JP2001180919A - Silicon carbide-carbon composite powder and its composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a silicon carbide composite powder with good compactibility in order to make a metal-silicon carbide composite material superior in both heat conductivity and machineability. SOLUTION: A silicon carbide-carbon composite powder, composed of α-type silicon carbide and carbon particles of which surface is coated with a film of α-type silicon carbide over 1 μm thickness, can be obtained by blending Si powder with C powder whose average particle diameter is larger that 10 μm in the ratio that satisfies the formula, 224.79x-0.78<y (x is the average diameter of C particle and y is the Si powder volume) and giving heat treatment at a high temperature. An excellent composite material comparable to the conventional Al-Si C composite material in heat conductivity and superior to that in machineability can be made of this powder by blending it with aluminum or other metal powders so that the ratio of the silicon carbide-carbon composite powder becomes 25 to 90% in the composition, and then by compacting and sintering the blended powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon carbide-carbon composite material having a high thermal conductivity useful for electronic equipment such as semiconductor devices and the like, and a carbon material used as a raw material thereof. The present invention relates to a semiconductor device using a silicon-carbon based composite powder and a composite material.

[0002]

2. Description of the Related Art In recent years, market demands for high-speed operation and high integration of semiconductor devices have been rapidly increasing. At the same time, the heat radiation board for mounting the semiconductor element of the device has been required to further improve the thermal conductivity in order to more efficiently release the heat generated from the element. In addition, other members in the same device and the same device arranged adjacent to the same substrate
In order to further reduce the thermal strain between them and the (peripheral member), it is also required to have a thermal expansion coefficient closer to them. Specifically, Si usually used as the semiconductor element, the thermal expansion coefficient of GaAs are each ^{4.2 × 10 -6 /℃,6.5×10 -6 / ℃} ,
Since that of alumina ceramics usually used as an envelope of a semiconductor device is about 6.5 × 10 ⁻⁶ / ° C., it is desired that the thermal expansion coefficient of the substrate be close to these values.

[0003] With the remarkable expansion of the application range of electronic equipment in recent years, the range of use of semiconductor devices has been further diversified. For this reason, the heat dissipation board used in these devices improves its thermal conductivity,
It is important to enhance the matching of the coefficient of thermal expansion with that of the peripheral members.

[0004] Conventionally, such a substrate is made of, for example, Cu.
-W-based and Cu-Mo-based composite alloys have been used. These substrates have a problem that the cost is high and the weight is large because the raw material is expensive. Therefore, recently, various types of composite materials composed of metal and ceramics have been researched and developed as inexpensive, lightweight, and highly thermally conductive materials. For example, taking a composite alloy containing aluminum (hereinafter simply referred to as Al) and silicon carbide (hereinafter simply referred to as SiC) as main components, for example,
It is industrially advantageous in that the raw materials are relatively inexpensive, lightweight and have high thermal conductivity. The density of pure commercially available pure Al and SiC alone is 2.7 g / cm ³ , respectively.
About 3.2 g / cm ³ , and the thermal conductivity was 2
It is about 40 W / m · K and about 300 W / m · K,
If the purity and defect concentration are further adjusted, the level of the thermal conductivity is expected to be further improved. The thermal expansion coefficients of pure SiC alone and Al alone are 4.2 ×
It is about 10 ⁻⁶ / ° C. and about 24 × 10 ⁻⁶ / ° C. By compounding them, the thermal expansion coefficient can be controlled in a wide range. In view of the above, this material has received particular attention.

[0005] Such an Al-SiC-based composite alloy and its manufacturing method are described in (1) JP-A-1-501489, (2) JP-A-2-243729, and (3) JP-A-6
1-222668 and (4) JP-A-9-1577.
No. 73 is disclosed. (1) relates to a method in which Al in a mixture of SiC and Al is melted and solidified by a casting method. (2) and (3) are both Si
The present invention relates to a method of infiltrating Al into voids of a C porous body. (3) relates to a so-called pressure infiltration method in which Al is infiltrated under pressure. Also, (4) relates to a method of sintering a compact of a mixed powder of SiC and Al or a hot-pressed compact in a mold and subjecting the compact to a liquid phase sintering at a temperature equal to or higher than the melting point of Al in a vacuum. It is.

