Heat dissipation member

Abstract

Provided is a novel heat dissipation member that is not available in the prior art.　The heat dissipation member 11 is for use in a semiconductor module 1 and consists of a SiSiC member comprising: a heat dissipation plate 12 having a semiconductor element 2 and an insulating substrate 3 arranged on one surface side; and a heat sink 13 formed integrally with the heat dissipation plate 12. The heat sink 13 preferably comprises a protrusion 14 protruding from the heat dissipation plate 12.

Description

Heat dissipation materials

[0001] The present invention relates to a heat dissipation member.

[0002] A semiconductor module generally comprises a semiconductor element, an insulating substrate, a heat sink, and a heat sink, in this order (Patent Documents 1 to 3). Heat generated by the semiconductor element is transferred to the heat sink via the insulating substrate and the heat sink, and is then released to the outside of the semiconductor module through the fins of the heat sink. A material with a coefficient of expansion close to that of the insulating substrate and high thermal conductivity is selected for the heat sink. On the other hand, the heat sink is basically only required to have good heat dissipation properties, and a metal with high thermal conductivity and easy processing is selected as its material.

[0003] JP 2010-219215 A International Publication No. 00 / 076940 JP 2001-185665 A

[0004] In semiconductor modules (power modules) that handle large amounts of power (for example, 8 to 12 MW), silicon carbide (SiC) is used as the semiconductor element and silicon nitride (Si ３ N ４ In this case, it is desirable to select a material for the heat sink that has an expansion coefficient close to that of silicon nitride. This increases the adhesion between the insulating substrate and the heat sink, making it easier for heat generated by the semiconductor element to move from the insulating substrate to the heat sink.

[0005] The heat sink and the heat sink are joined via a heat dissipation sheet. The heat dissipation sheet is a separate component from the heat sink and the heat sink, and has relatively low thermal conductivity. Therefore, when heat generated by the semiconductor element travels through the insulating substrate and the heat dissipation sheet to the heat sink, the heat transfer may be hindered by the heat dissipation sheet. In this case, heat dissipation may be insufficient.

[0006] The present invention has been made in view of the above points, and an object of the present invention is to provide a novel heat dissipation member that has not been available in the past.

[0007] As a result of extensive research, the present inventors have found that the above object can be achieved by employing the following configuration, and have completed the present invention.

[0008] That is, the present invention provides the following [1] to

[10] . [1] A heat dissipation component for use in a semiconductor module, which is a SiSiC component comprising a heat dissipation plate on one side of which a semiconductor element and an insulating substrate are arranged, and a heat sink formed integrally with the heat dissipation plate. [2] The heat dissipation component according to [1] above, wherein the heat sink comprises a plurality of protrusions protruding from the heat dissipation plate. [3] The number of protrusions per unit area of ​​the surface of the heat dissipation plate is 1 / cm. ２ [4] The heat dissipation member according to the above [2], wherein the cross-sectional area C of one of the protrusions when cut along the surface of the heat dissipation plate is Ｐ However, 1 to 100 mm ２ [5] The heat dissipation member according to any one of the above [2] to [4], wherein the surface area increase rate is 1.3 or more, provided that the surface area increase rate is the surface area S １ is the surface area S of the heat dissipation member when it is assumed that the protrusion is not provided. ２ The value is obtained by dividing by [6]. [6] The heat dissipation member according to any one of [1] to [5] above, having an average linear expansion coefficient of 2 to 5 ppm / K at 30 to 300°C. [7] The heat dissipation member according to any one of [1] to [6] above, having a thermal conductivity of 150 W / (m·K) or more. [8] The heat dissipation member according to any one of [1] to [7] above, having a SiC content of 90 vol% or less. [9] The heat dissipation member according to any one of [1] to [8] above, having an average particle size of SiC in the range of 2 to 100 μm.

[10] A semiconductor module having the heat dissipation member according to any one of [1] to [9] above.

[0009] According to the present invention, a novel heat dissipation member that has not been available before can be provided.

[0010] 1 is a cross-sectional view schematically showing a semiconductor module;

[0011] 1 is a cross-sectional view schematically showing a semiconductor module 1. The semiconductor module 1 generally comprises a semiconductor element 2, an insulating substrate 3, and a heat dissipation member 11, in this order. A plurality of conductor circuits 4 are formed on one surface of the insulating substrate 3. The semiconductor element 2 is fixed to one conductor circuit 4 via a solder layer 5, and is connected to another conductor circuit 4 by a wire 6. A metal layer 7 is formed over almost the entire surface of the other surface of the insulating substrate 3, and a heat dissipation member 11 is joined to the metal layer 7 via a solder layer 8.

