JPH11140559A - Composite material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite material reinforced by fibers composed of carbon and/or graphite and having low thermal expansion coefficient in facial direction and to provide a method for producing it. SOLUTION: This composite material composed of carbon and/or graphite- series fibers and a matrix of copper or a copper alloy is the one composed of carbon and/or graphite-series fibers and a matrix of copper or a copper alloy, and, as for the carbon and/or graphite-series fibers, the length thereof exceeds 40 μm, the aspect ratio and volume ratio lie in the range surrounded by the points A (4, 75), B (10, 75), C (30, 55), D (30, 25), E (20, 25) and F (4, 45) shown by the fig. 1, and, furthermore, they are oriented in the direction of the two-dimensional face at random. It has a low thermal expansion coefficient in the facial direction and is suitable as the material for a substrate for a semiconductor device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite material comprising carbon and / or graphite fibers and a matrix of copper or copper alloy and a method for producing the same, and more particularly to a substrate for a semiconductor device having a low thermal expansion coefficient in the plane direction. The present invention relates to a composite material comprising carbon and / or graphitic fiber and a matrix of copper or copper alloy, and a method for producing the same.

[0002]

2. Description of the Related Art Various materials having a combination of a reinforcing material made of ceramic or the like and a metal and having both advantages have been developed and put into practical use. One of them is a composite of carbon or graphitic fiber and copper. This composite material has a low thermal expansion property utilizing the lubricating properties of carbon and the high electrical conductivity of copper, and the low thermal expansion properties of carbon or graphite fibers and the high thermal conductivity of copper. It is used as a substrate for semiconductor devices having high thermal conductivity.

When such a composite material is used as a substrate for a semiconductor device, it is necessary to lower the coefficient of thermal expansion at least in the plane direction of the substrate. A fiber in which fibers are arranged is known (conventional example 1, JP-B-59-16406, JP-B-58-16615).

[0004] Further, there is known a carbon fiber in which a relatively long fiber having an aspect ratio of 200 or more is mixed, solidified, and isotropically oriented (Conventional Example 2, Japanese Patent Publication No. Sho 61-30).
No. 013). Further, a heat radiating member for a semiconductor device obtained by mixing a carbon fiber as short as 40 μm or less with copper or Al powder as a matrix and sintering under pressure has been proposed (Conventional Example 3, JP-A-9-64254). Gazette). Further, there has been proposed one in which carbon fibers are randomly oriented in a two-dimensional direction in a matrix of Al or an Al alloy (Conventional Example 4, Japanese Patent Application Laid-Open No. 4-147654).

As a method for producing a composite material, a powder metallurgy method has been generally used, and a hot press method or an HIP method is often used for producing a composite material such as metal powder and carbon. In particular, the HIP method is used for mass production. It can be said that this method has excellent properties. HI
When a composite material is manufactured by the P method, a composite material is manufactured by placing a compression-molded product of the mixture in a metal capsule, degassing, sealing, and subjecting the mixture to high-temperature and high-pressure treatment.
When a large deformation is performed in the production of the composite material by the HIP method, the body of the metal capsule and the center of the lid are preferentially deformed, and the compression molded body of the metal capsule is unevenly deformed. In order to prevent such non-uniform deformation of the capsule during the HIP process, it is known that the side wall of the capsule is formed into a bellows body in forming a mixture of Al powder and reinforcing material powder (conventionally). Example 5, Patent No. 2
No. 535401).

[0006]

However, in the above-mentioned conventional example 1, it is difficult to arrange the long fibers artificially because it takes time and effort to manufacture, and it is difficult to say that it is economical. However, when a high-temperature heat history such as Ag brazing is applied, an extremely large internal stress is locally generated, and there is a problem that the matrix cannot withstand the internal stress and there is a high risk of material breakage or deformation. .

In the above conventional example 2, fibers having a relatively long fiber length of 200 or more in aspect ratio are used. If the hot press method is used, the fibers cannot be sufficiently oriented in the plane direction. It is easy to be solidified while being bent, so that an extremely large internal stress is accumulated in the material, and there is a high risk of damage and deformation of the material due to heat history as in the above-mentioned conventional example 1 and there is sufficient reliability. I can't say it.

