sintering conditions include sintering temperature: 1300 ° C. to 2500 ° C. (preferably 2000 ° C. or higher), holding time: about 2 hours to 100 hours, atmosphere: vacuum. A SiC sintered body having a higher heat treatment temperature (for example, 2000 ° C. or more, further 2200 ° C. or more) and a longer heat treatment time (for example, 50 hours or more, further 70 hours or more), a thicker network and higher thermal conductivity. It can be. Alternatively, a commercially available porous body (sintered body) can be used. A porous body having a thickness corresponding to the thickness of the substrate to be manufactured is prepared.

When using SiC powder or SiC porous body, as described in Patent Document 1, an oxidation treatment is performed (heating temperature: 700 ° C. to 1000 ° C.), and an oxide film (mainly composed of SiO ₂ ) is formed on the surface. If the form is provided with a film, the wettability between SiC and molten Mg or the like can be improved. In this form, since the entire surface of SiC is covered with an oxide film, the wettability tends to be higher than when an infiltrant described later is used, and for example, the infiltration temperature may be lowered. The oxidation treatment may not be performed.

Alternatively, an infiltrant made of SiO ₂ can be included separately. In particular, when a powder made of SiO ₂ is used, it is easy to fill the mold with the infiltrant. If the SiO ₂ powder is smaller than the SiC powder, it is preferable because it is easily interposed between SiC. For example, the average particle diameter of the SiO ₂ powder is about 0.01 μm to 3 μm. If there is too much infiltrant, a large amount of MgO and Mg ₂ Si generated by the reaction of SiO ₂ and Mg may remain, leading to deterioration of thermal characteristics, and if it is too little, the effect of improving wettability can be obtained sufficiently. Therefore, the content of the infiltrant made of SiO ₂ is preferably 0.1% or more and 5% or less with respect to the total mass of the raw material SiC powder and the infiltrant.

<Filling into mold>
When manufacturing a composite material in the form of powder, the above-mentioned raw material powder (in the case of SiC powder, only SiC powder, coated SiC powder having an oxide film, or infiltrant-containing powder containing infiltrant) is desired. The composite material having the shape and thickness is filled by tapping or the like into a mold having a forming space capable of being molded (see Patent Document 1). When manufacturing a composite material in a network form, a porous body having a desired shape and thickness is placed in the mold. When the mixed form of the powder form and the network form is used, both the raw material powder and the desired porous body are stored in the mold.

  When manufacturing a coated substrate having a surface layer, for example, an appropriate spacer is prepared, and this spacer is also stored in a mold. Examples of the spacer include a plate-like body and a linear body made of naphthalene, anthracene, carbon, stainless steel (for example, SUS430), or the like. In particular, when using a molded body of a non-metallic inorganic material as a raw material (the above-mentioned powder molded body or sintered body), the molded body and the spacer can be easily stored in a molding die (see Patent Document 1). Excellent in properties. Alternatively, if the molded body is used as a raw material and the molded body can be self-supporting in the mold, a gap (a size corresponding to the thickness of the surface layer) is provided between the mold and the molded body. By selecting the size of the mold as described above, the surface layer can be formed even if the spacer is omitted. Or, it is a mold composed of a plurality of divided pieces, and the thermal expansion coefficient of the divided pieces is different from the thermal expansion coefficient of the bolts connecting the divided pieces (the thermal expansion coefficient of the bolts is large). The surface layer can also be formed by using a split type mold (see Patent Document 1).

