JP2012077323A - Aluminum-silicon-carbide composite and heat transfer member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum-silicon-carbide composite that stably warps when heat is transferred thereto, and a heat transfer member made thereof.SOLUTION: The Al-SiC composite 1 comprises an SiC porous body impregnated with a metal essentially comprising aluminum and has a multilayered structure equipped with a first layer 2 and a second layer 3, wherein the first layer 2 has a thermal expansion coefficient at 50-150°C of 6-9 ppm/K and the second layer 3 has a thermal expansion coefficient at 50-150°C larger by 4-8.5 ppm/K than that of the layer 2.

Description

  The present invention relates to an aluminum-silicon carbide composite and a heat transfer member comprising the same.

  2. Description of the Related Art In recent years, power modules mounted with power semiconductor elements (power devices) such as IGBTs (Insulated Gate Bipolar Transistors) are mounted on hybrid vehicles, electric vehicles, railway vehicles, and the like. In general, a heat transfer member that quickly transfers heat to the heat dissipation member is interposed between the heat dissipation member that dissipates and diffuses the heat generated by the semiconductor element and the ceramic substrate on which the semiconductor element is mounted. The ceramic substrate and the heat transfer member are joined by soldering or brazing.

  Use of a heat transfer member made of an aluminum-silicon carbide composite that has a small difference in thermal expansion coefficient from the ceramic substrate in order to prevent cracks from occurring at the joint due to repeated thermal cycles accompanying the operation of the semiconductor element. There are many. The aluminum-silicon carbide composite is also advantageous in that it is lightweight.

  By the way, the heat radiating member and the heat transfer member are usually attached with a plurality of bolts. However, when a gap is generated between the heat dissipation member and the heat transfer member, the heat transfer efficiency is significantly reduced. Therefore, it has been proposed that a convex warp is provided in advance on the surface of the heat transfer member on the heat dissipating member side, and the repulsive force is used to prevent the formation of a gap.

  This warp is formed by pressurizing the heat transfer member under heating using a jig having a predetermined shape (see, for example, Patent Document 1). Further, the surface of the heat transfer member may be cut with a cutting tool made of diamond or the like to form a warp.

Japanese Patent No. 3792180

  However, when forming a warp by using a jig at a high temperature and a high pressure, it is difficult to adjust the amount of warp, and the warp shape is not constant, and the warp surface is uneven, so that the heat dissipation member and the heat transfer member There is a problem that a gap may be formed between them.

  In addition, when warping is formed by cutting, the aluminum-silicon carbide composite is very hard, so that there is a problem that the cutting cost becomes very high.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an aluminum-silicon carbide composite in which warpage is stably generated when heat is transmitted, and a heat transfer member comprising the same.

  The aluminum-silicon carbide composite of the present invention is an aluminum-silicon carbide composite obtained by impregnating a silicon carbide porous body with a metal containing aluminum as a main component, and has a thermal expansion coefficient of 6 ppm / at 50 ° C to 150 ° C. A multilayer structure comprising a first layer having a K to 9 ppm / K and a second layer having a thermal expansion coefficient at 50 ° C. to 150 ° C. that is 4 ppm / K to 8.5 ppm / K greater than that of the first layer It is characterized by being.

  According to the aluminum-silicon carbide composite of the present invention, there is a predetermined difference between the thermal expansion coefficients of the first layer and the second layer. It occurs stably and does not warp at room temperature.

  In the aluminum-silicon carbide based composite of the present invention, the silicon carbide filling rate of the first layer is 65% to 85%, and the silicon carbide filling rate of the second layer is 10 than that of the first layer. It is preferable to be smaller by% to 50%. In this case, the first layer and the second layer having the thermal expansion coefficient can be reliably and easily formed.

  Moreover, in the aluminum-silicon carbide based composite of the present invention, the first layer is formed of a sintered body obtained by firing a molded body using a silicon carbide powder having a multi-grain blend as a raw material powder, and the second layer is It is preferably made of a sintered body obtained by firing a die-molded body made of silicon carbide powder of a single particle size and metal powder or carbon powder as raw material powder. In this case, the first layer and the second layer having the silicon carbide filling rate can be easily formed.