Further, in the above-mentioned conventional example 3, the fibers having a short length of 40 μm or less are used. However, in this case, the effect of lowering the thermal expansion coefficient of each fiber is remarkably reduced, and a very large amount of carbon fibers is required to obtain a desired thermal expansion coefficient. In this case, in order to obtain high thermal conductivity, it is necessary to use a high-grade fiber having a high degree of graphitization, and there is a problem that the cost is high. Further, in the above-mentioned conventional example 4, although carbon fibers are randomly oriented in the two-dimensional direction in the matrix of Al, when applied to a semiconductor device, they cannot be said to have sufficient reliability. It is.

Also, in the above-mentioned conventional example 5, it is shown that the capsule side wall portion of the HIP process is made bellows, but this relates to the molding of a mixture of Al powder and reinforcing material powder. It does not disclose an effect of preventing non-uniform deformation and at the same time aligning the orientation of carbon and / or graphitic fibers in a matrix made of copper or a copper alloy.

[0010] The present invention is reinforced by a fiber made of carbon and / or graphite, has a low coefficient of thermal expansion in the plane direction,
In particular, the present invention provides a composite material composed of carbon and / or graphite fibers and a matrix of copper or a copper alloy, which is suitable as a material for a substrate for a semiconductor device, and a method for producing the same.

[0011]

The present invention comprises carbon and / or graphite fibers and a matrix made of copper or a copper alloy, wherein the carbon and / or graphite fibers have a length of 40 μm. A (4,75) and B (10,7) shown in FIG.
5), C (30, 55), D (30, 25), E (2
0, 25), carbon and / or graphitic fibers and copper or copper within a range surrounded by points F (4, 45) and randomly oriented in a two-dimensional plane direction. A composite material consisting of an alloy matrix.

The composite material comprising carbon and / or graphitic fibers and a matrix of copper or a copper alloy according to the present invention preferably has an aspect ratio and a volume ratio of H of FIG.
(5,70), I (15,60), J (20,60),
K (20,40), L (10,40), M (5,50)
Are within the range surrounded by the dots. In the present invention, the volume ratio is defined as (carbon and / or
Or volume of graphitic fiber) / (volume of carbon and / or graphitic fiber + volume of copper or copper alloy of matrix)
It is.

The composite material comprising carbon and / or graphitic fibers and a matrix of copper or a copper alloy according to the present invention is characterized in that the matrix is copper or further Mo, W, C
It is a copper alloy containing one or more of r, Ag, and ceramic particles. Further, the composite material of the present invention comprising a matrix of carbon and / or graphite fibers and copper or a copper alloy is used as a substrate for a semiconductor device.

Further, according to the present invention, a compression molded product of a mixture of carbon and / or graphite fibers and a matrix powder is charged into a metal capsule having a bellows-like side wall, degassed, sealed, and subjected to hot hydrostatic pressure. A method for producing a composite material comprising carbon and / or graphitic fibers and a matrix of copper or a copper alloy, wherein a metal capsule in which the compression molded product is sealed is contracted in a uniaxial direction by pressurization. .

Further, according to the method for producing a composite material comprising a carbon and / or graphitic fiber and a matrix of copper or a copper alloy according to the present invention, the thickness of the lid portion of the metal capsule is reduced. The thickness is at least twice the thickness of the side wall. The method for producing a composite material comprising a carbon and / or graphite fiber and a copper or copper alloy matrix according to the present invention comprises the steps of: loading a compression-molded product into a metal capsule having a bellows-like side wall; It is characterized by being sealed afterwards.

The method for producing a composite material comprising carbon and / or graphitic fibers and a matrix of copper or copper alloy according to the present invention comprises the steps of: The compression molded product is characterized by being wrapped with a thin copper plate or foil.

Further, the method for producing a composite material comprising carbon and / or graphitic fibers and a matrix of copper or copper alloy according to the present invention is characterized in that hot isostatic pressing is performed at 800 ° C. or more, It is carried out at a temperature lower than the melting point of the alloy.