Japanese Patent Application Laid-Open No. 10-335538 discloses that (5) a liquid phase sintering method having a thermal conductivity of 1
An aluminum-silicon carbide composite material of 80 W / m · K or more is presented. This composite material is, for example, 10-70
After forming a mixed powder of the particulate SiC powder and the Al powder in the amount of 100% by weight, it contains 99% or more of nitrogen and has an oxygen concentration of 200%.
ppm or less, in a non-oxidizing atmosphere with a dew point of -20 ° C or less,
Obtained by a process of sintering at 600 to 750 ° C.
JP-A-10-280082 discloses that (6) its thermal expansion coefficient is 18 × 10 ⁻⁶ / ° C. or less and its thermal conductivity is 23.
A so-called net-shaped aluminum-silicon carbide based composite material having a size of 0 W / m · K or more and a size after sintering is close to a practical size is also proposed. Further, the present inventors have proposed in Japanese Patent Application No. 10-41447 a method (7) for producing the same composite material by combining the normal pressure sintering method and the HIP method. According to this, for example, a compact of Al-SiC-based mixed powder in which 10 to 70% by weight of particulate SiC is mixed is placed in a non-oxidizing atmosphere containing 99% or more of nitrogen gas at 600 ° C or more and a melting temperature of Al or less. Pressureless sintering in the temperature range and hot forging or sealing the sintered body in a metal container
By performing P, it is homogeneous and its thermal conductivity is 200 W /
It was introduced that an aluminum-silicon carbide composite material having a mK or more can be obtained.

Further, (8) Japanese Patent Application Laid-Open No. 9-157773 discloses a method of hot-pressing a mixture of (8) an Al powder and a SiC powder to simultaneously perform molding and sintering. The method is as follows: Al 10 to 80% by volume, balance SiC
And mixed powder at a temperature not lower than the melting point of Al 500
The hot pressing is performed at a pressure of kg / cm ² or more. According to this method, an aluminum-silicon carbide composite material having a thermal conductivity of 150 to 280 W / m · K is obtained. The present inventors have already filed Japanese Patent Application No. 10-260003.
After pre-heating the compact rapidly in No., while suppressing the production of aluminum carbide by high-speed hot forging,
It introduces that a dense and high thermal conductive Al-SiC-based composite material can be obtained.

[0008]

The method of manufacturing a composite material containing a metal and silicon carbide as main components has been described above by taking the Al-SiC system as an example. The sintering and infiltration methods resulting in have been of particular interest. Among the methods classified as the sintering method, there is the hot forging method described above. This method is the most suitable method for obtaining a dense and high thermal conductive material among the methods described above. However, in any of the above-mentioned methods including this method, since high hardness silicon carbide is usually contained, the compressibility at the time of molding the raw material powder is poor. Therefore, high pressure must be applied, and the abrasion of the mold becomes severe. This is the same for the hot forging die. In many cases, finishing processing of the material after compounding is necessary, but in this case, the problem of difficult processing is inevitable. Such a problem,
In particular, when the shape of the product is complicated or when the content of silicon carbide is large, it becomes remarkable.