  In the aluminum-silicon carbide based composite of the present invention, it is preferable that a metal layer containing more than 80% by weight of metal is not interposed between the first layer and the second layer. In this case, since the heat conduction is not hindered by the metal layer, the heat transfer performance is excellent.

  In the heat transfer member of the present invention, the first main surface is bonded to the ceramic substrate, and the second main surface located on the opposite side of the first main surface is fixed to the heat transfer member at a plurality of fixing portions. A heat transfer member made of the aluminum-silicon carbide composite of the present invention, wherein the surface of the first layer is machined to form the first main surface, The surface of the second layer is machined so that the surface roughness Ra is 3 μm or less to form the second main surface.

  According to the heat transfer member of the present invention, when heat is transferred to the heat transfer member due to the difference in thermal expansion coefficient between the first layer and the second layer, the warping that protrudes toward the fixed member increases the temperature. It is generated stably in response. The heat transfer member is fixed to the fixing member at a plurality of fixing portions. For this reason, the adhesion between the second main surface and the fixing member is high between the fixing portions and becomes stronger as the temperature increases, so that the heat transfer member and the fixing member are reliably in contact with each other. Furthermore, since the surface roughness Ra of the second main surface is 3 μm or less, the adhesion between the heat transfer member and the fixing member due to warpage becomes better.

  In the heat transfer member of the present invention, when the first main surface is heated, it is preferable that a warp of 3 μm to 8 μm occurs at 100 ° C.-200 mm on the second main surface. If the warpage is less than 3 μm, good adhesion between the heat transfer member and the fixing member cannot be obtained. On the other hand, if the warpage exceeds 8 μm, the bonded portion between the heat transfer member and the ceramic substrate may be affected, and peeling may occur.

  In the heat transfer member of the present invention, it is preferable that when the first main surface is heated to 300 ° C., the temperature of the second main surface is 250 ° C. or higher. In this case, it is ensured that the heat transfer performance of the heat transfer member is excellent.

The conceptual longitudinal cross-sectional view of the Al-SiC composite material which concerns on embodiment of this invention. The conceptual longitudinal cross-sectional view for demonstrating the preparation methods of an Al-SiC composite material. The conceptual longitudinal cross-sectional view for demonstrating the use condition of the heat-transfer member which concerns on embodiment of this invention.

  An aluminum-silicon carbide composite 1 (hereinafter referred to as “Al—SiC composite 1”) according to an embodiment of the present invention will be described.

  As shown in FIG. 1, the Al—SiC composite 1 has a multilayer structure in which a silicon carbide (SiC) porous body is impregnated with a metal mainly composed of aluminum (Al), and has a thermal expansion coefficient at 50 ° C. to 150 ° C. A first layer 2 having a thickness of 6 ppm / K to 9 ppm / K, preferably 6.5 ppm / K to 9 ppm / K, more preferably 7.1 ppm / K to 8.8 ppm / K, and 50 ° C. to 150 ° C. Second layer having a coefficient of thermal expansion greater than layer 2 by 4 ppm / K to 8.5 ppm / K, preferably 4.5 ppm / K to 8 ppm / K, more preferably 4.9 ppm / K to 7.7 ppm / K 3 is provided.

  The metal containing aluminum as a main component is a metal containing aluminum in an amount of 80% by weight or more, preferably 85% by weight or more, more preferably 90% by weight or more. A component is not specifically limited, Iron, copper, etc. may be contained.

  In the composite material of aluminum and SiC, when the filling rate of SiC increases by 10%, the thermal expansion coefficient of the composite material decreases by 2 ppm / K to 3 ppm / K. Therefore, the SiC filling rate of the layer 2 is 65% to 85%, preferably 67% to 81%, more preferably 70% to 80%, and the SiC filling rate of the layer 3 is 10% to 50% than the layer 2, If it is preferably reduced by 15% to 40%, more preferably 18% to 37%, the thermal expansion coefficients of the layers 2 and 3 can be made as described above.