[0012] There are no particular limitations on the semiconductor element 2, and a conventionally known semiconductor element can be used. When the semiconductor module 1 is a semiconductor module that handles high power, examples of the material of the semiconductor element include silicon carbide (SiC).

[0013] The insulating substrate 3 is made of aluminum oxide (Al ２ O ３ ), aluminum nitride (AlN), silicon nitride (Si ３ N ４ When the semiconductor element 2 is made of SiC, the insulating substrate 3 may be made of, for example, Si ３ N ４ is used.

[0014] Materials for the metal layer 7, the conductor circuit 4, and the wires 6 include conductive materials such as copper and aluminum.

[0015] <Heat Dissipation Member (SiSiC Member)> The heat dissipation member 11 is a SiSiC member. The SiSiC member is a composite material containing silicon (Si) and silicon carbide (SiC). The heat dissipation member 11 (also referred to as "SiSiC member 11") includes a heat dissipation plate 12 on one side of which a semiconductor element 2 and an insulating substrate 3 are arranged, and a heat sink 13 formed integrally with the heat dissipation plate 12. That is, in the heat dissipation member 11, the heat dissipation plate 12 and the heat sink 13 are formed seamlessly and integrally.

[0016] <<Heat Sink>> The heat sink 12 is a member that supports the insulating substrate 3, and is, for example, a plate-shaped member. As described above, the semiconductor element 2 and the insulating substrate 3 are arranged on one side of the heat sink 12. The heat sink 12 has a front surface 17, a back surface 18, and a side surface 19. The front surface 17 is the surface of the heat sink 12 on which the multiple protrusions 14 are provided. The back surface 18 is the surface of the heat sink 12 opposite to the front surface 17. The side surface 19 is a surface that connects the front surface 17 and the back surface 18.

[0017] <<Heat Sink>> The heat sink 13 is cooled by contact with a refrigerant. The cooling method may be air-cooling or water-cooling. As the heat sink 13 is cooled, heat generated from the semiconductor element 2 is transferred to the heat sink 13 via the insulating substrate 3 and the heat sink plate 12, and is then released to the outside of the semiconductor module 1. At this time, the heat sink 12 and the heat sink 13 are not joined via, for example, a heat dissipation sheet (not shown), but are formed integrally. Therefore, when the heat generated from the semiconductor element 2 moves from the heat sink 12 to the heat sink 13, the transfer of heat is less likely to be hindered. In other words, the heat dissipation is excellent.

[0018] 2 is a perspective view showing the heat dissipation member 11 having a plurality of protrusions 14. The heat sink 13 preferably has protrusions 14 protruding from the heat dissipation plate 12 as portions that come into contact with the refrigerant. The heat dissipation plate 12 and the protrusions 14 are formed seamlessly and integrally.

[0019] 1 and 2, the heat sink 13 preferably has a plurality of protrusions 14. This increases the area in contact with the refrigerant, thereby improving cooling efficiency. The number of protrusions 14 is set to 1 / cm per unit area of ​​the surface of the heat sink 12 (the surface on which the protrusions 14 are provided) from the viewpoint of improving heat dissipation by increasing density. ２ It is preferable that the number of particles is 5 or more per cm. ２ More preferably, it is 10 particles / cm or more. ２ From the viewpoint of ease of handling of the heat dissipation member 11, the number of protrusions 14 per unit area of ​​the surface of the heat dissipation plate 12 is preferably 500 / cm.２ It is preferable that the number of particles is 300 or less per cm. ２ It is more preferable that the protrusion 14 is as follows: The protrusion 14 may be provided so as to form a flow path for the coolant, and may be, for example, a plate-shaped protrusion 14 .

