JP6595740B1 - Metal-silicon carbide composite and method for producing the same - Google Patents

Abstract

The present invention has a high thermal conductivity and a thermal expansion coefficient close to that of a semiconductor element, and furthermore, it is suitable for use as a heat sink or the like of a semiconductor element. Provided is a metal-silicon carbide composite having a difference within 50 μm. A metal-silicon carbide composite formed by impregnating a silicon carbide porous body with a metal, wherein silicon carbide particles contained in the composite contain 5 volume% or less of particles having a particle size of 300 μm or more. There is provided a metal-silicon carbide composite characterized in that there is provided. [Selection] Figure 1

Description

  The present invention relates to a metal-silicon carbide composite with high thermal conductivity that is excellent in thermal conductivity and lightweight, and is suitable as a heat radiator such as a heat sink for semiconductor parts such as ceramic substrates and IC packages, and a method for producing the same.

As heat sinks for power modules, copper, aluminum, metals such as Cu—Mo and Cu—W, ceramics such as AlN, Si ₃ N ₄ and Al ₂ O ₃ , metals such as Al—SiC and ceramics are generally used. Composite materials and the like are used. Examples of the metal-silicon carbide composite used as the heat sink of the power module include an aluminum alloy-silicon carbide composite disclosed in Patent Document 1 and magnesium or a magnesium alloy and silicon carbide disclosed in Patent Document 2. The composite fee of The composite materials shown in these documents are lightweight, have high thermal conductivity, and have a thermal expansion coefficient close to that of module components such as semiconductor elements, and are suitable as heat sinks for power modules.

JP 2017-39997 A JP 2013-245374 A

  Generally, a ceramic circuit board is soldered to the surface of a heat sink for a power module. However, when a metal-silicon carbide composite such as Al-SiC is used as a heat sink, some metals such as aluminum are used. Since silicon solder does not get wet with silicon carbide, Ni plating is often applied to the surface. At this time, although it is possible to deposit Ni plating on silicon carbide, a special pretreatment using a catalyst or the like is necessary and the cost is high, so the surface of the metal-silicon carbide composite is impregnated. It is common to be covered with a metal layer.

  The metal layer covering the front and back surfaces of this metal-silicon carbide composite has a structure simulating a bimetal as shown in FIG. 1, but thermal stress is generated by a thermal cycle due to the difference in thermal expansion coefficient of each layer. . At this time, the greater the difference in thickness between the front and back metal layers, the greater the difference in thermal stress, and the change in warp due to thermal cycling. Since the change in the warp causes a gap between the heat sink and the cooling fin, and the heat dissipation characteristics are greatly deteriorated, it is preferable that the thicknesses of the metal layers on the front and back sides are uniform and have no difference.

  The thickness of the metal layer (hereinafter referred to as the surface layer) formed on the front and back of the metal-silicon carbide composite is greatly affected by the surface state of the silicon carbide porous body before impregnation with the metal. The surface accuracy of the silicon carbide based porous material affects the thickness and surface roughness when it is compounded, so surface machining is often performed, but silicon carbide is hard and particles are excluded from the silicon carbide based porous material. It is processed like this.

  When performing the chamfering process, if the silicon carbide porous body contains a large amount of coarse particles, the processed surface becomes uneven. In the composites of the prior art, the definition of the particle size of the silicon carbide particles constituting the material is only the average particle size, the coarse particles are not mentioned, and there is a problem that the thickness difference between the front and back layers tends to occur.

  The present invention has been made in view of the above circumstances, and its purpose is to have the same thermal conductivity and thermal expansion coefficient as the conventional one, but the surface layer has a small difference in thickness between the front and back surfaces, and warps even after a thermal cycle. It is to provide a metal-silicon carbide composite having a small change amount and a method capable of producing such a metal-silicon carbide composite at a low cost.

  That is, the present invention is a metal-silicon carbide composite formed by impregnating a silicon carbide porous material with a metal, and the silicon carbide particles contained in the composite contain 5% by volume of particles having a particle size of 300 μm or more. The present invention relates to a metal-silicon carbide composite characterized by the following.