In order to solve these difficult-to-process problems including powder compaction, composite materials comprising carbon and aluminum have been developed. If you choose carbon powder that is not as hard as diamond, its mixture with aluminum powder,
This is because the compressibility during molding is good and the final finish workability is also excellent. In addition, if the content of diamond is small, this problem becomes relatively mild. Therefore, such a material is a material that can solve the above-described problems of mold abrasion during molding and forging and difficult processing during finishing. However, on the other hand, aluminum and carbon are naturally easy to react with each other.
₄ C ₃ (aluminum carbide) is easily generated. Furthermore, Al ₄
C ₃ Since liable to be corroded by water, when used in an atmosphere moist composite material, sometimes Al ₄ C ₃ can not be maintained the shape of the eluted material. Attempts have been made to form a thin layer on the carbon surface to suppress the reaction with aluminum. For example, a coating layer of SiC has been formed on the surface of diamond particles.

[0010] Silicon carbide (Si) is uniformly formed on the surface of carbon particles.
There are several possible means for coating C). For example, there is a method such as a gas phase method of depositing SiC on the surface of carbon particles while flowing silicon tetrachloride (SiCl ₄ ) gas and methane (CH ₄ ) gas. However, in order to uniformly coat the surface of the carbon particles with SiC, it is necessary to allow these gases to enter the gaps between the carbon particles without unevenness. This is extremely difficult and, if possible, very costly. In addition, there is a coating by physical vapor deposition, but in this case, the coating can be uniformly applied only on a simple surface such as a flat plate.

[0011]

An object of the present invention is to solve the above-mentioned problems. That is, the present invention
Metals that combine high thermal conductivity comparable to l-SiC-based composite materials and remarkably superior machinability compared to the same materials.
It is intended to provide a silicon carbide-carbon based composite material. The present invention also provides a silicon carbide-carbon based composite powder capable of producing such a composite material with high productivity. Silicon carbide-carbon-based composite powder provided by the present invention, a part of the silicon carbide powder of the starting material is replaced with carbon powder,
The surface is covered with a thin film of silicon carbide. That is, the composite powder of the present invention is composed of α-type silicon carbide particles and α-type silicon carbide on the surface and has a thickness of 1 μm or more, and preferably a thickness of 1 to 3 μm.
m is a composite powder containing carbon particles on which a film m is formed. The amount of carbon particles in the composite powder is 25 to 90% by volume.

The silicon carbide-carbon composite material of the present invention is obtained by dispersing each particle of the composite powder in a metal matrix, wherein α-type silicon carbide particles are dispersed as a dispersed phase in the metal matrix; Carbon particles whose surfaces are coated with α-type silicon carbide have a total content of 30 to 80
It is a material that is dispersed by volume% and has a relative density of at least 80%. In a preferred embodiment of the present invention, the dispersed phase is 60 to 80% by volume dispersed and has a relative density of at least 90% or more. The “relative density” as used in the present invention is a ratio (%) of the measured density to the theoretical density. Particularly preferred matrix metals include aluminum or aluminum alloys. These materials are
It has a high thermal conductivity of usually 150 W / m · K or more, especially 300 W / m · K or more. Note that the present invention also includes a semiconductor device using these materials.

In the method for producing a composite powder according to the present invention, the silicon powder and the carbon powder are mixed with each other so that the carbon powder has an average particle diameter of x (μm);
When the amount of silicon is y (% by weight), 244.79x ^-0.78
<Y, preferably y <(282.
97x ^-0.61 +1)
A step of mixing these powders to form a mixture; and a step of heat-treating the mixture in an inert gas at a temperature in the range of 2000 to 2400 ° C. to form a composite powder. In this case, as a raw material carbon powder, a mesophase pitch powder at 3000 ° C.
There is a method using carbon powder, pyrolytic graphite or natural graphite powder graphitized at the above temperature.