[0018]

According to the composite material of the present invention comprising a carbon and / or graphitic fiber and a matrix of copper or a copper alloy,
Reinforced by carbon and / or graphitic fibers,
It has a low coefficient of thermal expansion in the plane direction, has small internal stress due to sintering and solidification, and has no danger of deformation or breakage due to thermal history. Further, according to the present invention, since the carbon and / or graphitic fibers are randomly oriented in the two-dimensional plane direction, the coefficient of thermal expansion in the plane direction perpendicular to the shrinkage axis can have a low value, and high thermal conductivity can be obtained. By using a graphitic fiber having a high graphitization rate, high heat conduction can be achieved in this direction, and if a material is cut out in a direction parallel to this surface, a product suitable as a substrate for a semiconductor device can be obtained. Can be.

Further, the production of the composite material comprising the carbon and / or graphitic fibers and the matrix of copper or copper alloy of the present invention is performed by hot isostatic pressing (HIP method). Since it is used and contracted in one axis direction, the fiber made of carbon and / or graphite can be oriented in a direction perpendicular to the contraction direction.

Since the composite material of the present invention uses copper or copper alloy as the matrix, it has good thermal conductivity. When the matrix is an Al composite material, harmful carbides such as Al ₄ C ₃ are formed at the interface between carbon and graphite fibers and Al, and are easily separated at the interface during a temperature cycle. The effect of reducing the thermal expansion cannot be sufficiently obtained, and there is a problem in reliability. However, there is no such problem in the matrix of copper or copper alloy. Further, it has heat resistance that enables Ag brazing between the package and the heat radiating substrate, and is also useful as a heat radiating substrate for a ceramic package.

The reasons for limiting the aspect ratio and volume ratio of the carbon and / or graphitic fibers of the present invention will be described. FIG. 1 shows the aspect ratio on the horizontal axis and the volume ratio of carbon and / or graphitic fibers on the vertical axis, and shows the aspect ratio of the composite material composed of carbon and / or graphite fibers and a matrix of copper or copper alloy. It is a figure which shows the relationship between a volume ratio. The aspect ratio and volume ratio of the carbon and / or graphitic fiber of the present invention are shown by A (4,75) and B (10,7) shown in FIG.
5), C (30, 55), D (30, 25), E (2
0, 25) and F (4, 45).

The aspect ratio is fiber length / fiber diameter. The reason for limiting the aspect ratio of the present invention is that the fiber made of carbon and / or graphite having an aspect ratio of less than 4
Since the fabrication is difficult and the cost is high, one having an aspect ratio of 4 or more was used. When the aspect ratio exceeds 30, the internal stress accumulated when the composite material is sintered and solidified is too large, and the risk of deformation and breakage due to heat history is large.

The reason for limiting the volume ratio is that if the volume ratio of carbon and / or graphitic fibers exceeds 75%, sintering and solidification becomes difficult, and even if sintering can be performed, the material becomes brittle, and characteristics as a composite material are obtained. Therefore, the characteristics required as a substrate for a semiconductor device cannot be satisfied. The volume ratio is 25%
If it is smaller, the coefficient of thermal expansion becomes too large, which is not appropriate. Therefore, the volume ratio is limited to 25% or more and 75% or less.

Furthermore, even if these conditions are satisfied,
In the region above the line L1 (dashed line) in FIG.
It is not suitable because the internal stress at the time of sintering and solidification becomes large, causing deformation and destruction due to heat history. Line L2
The thermal expansion coefficient cannot be reduced in the region below (dashed line). In particular, the thermal expansion coefficient cannot be reduced to a value suitable for a semiconductor device substrate. For these reasons, A (4,75), B (10,
75), C (30, 55), D (30, 25), E (2
(0,25), the aspect ratio of carbon and / or graphitic fibers and the volume ratio of the fibers in the region surrounded by the points of F (4,45). Particularly preferred are H (5,70) and I (15,6) in FIG. 2 showing the relationship between the aspect ratio and the volume ratio.
0), J (20, 60), K (20, 40), L (1
0,40) and M (5,50).

Further, the fibers are randomly oriented in the two-dimensional plane direction because the minimum fiber defined by the aspect ratio and the volume ratio can be used without using a long fiber that causes a problem of concentration of internal stress. This is because a predetermined low thermal expansion can be obtained with the fiber amount. FIG. 3 is a view showing an outline of the composite material of the present invention. In the composite material (2), carbon and / or graphitic fibers (1) are two-dimensionally oriented in a matrix (3) made of copper or a copper alloy. Are randomly oriented.