  According to the present invention, since the coarse particles in the metal-silicon carbide composite are reduced, the surface roughness of the silicon carbide porous body is reduced, the difference in thickness between the front and back surfaces of the surface layer is reduced, and the warp is stable during thermal cycling. A metal-silicon carbide composite having improved properties and a production method capable of producing such a metal-silicon carbide composite at low cost are provided.

1 is a cross-sectional view of a metal-silicon carbide composite according to the present invention. It is a figure explaining the effect of the present invention. It is a figure explaining the measuring method of the thickness of the surface layer in the metal-silicon carbide composite body which concerns on this invention. It is a figure explaining the measuring method of the curvature amount of the metal-silicon carbide composite based on this invention.

  Hereinafter, an embodiment of a metal-silicon carbide composite and a method for producing the same according to the present invention will be described with reference to the drawings.

[Definition]
In the following description, the symbol “to” means “above” and “below”. For example, “A to B” means not less than A and not more than B. The “main surface” means either the upper or lower surface of the metal-silicon carbide composite formed on the flat plate.

[Metal-silicon carbide composite]
As shown in FIG. 1, the metal-silicon carbide composite 1 according to this embodiment is a flat plate formed by impregnating silicon carbide particles with a metal whose main component is at least one of aluminum and magnesium. The metal-silicon carbide composite 1 is composed of a composite portion 2 and surface layers 3a and 3b provided on the main surface of the composite portion 2, and the surface layers 3a and 3b. Is made of a material containing a metal whose main component is at least one of aluminum and magnesium, and the silicon carbide particles contained in the composite part 2 have a particle size of 300 μm or more and 5% by volume or less. And

  Furthermore, the present invention is characterized in that the difference in thickness between the front side and the back side of the surface layer covering both main surfaces is within 50 μm.

  In addition, the metal-silicon carbide composite according to the present invention is characterized in that the amount of change in warpage when the heat cycle test is performed is within ± 50%.

  The metal-silicon carbide composite body 1 having the above-described configuration has high thermal conductivity and a thermal expansion coefficient close to that of a semiconductor element. Further, the difference in thickness between the surface layers of both main surfaces is reduced, and warpage is stable during thermal cycling. Improved.

[Silicon carbide powder]
The silicon carbide powder that is a raw material of the metal-silicon carbide composite is desired to have high thermal conductivity in the particles that constitute it, and is generally “green” with a high purity of 99% by mass or more of the silicon carbide component. It is preferable to use silicon carbide powder exhibiting “ In order to achieve the object of the present invention, it is only necessary to obtain a silicon carbide based porous material having a filling rate of 50 to 80% by volume, preferably 60 to 75% by volume, from the raw material silicon carbide powder. In order to increase the filling rate of the silicon carbide in the porous body, that is, the silicon carbide content in the metal-silicon carbide composite, the silicon carbide powder preferably has an appropriate particle size distribution. You may mix | blend powder suitably.

  Regarding the particle size of the silicon carbide powder, it is preferable to include silicon carbide particles having a particle size of 1 to 50 μm and silicon carbide particles having a particle size of 100 to 300 μm or less from the viewpoint of thermal conductivity.

On the other hand, in the metal-silicon carbide composite of the present invention, the silicon carbide particles contained in the metal-silicon carbide composite are characterized in that particles having a particle size of 300 μm or more are 5% by volume or less. This can be achieved by setting the silicon carbide powder used as a raw material to 5 vol% or less of particles having a particle size of 300 μm or more by an operation such as classification.
When the number of particles having a particle size of 300 μm or more is 5% by volume or more, unevenness on the surface of the silicon carbide based porous material becomes large. This is because the hardness of silicon carbide itself is high, and as shown in FIG. 2, when performing the chamfering process of the silicon carbide based porous material, the portions where coarse particles remain are convex and the particles are excluded from the silicon carbide based porous material. This is because the processed part becomes concave. On the other hand, when the number of particles having a particle size of 300 μm or more is 5% by volume or less, the unevenness on the surface of the silicon carbide based porous material can be reduced. The unevenness on the surface of the silicon carbide based porous material greatly affects the thickness of the surface layer formed on the front and back surfaces of the metal-silicon carbide composite after impregnating the metal. Becomes smaller. As described above, the greater the difference between the thicknesses of the front and back surface layers, the more thermal stress is generated by the thermal cycle due to the difference in thermal expansion coefficient between the layers, and the warp changes. The warp shape changes due to the change of the warp. When such a metal-silicon carbide composite is used as a heat sink for a power module, a gap is formed between the cooling fins and the heat dissipation characteristics are greatly deteriorated. Therefore, the surface layer of the metal-silicon carbide composite The thickness is preferably uniform and has no difference between the front and back.

