JP2001181066A - Silicon carbide-based porous body and composite material comprising aluminum and the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an SiC porous body preferable for a filter and to obtain an Al/SiC-based composite material having high thermal conductivity and preferable for a heat sink for a semiconductor device by compositing the body with Al or an Al alloy. SOLUTION: This SiC porous body is obtained by sintering SiC powder with C powder and has a three-dimensional skeleton sintered α-SiC hexagonal tabular particle, 30-60% porosity, 10-200 μm mean pore diameter, >=30 Mpa three-point bending strength and >=10 W/m.K thermal conductivity. The Al/SiC- based composite material of the SiC porous body infiltrated with Al or an Al alloy has 40-70 vol.% SiC based on the whole, >=200 W/m.K thermal conductivity at 20 deg.C and small coefficient of thermal expansion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an Al-based alloy having a high thermal conductivity and a low coefficient of thermal expansion, which is useful in a wide variety of fields such as various electronic and electrical devices, mechanical structural parts, and chemical devices.
The present invention relates to a Si-based composite material and a porous SiC body serving as a skeleton thereof.

[0002]

2. Description of the Related Art Porous ceramics, especially silicon carbide (S)
iC) A silicon carbide-based porous body having a three-dimensional skeletal structure in which particles are sintered and necked with each other via a grain boundary phase has attracted attention as various filters in recent years. Its main uses are directed to liquid filtration filters for recycling and drainage of semiconductor cleaning liquids, and particulate filters for purifying exhaust gas of automobile diesel engines.

In the case of the former liquid filtration filter,
Along with improving the ability to collect fine particles in the processing liquid and the processing ability to permeate the liquid, high corrosion resistance to the processing liquid is required. For this reason, attempts have been made to increase the porosity of ceramics having good corrosion resistance and to improve the average pore diameter and the structure of the pore diameter portion. In the case of the latter particulate filter, heat resistance and corrosion resistance under a high-temperature gas are required, as well as efficient collection of fine particulates in the processing gas and improvement of the ability to separate harmful gases. For this reason, improvements in ceramics similar to those described above are being promoted.

In addition, such a porous ceramic body includes:
When used as a filter or the like, it is necessary to have mechanical strength for maintaining the shape. In addition, particulate filters for purifying exhaust gas are required to have high thermal conductivity and low thermal expansion in the temperature range from room temperature to practical temperature in order to suppress deterioration of basic performance due to temperature rise of the filter itself. ing.

On the other hand, a ceramic porous material having such high thermal conductivity, low thermal expansion, and mechanical strength makes use of its characteristics to form a composite material which is composited with a metal. Has attracted attention as a material. As a promising candidate, the above-mentioned porous SiC body has been spotlighted as in the case of a filter.

[0006] As such a composite material, AC porous
There is a composite obtained by infiltrating l or Al alloy. Such an Al-SiC-based composite material is produced, for example, as follows. First, SiC powder is molded together with a binder, and this is sintered to form a porous body. Next, this S
By infiltrating molten Al or an Al alloy into the iC porous body, an Al-SiC-based composite material can be obtained. Such an Al-SiC-based composite material generally contains SiC in Al.
It has the structure of a particle-dispersed composite material in which particles are dispersed.

Although the above-mentioned conventional Al-SiC-based composite material has a thermal expansion coefficient close to the theoretical value of the thermal expansion coefficient applied to the particle-dispersed composite material, it has recently been used as a heat sink material for semiconductor devices. Therefore, there is a demand for a composite material having a smaller thermal expansion coefficient and a higher thermal conductivity.

[0008]

It has been studied to further reduce the coefficient of thermal expansion and increase the thermal conductivity of a conventional Al-SiC-based composite material having the structure of the above-mentioned particle-dispersed composite material. As a method for solving this, a porous body having a skeleton structure of SiC has been proposed.