The method for producing a composite material according to the present invention comprises the steps of mixing 30 to 80% by volume of the composite powder obtained by the above steps and 20 to 70% by volume of the metal powder to form a mixed powder; To form a compact, and sintering the compact at a temperature equal to or higher than the melting point of the metal component in the compact to form a sintered body. Further, the step of forming a sintered body includes a method of heating a formed body or a sintered body once sintered at a temperature equal to or higher than the melting point of the metal component, and then performing hot forging. In the present invention, aluminum or an aluminum alloy is used as a preferable matrix metal.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the composite powder of the present invention, a part of silicon carbide powder is replaced by carbon powder. In addition, a thin α of 1 μm or more, preferably 1 to 3 μm
A coating layer of type SiC is formed. The amount of carbon particles in the composite powder is 25 to 90% by volume. By using a carbon powder of such a form, when a composite with a metal is intended by using this powder, a reaction between the metal and the carbon can be suppressed. When the thickness of the coating is less than 1 μm, a reaction between the carbon particles and the metal at the time of compounding with the metal cannot be suppressed. When the thickness is increased, the high thermal conductivity of the carbon particles cannot be sufficiently utilized, so that the thickness is desirably controlled in the range of 1 to 3 μm.

The composite powder of the present invention comprises the carbon particles described above,
α-type silicon carbide particles. When silicon carbide is deposited on carbon powder by the procedure of the present invention, silicon carbide formed on the surface of carbon particles becomes α-type crystal-based particles. Note that α
Of the molds, those of the 6H type are particularly preferred.

In the silicon carbide-carbon composite material of the present invention, particles of the composite powder are dispersed as a dispersed phase in a metal matrix in an amount of 30 to 80% by volume. The relative density of the material is at least 80% or more. If the amount of dispersion is less than 30% by volume, the amount of metal increases and it becomes difficult to maintain the shape during sintering. On the other hand, if it exceeds 90% by volume, the wettability between the metal and the composite powder particles decreases, and the thermal conductivity after the composite decreases. If the relative density is less than 80%, the thermal conductivity is significantly reduced. In order to obtain a material having higher thermal conductivity and a relatively low coefficient of thermal expansion, it is desirable that the dispersion amount of the α-type silicon carbide particles is 60 to 80% by volume and the relative density is at least 90% or more. .

The matrix metal is a metal having excellent heat conductivity. For example, aluminum (Al), copper (Cu),
A material mainly containing a metal such as silver (Ag), gold (Au), or silicon (Si) is selected. In particular, aluminum (A
l) as a main component, that is, aluminum (A
l) or an alloy thereof is preferred. This is because by using aluminum as a main component, a lightweight and inexpensive composite material can be obtained.

The composite material of the present invention is usually 150 W / m ·
It has a high thermal conductivity of K or more. Further, depending on the amount of the dispersed particles and the method for preparing the same, a material having a high thermal conductivity of 250 W / m · K or more, or even 300 W / m · K or more can be obtained. Therefore, the material of the present invention can be advantageously used as a heat sink of a semiconductor device or a peripheral member thereof. For example, it is possible to provide a semiconductor device having a relatively large heat dissipation capacity, such as a power module used for power control of a drive unit of a vehicle such as an automobile or a machine tool.

Next, a method for producing the silicon carbide-carbon composite powder of the present invention will be described. The carbon powder of the above form in the composite powder of the present invention is obtained by converting the particle surface of the carbon powder into SiC. First, a mixture of silicon (Si) powder and carbon powder is prepared. It is desirable to use a carbon powder which has been graphitized. For example, natural or artificial graphite powder is good. In particular, those obtained by mesophase-based pitch graphitization at a temperature of 3000 ° C. or higher, pyrolytic graphite or natural graphite are preferable. In this case, assuming that the average particle size of the carbon powder is x (μm) and the silicon content is y (% by weight), the relationship of 244, 79x ^−0.78 <y is satisfied, and preferably y <(282. 97x
^Prepare both powders so as to satisfy the relationship of ^-0.61 +1). As the raw material silicon (Si) powder, it is not necessary to use a material having the highest possible purity, but a material containing a metal impurity element such as Al or Fe may be used. Also, the average particle size does not affect the thermal conductivity of the final composite. This is because after mixing with the carbon powder, the mixture is heated at a sufficiently high temperature to melt and sublime.