  The content of silicon carbide particles in the metal-silicon carbide composite is preferably 50% by volume to 80% by volume, more preferably 60% by volume to 70% by volume. When the content of the silicon carbide particles is 60% by volume or more, the thermal conductivity of the obtained metal-silicon carbide composite can be sufficiently ensured. Moreover, it is preferable that content of a silicon carbide particle is 70 volume% or less from the surface of a filling property. If it is 70 volume% or less, it is not necessary to process the shape of silicon carbide particles into a spherical shape or the like, and a metal-silicon carbide composite can be obtained at a stable cost.

  Further, the surface roughness is reduced by reducing the amount of coarse particles contained in the metal-silicon carbide composite. This can be expected to improve solder wettability on the metal-silicon carbide composite, reduce variation in bending strength, and the like.

[Measurement of particle size of raw material silicon carbide powder]
The particle diameter of the raw material silicon carbide powder can be measured by a particle size distribution measuring apparatus by a laser diffraction / scattering method according to JIS ZZ8825: 2013.

[Measurement of particle size of silicon carbide in composite]
The silicon carbide particle diameter in the metal-silicon carbide composite is determined as follows. First, the obtained metal-silicon carbide based composite is immersed in a chemical that dissolves only the metal part, thereby completely dissolving the metal part and collecting silicon carbide particles by filtration. About the obtained particle | grains, it can measure with the particle size distribution measuring apparatus by a laser diffraction and a scattering method according to JISZZ8825: 2013.

[Metal component]
The metal in the metal-silicon carbide composite according to one embodiment of the present invention is a metal containing one or more of aluminum and magnesium as a main component. For example, pure aluminum composed of 99.8% by mass or more of Al and unavoidable impurities, aluminum alloy consisting of additive elements and the balance of Al and unavoidable impurities, pure magnesium composed of 99.8% by mass or more of Mg and unavoidable impurities Further, a magnesium alloy or the like in which the additive element and the balance are made of Mg and inevitable impurities can be used. In the aluminum alloy and the magnesium alloy, it is preferable that the melting point is as low as possible in order to facilitate the management of the molten metal during the impregnation. Examples of such an alloy include an aluminum alloy containing 5 to 25% by mass of Si. By using an aluminum alloy containing 5 to 25% by mass of Si, an effect that the densification of the metal-silicon carbide composite is promoted can be obtained.

  Furthermore, when using the said aluminum alloy, since the coupling | bonding of a silicon carbide particle and a metal part becomes stronger by making Mg contain in an alloy, it is preferable. Other components in the aluminum alloy or magnesium alloy are not particularly limited as long as the characteristics of the alloy do not change extremely, and may include, for example, Fe, Cu, and the like.

[Silica sol]
In one embodiment of the present invention, a silica sol is added to a raw material silicon carbide powder in order to obtain a silicon carbide based porous material having a high filling rate by a wet molding method. As the silica sol, a commercially available solid content concentration of about 20% by mass can be used. As a compounding quantity of a silica sol, about 0.5-10 mass parts is sufficient in solid content concentration with respect to 100 mass parts of silicon carbide, Preferably it is 1-5 mass parts. If the amount is 0.5 parts by mass or more, the strength of the resulting molded body is sufficient even after firing. On the other hand, when the amount to be added is 10 parts by mass or less, the filling rate of silicon carbide in the obtained molded body is high, and desired characteristics can be exhibited.