For example, as reported on page 255 of "Summary of Powder and Powder Metallurgy Association (Fall 1999 Meeting)", first, SiC powder is molded together with a binder, and the resultant is molded in an inert gas. Baking at a temperature of 2000 ° C. or more. By this firing, a part of the SiC particles sublimates and gasifies, and when the SiC particles are re-folded as SiC, the SiC particles are sintered to form a SiC porous body having a skeleton structure. Melted Al or A is added to the porous SiC body having the skeleton structure.
By infiltrating the 1 alloy, an Al-SiC-based composite material can be obtained.

[0010] By forming the skeleton structure of the SiC particles in this way, even if the Al-SiC-based composite material has the same SiC content, the metal powder containing Al as a main component and the Si-based composite material have the same SiC content.
Al-based materials such as those obtained by a sintering method in which C powder is mixed and molded and sintered, and those obtained by a casting method in which SiC powder is poured into an Al melt and dispersed and solidified. The coefficient of thermal expansion is smaller than that of a so-called particle-dispersed composite material in which SiC particles are scattered in a matrix metal. This is because the thermal expansion of the Al portion is suppressed by forming the skeleton structure of SiC. Further, in the composite material having such a SiC skeleton structure, since the SiC particles having a high thermal conductivity are in a continuous phase, a higher thermal conductivity can be obtained than the particle-dispersed composite material.

However, even in the case of an Al—SiC-based composite material using such a porous SiC material having a skeleton structure of SiC particles, the thermal conductivity of the base SiC porous material itself is low, so that it is not suitable for a filter. Alternatively, the thermal conductivity is not sufficient for any use for semiconductor devices. That is, an Al-SiC-based composite material having such a skeleton structure usually has a continuous phase of SiC particles having a high thermal conductivity, and has a higher thermal conductivity than the particle-dispersed composite material. Nevertheless, nonetheless, for example, those described in the above summary of the lecture had a low thermal conductivity of about 170 W / m · K.

In view of the above circumstances, the present invention provides an SiC porous body having further improved thermal conductivity, and using the SiC porous body, has excellent mechanical strength and high thermal conductivity. -To provide a SiC-based composite material.

[0013]

In order to achieve the above object, the present invention provides a porous SiC body having a three-dimensional skeletal structure in which hexagonal plate-like α-type SiC particles are sintered and necked. The porosity is 30 to 60%, the average pore diameter is 10 to 200 μm, the three-point bending strength according to JIS is 30 MPa or more, and the thermal conductivity at 20 ° C. is 10 W / m · K.
It is characterized by the above.

Further, the Al—SiC-based composite material of the present invention using the above-mentioned porous SiC material comprises the above-mentioned porous SiC material,
It is composed of Al or an Al alloy impregnated in the iC porous body, SiC is 40 to 70% by volume of the whole, and the thermal conductivity at 20 ° C is 200 W / m · K or more and the average in the range of 20 to 200 ° C. The coefficient of thermal expansion y is −5.37 × ln (x) +25.10 <y <−8.04 × l in units of 10 ⁻⁶ / ° C.
n (x) +39.19 (in the formula, ln is a natural logarithm, and x represents a volume percentage of SiC)
Is within the range represented by

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a more robust SiC is obtained by devising a skeleton structure of a porous SiC material.
A skeletal structure of the particles was obtained. That is, as in the prior art,
Instead of firing C powder at high temperature, Si powder and carbon powder are mixed and fired at high temperature. At this time, a strong SiC particle skeletal structure can be produced by setting the compounding composition of each powder of Si and C to a slightly rich composition, that is, 71 to 73% by weight of Si as a whole.

Si and C react at a high temperature at which Si sublimates to form SiC. This reaction is caused by the melting of Si 1
Beginning at around 450 ° C., liquid Si and C powder react to form SiC. At this point, cubic 3C-type SiC is generated, but when the temperature further rises and exceeds 2000 ° C., the generated 3C-type SiC becomes hexagonal 6H-type SiC.
It is converted to C (α-type SiC), and becomes a hexagonal plate-shaped crystal as shown in the SEM photograph of FIG. 1 (the scale length shown in the figure corresponds to 200 μm). Simultaneously with the generation of the hexagonal plate crystal of SiC, the SiC particles are sintered and necked to form a three-dimensional skeleton structure.