  The high filling of SiC can be adjusted by using a SiC powder having a multi-particulate formulation in which coarse particles and fine particles are mixed when forming a SiC molded body (preform). On the other hand, the low filling of SiC can be adjusted by using a single-grained SiC powder at the time of molding, that is, by adding an aluminum powder or a carbon powder.

  Normally, when producing an Al-SiC composite material having a multilayer structure, SiC compacts having different SiC filling rates are separately produced, and impregnated with a metal mainly composed of aluminum in a state where these SiC compacts are stacked. It is possible. However, in this method, a metal layer is formed between the SiC molded bodies, and there arises a problem that cracks may occur due to the inhibition of heat conduction or the warpage caused by the difference in thermal expansion coefficient.

  Therefore, the Al—SiC composite 1 is preferably manufactured by integrally molding the high filling rate layer 2 and the low filling rate layer 3 using a vibration molding method. According to this, the metal layer is not formed at the boundary between the layers 2 and 3 having different SiC filling ratios, and the above problem does not occur.

  Specifically, referring to FIG. 2, SiC powder mixed with two particle sizes is used as the raw material powder for layer 2 having a high filling rate. The SiC powder blended in two particle sizes has an average particle size of 5 μm to 40 μm, preferably 5 μm to 30 μm, more preferably 10 μm to 25 μm, and an average particle size of 50 μm to 120 μm, preferably 50 μm to 100 μm, more preferably 60 μm. It consists of ˜80 μm SiC coarse powder, and the SiC fine powder occupies 10 wt% to 50 wt%, preferably 20 wt% to 40 wt%, more preferably 25 wt% to 35 wt%. In addition, as the raw material powder of the layer 2 having a high filling rate, a SiC powder mixed in a multi-particulate manner exceeding a two-particulate composition such as a three-particulate composition may be used.

  Water and a silica binder are added to the raw material powder, mixed and slurried, poured into a mold 4, and subjected to osmotic vibration molding for a predetermined time, for example, 60 minutes.

  On the other hand, as a raw material powder for the layer 3 having a low filling rate, a mixture of SiC powder having a single particle size and aluminum powder or carbon powder is used. The SiC powder having a single particle size is composed of SiC powder having an average particle size of 10 μm to 150 μm, preferably 20 μm to 100 μm, more preferably 30 μm to 70 μm. In the raw material powder, an aluminum powder having an average particle size of 15 μm to 45 μm, preferably 20 μm to 40 μm, more preferably 25 μm to 35 μm is 1 wt% to 5 wt%, preferably 1.5 wt% to 4 wt%, More preferably, it occupies 2 wt% to 3.5 wt%, or an average particle size of 0.5 μm to 5 μm, preferably 1 μm to 3.5 μm, more preferably 1 μm to 2.5 μm is 0.5 wt%. Occupying -5% by weight, preferably 1% -3.5% by weight, more preferably 1% -2.5% by weight.

  Water and a silica binder are added to the raw material powder and mixed to form a slurry, which is poured into the mold 4 from above the slurry, and subjected to osmotic vibration molding for a predetermined time, for example, 20 minutes.

  Then, after removing moisture, it is dried at 80 ° C to 300 ° C, preferably 100 ° C to 250 ° C, more preferably 150 ° C to 200 ° C, and 700 ° C to 1300 ° C, preferably 800 ° C to 1250 ° C, more preferably. Is fired at 1000 ° C. to 1150 ° C. in an air atmosphere or a nitrogen atmosphere. The firing time is appropriately determined in accordance with conditions such as the size of the SiC molded body, the amount charged into the firing furnace, and the firing atmosphere. During the calcination, the carbon powder may be burned off and the aluminum may be dissolved.

  As a result, a SiC molded body in which a layer having a high initial filling rate of SiC and a layer having a low initial filling rate of SiC are laminated is produced. Thereafter, if necessary, the SiC molded body is processed into a desired shape.