Next, this mixture is charged into a container of graphite or silicon carbide, and then heated in a first stage at a temperature of 1450 ° C. or more, which is the melting point of silicon (Si), in an atmosphere of an inert gas such as argon. Silicon (Si) melted by this heating
Reacts with the carbon particle surface to be converted to β-type SiC. The temperature is further raised and the second stage heating is performed at a temperature of 2000 ° C. or more. At this stage, the β-type SiC is transformed into α-type SiC whose crystal system is 6H. The rate of progress of this transformation increases as the temperature increases, but when it exceeds 2400 ° C., SiC
Is thermally decomposed and part of carbon is reprecipitated, so that the heating in the second stage is in the range of 2000 to 2400 ° C.

By using a raw material powder satisfying the above-mentioned relationship between the average particle diameter x of the carbon powder and the silicon amount y, α
The thickness of the type SiC coating is 1 μm or more, preferably 1 to 3 μm.
Control within the range of μm. That is, the amount of silicon used is adjusted in proportion to the specific surface area of the carbon particles as the raw material. For example, in order to form a SiC layer having an average thickness of 1.1 μm on the surface of spherical carbon particles having an average particle size of
0% by weight and 90% by weight of carbon. Further, for example, in order to form a SiC coating layer having the same average thickness on the surface of spherical carbon particles having an average particle diameter of 20 μm, the ratio of silicon is set to 26% by weight and carbon is set to 74% by weight.

The thermal conductivity of the composite material of the present invention depends on the average particle size of the carbon powder dispersed in the material. This also involves the thickness of the SiC coating layer on the surface. As the average particle size becomes smaller, the boundary area between the particles and the matrix metal increases, and as a result, the thermal conductivity of the composite material tends to decrease. On the other hand, if it gets too big,
Moldability tends to decrease, and high pressures tend to be required to make molded bodies, which also reduces the thermal conductivity of the composite material. Therefore, in the present invention, in order to obtain a composite material having excellent thermal conductivity, the correlation between the average particle diameter x of the carbon powder raw material used for preparing the composite powder and the amount y of Si used as the raw material of the SiC coating layer, Control to satisfy the relationship.

Using the composite powder obtained by the above procedure, the composite material of the present invention is produced by the following procedure. First, 30 to 80% by volume of the composite powder and 20 to 70% by volume of the metal powder to be a matrix are mixed to obtain a mixed powder. In order to obtain a higher thermal conductivity and a relatively lower coefficient of thermal expansion, it is desirable to adjust the amount of the composite powder to be 60 to 80% by volume and the balance to be a metal powder. The mixing method may be any known method. The mixed powder is desirably granulated by adding a small amount of an organic binder during or after mixing in order to improve the moldability.

Next, the mixed powder is formed. As a molding method, a known method is appropriately used depending on the shape of the molded body. Dry powder molding is the most efficient.

After that, if the molded body contains an organic binder, it is heated in a non-oxidizing atmosphere in advance to remove it, and then heated to a temperature not lower than the melting point of the contained metal in the non-oxidizing atmosphere. And sinter. This sintering step is preferably performed by hot forging. In this case, the preform is pre-heated in a non-oxidizing atmosphere at a temperature equal to or higher than the melting point of the contained metal, and then is charged into a mold and hot forged. Preheating is
For example, it is desirable to use a heating means such as a high-frequency induction heating method that can rapidly raise the temperature and equalize the temperature. This shortens the heating time (usually within a few minutes), so that even if there is an interface where the carbon particles and metal particles are in direct contact, the amount of low thermal conductive reactants generated there is suppressed. As a result, the usual sintering method (usually 3
As a result, a material having a high thermal conductivity can be obtained. In addition, the forging method can be performed in the air because the densification can be performed in a short time.