When the content of Si is 70% by weight, SiC1
Although a 00% powder is produced, a strong skeleton cannot be obtained with this. If Si has a slightly higher composition, surplus Si becomes a gas, which acts to cause necking of the generated SiC particles. However, if the amount of excess Si is too large, a Si phase having a low thermal conductivity is generated between the SiC particles, and the thermal conductivity of the porous SiC body is reduced. Conversely, if the amount of Si is too small,
Sintering between SiC particles does not proceed. From this perspective,
When mixing Si powder and C powder, Si
It is mixed so as to be in a range of ７３73% by weight.

The mixed powder of the Si powder and the C powder is formed into a compact and then sintered in an atmosphere of an inert gas such as Ar. The sintering temperature must be 2000 ° C. or higher, and if it is lower than 2000 ° C., sintering does not proceed. On the other hand, if the sintering temperature exceeds 2400 ° C., the sublimation of SiC becomes intense and the yield decreases. In addition, since a stronger SiC porous body can be obtained as the pressure at the time of forming a molded body is higher, it is usually 500 to 700.
It is preferable to use a molding pressure of about MPa.

The SiC porous body thus obtained is
SiC produced by molding and sintering particulate SiC powder
Compared to a porous body, the bond between SiC particles is stronger, the mechanical strength is higher, and the thermal conductivity is higher. That is, generally, the thermal conductivity of the 6H-type SiC crystal changes depending on the crystal axis direction, the thermal conductivity is small in the c-axis direction perpendicular to the plate-like surface, and is small in the a-axis direction parallel to the plate-like surface. high. Empirically, the thermal conductivity in the c-axis direction is about 0.7 times that in the a-axis direction (High Temperatures-High Pressures, 1997, vol.2).
9, pages 73-79). For these reasons, in the SiC porous body of the present invention, as shown in FIG. 2, heat is mainly conducted along the plate-like surface of a hexagonal plate-shaped 6H-type (α-type) SiC crystal, and thus the SiC porous body The material itself has a very high thermal conductivity.

Although the thermal conductivity and strength of the porous SiC material vary depending on the pore diameter and porosity, in the present invention, the porosity is 30 to 60%, the average pore diameter is 10 to 200 μm, and JIS.
It becomes a SiC porous body having a three-point bending strength of 30 MPa or more and a thermal conductivity at 20 ° C. of 10 W / m · K or more in accordance with the standard.
The porosity of the SiC porous body can be controlled by changing the particle size distribution and compaction pressure of the raw carbon powder. The porosity decreases as the carbon powder has a wider particle size distribution and the compaction pressure is higher. Also, as the average particle diameter of the raw carbon powder increases, the average pore diameter of the obtained SiC porous body increases, so that the mechanical strength tends to decrease. Therefore, it is preferable that the average particle size of the carbon powder be 160 μm or less.

The Al-SiC-based composite material can be formed by infiltrating molten Al or an Al alloy under pressure into the SiC porous body of the present invention.
If the metal infiltrating into the SiC porous body is an Al alloy,
-Si alloy, the SiC added
The wettability with the porous body is improved, and the coefficient of thermal expansion can be reduced. That is, the larger the amount of Si added to the Al alloy, the lower the coefficient of thermal expansion of the Al alloy. However, on the other hand, when the amount of Si increases, the thermal conductivity of the metal phase decreases. Therefore, in the present invention, the metal phase is Al-Si
In the case of forming an alloy, in order to balance these, an Al alloy to which Si is added up to 20% by weight of the entire Al alloy to be infiltrated is used, and the SiC is adjusted to be 40 to 70% by volume of the entire composite material.

The Al-SiC composite material of the present invention is a composite material having an extremely high thermal conductivity because heat is transmitted preferentially to a SiC skeleton portion where SiCs having an extremely high thermal conductivity are mutually bonded. According to the method of the present invention, general Si powder and C
Even if a powder is used, the thermal conductivity of A is 200 W / m · K or more.
An l-SiC-based composite material is obtained. Further, the impurity elements in the raw material Si powder and C powder, in particular, Al and Fe are reduced by 100 p.
pm or less, the thermal conductivity itself of the skeleton SiC is improved.
-An Al-SiC composite material of K or more can be obtained.

