Manufacturing method for heat dissipation structure

Abstract

To provide a manufacturing method of a heat dissipation structure in which a metal base plate and a metal heat dissipation plate of the heat dissipation structure having a large bonding area between the metal base plate and the metal heat dissipation plate of a metal-ceramic bonded substrate are bonded to each other with sufficient bonding strength without plating a bonding surface between the metal base plate and the metal heat dissipation plate even when a heating temperature at the time of bonding is lower than a conventional temperature.SOLUTION: After a surface treatment for roughening one surface of a metal heat dissipation plate 18 made of aluminum or an aluminum alloy is performed by blasting, a silver paste is applied to a plurality of application regions spaced apart from each other on one surface of the metal heat dissipation plate, and a metal circuit plate 12 made of aluminum or the aluminum alloy is bonded to one surface of the ceramic substrate 10, and a metal base plate 14 made of aluminum or the aluminum alloy is disposed so as to abut on the other surface. Thereafter, silver in the silver paste is sintered to form a silver bonding layer 16, and the metal base plate is bonded to one surface of the metal heat dissipation plate by the silver bonding layer to manufacture the heat dissipation structure.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a heat dissipation structure, and in particular to a method for manufacturing a heat dissipation structure in which a metal circuit plate made of aluminum or an aluminum alloy is bonded to one surface of a ceramic substrate, one surface of a metal base plate made of aluminum or an aluminum alloy is bonded to the other surface, and a metal heat dissipation plate made of aluminum or an aluminum alloy is bonded to the other surface of the metal base plate. [Background technology]

[0002] Conventionally, semiconductor devices that generate a large amount of heat, such as power modules used to control large currents in electric vehicles, trains, machine tools, etc., use metal-ceramic bonding substrates in which a metal circuit plate (on which semiconductor elements such as power semiconductor elements are mounted) is bonded to one side of a ceramic substrate, and a metal base plate (on which a heat dissipation member such as a heat sink is attached) is bonded to the other side.

[0003] As a method for producing a heat dissipation structure in which a heat dissipation member such as a heat sink is attached to such a metal-ceramic bonding substrate, a method has been proposed in which a power module substrate having an insulating substrate on one side thereof having a circuit layer formed thereon and a metal layer formed on the other side thereof is formed on at least one surface of the heat sink and the surface of the metal layer opposite the insulating substrate, and the power module substrate and the heat sink are laminated together with the layer of paste-like bonding material composition therebetween, and the power module substrate and the heat sink are heated in the lamination direction at a temperature of 150°C to 300°C under a pressure of 1 MPa or less to produce a power module substrate with a heat sink (see, for example, Patent Document 1).

[0004] Also, an insulating substrate having a plate-shaped Al-based metal member made of Al or an Al alloy bonded to the surface of a ceramic plate, and a heat dissipating base plate made of Al or an Al alloy are prepared in a combination such that the average Mg content MgM, expressed as MgM=(Mg1+Mg2) / 2 (where Mg1 is the Mg content (mass%) of the Al-based metal member, and Mg2 is the Mg content (mass%) of the heat dissipating base plate), is 0.2 to 1.5 mass%, and a silver sheet is sandwiched between the Al-based metal member of the insulating substrate and the heat dissipating base plate to form a laminate in which the Al-based metal member, silver sheet, and heat dissipating base plate are laminated, and the compressive stress in the stacking direction between the Al-based metal member and the heat dissipating base plate of this laminate is set to 1.0 to 10.0 MPa, and the laminate is then placed in an inert gas atmosphere or a 1.3 × 10 -2 A method has been proposed for manufacturing a heat dissipation structure by heating the Al-based metal member and the heat dissipation base plate in a vacuum of 100 Pa or less to a maximum temperature of 400 to 600°C, thereby forming a plate-shaped Ag-rich layer between the Al-based metal member and the heat dissipation base plate, the Ag-Al alloy phase having a composition of 5.0 to 20.0 mass% Al, 0.1 to 2.0 mass% Mg, 1.0 mass% or less Si, and the remainder Ag, in terms of mass proportions relative to the total content of Ag, Al, Mg, and Si, and then joining the Al-based metal member and the heat dissipation base plate via the Ag-rich layer (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-87607 A (paragraph number 0011) [Patent Document 2] JP 2023-35714 A (paragraph number 0014) Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, power semiconductor elements have become increasingly miniaturized, resulting in an increase in the heat density generated by the elements. In order to utilize the spread of heat for cooling, there is a demand to increase the area of ​​the metal base plate (the surface to which the metal heat sink is bonded) of metal-ceramic bonding substrates for power modules to 20 mm x 20 mm or more.