[Surface layer]
When the metal-silicon carbide composite of the present invention is used as a heat sink of a semiconductor element, it is desirable that a surface layer 3 made of a material containing a metal containing aluminum or magnesium is present on both sides of the composite. As a result, it is possible to expect the effect of improving the adhesion when plating on both sides of the composite. Furthermore, the effect that the surface roughness of both surfaces of the composite is improved is also obtained.

  Here, although the said surface layer 3 consists of a material containing the metal containing aluminum or magnesium similarly to the said metal component, the impurity other than that etc. may be contained.

  About the thickness of the said surface layer, it is preferable that they are 10 micrometers or more and 150 micrometers or less by average thickness. If the average thickness is 10 μm or more, the silicon carbide particles are not exposed to the composite surface in the subsequent treatment, and the target surface accuracy and adhesion of the plating layer can be ensured. Further, the total average thickness of the surface layers 3 on both sides is preferably 20% or less of the thickness of the metal-silicon carbide composite 1. If the average thickness of the surface layer is 150 μm or less and the total thickness is 20% or less of the thickness of the composite, the metal-silicon carbide composite having sufficient thermal conductivity in addition to surface accuracy and adhesion of the plating layer You can get a body.

  The thickness difference between the front side and the back side of the surface layer covering both main surfaces of the metal-silicon carbide composite is preferably 50 μm or less. If the difference in thickness between the front side and the back side of the surface layer is 50 μm or less, the difference in thermal expansion coefficient between the surface layer and the composite part even when the metal-silicon carbide composite is exposed to an environment where the temperature changes rapidly. The difference in thermal stress caused by the thermal cycle is small, and the amount of change in warpage caused by the thermal cycle is small. Thereby, it is possible to prevent a gap from being generated between the heat sink and the cooling fin and greatly reducing the heat dissipation characteristics.

  Regarding the introduction of the surface layer 3, for example, when impregnating a silicon carbide porous body with a metal component, an aluminum foil, a magnesium foil, an alumina fiber, or the like is provided between the silicon carbide porous body and a mold used for impregnation. It can be carried out by arranging ceramic fibers and combining them with metal components. In addition, after obtaining the composite, it can be introduced by spraying the surface, applying a metal foil by cold spraying or hot pressing, or the like.

[Thickness of surface layer covering both main surfaces]
The thickness of the surface layer covering both main surfaces in the metal-silicon carbide composite is determined as follows. The metal-silicon carbide composite is cut with a diamond processing jig along a straight line passing through 20% of the total length of the composite from the end portion shown by a dotted line in FIG. 3 and a middle line of the composite. Thereafter, the surface portion of the circled portion in FIG. 3 was observed with a scanning electron microscope at 100 times. The distance from the outermost surface to the silicon carbide particles was measured at five locations at intervals of 200 μm, and the average of the five points was calculated to obtain the thickness of the surface layer. Here, the surface layer is a region made of metal A or B located on the outermost surfaces of both main surfaces. The difference in thickness of the surface layer is the absolute value of the difference in thickness between the two main surface surface layers obtained by the above method, that is, | (surface layer thickness of the front main surface) − (thickness of the surface layer of the back main surface). | (Μm).

[Warpage of metal-silicon carbide composite]
The warp of the metal-silicon carbide composite is determined as follows. An arbitrary 10 cm length on the main surface midline of the composite is measured with a contact type three-dimensional measuring machine, and the start point is A and the end point is B. The distance (arrow part) to the maximum point with respect to the line segment AB in FIG. 4 is taken as the warp of the metal-silicon carbide composite.

[Production method]
Hereinafter, the manufacturing method by the molten metal forging method is demonstrated about the metal-silicon carbide based composite which concerns on one Embodiment of this invention. However, the metal-silicon carbide composite according to the present invention is not limited to the one manufactured by the molten metal forging method.