  Next, it dissolves at a temperature of 700 ° C. to 900 ° C., preferably 700 ° C. to 850 ° C., more preferably 750 ° C. to 850 ° C. at an osmotic pressure of 5 MPa to 90 MPa, preferably 10 MPa to 50 MPa, more preferably 10 MPa to 30 MPa. The SiC molded body is impregnated with a metal containing aluminum as a main component. The metal containing aluminum as a main component is an alloy made of the above-described metal, and specifically, a 1000 series aluminum alloy that is a pure aluminum alloy, for example, A1050, A1070, A1080, A1085, and A1100. Is most preferred. Further, it may be a 2000 series or 3000 series aluminum alloy.

  Although the impregnation method is not particularly limited, for example, a SiC molded body is set in the mold 4, the mold 4 is preheated, and another molten metal is injected into the mold 4 to perform high pressure casting. Also good.

  Thereby, the Al-SiC composite 1 in which the layer 2 having a high SiC filling rate and the layer 3 having a low SiC filling rate are laminated is manufactured.

  Hereinafter, the heat transfer member 11 according to the embodiment of the present invention will be described.

  With reference to FIG. 3, the heat transfer member 11 is obtained by processing the above-described Al—SiC composite 1 as a material. Specifically, the surface of layer 2 is machined to a thickness of 2 mm to 6 mm, preferably 3 mm to 5 mm, more preferably 3 mm to 4 mm, and the surface of layer 3 is machined to 2 mm to The thickness is 6 mm, preferably 3 mm to 5 mm, more preferably 3 mm to 4 mm.

  As a result, the heat transfer member 11 has a thermal expansion coefficient at 50 ° C. to 150 ° C. of 6 ppm / K to 9 ppm / K, and a thermal expansion coefficient at 50 ° C. to 150 ° C. of 4 ppm / It becomes a flat multilayer structure provided with the second layer 13 that is larger by K to 8.5 ppm / K. The ratio of the layer 12 to the total thickness of the heat transfer member 11 is 40% to 60%, preferably 45% to 55%, and more preferably 48% to 52%. If the thickness of the heat transfer member 11 is too thin, the heat transfer member 11 may be damaged due to an impact or the like. If the thickness is too thick, the heat transfer performance may be deteriorated.

  The surface 13a of the layer 13 is machined to have a surface roughness Ra of 1 μm to 3 μm, preferably 1.5 μm to 3 μm, more preferably 1.8 μm to 2.7 μm, and is bonded to the ceramic substrate 5. The upper surface 13a is the first main surface. The surface 12a of the layer 12 is machined using a polishing tool such as a grindstone so that the surface roughness Ra is 1 μm to 3 μm, preferably 1.5 μm to 3 μm, more preferably 1.8 μm to 2.7 μm. Then, it comes into contact with the fixing member 6 and becomes the lower surface 12a that is the second main surface located on the opposite side of the first main surface 13a. Note that the flatness of both the upper surface 13a and the lower surface 12a is 4 μm or less, preferably 3 μm or less, and more preferably 2.7 μm or less so that it is flat at room temperature.

  In order to fix the heat transfer member 11 to the fixing member 6, through holes 11 a through which fasteners 7 such as bolts are inserted are formed in the plurality of corners of the heat transfer member 11 by cutting. The heat transfer member 11 is a member interposed between the fixing member 6 which is a heat radiating member such as a heat radiating fin and the ceramic substrate 5, and is also referred to as a heat conductor base or simply a base.

  The ceramic substrate 5 is formed of ceramics such as alumina, aluminum nitride, silicon nitride. Although not shown, a circuit layer is formed on the upper surface of the ceramic substrate 5, and a semiconductor element is bonded on the circuit layer. The semiconductor element is a semiconductor element that generates a large amount of heat, such as an IGBT, but is not limited thereto.

  Although not shown, a plating film is formed on the upper surface 13 a of the heat transfer member 11. This plating film is made of nickel (Ni) as a main component, and is formed by electroless plating or electroplating using a nickel alloy or pure nickel.

  Between the lower surface 5a of the ceramic substrate 5 and the upper surface 13a on which the plating film of the heat transfer member 11 is formed, a solder material or a brazing material made of a material having excellent thermal conductivity is interposed, so that the heat transfer with the ceramic substrate 5 is achieved. The member 11 is joined by soldering or brazing.