The Al-SiC composite material is made of Si
Since the three-dimensional skeletal structure of the C porous body suppresses the expansion of Al or Al alloy, Al-S having a structure in which SiC particles are dispersed
Compared with the iC-based composite material, the coefficient of thermal expansion becomes smaller even with the same SiC content. That is, the Al-SiC of the present invention
In the system composite material, the average coefficient of thermal expansion y (unit 10 ⁻⁶ / ° C.) in the range of 20 to 200 ° C. is −5.37 × ln (x) +25.10 <y <−8.04 × l
n (x) +39.19 (in the formula, ln is a natural logarithm, and x represents a volume percentage of SiC)
Meet the relationship.

The average coefficient of thermal expansion of the Al-SiC composite material varies depending on the Si content of the Al matrix.
Specifically, it is in the range of 2.0 to 10.0 × 10 ⁻⁶ / ° C., and shows a small thermal expansion coefficient as compared with the particle-dispersed composite material having the same composition. In order to reduce the coefficient of thermal expansion,
In addition to Si, trace elements such as Mg and Fe may be added to improve the wettability of SiC and Al alloy.

As described above, the porous SiC body of the present invention has a three-dimensional skeleton structure in which hexagonal plate-shaped α-type SiC particles are sintered and necked, has heat resistance and corrosion resistance, and has high mechanical strength. It can be used as various filters with high permeation performance, and exhibits excellent functions especially as a filter for liquid filtration and a particulate filter material for purifying exhaust gas of automobile diesel engines. Moreover, since the SiC porous body has a skeletal structure in which hexagonal plate-like SiC crystals are entangled with each other and are strongly bonded, the particle size is smaller than the apparent pore diameter of the porous body measured by the mercury intrusion method. Particles can be trapped and have excellent permeation performance.

The Al-SiC composite material of the present invention has a low coefficient of thermal expansion and a high thermal conductivity, so that it can be used for various heat dissipating materials, and particularly as a heat sink material for semiconductor devices. It is suitable.

[0027]

【Example】Example 1  As shown in Table 1 below, commercially available with an average diameter of 7 to 175 μm
Graphite (C) powder and Si powder with an average particle size of 20 to 36 μm
And a composition having a Si content of 70.5 to 73.5% by weight.
After mixing, the molding is performed at a molding pressure of 100 to 700 MPa.
Each of these compacts was placed in an atmosphere of Ar gas at 1 atm.
Sintering at a sintering temperature of 1900-2400 ° C
In this manner, porous SiC bodies were produced.

For comparison, a conventional porous SiC material obtained by sintering SiC powder was similarly described as Samples 6, 15, 27 and 28. The average particle size of the SiC powder used in these comparative samples was 30 μm for Sample 6.
m, sample 15 is 50 μm, sample 27 and sample 28 are 70 μm
m and the impurities Al and F contained in each SiC powder.
The amount of e (unit: ppm) is as shown in Table 1.
In the samples of these comparative examples, each of the above-mentioned SiC powders was molded at a molding pressure shown in Table 1, and then sintered in Ar gas at 1 atm at a temperature shown in Table 1.

[0029]