[0007] However, when the area of ​​the metal base plate (the surface to which the metal heat sink plate is bonded) of a conventional metal-ceramic bonding substrate for power modules is increased to 20 mm x 20 mm or more, there is a problem in that sufficient bonding strength (shear strength) cannot be obtained between the metal base plate and the metal heat sink plate.

[0008] For example, in the method of Patent Document 1, if the area of ​​the metal layer of the insulating substrate to which the heat sink is bonded via the bonding layer (layer of the paste-like bonding material composition) is increased, a sufficient bonding strength between the heat sink and the bonding layer may not be obtained, and in order to obtain a sufficient bonding strength, it is necessary to provide a silver or gold plating layer on the surface of the top plate of the heat sink. This requires precious metal plating such as silver or gold plating, and a plating process is required, which increases the manufacturing cost.

[0009] Furthermore, in the method of Patent Document 2, the laminate of the Al-based metal member, silver sheet, and heat dissipating base plate must be heated to a high temperature so that the maximum temperature reached is 400 to 600°C. Therefore, if the area of ​​the Al-based metal member to which the heat dissipating base plate is joined via the silver sheet is increased, the difference in thermal expansion between the Al-based metal member and the heat dissipating base plate increases, resulting in greater warping of the heat dissipating structure and possibly making it difficult to assemble power modules, etc.

[0010] Therefore, in view of the above-mentioned conventional problems, the present invention aims to provide a method for manufacturing a heat dissipation structure in which the bonding surface between the metal base plate and the metal heat dissipation plate of a heat dissipation structure having a large bonding area between the metal base plate and the metal heat dissipation plate of a metal-ceramic bonding substrate is not plated, and the metal base plate and the metal heat dissipation plate can be bonded to each other with sufficient bonding strength even when the heating temperature during bonding is lower than conventionally. [Means for solving the problem]

[0011] As a result of intensive research by the inventors to solve the above problems, a metal-ceramic bonding substrate is prepared in which a metal circuit plate made of aluminum or an aluminum alloy is bonded to one surface of a ceramic substrate and one surface of a metal base plate made of aluminum or an aluminum alloy is bonded to the other surface of the ceramic substrate, and a metal heat sink made of aluminum or an aluminum alloy is also prepared, one surface of the metal heat sink is subjected to a surface treatment by blasting to roughen the surface, and then silver paste is applied to a plurality of application areas spaced apart from each other on one surface of the metal heat sink, The present inventors discovered that by placing a metal base plate so that the other side of the metal base plate abuts on the silver paste, then sintering the silver in the silver paste to form a silver bonding layer, and bonding the metal base plate to one side of the metal heat sink using this silver bonding layer, it is possible to bond the metal base plate and the metal heat sink with sufficient bonding strength to each other even when the heating temperature during bonding is lower than conventional, without plating the bonding surface between the metal base plate and the metal heat sink of a heat dissipation structure having a large bonding area between the metal base plate and the metal heat sink of a metal-ceramic bonding substrate, and thus completed the present invention.

[0012] That is, the method for manufacturing a heat dissipation structure according to the present invention is characterized by preparing a metal-ceramic bonding substrate in which a metal circuit plate made of aluminum or an aluminum alloy is bonded to one side of a ceramic substrate and one side of a metal base plate made of aluminum or an aluminum alloy is bonded to the other side, and preparing a metal heat sink made of aluminum or an aluminum alloy, roughening one side of the metal heat sink by blasting, applying silver paste to a plurality of spaced apart application areas on one side of the metal heat sink, and placing the metal base plate so that the other side of the metal base plate abuts on the silver paste, and then sintering the silver in the silver paste to form a silver bonding layer, and bonding the metal base plate to one side of the metal heat sink plate by this silver bonding layer.