The composite material of the present invention has a low coefficient of thermal expansion in the plane direction. When applied as a substrate for a semiconductor device, the coefficient of thermal expansion is suitably 5 to 11 ppm / ° C., depending on the form of the semiconductor device.
-9.0 ppm / ° C is preferable, and the low thermal expansion coefficient in the plane direction of the composite material of the present invention can meet such a requirement.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The aspect ratio and volume ratio of the carbon and / or graphitic fibers of the present invention have been described above. The diameter of the carbon and / or graphitic fibers is preferably 5 to 20 μm, and is preferably used. Is 8 to 12 μm. Its length exceeds 40 μm. The upper limit of the average fiber length is determined by its aspect ratio (fiber length / fiber diameter).

The matrix of the present invention is copper or a copper alloy. As the matrix, only copper may be used, but copper or a copper alloy obtained by further adding one or more of Mo, W, Cr, Ag, and ceramic particles to copper may be used. Depending on the application, for example, one or more of high melting point metals such as Mo, W, and Cr are added for the purpose of increasing the strength. Further, ceramic particles are added. Ag or the like may be added to improve heat resistance.

In the method for producing a composite material of the present invention, carbon or graphite fibers are mixed with a powder mainly composed of copper as a matrix by a method such as a ball mill. As a matrix, Mo, W, Cr, Ag is added to Cu.
The raw material mixture obtained by adding one or more of the above powders or ceramic particles and mixing by a method such as a ball mill is put into a compacting mold and pressed to obtain a compression molded product of the mixture.

A compression molding of a mixture of carbon and / or graphitic fibers and a matrix powder is prepared by HIP.
The process of sintering and solidifying using the (hot isostatic pressing) method will be described with reference to the drawings. 4 to 6 show a step of sintering and solidifying the compression molded product of the present invention by HIP. First, as shown in FIG. 4, carbon and / or graphite fibers (1) and matrix powder ( The side wall of the compression molded product (8) with (7) is loaded into a metal capsule composed of a bellows body (9), and the lids (11) and (12) and the bellows body (9) are subjected to electron beam welding in a vacuum. And vacuum sealed.

Stainless steel is mainly used as the material of the metal capsule whose side wall is formed of the bellows body (9). Among stainless steels, SUS304 is desirable from the viewpoint of weldability. In addition, a bellows body (9), lids (11) and (12)
Are preferably made of the same material. Further, the metal capsule whose side wall is formed of a bellows body may be cylindrical or rectangular cylindrical. A cylindrical shape is preferable in terms of uniformity of pressurization, and a rectangular cylindrical shape is preferable in terms of yield when a predetermined member is obtained from a billet. Further, the bellows body of the side wall of the metal capsule is illustrated as having an arc shape, but is not limited thereto, and may be a triangular bellows.

When the volume ratio of the carbon or graphite fiber is increased, the shape retention of the compression molded product is lost. Therefore, it is preferable to wrap the material with a thin copper plate or foil. For example, copper foil (13) is laid in advance along the inner surface of the compacting die, and a mixture of carbon or graphite fiber (1) and matrix powder (7) is filled therein and compacted. The compression molded product (8) of the green compact is given a form wrapped in a copper foil (13) so as to give shape retention,
As shown in FIG. 5, it is preferable that the side wall is loaded into a metal capsule constituted by a bellows body (9), and the lids (11) and (12) are closed by vacuum.

Next, as shown in FIG. 6, the side wall is loaded into the metal capsule of the bellows body (9), and the lid (11) (1)
The compression molded article (8) vacuum-sealed in 2) is HIPed. The bellows (9) of the side wall of the metal capsule contracts in the axial direction of its body. As the shrinkage proceeds, the strength in the plane direction perpendicular to the axis of the metal capsule body increases, but the shrinkage further proceeds in the axial direction. As a result, the same pressure shrinkage occurs everywhere in the plane perpendicular to the axis, so that the volume ratio and orientation of the fibers (1) made of carbon or graphite are the same in this plane. By pressurizing and contracting in the uniaxial direction as described above, the fiber (1) made of carbon or graphitic material is oriented in a plane perpendicular to the direction of the contraction axis, and carbon and / or graphitic fiber is formed in the matrix (3). (1) is randomly oriented in the two-dimensional plane direction, and the composite material of the present invention can be easily obtained with a high yield.