<Composite>
The raw material nonmetallic inorganic material filled in the mold is brought into contact with molten Mg or the like, and composited with Mg or the like interposed in the space surrounded by the nonmetallic inorganic material. In the covering form, the space formed between the mold and the nonmetallic inorganic material is filled with Mg or the like to form the surface layer at the same time. If an inert atmosphere such as argon (Ar) or nitrogen (N ₂ ) is used during infiltration, Mg or the like is hardly oxidized. In particular, an Ar atmosphere is preferable because nitride formation can be suppressed. When the atmospheric pressure during infiltration is a vacuum atmosphere of atmospheric pressure or lower, generation of pores due to entrainment of gas components in the atmosphere can be suppressed, and a dense composite material can be easily obtained. On the other hand, it is preferable to set the atmospheric pressure to atmospheric pressure because the facility can have a simple structure and the scattering of Mg vapor can be suppressed. Although the infiltration temperature depends on the metal component, it is preferably 650 ° C or higher and 1000 ° C or lower. The higher the infiltration temperature, the higher the wettability and the reduction of pores, but defects such as shrinkage and gas holes, Mg, etc. Since boiling can occur, it is preferably 900 ° C. or lower, more preferably 680 ° C. or higher and 850 ° C. or lower.

  Solidification of molten Mg, etc. (molten metal) can be achieved by setting the inert atmosphere, atmospheric pressure: atmospheric pressure or higher to suppress the formation of defects and oxides during solidification, resulting in a high-quality composite material. . In addition, when producing a composite material having a large flat area, if cooling is performed in one direction (preferably in the direction opposite to the infiltration direction of the molten metal), internal defects such as shrinkage cavities are difficult to form, and high quality is achieved. A composite material is preferably obtained. When manufacturing a small composite material having a small plane area, it is not necessary to perform the above-described cooling in one direction. For example, a high-quality composite material can be obtained even when uniform cooling is performed as a whole. As the cooling rate during solidification increases, the generation of internal defects and the growth of crystallized substances in the metal component can be suppressed, and a high-quality composite material can be obtained. In order to increase the cooling rate, for example, the component material of the mold is made of a material having excellent thermal conductivity (for example, carbon, graphite, stainless steel, etc.), or forced cooling such as air cooling or water cooling using a fan is performed. To do.

[Coating process]
And, in the method for producing a composite member of the present invention, the desired regions (part or all of one surface, part or all of each surface) on the front and back surfaces of the prepared composite material substrate are subjected to a cold spray method. The greatest feature is to form a metal layer made of a desired metal.

  A known film forming apparatus and film forming conditions can be used for forming the metal layer by the cold spray method. Typically, the film forming apparatus includes a cylinder part that stores high-pressure gas used as a carrier gas and a carrier gas, a carrier pipe through which the high-pressure gas from the cylinder part circulates, and heating that heats the pipe. , A transport pipe through which high-pressure gas from the cylinder part is circulated, a powder supply section for supplying metal powder to the pipe, a carrier pipe and a transport pipe connected to the metal transported by the transport gas A spray gun in which powder and carrier gas are introduced and metal powder is discharged from the nozzle port by the carrier gas, and an object (here, the substrate) on which the metal layer is formed so as to face the nozzle port provided in the spray gun. The thing provided with the support part to support is mentioned. Examples of the gas species include nitrogen, helium, argon, and air. The temperature of the carrier gas can be selected according to the melting point or softening point of the metal powder. The gas pressure can be selected according to the material and particle size of the metal powder.

  The metal powder used as the raw material for the metal layer is selected from those made of a desired metal (typically, see the section of the metal layer described above). The size of the metal powder depends on the film formation conditions (carrier gas temperature, gas pressure, distance from the nozzle port to the target, etc.) and the metal material (ease of plastic deformation), but the thickness of the metal layer. To some extent. The metal powder has an average particle size of about 1 μm to 200 μm, particularly about 3 μm to 50 μm, and the thickness is less than 0.5 mm (500 μm), further 0.3 mm (300 μm) or less, particularly 0.2 mm (200) μm or less. It is a thin film, and it is easy to form a smooth metal layer (film) having a surface roughness Ra of 10 μm or less, further 8.5 μm or less, particularly 7.5 μm or less. In addition, when a film is formed using a fine powder, it tends to be easily polished even when polishing after film formation.