[0027]

Example 1 A carbon (C) powder shown in Table 1 and a commercially available silicon (Si) powder having an average particle diameter of 30 μm were prepared. In addition, "M" of the type indication of the carbon powder described in the "raw powder" column of Table 1
“G” is obtained by heat-treating a mesophase pitch in an argon gas at 3500 ° C. for 2 hours to obtain a powder composed of spherical graphite particles, and also indicates “TG” and “NG”.
Are commercially available pyrolytic graphite and natural graphite powders, respectively. Each of these powders was weighed out at the weight ratio described in the “Blending composition” column of the same table, and the average particle size of the C powder particles was determined using a ball mill of silicon carbide lining pot / ball. Each of them was dry-pulverized and mixed until the size was as described in the column of "Average Particle Size of C in". The weight ratio of each component powder in the mixed powder after drying was almost the initial mixing ratio as a result of the chemical analysis. The average particle size was confirmed by a particle size distribution measuring device using laser interference. These results
It is as described in the “mixed powder” column of the same table. Each of these powders was first placed in argon gas at atmospheric pressure at 1500 ° C. for 30 minutes.
After holding for 1 minute, the temperature was raised continuously, and
It was kept at the temperature described in the column for 2 hours and cooled naturally.
The average thickness of the SiC film on the surface of the carbon particles of the obtained composite powder was confirmed by observing the cross section with a transmission electron microscope. The volume ratio of the components in the powder was determined by analyzing the weight ratio of SiC to C in the powder, and the respective theoretical densities, that is, 3.2 g / cm ^{3 for} the former and 2.2 g for the latter.
/ Cm ³ . The results are also shown in the table.

[0028]

[Table 1]

[0029] From the above results, the average particle size x of the carbon powder in the mixed powder exceed 10 [mu] m, and a weight ratio y of this and Si powder, in particular of the aforementioned formula 244.79x ^-0.78 <y <
(282.79x ^-0.61 +1), and the heat treatment conditions are 200
It can be seen that carbon particles having a SiC film thickness in the range of 1 to 3 µm can be obtained within the range of 0 to 2400 ° C.

Example 2 Each of the composite powder samples shown in Table 1 and the powder mainly containing aluminum shown in Table 2 were mixed in a volume ratio shown in Table 3 using a rocking mixer. In Table 2, components inevitably contained in trace amounts are not described. These powders were dry-press-molded at a molding pressure shown in Table 3 into a shape having an outer diameter of 30 mm and a thickness of 3 mm. Thereafter, under each condition described in the same table, these compacts were preheated at 660 ° C. in a nitrogen atmosphere, immediately transferred into a die steel mold preheated to 450 ° C., and forged at a pressure of 900 MPa. . Further, a material which was separately heated and sintered at 660 ° C. for 2 hours in nitrogen was also prepared. The relative density of the obtained composite material (the value obtained by dividing the measured density by the theoretical density) and the thermal conductivity at 25 ° C.
A sample having a thickness of 0 nm and a thickness of 2 mm was cut out and confirmed by a laser flash method), and an average thermal expansion coefficient at 25 to 200 ° C (confirmed by a differential transformer method) was confirmed. The presence or absence of aluminum carbide (Al ₄ C ₃ ) in the material was confirmed by X-ray diffraction, and the results are also shown in Table 3. As described in Table 3, the presence or absence of the formation of aluminum carbide (Al ₄ C ₃ ) was reliably detected in the X-ray diffraction patterns of Samples 12, 14, 17 and 37,
Other samples could not be detected on the same pattern.

[0031]

[Table 2]

Grinding was carried out using a cemented carbide tool, and the workability of each sample was evaluated. The results are as shown in Table 3. The evaluation method was as follows: using a specimen of which the thermal conductivity was confirmed, an outer diameter of 20 m using a cemented carbide tool.
grinding one side of m until the thickness becomes 1 mm,
Thereafter, the wear amount of the flank of the tool is checked.
In this case, when the wear amount was less than 0.2 mm, the workability was evaluated as good (shown by ○ in Table 3), and the wear amount was 0.2 m.
Those having m or more were evaluated as having poor workability (indicated by X in Table 3). Samples 1, 5, 22, and 34 were judged to have poor workability, but the other samples were judged to be good. For comparison, an Al-SiC-based composite material having an SiC content of 70% by volume and a balance of Al under the same test conditions was also evaluated.