[0020] (Shape of the Protrusion) The shape of the protrusion 14 is not particularly limited and can be appropriately set from the viewpoint of improving fluid flow and preventing or reducing interference with other components. Examples of shapes include a cylindrical shape; a polygonal prism (including a plate-like shape); a shape combining a cylindrical shape and a polygonal prism; and a shape obtained by partially modifying these shapes (hereinafter also referred to as a "deformed shape"). FIG. 2 illustrates a cylindrical protrusion 14. Specific examples of modified shapes include a shape in which an arbitrary uneven portion or through-holes are formed on the bottom surface 15 and / or side surface 16 of the protrusion 14 (the exposed surface of the protrusion 14 excluding the bottom surface 15); a shape in which the protrusion 14 tapers (decreases in cross-sectional area) from the surface 17 of the heat sink 12 toward the bottom surface 15; and the like. Of these, a cylindrical shape is preferred for the protrusion 14 because it does not obstruct the flow of the refrigerant (both gas and liquid) and can ensure a sufficient surface area.

[0021] (Height H of Protrusion) The height H of the protrusion 14 (the shortest distance from the bottom surface 15 to the surface 17 of the heat sink 12) is preferably 1 mm or more, more preferably 3 mm or more, and even more preferably 5 mm or more. On the other hand, the height H is preferably 50 mm or less, more preferably 40 mm or less, even more preferably 30 mm or less, and particularly preferably 20 mm or less.

[0022] (cross-sectional area of ​​the protrusion C Ｐ ) Cross-sectional area C of the protrusion 14 when cut along the surface 17 of the heat sink 12 Ｐ is 1 mm ２ More than 3 mm is preferable. ２ On the other hand, the cross-sectional area C Ｐ is 100 mm ２ Preferably less than 70 mm ２ Less than 50 mm is more preferable. ２ More preferably, 30 mm or less ２ The following is particularly preferred: 15 mm２ The following is most preferred: Cross-sectional area C Ｐ is the cross-sectional area of ​​one protrusion 14.

[0023] (cross-sectional area of ​​the protrusion C Ｖ ) The cross-sectional area C of the protrusion 14 when cut along a direction perpendicular to the surface 17 of the heat sink 12 so that the cross-sectional area of ​​the protrusion is maximized. Ｖ is 1 mm ２ More than 10 mm is preferable. ２ On the other hand, the cross-sectional area C Ｖ is 500 mm ２ Preferably less than 250 mm ２ Less than 100 mm is more preferable. ２ More preferably, 80 mm or less ２ The following is particularly preferred: 60 mm ２ The following is most preferred: Cross-sectional area C Ｖ is the cross-sectional area of ​​one protrusion 14.

[0024] (Surface Area Increase Rate Due to Protrusions) The surface area S of the heat dissipation member 11 having the protrusions 14 １ The surface area S of the heat dissipation member 11 when it is assumed that the protrusion 14 is not provided is ２ The value obtained by dividing by (S １ / S ２ ) is called the "surface area increase rate." １ and surface area S ２ do not include the areas of the rear surface 18 (the surface on which the protrusions 14 are not provided) and the side surfaces 19 of the heat sink 12. Because sufficient cooling efficiency can be obtained, the surface area increase rate is preferably 1.3 or more, more preferably 1.5 or more, and even more preferably 2 or more. Furthermore, the greater the surface roughness of the protrusions, the easier it is to increase the surface area, so a larger surface roughness of the protrusions is preferred. The surface roughness (Sa) of the protrusions is preferably 1 μm or more, more preferably 5 μm or more. While there is no particular upper limit, 500 μm or less is preferred. The surface roughness (Sa) of the protrusions can be determined by observing any area of ​​the protrusions 14 using a laser microscope (Keyence VK-X1000) and using image analysis software (Keyence VK-H2X).

[0025] The height H and cross-sectional area C Ｐ , cross-sectional area C Ｖ The surface area increase rate can be determined without destroying the heat dissipation member 11 by observing the heat dissipation member 11 using an X-ray CT scanner (model number: SHIMADZU SM4-225CT FPD) and using image analysis software on the obtained data.

[0026] <<Average Linear Expansion Coefficient>> The average linear expansion coefficient (hereinafter also simply referred to as "expansion coefficient") of the heat dissipation member 11 at 30 to 300°C is preferably 2 ppm / K or more, more preferably 2.5 ppm / K or more, and even more preferably 3 ppm / K or more. On the other hand, the expansion coefficient of the heat dissipation member 11 is preferably 5 ppm / K or less, more preferably 4.5 ppm / K or less, and even more preferably 4 ppm / K or less. An example of a method for adjusting the expansion coefficient of the heat dissipation member 11 to fall within the above range is to adjust the SiC content of the heat dissipation member 11 to fall within the range described below. The average linear expansion coefficient is measured, for example, using a thermal dilatometer (LIX-1 manufactured by Advance Riko Co., Ltd.) in accordance with the method described in JIS R 1618.