  When the metal layer is formed by the cold spray method, unlike the case of using a cast or hot press method, a metamorphic phase due to heat is not substantially formed between the substrate and the metal layer. Therefore, the absence of a metamorphic phase between the substrate and the metal layer is one of the grounds indicating that the metal layer was formed by the cold spray method. Further, when the metal layer is formed by the cold spray method, it is easier to increase the purity of the metal than when using the electroplating method or the electroless plating method, for example, the purity (mass ratio) is 85% or more, more than 90%, In particular, a metal layer of 95% or more can be formed. Therefore, the high purity of the metal constituting the metal layer is one of the grounds indicating that the metal layer was formed by the cold spray method. For confirmation of the presence or absence of metamorphic phase in the metal layer, purity measurement, for example, SEM observation of the cross-section of the composite member (metal layer), component analysis by the EDX analyzer attached to the SEM, the surface of the composite member (metal layer) For example, it is possible to use component analysis by an Auger electron spectrometer.

[Polishing process]
By forming the metal layer by the cold spray method as described above, a metal layer having a thickness of less than 0.5 mm and a surface roughness of Ra of 10 μm or less can be obtained without performing post-treatment such as polishing. By further polishing, the thickness can be 0.1 mm or less, further 0.05 mm or less, and the surface roughness Ra can be 3.5 μm or less, further 0.5 μm or less. In particular, in the method for producing a composite member of the present invention, since the thickness of the formed metal layer is as thin as less than 0.5 mm, even if the polishing amount is small, specifically 0.1 mm or less, Ra 3.5μm or less can be achieved. Further, unlike the metal rolled plate, the metal layer formed by the cold spray method has substantially no orientation and isotropic structure, so that the residual stress during polishing is released. It is difficult to get up and deformation is small. For this reason, it is easy to polish. Thus, since the polishing amount is as small as 0.1 mm or less and polishing is easy, workability is excellent even when a polishing step is provided. In addition, since light polishing with a small amount of polishing may be used, warping is hardly caused by polishing or is not substantially generated. Therefore, a composite member having excellent flatness can be obtained. When the polishing amount is in the range of 0.1 mm or less, the larger the surface roughness, the smaller the surface roughness (for example, Ra 0.5 μm or less), the smaller (for example, 0.03 mm (30 μm) or less), the shorter the working time. Can be achieved.

[Other processes]
In addition, as one step of the above manufacturing method, the substrate or the composite member comprising the metal layer is heated to a temperature of 300 ° C. or higher and lower than the solidus temperature (melting point) of the metal component of the substrate and the constituent metal of the metal layer. A compression treatment step of applying pressure at a pressure of 1 ton / cm ² or more while heating can be provided. By applying such a hot press to the substrate or the composite member, pores in the substrate can be reduced, and a dense substrate or composite member having a low porosity can be obtained. Can be suppressed.

[Test example]
A substrate made of Mg-SiC composite material with pure magnesium as the metal component and SiC as the non-metallic inorganic material is fabricated, and a metal layer is formed on this substrate by the cold spray method, and a composite member including the metal layer is fabricated. The surface properties and the adhesion to the solder were examined.

  The substrate was produced as follows. As a raw material metal, a pure magnesium ingot (commercially available product) comprising 99.8% by mass or more of Mg and the balance of inevitable impurities was prepared.

For samples No. 1 to No. 20, two types of SiC powders with different particle sizes (both commercially available): # 120 (average particle size: about 110 μm), # 1000 (average particle size: about 15 μm), As an infiltrant, an infiltrant-containing powder prepared by mixing a powder (commercial product) made of SiO ₂ having an average particle size of 0.3 μm was prepared. The amount of SiO ₂ powder was 1.0 wt% based on the total amount of the infiltrant-containing powder.