[0033]

[Table 3]

From the above results, it can be seen that SiC within the scope of the present invention
Using a C-based composite powder, a powder compact obtained by mixing the same with a metal mainly composed of Al at a volume ratio of 30 to 80% of the composite powder is formed at a temperature not lower than the melting point of the metal component in the compact. By sintering or forging, the thermal conductivity is 150 W / m
It can be seen that a composite material having a remarkably excellent machinability can be obtained with respect to an Al—SiC-based composite material having a K of not less than the same and having the same SiC amount.

Example 3 The same composite powder as Sample 2 of Example 1 and various metal powders shown in Table 4 were mixed in the same procedure as in Example 2, and the composition of the metal powder was 30% by volume and the balance of the composite powder was Was prepared. These powders were dry-molded in the same manner as in Example 2,
Each compact was hot forged under the respective conditions shown in Table 5. Note that Sample 27 is a sample using D for metal powder, and Sample 28 is a sample using E for metal powder. Table 5 also shows the results of evaluating the obtained composite material in the same manner as in Example 2.

[0036]

[Table 4]

[0037]

[Table 5]

From the above results, by mixing the metal powder of the main component other than aluminum with the composite powder of the present invention and forming a composite at a temperature equal to or higher than the melting point of the metal, a metal-carbonized material having excellent heat conductivity can be obtained. It can be seen that a silicon-carbon based composite material can be obtained.

Example 4 A power module semiconductor device as shown in FIG. 1 was manufactured from the above-described example samples using a heat-radiating substrate manufactured by the same procedure as samples 2 to 4 and 23 to 32. In FIG.
Is a heat dissipation substrate made of the material of the present invention, 2 is a small substrate made of electrically insulating aluminum nitride ceramics (thermal conductivity 170 W / m · K) brazed on the substrate, 3 is
The silicon semiconductor element 4 is a cooling structure made of an aluminum alloy that is mechanically fixed to a heat dissipation substrate. The upper and lower surfaces of the substrate 1 and the lower surface of the substrate 2 are plated with nickel.
On the upper surface of the substrate 2, a copper conductor circuit layer is formed via a W metallization layer and a nickel plating layer. At the interface between the substrate 1 and the cooling structure 4, a thin layer of silicone oil is formed in advance. The semiconductor elements are connected by Ag-Sn based solder. The connection between the members, especially around the periphery of the substrate 1, was good and there was no problem.

Using each assembly having such a configuration, 1000 cycles of a heating / cooling cycle of holding at -60 ° C. for 30 minutes and then holding at 150 ° C. for 30 minutes were performed. No deterioration was observed. From the above results, it has been found that the composite material manufactured by the method of the present invention can be used without any problem even when used for a member of a semiconductor device used under severe practical conditions.

It was also evaluated that the material of the present invention was mounted on a semiconductor device such as a personal computer having a lower output and a lower heat load than this type of module, but it was confirmed that there was no problem in its practical reliability. Was.

[0042]

As described above, according to the present invention,
After the Si powder and the C powder having an average particle size of more than 10 μm,
244. between the average particle size x of the former and the amount y of the former.
79x ^-0.78<Y, preferably y <(28
2.79x^-0.61+1)
By heat-treating this at a high temperature, SiC-C based
A composite powder with excellent heat conductivity and moldability can be obtained
You. 30-80% by volume of this powder and the balance of aluminum and other
Obtained by mixing with the composition with metal powder, molding and sintering
The composite material is compared with the conventional Al-SiC-based composite material.
In addition to showing high thermal conductivity comparable to that,
Remarkably superior in machinability compared to
It is a very useful material in industry.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a semiconductor device using a composite material of the present invention described in an example of the present invention.