[0027] As described above, when the material of the semiconductor element 2 is SiC, the material of the insulating substrate 3 is, for example, Si ３ N ４ is used. ３ N ４ The expansion coefficient of the heat dissipation member 11 is, for example, 2 to 3 ppm / K, depending on the impurity content. In this case, if the expansion coefficient of the heat dissipation member 11 is within the above range, the insulating substrate 3 and the heat dissipation member 11 have similar expansion coefficients, so warping caused by the difference in expansion coefficients is unlikely to occur. In other words, peeling due to warping is unlikely to occur.

[0028] <<Thermal Conductivity>> The thermal conductivity of the heat dissipation member 11 is preferably 150 W / (m·K) or more, more preferably 160 W / (m·K) or more, and even more preferably 165 W / (m·K) or more. A method for adjusting the thermal conductivity of the heat dissipation member 11 to fall within the above range includes, for example, adjusting the SiC content of the heat dissipation member 11 to fall within the range described below. The thermal conductivity is measured at room temperature (23°C) by a flash method using xenon lamp light from an LFA 467 (Nanoflash) manufactured by NETZSCH.

[0029] <<SiC Content>> The heat dissipation member 11 is required to contain an appropriate amount of elemental Si. Therefore, the SiC content of the heat dissipation member 11 is preferably 90 vol% or less, more preferably 75 vol% or less, even more preferably 60 vol% or less, and particularly preferably 50 vol% or less. As will be described later, SiC has a higher density than elemental Si. Therefore, when the SiC content of the heat dissipation member 11 is low, the heat dissipation member 11 is relatively lighter than when the SiC content is high.

[0030] On the other hand, if the content of simple substance Si is too high, the strength (four-point bending strength, etc.) of the heat dissipation member 11 may be insufficient. For this reason, in order to obtain sufficient strength, the SiC content of the heat dissipation member 11 is preferably 10% by volume or more, more preferably 20% by volume or more, and even more preferably 30% by volume or more.

[0031] The SiC content (unit: volume %) is determined from an optical microscope photograph as follows. In a microscope photograph of a cross section of the heat dissipation member 11, the gray parts are SiC, and the lighter, white parts are elemental Si. From a microscope photograph of an arbitrary cross section of the heat dissipation member 11, the area ratios of SiC and elemental Si are determined using image analysis software (WinROOF2015), and the determined area ratios are used as the respective volume ratios. The SiC content is determined by using an average value determined from any five fields of view.

[0032] <<Average grain size of SiC>> The heat dissipation member 11 has a cross-sectional area C Ｐ is small (for example, 5 mm ２Consider a case where the heat dissipation member 11 has cylindrical or polygonal pillar-shaped protrusions 14 (which are equal to or less than 100 μm). In this case, if the average particle size of the SiC constituting the protrusions 14 is too large, the amount of bonding between the SiC particles becomes relatively small, and the shape of the protrusions 14 is easily distorted. For this reason, the average particle size of the SiC in the heat dissipation member 11 including the protrusions 14 is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 60 μm or less, even more preferably 40 μm or less, particularly preferably 20 μm or less, and most preferably 15 μm or less.

[0033] On the other hand, the average particle size of SiC in the heat dissipation member 11 is preferably 2 μm or more, more preferably 5 μm or more, and even more preferably 8 μm or more.

[0034] The average particle size of SiC, like the SiC content, is determined from an optical microscope photograph. The particle size (circle equivalent diameter) of each SiC particle is measured from a microscope photograph of an arbitrary cross section of the heat dissipation member 11 using image analysis software (WinROOF2015). The average value of the particle sizes of SiC determined in any five fields of view is defined as the average particle size of SiC.

[0035] <<Four-Point Bending Strength>> The four-point bending strength of the heat dissipation member 11 is preferably 130 MPa or more, more preferably 160 MPa or more, and even more preferably 200 MPa or more. The four-point bending strength is measured at 20°C in accordance with the bending strength test method (four-point bending strength) described in JIS R 1601:2008.