  For samples No. 21 to No. 40, commercially available SiC sintered bodies (relative density: 80%, length 200 mm × width 150 mm) were prepared. For samples No. 21 to No. 30, a sintered body having a thickness of 5 mm was prepared, and for samples No. 31 to No. 40, a sintered body having a thickness of 4 mm was prepared. Each SiC sintered body was oxidized at 1000 ° C. for 2 hours to form an oxide film on the surface.

  Prepared raw material: Infiltrant-containing powder or SiC sintered body on which an oxide film is formed is stored in a mold (mold). In this test, the mold was a rectangular parallelepiped box that was opened on one side, and a carbon mold that was formed integrally by combining a plurality of divided pieces was prepared. In addition, the mold is a forming space in which a rectangular plate with a length of 200 mm x width 150 mm x thickness 5 mm (sample No. 1 to No. 30) or thickness 6 mm (sample No. 31 to No. 40) can be molded. The thing which has (cavity) was prepared. Further, the mold has an ingot placement portion connected to the periphery of the opening. The ingot placing part is configured to flow into an opening (thickness 5 mm or 6 mm) in the formation space when the placed ingot is melted. In addition, although the shaping | molding die may utilize what was integrally formed in the box shape instead of the form integrally formed by combining several division | segmentation pieces, the above-mentioned division | segmentation form is the composite material after infiltration. Easy to take out.

  Samples No. 1 to No. 20 were filled with the infiltrant-containing powder while applying vibration (tapping) to the mold, so that the packing density of the SiC powder in the mold cavity was about 72%. The amount of powder was adjusted. For samples No. 21 to No. 30, a 5 mm thick SiC sintered body was housed in a mold having a cavity thickness of 5 mm. In samples No. 21 to No. 30, there is substantially no gap between the inner surface of the cavity and the SiC sintered body. For samples No. 31 to No. 40, in the mold with a cavity thickness of 6 mm, a gap of 1.0 mm is provided between the front and back surfaces of the SiC sintered body (two sides of 200 mm × 150 mm) and the inner surface of the cavity. A SiC sintered body having a thickness of 4 mm was accommodated so as to provide a gap of 2.0 mm in total on the front and back surfaces.

  In this test, a commercially available release agent was applied to the mold cavity (inner peripheral surface) where it was in contact with the molten metal or SiC. By applying the release agent, it is easy to take out the composite material after infiltration, and the workability is excellent. Application of the release agent can be omitted.

  After the infiltrant-containing powder and the SiC sintered body are stored in the mold, the ingot is placed on the ingot mounting portion, and the mold is heated to a predetermined temperature to melt the ingot. The mold is heated by inserting the mold into a heatable atmosphere furnace. For samples No. 1 to No. 20 using SiC powder, infiltration temperature: 710 ° C., Ar atmosphere, atmospheric pressure: atmospheric pressure, for samples No. 21 to No. 40 using SiC sintered bodies, The atmosphere furnace was adjusted so that the infiltration temperature was 680 ° C., Ar atmosphere, and atmospheric pressure was atmospheric pressure.

  The molten pure magnesium flows into the cavity from the opening of the mold, and infiltrates between the SiC particles filled in the cavity or in a space surrounded by a mesh formed by SiC. For samples No. 31 to No. 40, the melted pure magnesium is also filled in the gap between the cavity and the SiC sintered body. After infiltration and filling, the mold is cooled to solidify the pure magnesium. Here, the bottom side of the mold was positively cooled so as to be cooled in one direction from the bottom of the mold toward the opening, that is, in the direction opposite to the infiltration direction of the molten metal.

  After cooling, when the molded product was taken out from the mold, it was a plate-shaped molded product with a length of 200 mm × width 150 mm × thickness 5 mm (sample No. 1 to No. 30), and a plate-shaped molded product with a thickness of 6 mm. (Sample Nos. 31 to 40) were obtained. For samples No. 31 to No. 40, each of the front and back surfaces was removed by cutting 0.5 mm in thickness, 1.0 mm in total, and adjusted to 5 mm in thickness.