[Table 1] Si particle size C particle sizeAl content (ppm) Fe content (ppm) Si powder molding pressure Sintering temperaturesample (μm) (μm) Si powder C powder Si powder C powder (wt%) (MPa) (℃)  1 * 20 11 120 110 120 135 70.5 100 2300 2 20 11 120 110 120 135 71.0 100 2300 3 20 11 120 110 120 135 72.0 100 2300 4 20 11 120 110 120 135 73.0 100 2300 5 * 20 11 120 110 120 135 73.5 100 2300 6 * Porous SiC powder (Al content 110, Fe content 120 in SiC powder) 100 2300 7 20 11 90 85 90 88 72.0 100 2300 8 20 11 1 2 1 2 72.0 100 2300 9 20 11 120 110 120 135 72.0 100 2300 10 20 11 120 110 120 135 72.0 500 2300 11 20 11 120 110 120 135 72.0 700 2300 12 20 11 1 2 1 2 72.0 300 2300 13 20 11 1 2 1 2 72.0 500 2300 14 20 11 1 2 1 2 72.0 700 2300 15 * Porous SiC powder (Al content 1 and Fe content 1 in SiC powder) 700 2300 16 20 11 120 110 120 135 72.0 100 2400 17 20 11 120 110 120 135 72.0 100 2000 18 * 20 11 120 110 120 135 72.0 100 1900 19 36 7 120 110 120 135 72.0 100 2300 20 36 11 120 110 120 135 72.0 100 2300 21 36 75 120 110 120 135 72.0 100 2300 22 36 153 120 110 120 135 72.0 100 2300 23 * 36 175 120 110 120 135 72.0 100 2300 24 20 11 1 2 1 2 72.0 700 2300 25 20 11 1 2 1 2 72.0 700 2300 26 20 11 1 2 1 2 72.0 700 2300 27 * Porous body of SiC powder (Al content in SiC powder 1, Fe content 2) 700 2300 28 * Porous body of SiC powder (Al content in SiC powder 1, Fe content 2) 700 2300 (Note) Samples marked with * are comparative examples.

The relative density, average pore diameter, thermal conductivity at 20 ° C., and three-point bending strength of each of the obtained SiC porous bodies were measured. The results are shown in Table 2 below. Although the porosity of each porous body is not described in Table 1, the density value in the table is 100%.
It is a value subtracted from%. Next, Al (Si content 0 wt%) or an Al-Si alloy (Si content 10 to 20 wt%) having a composition shown in Table 2 below is melted while being maintained at 660 ° C., and the pressure is 200 MPa. Was infiltrated. The thermal conductivity and the thermal expansion coefficient of each of the obtained Al-SiC-based composite materials were measured, and the results are also shown in Table 2.
The relative density of each composite material was 100% in all samples. Also, an Al-SiC in which Al or an Al alloy is similarly infiltrated into a porous SiC body prepared using SiC powder.
Table 3 also shows the results of similar evaluations for the system composite material.

[0031]

[Table 2]SiC porous body Al-SiC composite material  Density Pore size Thermal conductivity Bending strength Al composition Thermal conductivity Thermal expansion coefficientsample (%) (μm) (W / m ・ K) (MPa) (Siwt%) (W / m ・ K) (× 10 ⁻⁶ / ℃)  1 * 40 23 8 85 0 170 12.3 2 40 23 10 102 0 203 9.00 3 40 23 15 115 0 245 8.30 4 40 23 11 102 0 202 8.70 5 * 40 23 8 75 0 199 9.00 6 * 40 23 8 70 0 188 12.30 7 40 23 15 115 0 276 8.30 8 40 23 15 115 0 299 8.30 9 51 25 27 140 0 240 6.30 10 60 27 42 170 0 238 4.80 11 70 29 58 200 0 233 3.50 12 51 25 27 140 0 321 6.30 13 60 27 42 170 0 335 4.80 14 70 29 58 200 0 346 3.50 15 * 70 29 40 85 0 288 7.50 16 40 23 15 115 0 245 8.30 17 40 23 11 102 0 235 9.10 18 * 40 23 7 50 0 199 12.30 19 40 10 15 122 0 245 8.40 20 40 23 15 115 0 247 8.40 21 40 100 15 62 0 249 8.40 22 40 199 15 35 0 251 8.40 23 * 40 206 15 30 0 251 8.40 24 70 29 58 200 0 346 3.60 25 70 29 58 205 10 335 3.00 26 70 29 58 209 20 321 2.50 27 * 70 31 42 102 10 288 6.90 28 * 70 30 42 112 20 268 6.40 (Note) Samples marked with * in the table are comparative examples.