  Here, the manufacturing method of the metal-silicon carbide composite can be broadly divided into two types: an impregnation method and a powder metallurgy method. Of these, many are actually commercialized by impregnation methods from the viewpoint of characteristics such as thermal conductivity. There are various impregnation methods, and there are a method performed at normal pressure and a high-pressure forging method performed under high pressure. High pressure forging methods include a molten metal forging method and a die casting method.

  A method suitable for one embodiment of the present invention is a high-pressure forging method in which impregnation is performed under high pressure, and a molten forging method is preferable for obtaining a dense composite having excellent characteristics such as thermal conductivity. The molten metal forging method is generally a method in which a powder or porous material such as ceramics is charged in a high-pressure vessel, and a molten metal is impregnated at high temperature and high pressure to obtain a composite.

  The manufacturing method of the composite_body | complex which concerns on one Embodiment of an invention consists of a raw material classification process, a shaping | molding process, a calcination process, a surface processing process, and an impregnation process. By this method, the metal-silicon carbide composite according to the present invention can be produced in a large amount at a low cost.

[Raw material classification process]
The silicon carbide powder is classified, and the classified powder is obtained by adjusting the silicon carbide having a particle diameter of 300 μm or more to 5% by volume or less. As a classification method, a known method such as sieve mesh, gravity field classification, inertial force field classification, centrifugal force field classification, or the like can be used. Through this step, silicon carbide particles suitable for the metal-silicon carbide composite according to one embodiment of the present invention can be obtained.

[Molding process]
A predetermined amount of silica sol is added to and mixed with the silicon carbide powder to form a desired shape. As a molding method, dry press molding, wet press molding, extrusion molding, cast molding, or the like can be used.

[Calcination process]
The molded body obtained in the molding step is heated in the atmosphere or in an inert gas atmosphere such as nitrogen at a temperature of 800 to 1100 ° C. to obtain a silicon carbide based porous body. Chamfering can be performed through the molding process and the calcining process.

[Chamfering process]
A known method can be used as the chamfering method, and examples thereof include milling. Further, in the chamfering process, the thickness of the silicon carbide based porous body can be adjusted by performing a chamfering process on the silicon carbide based porous body using a diamond processing jig. By this step, the metal-silicon carbide composite when composited has a desired thickness and surface roughness.

[Impregnation process]
In order to prevent cracking and the like due to thermal shock, the silicon carbide porous body that has been subjected to chamfering processing is preliminarily heated, impregnated with a molten metal composed of a metal component heated to a temperature higher than the melting point, and then cooled. A metal-silicon carbide composite is obtained. By this step, a metal-silicon carbide composite according to the present invention having a desired thermal conductivity is obtained.

In the metal-silicon carbide based composite according to an embodiment of the present invention, the composite has a thermal conductivity of 180 W m ⁻¹ K ⁻¹ or more and a thermal expansion coefficient of 9 × 10 ⁻ when heated from room temperature to 150 ° C. ^The form which is 6K- ¹ or less can be mentioned.

[Change in warpage of metal-silicon carbide composite]
A form in which the amount of change in warpage when a heat cycle test is performed on the metal-silicon carbide composite of one embodiment of the present invention is within ± 50% can be mentioned. Here, the amount of change in warpage is [(warpage amount after heat cycle test) − (warpage amount before heat cycle test)] / (warpage amount before heat cycle test) × 100 (%).
Note that the amount of change in warpage when the heat cycle test is performed is preferably within ± 30%, and more preferably within ± 20%. In addition, the heat cycle test conditions include, for example, 100 cycles of a cycle in which exposure to a gas phase maintained at −40 ° C. for 30 minutes and subsequent exposure to a gas phase maintained at 125 ° C. for 30 minutes is performed 100 times. It is done.
If the amount of change in the warp when the heat cycle test is performed is within ± 50%, when the metal-silicon carbide composite is used as a heat sink, it is between the heat sink and the cooling fin even after the thermal cycle. It is difficult for gaps to occur, and deterioration of heat dissipation characteristics can be prevented.