  The components of the molded product having a thickness of 5 mm obtained as described above were examined using an EDX apparatus. As a result, it was confirmed that all of samples No. 1 to No. 40 were Mg and SiC, and the rest: Mg—SiC composite material which was an inevitable impurity, and was the same as the raw material used. For samples No. 31 to No. 40, the components were examined in the intermediate region (region of thickness 4 mm) excluding the surface layer region from the surface to 0.5 mm in the thickness direction in the obtained molded product. Moreover, about the sample No.31-No.40, when the component of the surface layer area | region was investigated with the EDX apparatus, it confirmed that it was Mg and an unavoidable impurity and was the composition similar to the ingot used for the raw material.

  Molded product of 5 mm thickness obtained as described above (Sample No. 1 to No. 30: Composite material of 5 mm thickness, Sample No. 31 to No. 40: Intermediate region consisting of composite material of 4 mm thickness ) Was subjected to CP (Cross-section Polisher) processing to obtain a cross section, and this cross section was examined by SEM observation. As a result, Samples No. 1 to No. 20 were present in the same manner as the raw material SiC powder, in which granular SiC was dispersed and present, the network part was not formed. In Samples No. 21 to No. 40, SiC was bonded together by SiC, and SiC existed in a continuous network. That is, a network part was formed, which was the same as the raw material SiC sintered body used.

  When the above-mentioned CP cross section was observed by SEM (50 times or 100 times), it was confirmed that pure magnesium was infiltrated between SiC in any of samples No. 1 to No. 40. Further, in Samples No. 1 to No. 20, it was confirmed that fine SiC particles were interposed between coarse SiC particles.

  In addition, for sample No. 31 to No. 40, when the CP cross section of the region including the surface layer region described above was observed with SEM (100 times), SiC was contained so as to cover the intermediate region made of Mg-SiC composite material. It was confirmed that there was a non-existing area. That is, it was confirmed that Samples No. 31 to No. 40 were provided with a surface layer made of pure magnesium in combination with the component analysis described above. Furthermore, this observation image shows that (1) the metal component of the Mg-SiC composite region and the metal component constituting the surface layer are composed of a continuous structure, and (2) the average thickness of the surface layer. It was confirmed that the length was about 0.5 mm.

  Further, a molded product having a thickness of 5 mm obtained as described above (sample No. 1 to No. 30: a composite material having a thickness of 5 mm, sample No. 31 to No. 40: a composite material having a thickness of 4 mm. For the intermediate region), the SiC content in the composite material was measured. Sample No. 1 to No. 20 was 72% by volume, and sample No. 21 to No. 40 was 80% by volume. It matched the packing density or the relative density of the raw materials. The SiC content of each composite material is determined by observing an arbitrary cross section of the composite material with an optical microscope (50 times), and processing this observation image with a commercially available image analyzer, and calculating the total area of SiC in the cross section. The total area was regarded as the volume ratio based on this cross section (area ratio≈volume ratio), the volume ratio of the cross section with n = 10 was determined, and the average value was obtained. Note that SEM may be used for cross-sectional observation.

  Further, the thermal conductivity (W / m · K) and the thermal expansion coefficient (ppm / K) of the molded product having a thickness of 5 mm obtained as described above were measured. The results are shown in Table 1. The thermal conductivity and the thermal expansion coefficient were measured using a commercially available measuring instrument by cutting out a test specimen from the obtained molded product (samples No. 31 to No. 40 were measured with the surface layer removed). . The coefficient of thermal expansion was measured in the range of 30 ° C to 150 ° C.