[0036] <Density> The density of the heat dissipation member 11 is 2.3 g / cm ３ More than 2.5 g / cm is preferred. ３ More preferably, 2.6 g / cm ３ On the other hand, the density of the heat dissipation member 11 is 3.2 g / cm ３ Preferably, 3.1 g / cm or less ３ More preferably, 3.0 g / cm or less ３ The following is more preferred: The density is measured in accordance with the method described in JIS Z 8807-2012.

[0037] [Method for Manufacturing Heat Dissipation Member (SiSiC Member)] Next, a method for manufacturing the heat dissipation member 11 will be described.

[0038] <Preparation of SiC Molded Body> First, a SiC molded body (not shown) containing SiC particles is formed. The SiC molded body is also a porous body having a large number of pores. Therefore, as described below, the SiC molded body is impregnated with molten elemental Si. The porosity of the SiC molded body is preferably 30% by volume or more, more preferably 40% by volume or more. On the other hand, the porosity of the SiC molded body is preferably 70% by volume or less, more preferably 65% ​​by volume or less, and even more preferably 60% by volume or less. The porosity is measured using a mercury porosimeter.

[0039] The dimensions and shape of the SiC molded body are appropriately set depending on the dimensions and shape of the heat dissipation member 11 (SiSiC member 11) to be finally obtained. For example, if the heat dissipation member 11 to be finally obtained has a protrusion 14, a SiC molded body having a protrusion of the same shape as this protrusion 14 is produced.

[0040] As a method for producing a SiC molded body, the 3D printing method described below is preferred.

[0041] <<3D Printing Method>> To produce a SiC molded body, a 3D (three-dimensional) printing method such as laser irradiation molding or binder jet molding is used. In the 3D printing method, layers are formed one by one and sequentially stacked to obtain a SiC molded body, which is a laminated body of a desired shape. The thickness of each layer stacked sequentially is, for example, 0.01 to 0.3 mm.

[0042] In laser irradiation molding, a layer containing SiC particles and a binder is irradiated with a laser. The heat from the laser melts and solidifies the binder in the irradiated area, bonding the SiC particles together. This process is repeated for each layer to produce a SiC molded body.

[0043] In binder jet molding, a binder is sprayed from an inkjet nozzle onto a layer containing SiC particles. In the region where the binder is sprayed, the SiC particles bond together. This process is performed for each layer that is sequentially stacked to produce a SiC molded body. In binder jet molding, a curing agent (e.g., an aqueous solution of an acidic substance containing xylene sulfonic acid, sulfuric acid, etc.) may be added to the layer containing SiC particles in advance, and the binder may react (cure) only in the region where the sprayed binder comes into contact with the curing agent. The content of the curing agent is, for example, 0.1 to 1 mass% relative to the SiC particles. Alternatively, the binder may be sprayed onto the layer containing SiC particles without using a curing agent, followed by heat treatment to harden the binder. The heat treatment temperature is, for example, 150 to 250°C.

[0044] The SiC particles are preferably α-SiC. The average particle size of the SiC particles used is appropriately selected so that the final SiSiC member 11 has a desired average particle size. The average particle size of the SiC particles is measured using a laser diffraction / scattering particle size distribution analyzer (MT3300EXII, manufactured by Microtrac Bell).

[0045] Examples of binders include thermosetting resins such as phenolic resins; self-hardening resins such as furan resins; and the like.

[0046] Incidentally, Patent Documents 1 to 3 specifically describe methods for producing SiC molded bodies that are different from 3D printing. For example, see Example 1 (

[0068] to

[0069] ) of Patent Document 1, Example 1 (pages 13 to 18) of Patent Document 2, and Example 1 (

[0054] to

[0060] ) of Patent Document 3. Specifically, Patent Document 1 (

[0068] ) describes in "Example 1" that "SiC powder having an average particle size of 50 μm and SiC powder having an average particle size of 10 μm were mixed in a weight ratio of 7:3, and an organic binder and water were added to the mixture to prepare a slurry, and a molded body was formed using the slurry by a slurry casting method."

[0047] However, using the methods described in Patent Documents 1 to 3, the cross-sectional area C Ｐ is small (for example, 5 mm ２ When a SiC molded body having cylindrical or polygonal pillar-shaped protrusions (described below) is produced, the protrusions tend to be misshapen (or the protrusions that are formed tend to be misshapen). In contrast, when a SiC molded body is produced using the above-described 3D printing method, the misshapen protrusions are less likely to be formed (or the protrusions that are formed tend to be misshapen).