As can be seen from Table 2, the SiC porous body according to the embodiment of the present invention has high mechanical strength and thermal conductivity, and particularly has the characteristics of a porous body prepared using Si powder and C powder having few impurities. Is better. In addition, the Al-
The SiC-based composite material had a low coefficient of thermal expansion and a high thermal conductivity. On the other hand, SC produced by sintering SiC powder
Al-Si in which iC porous body is impregnated with Al or Al alloy
The thermal expansion coefficient of the C-based composite material was larger than that of the present invention.

[0033]Example 2  Each SiC of Samples 3, 6, 14, and 15 of Example 1 above
Using a porous body, outer diameter 8 mm, wall thickness 0.2 mm, length 5
mm SiC porous body, one end of which is sealed with resin
Thus, a pipe-shaped filter was produced. Each of these pipes
The following experiment was conducted using the filter, and the results are shown in the table below.
3 is shown.

(1) From the inside to the outside of the pipe-shaped filter, 100 ml of a suspension of polyethylene particles having a particle size of 10, 20, and 30 μm (concentration: 10 ppm) was applied at a pressure of 0.1 MPa.
The mixture was filtered through a, and the collection rate of the particles was measured. (2) Pure water was continuously supplied from the inside to the outside of the pipe-shaped filter at a pressure of 0.1 MPa, and the permeation flow rate was measured. (3) Air pressure was applied to the inside of the pipe-shaped filter, and the pressure resistance at which the filter was destroyed was measured while increasing the pressure. (4) After collecting particles having a particle diameter of 30 μm in the above experiment (1), apply 100 W of electric power to both ends of the filter to generate electricity and generate heat, and burn until the collected polyethylene particles are completely burned. The time was measured.

[0035]

[Table 3]Particle collection rate (%) Permeate flow pressure Withstand combustion timesample 10 μm 20 μm 30 μm (l / sec / m) (MPa) (sec)  3 100 100 100 560 0.8 5 6 * 15 85 100 185 0.5 13 14 85 100 100 420 1.3 3 15 * 0 75 100 136 0.812 (Note) Samples marked with * in the table are comparative examples.

It can be seen that the filter manufactured from the porous SiC body of the present invention is superior in performance to the filter manufactured from the conventional porous body obtained by sintering SiC particles.
That is, since it has a complicated pore structure in which hexagonal plate-like α-type SiC particles are bonded, particles smaller than the apparent pore diameter (see Table 2) measured by the mercury intrusion method can be collected and transmitted. Excellent performance. In addition to having high transmission performance, it is also excellent in pressure resistance due to high strength.
Further, it has been found that the high thermal conductivity reduces the burning time of the collected polyethylene particles, and is therefore effective as a particulate filter for diesel engines.

[0037]Example 3  Same manufacturing method as Samples 3, 7, 13 and 19 in Example 1 above
Heat-dissipating substrate made of Al-SiC-based composite material prepared by the method
The power module semiconductor device shown in FIG.
The device was manufactured. In FIG. 1, 1 is the composite material of the present invention.
The heat dissipation board consisting of
Aluminum nitride ceramics with thermal conductivity (thermal conductivity 170
W / m · K) substrate, 3 is a silicon semiconductor device, 4 is
From an aluminum alloy mechanically fixed to the heat sink 1
Cooling structure. In addition, the upper and lower surfaces of the heat radiation substrate 1 and the substrate
2 is nickel plated on the lower surface and W
Copper conductor circuit via tally layer and nickel plating layer
A layer is formed. Further, the heat radiating substrate 1 and the cooling structure 4
Interface, a thin layer of silicone oil is formed in advance.
Have been. The semiconductor element 3 is connected with Ag-Sn based solder.
Have been. In addition, contact between each member, especially around the heat radiation substrate 1 is described.
The connection was good and there was no problem.

Using each assembly having such a structure, 1000 cycles of heating and cooling were performed at -60.degree. C. for 30 minutes and then at 150.degree. C. for 30 minutes. No deterioration was observed. From the above results, it has been found that the Al-SiC-based 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. Incidentally, the composite material of the present invention,
An evaluation was also made of mounting on a semiconductor device such as a personal computer having a lower output and a lower thermal load than this type of module, but it was confirmed that there was no problem in the practical reliability.