  Ni plating treatment is performed on the surface of the metal-silicon carbide composite of one embodiment of the present invention, and a ceramic substrate such as an aluminum nitride substrate or a silicon nitride substrate is mounted by soldering, etc. It can be used as a heat dissipation component. In this heat dissipation component, the amount of change in the warpage of the composite is small even after a thermal cycle, so cracks between circuits on the ceramic substrate and circuit peeling are difficult to see, and it is suitable for use as a heat dissipation component even in environments where temperature changes are severe can do.

  In the above, the metal-silicon carbide composite according to the present invention, the heat dissipation component using the same, and the production method thereof have been described with reference to one embodiment of the present invention, but the present invention is not limited thereto. Absent.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[Examples 1-8, Comparative Examples 1-2]
Commercially available high-purity silicon carbide powder is classified, silicon carbide powder A (particle diameter 300 μm or more), silicon carbide powder B (particle diameter 100 μm or more and less than 300 μm), silicon carbide powder C (particle diameter 50 μm or more and less than 100 μm) Silicon carbide powder D (particle diameter of 1 μm or more and less than 50 μm) and silicon carbide powder E (particle diameter of less than 1 μm) were obtained. These silicon carbide powders were blended in compositions as shown in Table 1 (Examples 1 to 8 and Comparative Examples 1 and 2), 3 wt% of silica sol was added, and then mixed for 30 minutes with a stirring mixer. The particle size of each silicon carbide powder was measured in accordance with JIS ZZ8825: 2013 with a particle size distribution measuring apparatus (product name “LS230”, manufactured by Beckman Coulter, Inc.) using a laser diffraction / scattering method. The mixture was molded into a shape of 100 mm × 100 mm × 6 mm at a pressure of 10 MPa.

  The obtained molded body was heated in the atmosphere at a temperature of 900 ° C. for 2 hours to obtain a silicon carbide based porous body. Next, the obtained silicon carbide porous body was subjected to chamfering with a diamond processing jig, so that the thickness was 4.8 mm. In addition, the thickness of the silicon carbide based porous material after processing was confirmed with a micrometer at the center of the main surface. Each of the 10 samples was separated by a stainless steel (SUS304) plate coated with a release agent, and an iron plate having a thickness of 12 mm was arranged on both ends, and then fixed with 10 mmφ bolts and nuts to form one block.

  Next, the block was preheated to a temperature of 600 ° C. in an electric furnace, and then placed in a pre-heated press mold having an internal dimension of 250 mmφ × 300 mm, containing 12% silicon and 1% magnesium. Then, a molten aluminum alloy having a composition composed of aluminum and inevitable impurities in the balance and having a temperature of 800 ° C. was poured and pressurized at a pressure of 60 MPa for 10 minutes to impregnate the silicon carbide based porous material with the aluminum alloy. The obtained metal lump containing the composite is cooled to room temperature, then cut along the side shape of the release plate with a wet band saw, and the sandwiched stainless steel plate is peeled off, and the metal-silicon carbide of 100 mm × 100 mm × 5 mm A complex was obtained.

  The obtained metal-silicon carbide composite was prepared using a diamond processing jig, a thermal expansion coefficient measurement specimen (3 × 4 × 20 mm), and a room temperature thermal conductivity measurement specimen (25 × 25 × 2 mmt). ). Further, the metal-silicon carbide composite is cut with a diamond processing jig along the straight line passing through 20% of the total length of the composite from the end portion and the center line of the composite main surface, as indicated by the dotted line in FIG. did. Then, after obtaining the cross section of the composite for the portion indicated by ○ in FIG. 3, the surface portion was observed with a scanning electron microscope at 100 times. The distance from the outermost surface to the silicon carbide particles was measured at five locations at intervals of 200 μm, and the average of the five points was calculated to obtain the thickness of the surface layer. The obtained results are shown in Table 2. As shown in Table 2, the metal-silicon carbide composites according to Examples 1 to 8 had a smaller thickness difference between the front and back surfaces than the metal-silicon carbide composites according to Comparative Examples 1 and 2. . Further, it was confirmed by an energy dispersive X-ray analyzer that the region was composed of a metal mainly composed of aluminum.