  The heat transfer member 11 to which the ceramic substrate 5 is bonded is fixed to a fixing member 6 made of a metal such as aluminum or steel using a plurality of fasteners 7. Here, through holes 11 a are formed at four corners of the heat transfer member 11, and the heat transfer member 11 and the fixing member 6 are fastened by bolts 7 respectively inserted through the through holes 11 a.

  The heat transfer member 11 transfers the heat generated by the semiconductor element to the fixed member 6. In the heat transfer member 11, when the upper surface 13a is heated to 300 ° C, the temperature of the lower surface 12a is 250 ° C or higher, preferably 280 ° C or higher, more preferably 295 ° C or higher, and the heat transfer performance is excellent.

  When heat is transferred to the heat transfer member 11, the temperature of the ceramic substrate 5 and the heat transfer member 11 rises and thermally expands. On the other hand, when the heat generation from the semiconductor element stops, the temperature of the ceramic substrate 5 and the heat transfer member 11 decreases and the heat shrinks.

  Since the difference in thermal expansion coefficient between the ceramic substrate 5 and the layer 13 bonded to the ceramic substrate 5 of the heat transfer member 11 is small, the ceramic substrate is caused by these differences in the thermal cycle of thermal expansion and thermal contraction described above. The thermal stress generated between 5 and the layer 13 is small. Therefore, it is prevented that a crack or the like is generated at the joint portion between them and is damaged.

  Further, there is a predetermined difference in thermal expansion coefficient between the layer 12 and the layer 13, and the layer 13 has a larger thermal expansion coefficient than the layer 12, so that when the heat is transferred to the heat transfer member 11, the fixing member 6 A warp that protrudes to the side, that is, downward (hereinafter referred to as “downward warp”) occurs. The amount of warpage is 3 μm to 8 μm, preferably 3.5 μm to 7.5 μm, more preferably 4 μm to 7 μm per 100 ° C.-200 mm.

  Since the lower surface 12a of the heat transfer member 11 is flat at room temperature and the four corners are fixed to the fixing member 6 with bolts 7, the close contact between the lower surface 12a and the fixing member 6 is high and the temperature is high due to downward warping. It becomes stronger as it becomes. Therefore, the heat transfer member 11 and the fixing member 6 are reliably in contact with each other. Furthermore, since the surface roughness Ra of the lower surface 12a is 3 μm or less, the adhesion between the heat transfer member 11 and the upper surface 6a of the fixing member 6 due to warpage becomes better.

  If the amount of warpage is less than 3 μm, good adhesion between the heat transfer member 11 and the fixing member 6 cannot be obtained. On the other hand, if the amount of warpage exceeds 8 μm, it may affect the joint between the heat transfer member 11 and the ceramic substrate 5 and may cause peeling.

  Although the embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited to this. For example, although the case where the Al—SiC composite 1 and the heat transfer member 11 are composed of the two layers 2, 3, 12, and 13 having different thermal expansion coefficients has been described, the present invention is not limited thereto. For example, one or a plurality of layers having a thermal expansion coefficient between these two layers 2, 3, 12, and 13 may be provided between the two layers 2, 3, 12, and 13. It suffices if it increases substantially intermittently or continuously from the surface toward the upper surface 13a.

[Examples and Comparative Examples]
Hereinafter, examples and comparative examples will be described. Table 1 summarizes Examples 1-10.

[Example 1-10]
Two particle size blending (particle size # 90 / particle size # 800 = 7/3 (Example 1-4), particle size # 180 / particle size # 1000 = 7/3 (Example 5-8), particle size # 90 / Particle size # 500 = 3/7 (Examples 9 and 10)) raw material powder made of SiC powder (manufactured by Taiheiyo Random Co., Ltd. or Shinano Denki Smelting Co., Ltd.) and ion-exchange water and silica binder (Nissan Chemical Industries SiC slurry added and mixed was poured into a mold 4 and subjected to permeation vibration molding for 60 minutes.