The composite material of the present invention is compressed and uniaxially contracted, so that the matrix (3) contains carbon and / or carbon.
Alternatively, the graphitic fibers (1) are randomly oriented in the two-dimensional plane direction.
(B). As shown in FIG. 7 (a), a metal capsule (23) is charged with a compression-molded product of carbon / graphitic fiber (1) and matrix powder (20), and a lid (2) is formed.
1) Vacuum seal in (22). When this was subjected to HIP processing, as shown in FIG. 7B, the center portions of the metal capsule (23) and the lids (21) and (22) were preferentially deformed, and depending on the state of the deformation. In addition, the orientation of the fiber (1) was largely varied as a whole.

Therefore, in the production of the composite material of the present invention, a metal capsule having a bellows-like side wall is contracted in a uniaxial direction by hot isostatic pressing (HIP method) to remove carbon and / or graphite from the material. The fibers are oriented in a direction perpendicular to the shrinking direction. Even when a metal capsule having a bellows-like side wall is used, nonuniform capsule deformation may occur. For example, as shown in FIG. 8, the side wall of the compression-molded product is loaded into the metal capsule of the bellows body (9) by HIP treatment, and the side wall of the compression-molded product is vacuum-sealed with the lids (17) and (18). Although it contracts in the axial direction of the body composed of the bellows body (9), the central part of the lids (17) and (18) may be deformed, and the orientation of the fiber (1) may vary as a whole. In order to cope with the occurrence of such non-uniform deformation, the lid of the metal capsule is made twice or more the thickness of the bellows forming the side wall, so that the bellows forming the side wall is given priority over the lid. To sufficiently increase the packing density. With this configuration, it is possible to prevent a large pressure from being applied to the lid until the packing density is sufficiently increased, so that the dent of the lid can be suppressed.

Instead of making the lid of the metal capsule more than twice the thickness of the side wall bellows, a spacer may be used. For example, as shown in FIG. 9, a copper foil (1) of carbon and / or graphitic fiber (1) and matrix powder (7) is used.
The compression molded product (8) wrapped in 3) is loaded into a metal capsule of the side wall bellows (9), and a spacer (14) is put therein.
Cover with lids (11) and (12) and vacuum seal. Oxygen-free copper and graphite are preferable as the material of the spacer. This is HIP
When processed, as shown in FIG. 10, the side wall bellows (9) of the metal capsule shrinks in one axis direction and the matrix (3)
Then, the carbon and / or graphitic fibers (1) are randomly oriented in the two-dimensional plane direction. Further, in FIG. 9, the spacer to be inserted into the metal capsule is disposed on the compression molded product, but may be disposed above and below the compression molded product.

The case of using the composite material of the present invention comprising a matrix of carbon and / or graphite fibers and copper or a copper alloy as a substrate for a semiconductor device will be described with reference to FIG. The composite material of the present invention is one in which carbon and / or graphitic fibers are randomly oriented in a two-dimensional plane direction. Such a composite material is made such that the fibers are oriented in the plane direction of the semiconductor substrate. For semiconductor devices.

Specifically, as shown in FIG. 11, the composite material of the present invention is cut out so that the fibers are oriented in the plane direction of the substrate, processed into a predetermined shape, and used as a semiconductor device substrate (4). . A plating layer made of Ni, Au, Pd, or the like is formed on the semiconductor device substrate (4) as necessary,
The semiconductor element (6) is mounted thereon. The semiconductor device substrate (4) is bonded to a package envelope (5) made of alumina, Kovar, or the like.

As described above, the composite material of the present invention is used as a substrate for a semiconductor device. By controlling the aspect ratio and the fiber volume ratio, it is possible to obtain a thermal expansion coefficient suitable for bonding to various semiconductor package materials. it can. Therefore,
It is possible to suppress warpage or the like caused by a difference in thermal expansion when the substrate is joined to an envelope of a package made of alumina, Kovar, or the like, and it is possible to join a terminal made of glass ceramic without warping. In addition, since a thermal stress generated between the semiconductor chip and the heat-generating semiconductor chip can be reduced, a highly reliable semiconductor device can be obtained.