[0048] <Si Impregnation> Next, the SiC molded body is impregnated with silicon (Si). Hereinafter, this process is also referred to as "Si impregnation." Specifically, for example, the SiC molded body and elemental Si are brought into contact with each other and then heated to melt the elemental Si. As a result, the molten elemental Si is impregnated into the porous SiC molded body by capillary action. In this way, the SiSiC member 11, which is a composite material in which the SiC molded body is impregnated with elemental Si, is obtained. At this time, by melting the elemental Si while it is placed on the top surface of the SiC molded body, gravity is utilized to facilitate the impregnation of the molten elemental Si into the SiC molded body. The environment in which the elemental Si is melted is preferably a reduced-pressure environment.

[0049] The heating temperature may be any temperature equal to or higher than the melting point of Si. The melting point of Si varies slightly depending on the measurement method, but is generally 1410 to 1414° C. The heating temperature is preferably 1420° C. or higher.

[0050] The amount of Si introduced into the SiC compact is appropriately set depending on the SiC content of the SiSiC member 11 to be finally obtained.

[0051] The resulting SiSiC member 11 is sintered by the heat applied when melting the Si element. That is, SiC molecules bond with each other and SiC molecules bond with Si to obtain a dense sintered body. Therefore, the resulting SiSiC member 11 is a composite material containing Si and SiC, and is also a sintered body.

[0052] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples described below. Below, Example 1 is an example, and Examples 2 to 4 are reference examples.

[0053] Example 1: A SiC molded body was produced using a 3D printing method. That is, a SiC molded body was produced by a binder jet molding method using a powder lamination type 3D printer. Specifically, first, a layer (thickness: 0.03 mm) was formed using SiC particles, and a binder was sprayed onto the formed layer from an inkjet nozzle. This process was repeated to form 292 cylindrical protrusions (cross-sectional area C Ｐ : 3.14 mm ２ A SiC compact was fabricated in which an integrally formed SiC molded body (diameter: 10 mm, height H: 6 mm) was formed. α-SiC powder (average particle size: 10 μm, manufactured by Shinano Electric Refining Co., Ltd.) was used as the SiC particles. BA005 manufactured by ExOne was used as the binder.

[0054] Next, Si impregnation was carried out. More specifically, first, elemental Si was placed on the SiC molded body in a reactor. The amount of elemental Si placed was adjusted so that the SiC content (unit: volume %) of the resulting SiSiC member would be the value shown in Table 1 below (the same applies hereinafter). Thereafter, the reactor was heated to 1470°C in a reduced pressure environment. This caused the elemental Si to melt and be impregnated into the SiC molded body.

[0055] In this way, a SiSiC member, which is a sintered body containing elemental Si and SiC, was obtained as a heat dissipation member. Example 2: A SiC molded body was produced in the same manner as in Example 1, except that α-SiC powder having an average particle size of 30 μm was used as the SiC particles. Thereafter, SiSiC impregnation was carried out on the SiC molded body in the same manner as in Example 1, to produce a SiSiC member. Example 3: A SiC molded body was produced in the same manner as in Example 1, except that α-SiC powder having an average particle size of 50 μm was used as the SiC particles. Thereafter, Si impregnation was carried out on the SiC molded body in the same manner as in Example 1, to produce a SiSiC member.

[0056] Example 4 A SiC molded body was produced in accordance with the method described in Example 1 (

[0068] to

[0069] ) of Patent Document 1. Thereafter, in the same manner as in Example 1, the SiC molded body was impregnated with Si to produce a SiSiC member.

[0057] Example 5 A SiC molded body was produced in accordance with the method described in Example 1 (pages 13 to 18) of Patent Document 2. Thereafter, the SiC molded body was impregnated with Si in the same manner as in Example 1 to produce a SiSiC member.

[0058] Example 6 A SiC molded body was produced in accordance with the method described in Example 1 (

[0054] to

[0060] ) of Patent Document 3. Thereafter, in the same manner as in Example 1, the SiC molded body was impregnated with Si to produce a SiSiC member.

[0059] In this manner, SiSiC members (heat dissipation members) of Examples 1 to 6 were obtained.