[0039]

According to the present invention, hexagonal plate-like α-type SiC
By having a three-dimensional skeletal structure in which crystals are strongly bonded, it is possible to provide a SiC porous body having both high mechanical strength and thermal conductivity. By infiltrating Al or an Al alloy into the SiC porous body, it is possible to provide an Al-SiC-based composite material having a high thermal conductivity and a small thermal expansion coefficient.

When the porous SiC body of the present invention is used as a filter, it has excellent trapping performance and permeation performance, and at the same time, the thickness of the filter can be set thin because of its high strength. In addition, this SiC porous body has high thermal conductivity,
Since the collected soot and the like can be efficiently burned, it is suitable as a particulate filter for purifying exhaust gas of diesel engines. Furthermore, the Al-
Since the SiC-based composite material has high thermal conductivity, it is effective as a heat sink for a semiconductor device.

[Brief description of the drawings]

FIG. 1 is an SEM photograph of SiC particles constituting a porous SiC body of the present invention.

FIG. 2 is a schematic diagram illustrating a state where heat is transmitted through a porous SiC body of the present invention.

FIG. 3 is a schematic cross-sectional view showing a semiconductor device using the Al—SiC-based porous body of the present invention as a heat dissipation substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat dissipation board 2 Substrate 3 Semiconductor element 4 Thermal structure

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D019 AA01 AA03 BA01 BA02 BB06 BB07 BC12 BD01 CA03 CB06 4G001 BA60 BA62 BB22 BC47 BC52 BC54 BC77 BD03 BD05 BE31 BE33 4G019 FA11 FA13 5F036 AA01 BB01 BD03 BD14

Claims (10)

[Claims] 1. A SiC porous body having a three-dimensional skeletal structure in which hexagonal plate-like α-type SiC particles are sintered and necked,
The porosity is 30 to 60% and the average pore diameter is 10 to 200 μ
m, JIS-compliant three-point bending strength of 30 MPa or more, 20
A porous SiC material having a thermal conductivity at 10 ° C. of 10 W / m · K or more. 2. A liquid filtration filter comprising the porous SiC material according to claim 1. 3. A particulate filter for purifying exhaust gas of an automobile diesel engine, comprising the porous SiC body of claim 1. 4. The SiC porous body according to claim 1, comprising Al or an Al alloy impregnated in said SiC porous body.
C is 40 to 70% by volume of the whole, and the thermal conductivity at 20 ° C. is 2
The average thermal expansion coefficient y in the range of not less than 00 W / m · K and 20 to 200 ° C. is −5.37 × ln (x) +25.10 <y <−8.04 × l in units of 10 ⁻⁶ / ° C.
n (x) +39.19 (in the formula, ln is a natural logarithm, and x represents a volume percentage of SiC)
Al-SiC characterized by being within the range represented by:
Based composite materials. 5. The thermal conductivity at 20 ° C. is 250 W / m · K.
It is above, The Al- of Claim 4 characterized by the above-mentioned.
SiC-based composite material. 6. A semiconductor device using the composite material according to claim 4 as a heat sink. 7. The method for producing a porous SiC body according to claim 1, wherein the Si powder and the carbon powder have a total Si content of 71 to 7%.
A method for producing a porous SiC material, which comprises mixing at 3% by weight to form a molded body, and then performing heat treatment at a temperature of 2000 to 2400 ° C in an inert gas atmosphere. 8. Fe contained in Si powder and carbon powder.
The method for producing a porous SiC body according to claim 7, wherein the impurity amounts of Al and Al are each 100 ppm or less. 9. The method for producing an Al—SiC-based composite material according to claim 4, wherein molten Al or an Al alloy is infiltrated under pressure into the SiC porous material according to claim 1. A method for producing an Al-SiC-based composite material. 10. The method for producing an Al—SiC-based composite material according to claim 9, wherein the amount of Si in the Al alloy is up to 20% by weight of the entire Al alloy.