[0040]

Embodiment 1 A first embodiment of the present invention will be described with reference to FIGS. 5, 6 and Tables 1 and 2. FIG. First, fiber diameter 10μm,
Graphite fiber having an average fiber length of 200 μm and an average diameter of 20 μm
A predetermined weight of fiber and copper powder are weighed and mixed using a copper powder having a thickness of 50 m so that the volume ratio of the graphite fiber becomes 50%, and mixed by a ball mill. 35μ
m of copper foil was placed in a metal mold, and pressed under a pressure of 1 t / cm ² to form a compression molded product. The filling rate of this compression molded product (the ratio of the mixture of fiber and copper powder to the volume of the compression molded product) was about 40%.

Next, the compression molded product formed as described above is loaded into a metal capsule as shown in FIG. A compression molded product (8) of the graphite fiber (1) wrapped in the copper foil (13) and the copper powder (7) serving as a matrix was prepared with an inner diameter of 65 mm.
A metal capsule having a thickness of 0.6 mm and a bellows pitch of 10.0 mm and having a bellows-like side wall made of SUS304 and having a bellows-like side wall (9) is placed in a metal capsule.
1) (12) was vacuum-sealed by electron beam welding in vacuum.

Next, HIP treatment was performed under the conditions of 1500 atm and 1000 ° C. for 2 hours. As shown in FIG. 6, the bellows-like side wall (9) of the metal capsule was uniformly crushed along the axial direction of the cylinder by the HIP treatment, and the compression molded product was contracted in one axial direction. The compression molded product (8) having a height of about 60 mm was shrunk in the uniaxial direction to obtain a fiber reinforced composite material having a height of about 25 mm. The graphitic fibers (1) were randomly oriented in a two-dimensional plane direction in the copper matrix (3).

As a comparative example, HIP processing was performed as shown in FIGS. 7 (a) and 7 (b). As in the first embodiment,
A compression molded product is formed, and the compression molded product of the graphite fiber (1) and the copper powder (20) serving as a matrix is placed in a cylindrical metal capsule (23) having an inner diameter of 65 mm and a thickness of 0.6 mm,
Vacuum sealing was similarly performed with lids (21) and (22). This is 15
HIP treatment was performed under the conditions of 00 atm and 1000 ° C. for 2 hours. After the processing was completed, these were taken out of the HIP device.
As shown in FIG. 7 (b), the central part of the metal capsule (23) and the lids (21) and (22) has a large concave and irregular shape, and the orientation of the fiber (1) is generally changed according to the deformation state. Was widely scattered.

With respect to the composite materials of Example 1 and Comparative Example, samples having a diameter of 9 mm and a thickness of 4 mm were taken every 1 cm from the center. The sample was taken so as to be perpendicular to the cylinder axis direction of the HIP-treated metal capsule. Table 1 shows the measured densities (g / cm ³ ) of the samples of Example 1 and Comparative Example, and Table 2 shows the measured thermal conductivity (W / mK) by the laser flash method. .

[Table 1]

[Table 2]

As is clear from Table 1, in Example 1, the sampling positions were 0 cm and 1 cm from the center.
Each of 2 cm and 3 cm has a density of 5.55 (g / cm
³ ) It is constant. On the other hand, in the comparative example, the density varies. Further, in Example 1, the thermal conductivity shown in Table 2 is almost constant regardless of the sampling position. On the other hand, in the comparative example, variation occurs.

From the results of Tables 1 and 2, it can be said that the volume ratio of copper in the fiber and the matrix is constant in Example 1 since the density is constant regardless of the sampling position. In addition, since the thermal conductivity is constant, it can be said that the orientation state of the fibers is the same in any direction perpendicular to the compression axis regardless of the sample collection position. On the other hand, in the comparative example, the density also varied, and the thermal conductivity further varied. From this, as shown in FIG. 7 (b), it can be seen that the volume ratio and orientation of the fibers greatly differ depending on the sampling position due to the irregular deformation of the capsule.

The sample of Example 1 was dissolved using an acid, and the average aspect ratio was 10.2. The raw material graphite fiber has a fiber diameter of 10 μm and an average fiber length of 200 μm. The average aspect ratio of the composite material obtained by mixing in a ball mill, compression molding by dry press, or HIP is 10%. .2.