[0060] <Various Physical Properties> The SiSiC members of Examples 1 to 6 were measured for expansion coefficient, thermal conductivity, SiC content, average grain size of SiC, four-point bending strength, density, and surface area increase rate (S １ / S ２ ) was measured. Ｐ (average value) 、 The retention rate of the height H of the protrusions and the thickness of the protrusions were measured according to the following method. Furthermore, for the SiSiC members of Examples 1 to 4, the heat dissipation amount of each member was evaluated by a heat dissipation amount simulation. The physical property measurements and simulation results are shown in Table 1 below. For Example 1, the surface roughness (Sa) of the protrusions was measured using a laser microscope (Keyence VK-X1000) and was found to be 9.4 μm. Note that when these physical property values ​​were not measured, a "-" is entered in Table 1 below. "Cannot be measured" in the table means that it was possible to visually confirm that the shape of the protrusions had been distorted.

[0061] Cross-sectional area C of the protrusion Ｐ The average value of the cross-sectional area C of each of the 25 protrusions randomly selected from the plurality of protrusions formed on the SiSiC member was ＰThe retention rate of the protrusion height H was determined by the following method. First, 25 protrusions were randomly selected from the plurality of protrusions formed on the SiSiC member. Then, for each of the 25 protrusions, the ratio of the height of the actually produced protrusion to the height (6 mm) set by the 3D printer (actual height / set height) was determined, and the proportion of the 25 protrusions whose height ratio was within a predetermined range (0.95 to 1.05) was calculated to determine the retention rate of the protrusion height H. The surface area increase rate (S １ / S ２ In the measurement of the surface area increase ratio, Example 4, in which the slip casting method was used to prepare the SiC compact, had a surface area increase ratio of 1.22. The surface area increase ratios of Example 5, in which the slip casting method was used, and Example 6, in which the slip extrusion method was used, were determined to be clearly less than 1.3 based on the visually visible shape of the protrusions. The heat dissipation amount was simulated using simulation software (Simcenter STAR-CCM+ 2020.1 (Build 15.02.007-R8)), with the temperature of the semiconductor element side of the SiSiC member set to 150°C and the heat transfer coefficient of the protrusions set to 10,000 W / (m ２ ・K) and calculated assuming water-cooling.

[0062]

[0063] <Summary of Evaluation Results> As shown in Table 1 above, the SiSiC members of Examples 1 to 3 had better protrusion conditions, as represented by the height H maintenance rate, and higher heat dissipation rates than the SiSiC members of Examples 4 to 6, and therefore had superior heat dissipation capabilities. This demonstrates that the heat dissipation members according to the embodiments of the present invention have excellent heat sink capabilities. The entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2022-80009, filed on May 16, 2022, are hereby incorporated by reference as part of the disclosure of the present specification.

[0064] 1: Semiconductor module 2: Semiconductor element 3: Insulating substrate 4: Conductive circuit 5: Solder layer 6: Wire 7: Metal layer 8: Solder layer 11: Heat dissipation member (SiSiC member) 12: Heat sink 13: Heat sink 14: Protrusion 15: Bottom surface of protrusion 16: Side surface of protrusion 17: Surface of heat sink 18: Back surface of heat sink 19: Side surface of heat sink

Claims

1. a heat sink on one side of which a semiconductor element and an insulating substrate are disposed; A SiSiC member comprising: a heat sink formed integrally with the heat dissipation plate, The heat sink includes a plurality of protrusions protruding from the heat dissipation plate, A heat dissipation member for use in a semiconductor module, wherein the number of said protrusions per unit area of ​​the surface of said heat dissipation plate is 1 / cm 2 or more.

2. A cross-sectional area C of one of the protrusions when cut along the surface of the heat sink. Ｐ However, 1 to 100 mm ２ The heat dissipation member according to claim 1 .

3. The heat dissipation member according to claim 1 , wherein a surface area increase rate is 1.3 or more. However, the surface area increase rate is the surface area S １ The surface area S of the heat dissipation member when it is assumed that the protrusion is not provided ２ This is the value obtained by dividing by

4. The heat dissipation member according to any one of claims 1 to 3, having an average linear expansion coefficient at 30 to 300°C of 2 to 5 ppm / K.

5. The heat dissipation member according to any one of claims 1 to 3, having a thermal conductivity of 150 W / (m·K) or more.

6. The heat dissipation member according to any one of claims 1 to 3, wherein the SiC content is 90 volume % or less.

7. The heat dissipation member according to any one of claims 1 to 3, wherein the average grain size of the SiC is in the range of 2 to 100 µm.

8. A semiconductor module comprising the heat dissipation member according to any one of claims 1 to 3.