  Thereafter, on that, single particles (particle size # 240 (Examples 1, 5, 9), particle size # 320 (Examples 2, 6, 10), particle size # 500 (Examples 3, 4, 7, 8) SiC powder (manufactured by Shinano Denki Smelting Co., Ltd.) and particle size # 500 aluminum powder (manufactured by Minalco Co., Ltd.) (Examples 1, 2, 4-7, 9, 10) or 2.5 μm in particle size A SiC slurry prepared by adding ion-exchanged water and silica binder (manufactured by Nissan Chemical Industries, Ltd.) to a raw powder mixed with carbon powder (manufactured by Showa Denko KK) (Examples 3 and 8) is poured into a mold 4 and oscillated for 20 minutes The aluminum powder was added at 3% by weight to the SiC powder, the carbon powder was added at 2% by weight with respect to the SiC powder, and 10% by weight of silica binder and 25% by weight of ion-exchanged water. % To make a slurry .

  Then, after removing moisture, it was dried at 200 ° C. and baked at 1100 ° C. for 16 hours. Thereby, a SiC molded body of 200 mm × 100 mm × 15 mm was produced. Then, the SiC molded body was raw-processed so that each layer had a thickness of 3.5 mm and a total thickness of 7 mm.

  Thereafter, a pure aluminum-based alloy (A1050) melted at a temperature of 800 ° C. at an osmotic pressure of 80 MPa was impregnated in the SiC molded body to produce an Al—SiC composite 1.

  Thereafter, the upper and lower surfaces of the Al—SiC composite 1 were each cut by 1 mm. The lower surface 12a of the heat transfer member 11 was polished with a grindstone having a particle size of # 800 or less so that the surface roughness Ra was 3 μm or less. And the through-hole 11a of diameter 8mm was formed in the four corners of the heat-transfer member 11 by a cutting process, and the heat-transfer member 11 was produced. In addition, the through hole 11a was processed so that the center of the hole comes to a position 15 mm from the end face.

  Thereafter, electroless plating of nickel is applied to the upper surface 13a of the heat transfer member 11, and the eutectic having a weight ratio of lead and tin of 37:63 between the upper surface 13a and the lower surface 5a of the ceramic substrate 5 made of aluminum nitride. It joined by interposing solder. Thereafter, the heat transfer member 11 was fixed to the fixing member 6 made of an aluminum plate having a thickness of 7 mm with four bolts 7.

  And the heater was mounted in the heat-transfer member 11, the upper surface 13a was heated to 300 degreeC, the temperature of the lower surface 12a in that case was measured with the thermography camera, and the temperature difference of an up-and-down surface was calculated | required. In all Examples 1-10, the temperature difference between the upper and lower surfaces was 21 ° C. to 46 ° C., and the heat transfer performance of the heat transfer member 11 was good. From this, it was found that the heat transfer member 11 was in good contact with the fixing member 6 when heat was transferred. In addition, no defects such as cracks occurred at the joint between the heat transfer member 11 and the ceramic substrate 5.

  Table 2 summarizes Comparative Examples 1-5.

[Comparative Example 1]
SiC compacts having the same particle size formulation as in Example 1 and a high filling factor and a low filling factor were separately molded. Then, these were stacked and impregnated with A1005 under the same conditions as in Example 1. An aluminum layer having a width of about 100 μm was formed on the boundary surfaces having different SiC filling rates of the Al—SiC composite. The temperature difference between the upper and lower surfaces was 61 ° C., and it was found that the heat transfer performance of the heat transfer member was inferior. This is presumably because heat conduction was hindered by the aluminum layer formed on the boundary surface of the heat transfer member.

[Comparative Example 2]
A heat transfer member was produced in the same manner as in Example 1 except that the SiC powder had a particle size blend of only # 180 / particle size # 1000 and the SiC filling rate of each layer was the same. The temperature difference between the upper and lower surfaces was 69 ° C., indicating that the heat transfer performance of the heat transfer member was inferior. This is considered to be because no warp occurred and a gap was generated between the heat transfer member and the fixing member.