In addition, a molded product having a thickness of 5 mm obtained as described above is used as a substrate, and a metal powder is sprayed onto the substrate in a high-pressure, high-speed gas stream by a cold spray method, and the target thickness is 20 μm to 150 μm. The metal layer was formed. By this step, a composite member comprising a substrate made of an Mg—SiC composite material and a metal layer provided on one surface of the front and back surfaces of the substrate was obtained. As raw materials for the metal layer, metal powders of the materials shown in Table 1 (all commercially available products having an average particle diameter of 20 μm) were prepared. A cold spray apparatus was used to form the metal layer. The film forming conditions were as follows: carrier gas and carrier gas: nitrogen (N ₂ ), carrier gas heating temperature: 500 ° C., gas pressure: 3 MPa. For some samples, after the film formation, the metal layer was polished to adjust (reduce) the thickness. Table 1 shows the polishing amount (removed thickness). In addition, all the samples subjected to the polishing did not warp by this polishing.

  With respect to the composite member comprising the metal layer obtained as described above, the thickness (μm), surface roughness (Ra (μm)), and adhesion (MPa) of the metal layer were examined. The results are shown in Table 1. The sample with the metal layer polished was examined for surface roughness and adhesion after polishing.

  The thickness of the metal layer was examined as follows. Using a commercially available micrometer, the thickness (n = 10 average thickness) of the sample before the film formation by the cold spray method (the above-mentioned molded product), the sample after the film formation (a composite member having a metal layer) The thickness (average thickness of n = 10) was measured, and the difference in thickness of the sample before and after film formation was taken as the thickness of the metal layer. For the sample with the metal layer polished, the thickness of the sample after polishing is measured as described above (n = 10 average thickness), and the difference between the thickness after polishing and the thickness before film formation is And the thickness.

  The surface roughness (Ra: arithmetic average roughness, JIS B 0601 (2001) / ISO 4287 (1997)) of the metal layer was measured using a commercially available surface roughness meter.

  The adhesion was examined as follows. A sample with a rod in which a copper rod having a diameter of 8 mm is joined to the metal layer of each sample by soldering is prepared. The rod of the sample with the rod was pulled by a commercially available tensile testing machine, the tensile force at the time when the rod was peeled off from the composite member was measured in MPa, and this tensile force was defined as the adhesion force.

  Further, for the vicinity of the boundary between the metal layer and the substrate in the composite member obtained as described above, the CP cross section was taken as described above, and the sample was observed with SEM (50 times or 100 times). In No.30, the metal layer is in direct contact with both pure magnesium and SiC. In Samples No.31 through No.40, the metal layer is in direct contact with the surface layer made of pure magnesium. I confirmed. FIG. 1 is a SEM photograph of the CP cross section of sample No. 2 as described above. As shown in FIG. 1, it can be seen that the metal layer made of Ni is in close contact with the surface of the Mg—SiC composite material. Moreover, it turns out that a powder grain boundary is not seen substantially but a metal layer is a uniform state. In the substrate shown in FIG. 1, the region in the vicinity of the boundary between the metal layer and the substrate (the central portion in FIG. 1) is polished and flattened by the ion beam and looks smoother than the lower portion in FIG.

  As shown in Table 1, it can be seen that all of the substrates included in samples No. 1 to No. 40 are excellent in thermal conductivity and in consistency with thermal expansion coefficients of general semiconductor elements and the like. Specifically, each substrate has a thermal conductivity of 180 W / m · K or more (for sample No. 1 to No. 20, 200 W / m · K or more, further 220 W / m · K or more, sample No. 21 to In No.40, 250 W / m ・ K or more, and further 280 W / m ・ K or more), and coefficient of thermal expansion is 10 ppm / K or less (in sample No.1 to No.20, 7.3 ppm / K to 7.7 ppm / K, In sample No. 21 to No. 40, it is 4.0 ppm / K to 4.4 ppm / K).

  And, by using the cold spray method, it is possible to form a thin metal layer of less than 0.5 mm as intended, and this metal layer has a small surface roughness (Ra 10 μm or less). In addition, when polishing this metal layer, the surface of the metal layer can be made smoother (Ra: 3.5 μm) even if the polishing amount is as small as 0.1 mm (100 μm) or less (even light polishing). Hereinafter, it can be seen that 0.5 μm or less). One reason for this is that the metal layer has an isotropic structure and can be easily polished. Furthermore, since the amount of polishing was small, warping did not occur as described above, the polishing time could be shortened, and it was confirmed that the workability was excellent.