[Explanation of symbols]

 1, heat dissipation substrate 2 made of composite material of the present invention 2, ceramics substrate 3, silicon semiconductor element 4, cooling structure

Claims (16)

[Claims] 1. Silicon carbide comprising α-type silicon carbide particles and carbon particles having a surface of α-type silicon carbide having a thickness of 1 μm or more formed thereon, wherein the amount of the carbon particles is 25 to 90% by volume. -Carbon-based composite powder. 2. The silicon carbide-carbon based composite powder according to claim 1, wherein said coating has a thickness of 1 to 3 μm. 3. In a metal matrix, as a dispersed phase,
A silicon carbide-carbon composite material in which α-type silicon carbide particles and carbon particles whose surfaces are covered with α-type silicon carbide particles are dispersed in an amount of 30 to 80% by volume and have a relative density of 80% or more. 4. The silicon carbide-carbon based composite material according to claim 3, wherein the dispersed phase is dispersed at 60 to 80% by volume and has a relative density of 90% or more. 5. The silicon carbide-carbon composite material according to claim 3, wherein the metal is aluminum or an aluminum alloy. 6. The silicon carbide-carbon composite material according to claim 5, which has a thermal conductivity of 150 W / m · K or more. 7. The silicon carbide-carbon composite material according to claim 5, which has a thermal conductivity of 250 W / m · K or more. 8. The silicon carbide-carbon composite material according to claim 5, which has a thermal conductivity of 300 W / m · K or more. 9. A semiconductor device using the silicon carbide-carbon composite material according to claim 3. 10. A silicon powder and a carbon powder having an average particle diameter of more than 10 μm are mixed, and the average particle diameter of the carbon powder is x.
([Mu] m), when the silicon content was y (wt%), 2 44.7
Preparing a mixture thereof such that 9x ^−0.78 <y is satisfied;
A heat treatment in a temperature range of 00 ° C. to form a composite powder. 11. The step of preparing the mixture,
Between the x and y, y <(282.97x
^The method for producing a silicon carbide-carbon based composite powder according to claim 10, wherein the mixture is adjusted so as to satisfy ^-0.61 +1). 12. The carbon powder according to claim 10, wherein the carbon powder in the step of preparing the raw material is a carbon powder obtained by graphitizing a mesophase pitch powder at a temperature of 3000 ° C. or more, pyrolytic graphite, or natural graphite. A method for producing a silicon carbide-carbon composite powder. 13. Mixing a silicon powder with a carbon powder having an average particle size of more than 10 μm, and setting the average particle size of the carbon powder to x
(Μm), when the amount of silicon is y (% by weight), 244.7
Preparing a mixture thereof so as to satisfy 9x ^-0.78 <y <(282.97x ^-0.61 +1), and subjecting the mixture to a heat treatment in an inert gas at a temperature in the range of 2000 to 2400 ° C to obtain a composite powder A step of mixing 30 to 80% by volume of the composite powder and 20 to 70% by volume of the metal powder to form a mixed powder; a step of forming the mixed powder to form a molded body; Sintering at a temperature equal to or higher than the melting point of the metal component to form a sintered body. 14. In the step of preparing the mixture,
Between the x and y, y <(282.97x
^The method for producing a silicon carbide-carbon composite material according to claim 13, wherein the mixture is adjusted so as to satisfy ^-0.61 +1). 15. The carbonization according to claim 13, wherein, in the step of forming the sintered body, the compact is pre-heated at a temperature equal to or higher than the melting point of the metal component in the compact and then hot forged. A method for producing a silicon-carbon composite material. 16. The method for producing a silicon carbide-carbon composite material according to claim 13, wherein the metal is aluminum or an aluminum alloy.