[0048]

Embodiment 2 A second embodiment will be described with reference to FIGS. 12 (a) and 12 (b) and FIGS. 13 (c) and 13 (d). FIG. 12 (a)
13 (b) and FIGS. 13 (c) and 13 (d), the horizontal axis represents the aspect ratio, and the vertical axis represents the volume fraction of carbon and / or graphite. Fiber diameter 10 μm as carbonaceous fiber, Cu-
Composite materials having various aspect ratios and various volume ratios were produced in the same manner as in Example 1 using a 20 vol% Mo alloy as a matrix. This was heat-treated at 850 ° C. for 2 hours in a reducing atmosphere, and its deformation behavior was investigated. Further, the thermal expansion coefficient was measured, and it was examined whether the value was an appropriate value (5 to 11 ppm). Based on these results, it was examined whether each composite material had appropriate characteristics as a substrate for a semiconductor device.

FIG. 12 (a) shows the produced composite material with a circle. FIG. 12 (b) shows the deformation behavior due to the heat treatment. The mark “○” indicates that the deformation is not performed or the deformation is slight, and the mark “X” indicates that the deformation is remarkable or broken. FIG. 13 (c) shows the deformation behavior due to thermal expansion. The mark ○ indicates an appropriate value (5 to 11 ppm), and the mark x indicates too high or too low. FIG. 13 (d) shows the results of the comprehensive evaluation.
The mark is unsuitable as a substrate for a semiconductor device. FIG.
As is clear from the results shown in (a), (b) and FIGS. 13 (c) and (d), it is possible to have suitable characteristics only when the aspect ratio and the volume ratio are within the ranges specified in the present invention. I understand.

[0050]

Embodiment 3 A third embodiment will be described with reference to FIG. Graphite fibers having a fiber diameter of 10 μm and an average fiber length of 200 μm and copper powder having an average diameter of 10 μm were blended so that the volume ratio of the graphite fibers became 60%, and a composite material was produced in the same manner as in Example 1. When the aspect ratio was determined in the same manner as in Example 1, it was 7.5. This composite material was cut out so that the orientation surface of the graphitic fibers was in the plane direction, and as shown in FIG. 11, an envelope (5) made of alumina was brazed to a semiconductor device substrate (4) by Ag brazing. . At this time, no warpage or the like was observed in the substrate (4). Further, the semiconductor element (6) was attached thereto, and 500 temperature cycles of −40 ° C. → 125 ° C. were performed. As a result, no peeling of the semiconductor element (6) from the substrate (4) was observed.

[0051]

[Embodiment 4] A fourth embodiment will be described with reference to FIGS.
This will be described with reference to Table 4. The raw material mixture was mixed to form a compression molded product in the same manner as in Example 1 described above, and the same HIP treatment as in Example 1 was performed. As shown in FIG. 5, one of the bellows body cylinders (9) having a side wall having an inner diameter of 150 mm, a wall thickness of 1.0 mm, and a pitch of 15 mm (see FIG. 5). And encapsulated in a vacuum with lids (11) and (12) each having a thickness of 2.0 mm.

The other is shown in Tables 3 and 4 under “Lid Thickness 0.6”.
mm + spacer ”), as shown in FIG. 9, the side wall of the compression molded product was 150 mm in inner diameter, 1.0 mm in thickness, and 15 mm in pitch.
A 10 mm thick spacer (1) made of oxygen-free copper
4) was put in, and lids (11) and (12) each having a thickness of 0.6 mm were sealed in a vacuum. Further, (see Table 3 and Table 4, “Lid Thickness 0.
As shown in FIG. 8, the compression-molded product was placed in a metal capsule consisting of a bellows-shaped cylinder (9) having an inner diameter of 150 mm, a wall thickness of 1.0 mm, and a pitch of 15 mm.
6 mm lids (17) and (18) were placed and vacuum sealed. In each case, SUS304 was used as the material of the metal capsule and the lid of the bellows body.

As a result of the HIP processing, when the “lid thickness is 2.0 mm” shown in FIG. 5, the lid (1
1) and (12) were parallel to each other, no dents or the like were observed, and the compression molded product shrunk in one axis direction. In the case of “cover thickness 0.6 mm + spacer” shown in FIG. 9, the cover thickness is 0.6 mm. However, since a 10 mm thick spacer is inserted, dents and the like occur as shown in FIG. 10. Did not. On the other hand, in the case of “cover thickness 0.6 mm”, the center portions of the covers (17) and (18) were deformed as shown in FIG. The deformation was such that the central portions of the lids (17) and (18) were depressed by about 3 mm with respect to the peripheral portions.