  In addition, it can be seen that all the samples have high adhesion between the composite member and the target object (here, the copper rod) through the solder, which exceeds 10 MPa that is practically required for the heat dissipation member of the semiconductor element. . From this, it was confirmed that the metal layer provided in the composite member of each sample can be used favorably for the solder base.

  From the above test, a composite member in which a thin and smooth metal layer is directly provided on a substrate made of an Mg-SiC composite material can be used well as a base of solder. It can be said that a heat dissipation structure with excellent heat dissipation can be constructed. In particular, since the metal layer is thin, the distance between the composite member and the solder is short, and the low thermal conductivity substance is not interposed between the composite member and the metal layer. It can be said that the member can construct a heat dissipation structure with excellent heat dissipation. Moreover, it can be said that such a thin and smooth metal layer can be easily formed by a cold spray method.

  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 material, content, size, shape, composition of the metal component and surface layer of the non-metallic inorganic material in the composite material, surface layer formation region (forms provided only on one surface of the substrate, etc.), composition of the metal layer The formation region and the like can be changed as appropriate. For example, when the metal layer is composed of a composition that can join a semiconductor element or the like such as solder (for example, lead or lead alloy), it is expected that the semiconductor element or the like can be placed without using solder separately. Is done.

  The composite member of the present invention has a high thermal conductivity, excellent consistency with the thermal expansion coefficient of the semiconductor element and its peripheral components, and a metal layer that can be used as a solder base. It can utilize suitably for the raw material of a member. The manufacturing method of the composite member of this invention 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 (7)

A composite member comprising a nonmetallic inorganic material, a substrate made of a composite material in which magnesium or a magnesium alloy is combined as a metal component, and a metal layer provided on at least a part of the surface of the substrate,
The composite material contains 50% by volume or more of SiC as the non-metallic inorganic material,
The metal layer is
It is composed of a metal different from the metal component in the composite material,
Of the material constituting the surface of the substrate, is formed in direct contact with at least the metal component,
The thickness is 0.001mm or more and less than 0.5mm,
A composite member with a surface roughness Ra of 10 μm or less.   2. The composite member according to claim 1, wherein the metal layer is composed of one kind of metal selected from nickel, nickel alloy, copper, copper alloy, gold, gold alloy, silver, and silver alloy.   3. The composite member according to claim 1, wherein the metal layer is formed in direct contact with both the non-metallic inorganic material and the metal component constituting the surface of the substrate.   4. The composite member according to claim 1, wherein the substrate has a thermal conductivity of 180 W / m · K or more and a thermal expansion coefficient of the substrate of 10 ppm / K or less.   5. A semiconductor device comprising: a heat radiating member constituted by the composite member according to claim 1; and a semiconductor element placed on the heat radiating member. A composite member for producing a composite member comprising the metal layer by forming a metal layer on at least a part of the surface of a substrate made of a composite material in which a nonmetallic inorganic material and magnesium or a magnesium alloy are combined as a metal component A manufacturing method of
As the non-metallic inorganic material, a preparation step of preparing a substrate made of a composite material containing SiC by 50 volume% or more,
A powder made of a metal different from the metal component in the composite material is prepared, and at least a part of the surface of the substrate has a thickness of 0.001 mm to less than 0.5 mm and a surface roughness of Ra by a cold spray method. A method for producing a composite member comprising a coating step of forming a metal layer having a thickness of 10 μm or less. Furthermore, comprising a polishing step for polishing the surface of the metal layer,
7. The method for producing a composite member according to claim 6, wherein the thickness removed by polishing in the polishing step is 0.3 mm or less.