[Comparative Example 3]
Although it is SiC powder of the same particle size mixing as Example 5, 1.3 times the aluminum powder of particle size # 240 is added to the SiC powder of the low filling rate side 1.3 times of Example 1, and the low filling rate layer of a SiC molded object The SiC filling rate was 25%. And the heat-transfer member was produced by the method similar to Example 1 except this. When the upper surface of the heat transfer member was heated to 300 ° C., cracks occurred in the solder at the joint between the ceramic substrate and the heat transfer member. This is considered to be because a large warp occurred due to the difference in the thermal expansion coefficient between the layers due to the difference in the SiC filling rate.

[Comparative Example 4]
The particle size combination of SiC powder on the high filling rate side is particle size # 90 / particle size # 500 (filling rate 67%), and the particle size combination of SiC powder on the low filling rate side is particle size # 90 / particle size # 320 (packing) The difference in the SiC filling rate was made small. Except this, the heat-transfer member was produced by the same method as Example 1. The temperature difference between the upper and lower surfaces was 68 ° C., indicating that the heat transfer performance of the heat transfer member was inferior. This is presumably because the difference in thermal expansion coefficient between the layers of the heat transfer member was small, and a sufficient amount of warpage did not occur.

[Comparative Example 5]
A heat transfer member was produced in the same manner as in Example 1 except that the surface roughness Ra of the lower surface was 6.89 μm. The temperature difference between the upper and lower surfaces was 64 ° C., and it was found that the heat transfer performance of the heat transfer member was inferior. This is considered to be because the heat transfer member and the fixing member did not adhere well because the lower surface, which is the contact surface of the heat transfer member to the fixing member, was rough.

  DESCRIPTION OF SYMBOLS 1 ... Aluminum-silicon carbide composite (Al-SiC composite), 2 ... 1st layer (SiC low filling rate layer), 3 ... 2nd layer (SiC high filling rate layer), 4 ... type | mold, 5 DESCRIPTION OF SYMBOLS ... Ceramic substrate, 6 ... Fixing member (heat dissipation member), 7 ... Fastener (bolt), 11 ... Heat transfer member, 12 ... 1st layer (SiC low filling rate layer), 12a ... 2nd main surface (lower surface) ), 13 ... 2nd layer (SiC high filling rate layer), 13a ... 1st main surface (upper surface).

Claims (7)

An aluminum-silicon carbide composite in which a silicon carbide porous body is impregnated with a metal mainly composed of aluminum,
A first layer having a thermal expansion coefficient at 50 ° C. to 150 ° C. of 6 ppm / K to 9 ppm / K, and a thermal expansion coefficient at 50 ° C. to 150 ° C. of 4 ppm / K to 8.5 ppm / An aluminum-silicon carbide based composite having a multilayer structure including a second layer larger by K.   The silicon carbide filling factor of the first layer is 65% to 85%, and the silicon carbide filling factor of the second layer is 10% to 50% smaller than that of the first layer. Item 4. The aluminum-silicon carbide composite according to Item 1.   The first layer is made of a sintered body obtained by firing a molded body using a silicon carbide powder having a multi-grain composition as a raw material powder, and the second layer is made of silicon carbide powder and a metal powder or carbon powder having a single grain composition. The aluminum-silicon carbide composite according to claim 1 or 2, comprising a sintered body obtained by firing a molded body as a raw material powder.   4. The aluminum-carbonization according to claim 1, wherein a metal layer containing a metal exceeding 80 wt% is not interposed between the first layer and the second layer. 5. Silicon composite. The first main surface is bonded to the ceramic substrate, and the second main surface located opposite to the first main surface is in contact with a fixing member fixed to the heat transfer member at a plurality of fixing portions; A heat transfer member comprising the aluminum-silicon carbide composite according to any one of Items 1 to 4,
The surface of the first layer is machined to be the first main surface, and the surface of the second layer is machined so that the surface roughness Ra is 3 μm or less. A heat transfer member characterized by having a main surface.   6. The heat transfer member according to claim 5, wherein when the first main surface is heated, warpage of 3 μm to 8 μm per 100 ° C.-200 mm occurs on the second main surface.   The heat transfer member according to claim 5 or 6, wherein when the first main surface is heated to 300 ° C, the temperature of the second main surface is 250 ° C or higher.

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