For these materials, samples were taken in the same manner as in Example 1 and the density and the thermal conductivity were measured.
Table 3 shows the density (g / cm ³ ), and Table 4 shows the thermal conductivity (W / m ³ ).
K).

[Table 3]

[Table 4]

From the results shown in Tables 3 and 4, it was found that “the lid thickness was 2.0 m.
“m” and “cover thickness 0.6 mm + spacer” are constant regardless of the sampling position, so that the volume ratio of fiber to copper in the matrix is constant, and the fiber orientation in any direction perpendicular to the compression axis It can be said that the state is the same and the thermal conductivity is constant. In contrast, “Lid thickness 0.6
In the case where a dent of “mm” occurred, the density also varied, and the thermal conductivity also varied.

[0056]

As described above, according to the composite material and the method for producing the same of the present invention, the composite material is reinforced by carbon and / or graphite fibers, has a low coefficient of thermal expansion in the plane direction, and has a sintered body. This has the effect that the internal stress due to solidification is small and there is no danger of deformation or breakage due to heat history.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between an aspect ratio and a volume ratio of the present invention.

FIG. 2 is a diagram showing a relationship between an aspect ratio and a volume ratio according to the present invention.

FIG. 3 is a diagram showing an outline of the composite material of the present invention.

FIG. 4 illustrates an embodiment and an example of the present invention.

FIG. 5 illustrates an embodiment and an example of the present invention.

FIG. 6 is a diagram illustrating an embodiment and an example of the present invention.

FIG. 7 shows a comparative example.

FIG. 8 shows a comparative example.

FIG. 9 illustrates an embodiment and an example of the present invention.

FIG. 10 illustrates an embodiment and an example of the present invention.

FIG. 11 illustrates an embodiment and an example of the present invention.

FIG. 12 is a diagram illustrating a relationship between an aspect ratio and a volume ratio according to an example of the present invention.

FIG. 13 is a diagram illustrating a relationship between an aspect ratio and a volume ratio according to an example of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Carbon or graphite fiber 2 Composite material 3 Matrix 4 Semiconductor device substrate 5 Semiconductor device envelope 6 Semiconductor element 7 Matrix powder 8 Compression molded product 9 Bellows 11, 12 Lid 13 Copper foil 14 Spacer

Claims (6)

[Claims] 1. A carbon and / or graphite fiber and a matrix made of copper or a copper alloy, wherein the carbon and / or graphite fiber has a length exceeding 40 μm, and has an aspect ratio and The volume ratio A shown in FIG.
(4,75), B (10,75), C (30,55),
D (30, 25), E (20, 25), F (4, 45)
A composite material comprising carbon and / or graphitic fibers and a matrix of copper or a copper alloy, characterized by being randomly oriented in a two-dimensional plane direction within a range surrounded by the above-mentioned points. 2. The carbon and / or carbon according to claim 1, wherein the composite material is used as a substrate for a semiconductor device.
Or, a composite material comprising a graphite fiber and a copper or copper alloy matrix. 3. A compression-molded product of a mixture of carbon and / or graphite fibers and a matrix powder is loaded into a metal capsule having a bellows-like side wall, degassed, sealed, and hot isostatically pressed. The metal capsule in which the compression molded product is sealed is contracted in one axis direction.
Or a method for producing a composite material comprising a carbon and / or graphite fiber and a matrix of copper or a copper alloy according to 2. 4. The carbon and / or graphite according to claim 3, wherein the thickness of the lid portion of the metal capsule is at least twice the thickness of the side wall portion of the bellows-shaped metal capsule. A method for producing a composite material comprising a fiber and a matrix of copper or a copper alloy. 5. The carbon- and / or graphitic fiber and copper or carbon-containing material according to claim 3, wherein the compression-molded product is charged into a metal capsule having a bellows-like side wall, a spacer is put in, and the container is sealed after deaeration. A method for producing a composite material comprising a matrix of a copper alloy. 6. A compression-molded product of a mixture comprising a powder of carbon and / or graphite and a powder of a matrix, which is wrapped with a thin copper plate or foil. 5. A method for producing a composite material comprising a carbon and / or graphite fiber and a matrix of copper or a copper alloy according to item 1.