  The particle size of silicon carbide contained in the obtained metal-silicon carbide composite was determined in the following manner using Example 1 as an example. First, the composite ground to the same shape as the test sample for measuring thermal conductivity at room temperature was immersed in a 20% aqueous sodium hydroxide solution to completely dissolve only the metal part. Thereafter, the silicon carbide particles were collected by filtration, and the particle size of the silicon carbide was measured by a particle size distribution measuring apparatus by a laser diffraction / scattering method in accordance with JIS ZZ8825: 2013. Regarding the obtained results, when a histogram having a pitch of 5 μm was prepared, two peaks separated by 50 μm or more were confirmed. At this time, it was confirmed that the peak with the smaller particle size was within the range of 1 μm or more and less than 50 μm, and the peak with the larger particle size was within the range of 100 μm or more and less than 300 μm. The area ratio of both peaks was approximately 25:75.

  Next, the thermal expansion coefficient from room temperature to 150 ° C. and the thermal conductivity at room temperature by the laser flash method were measured by a thermal dilatometer using each test specimen. In addition, an arbitrary 10 cm length on the midline of the main surface of the composite is measured with a contact type three-dimensional measuring machine (manufactured by ACCRETECH, product name “CONTOURCODE 1600D”, and so on), and the start point is A and the end point is B did. The distance to the maximum point with respect to this line segment AB (arrow part in FIG. 4) was taken as the amount of warpage of the metal-silicon carbide composite. Furthermore, the density of the composite was measured by the Archimedes method using a test sample for measuring thermal conductivity, and the volume fraction of silicon carbide particles was calculated from the density value. The obtained results are shown in Table 3.

  Furthermore, using these metal-silicon carbide composites, a heat cycle test was performed 100 times at a temperature range of −40 ° C. to 125 ° C. Thereafter, the amount of warpage with respect to a length of 10 cm of the main surface of the composite was measured by a contact type three-dimensional measuring machine, and the amount of change in warpage with respect to the initial value was calculated. At this time, the warpage change amount was [(warpage amount after heat cycle test) − (warpage amount before heat cycle test)] / (warpage amount before heat cycle test) × 100 (%). The obtained results are shown in Table 3.

  As shown in Table 3, the metal-silicon carbide composites according to Examples 1 to 8 are warped after performing a heat cycle test, as compared with the metal-silicon carbide composites according to Comparative Examples 1 and 2. The amount of change was small, and it had a low thermal expansion coefficient and high thermal conductivity.

  In contrast, in the metal-silicon carbide composites of Comparative Examples 1 and 2, the absolute value of the warpage change amount exceeded 50% even after the heat cycle test. This is considered to be because 5 vol% or more of silicon carbide powder having a particle diameter of 300 μm or more was contained.

* 1 Warp amount for sample length 10cm * 2 Heat cycle −40 ° C to 125 ° C (30 minutes each) × Warp change after 100 cycles

[Example 9]
In Example 9, the metal to be impregnated in Example 2 is made of commercially pure magnesium in which 99.8% by mass or more is magnesium and the balance is inevitable impurities, and the other components are manufactured in the same manner as in Example 3. did. The density of the composite was 2.69 g cm ⁻³ , and the average thickness of the front and back surface layers was 90 μm on the front surface and 98 μm on the back surface. Further, the thermal conductivity was 197 W m ⁻¹ K ⁻¹ , the thermal expansion coefficient was 7.5 ppm K ⁻¹ , and the amount of warpage with respect to the main surface length of 10 cm was 46 μm. Furthermore, the heat cycle test was done like Examples 1-6. As a result, the warpage change amount was 8%. That is, even when a metal containing magnesium as a main component was used as the metal to be impregnated, the same results as when using a metal containing aluminum as a component were obtained.

[Examples 10 and 11]
For the silicon carbide based porous material produced in Example 3, when the 10 samples were separated by a stainless steel (SUS304) plate coated with a release agent, a metal plate was interposed between the silicon carbide porous material and the stainless steel plate. Arranged. The size of the metal plate was 100 mm in length, 100 mm in width, and 50 μm in thickness. Table 4 shows the materials of the disposed metal plates and the impregnated molten metal. Otherwise, a composite was prepared in the same procedure as in Example 3. Table 5 shows the average thicknesses of the front and back surface layers. The density of each composite, the thermal conductivity at room temperature, the thermal expansion coefficient from room temperature to 150 ° C., the amount of warpage with respect to the main surface length of 10 cm, and Examples 1 to Table 6 shows the amount of change in warpage after performing the heat cycle test in the same manner as in Table 8. Even when a metal-silicon carbide composite is produced using a metal to be impregnated and a metal plate of a metal different from the metal to be impregnated, a metal having a small thickness difference between the front surface and the back surface, as in Examples 1 to 8. -A silicon carbide composite was obtained, and a metal-silicon carbide composite having a small amount of change in warpage and having a low thermal expansion coefficient and high thermal conductivity even after a heat cycle test was obtained.

[Examples 12 and 13, Comparative Example 3]
The metal-silicon carbide composite produced in Example 2 was subjected to electroless Ni plating treatment to form a 5 μm thick plating layer on the composite surface. A solder paste having a thickness of 100 μm is screen-printed on the plated composite surface, and a commercially available aluminum nitride substrate is mounted in Example 12 and a commercially available silicon nitride substrate is mounted in Example 13, and 5% in a reflow furnace at a temperature of 300 ° C. The ceramic substrate was joined by heat treatment for a minute. In Comparative Example 3, the aluminum nitride substrate was bonded to the copper plate after plating in the same procedure as in Examples 12 and 13. Using the composites obtained by bonding these ceramic substrates, 1000 heat cycle tests were performed at a temperature range of −40 ° C. to 125 ° C. In Examples 12 and 13, there was no crack between the circuits of the ceramic substrate or peeling of the circuit even after the heat cycle test, and the reliability suitable as a heat dissipation component was shown. On the other hand, in Comparative Example 3, cracks occurred between the circuits of the ceramic substrate after 30 heat cycles.

DESCRIPTION OF SYMBOLS 1 Metal-silicon carbide composite 2 Composite part 3a, 3b Surface layer

Claims (5)

  A metal-silicon carbide composite obtained by impregnating a silicon carbide based porous material with a metal containing at least one of aluminum and magnesium as a main component, wherein both main surfaces of the metal-silicon carbide composite are aluminum Or 5% by volume of particles having a particle size of 300 μm or more with respect to the silicon carbide particles that are coated with a surface layer containing a metal whose main component is at least one of magnesium and contained in the metal-silicon carbide composite. A metal-silicon carbide composite, characterized in that:   2. The metal-silicon carbide composite according to claim 1, wherein the thickness difference between the front side and the back side of the surface layer covering both main surfaces of the metal-silicon carbide composite is within 50 μm.   3. The metal-silicon carbide composite according to claim 1, wherein the amount of change in warpage when the heat cycle test is performed is within ± 50%. The method for producing a metal-silicon carbide composite according to any one of claims 1 to 3, comprising the following steps 1) to 5):
1) A raw material classification step of classifying silicon carbide powder to obtain a classified powder by setting silicon carbide having a particle diameter of 300 μm or more to 5% by volume or less;
2) A molding step in which a silica sol is added to the classified powder and mixed, and then the mixture is pressure-molded to obtain a molded body;
3) A calcining step of heating the obtained molded body to 800 to 1100 ° C. in the atmosphere or an inert gas atmosphere such as nitrogen to obtain a silicon carbide based porous body;
4) A chamfering step of chamfering the obtained silicon carbide based porous material with a diamond processing jig;
5) An impregnation step of obtaining a metal-silicon carbide composite by impregnating the obtained silicon carbide porous body with a molten metal and then cooling. A heat-radiating component comprising the metal-silicon carbide composite according to any one of claims 1 to 3.