[0013] In this method for manufacturing a heat dissipation structure, each of the multiple coated areas is preferably surrounded by a non-coated area on one side of the metal heat sink where no silver paste is applied. In this case, the non-coated areas are preferably arranged in a grid pattern on one side of the metal heat sink, and each of the multiple coated areas is preferably a rectangular area. Furthermore, the arithmetic mean roughness Ra of one side of the metal heat sink is preferably set to 1.7 μm or more, and the ten-point mean roughness Rz is preferably set to 8 μm or more by blasting. Sintering of the silver in the silver paste is preferably performed by heating a second metal while applying pressure to the metal heat sink. This heating is preferably performed at a temperature below 400°C, and preferably includes a first heating step at a temperature of 60°C to less than 120°C, a second heating step at a temperature of 120°C to less than 190°C, a third heating step at a temperature of 190°C to less than 300°C, and a fourth heating step at a temperature of 300°C to less than 400°C. In addition, as a pretreatment for the blasting treatment, it is preferable to chemically polish one surface of the metal heat sink with an aqueous sodium hydroxide solution, and as a posttreatment for the blasting treatment, it is preferable to immerse one surface of the metal heat sink in an aqueous nitric acid solution.In addition, it is preferable that the metal heat sink and the metal base plate are made of pure aluminum with an aluminum purity of 99.0% or more. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a method for manufacturing a heat dissipation structure in which the bonding surface between the metal base plate and the metal heat dissipation plate of a heat dissipation structure having a large bonding area between the metal base plate and the metal heat dissipation plate of a metal-ceramic bonding substrate is not plated, and the metal base plate and the metal heat dissipation plate can be bonded to each other with sufficient bonding strength even when the heating temperature during bonding is lower than conventional. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view of a heat dissipation structure manufactured by an embodiment of a method for manufacturing a heat dissipation structure according to the present invention. [Figure 2] FIG. 2 is a perspective view of the heat dissipation structure of FIG. [Figure 3]1 is a plan view showing a state in which silver paste is applied to the surface of a metal heat sink in an embodiment of a method for manufacturing a heat dissipation structure according to the present invention; FIG. [Figure 4] 10A and 10B are diagrams illustrating a method for measuring the bonding strength between the metal base plate and the metal heat sink plate of the heat dissipation structures of Examples and Comparative Examples. [Figure 5] FIG. 10 is a plan view showing a state in which silver paste is applied to the surface of a metal heat sink plate of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a method for manufacturing a heat dissipation structure according to the present invention will be described in detail with reference to the accompanying drawings.

[0017] In an embodiment of the method for manufacturing a heat dissipation structure according to the present invention, a metal-ceramic bonding substrate is prepared in which a metal circuit plate 12 made of aluminum or an aluminum alloy is bonded to one surface of a ceramic substrate 10 made of aluminum nitride, alumina, silicon nitride, or the like, and one surface of a metal base plate 14 made of aluminum or an aluminum alloy is bonded to the other surface. A metal heat sink 18 made of aluminum or an aluminum alloy is also prepared, and one surface of the metal heat sink 18 is roughened by surface treatment (blasting) to a roughness of 1.7 μm or more (preferably 1.8 to 4 μm, more preferably 1.8 to 4 μm). After that, the surface is treated so that the surface roughness becomes 1.9 to 3 μm (and more preferably 1.9 to 3 μm), and the ten-point height difference Rz becomes 8 μm or more (preferably 8 to 15 μm), silver paste 16' is applied (preferably to a thickness of 100 to 150 μm) to a plurality of spaced-apart application areas on one side of metal heat sink 18, and a metal-ceramic bonding substrate is placed so that the other side of metal base plate 14 abuts on this silver paste 16', and then the silver in silver paste 16' is sintered to form silver bonding layer 16, and metal base plate 14 is bonded to one side of metal heat sink 18 by this silver bonding layer 16, thereby producing the heat dissipation structure shown in Figures 1 and 2.

[0018] The joining method between the metal circuit plate 12 and the ceramic substrate 10 and between the ceramic substrate 10 and the metal base plate 14 may be direct joining by a so-called molten metal joining method, or may be brazing using a known brazing material such as an aluminum alloy (e.g., an Al-Si alloy).

[0019] The surface treatment may be performed not only on one surface of the metal heat sink 18, but also on the other surface of the metal base plate 14. By roughening the bonding surface of the metal heat sink 18 with the metal base plate 14 (and the bonding surface of the metal base plate 14 with the metal heat sink 18) in this way, the bonding strength (shear strength) can be increased by the anchor effect, so that even if the bonding surfaces of the metal base plate 14 and the metal heat sink 18 have a large area of ​​20 mm x 20 mm or more (preferably 100 mm x 100 mm or less, and more preferably 50 mm x 50 mm or less), they can be bonded to each other with sufficient bonding strength.

[0020] As shown in FIG. 3, each of the multiple coated regions is preferably a substantially rectangular coated region (b = 2 to 15 mm, preferably 3 to 10 mm) surrounded by a grid-like (or square-like) non-coated region where no silver paste is applied, and spaced apart from each other by a predetermined distance (a = 5 mm or less, preferably 4 mm or less, more preferably 3 mm or less). By applying silver paste 16′ to the multiple spaced-apart coated regions (preferably spaced-apart coated regions surrounded by grid-like (or square-like) non-coated regions where no silver paste is applied), the non-coated regions serve as passages for gas (generated during desolvation of the solvent contained in silver paste 16′), promoting desolvation and promoting uniform sintering. This is believed to enable good bonding even when heated at a low temperature below 400°C. The multiple spaced-apart coated regions may also be multiple spaced-apart, substantially triangular or hexagonal coated regions of a predetermined size and spaced apart from each other.

[0021] Furthermore, by performing surface treatment so that the ten-point average roughness Rz is 8 μm or more, a gap is formed between one surface of the metal base plate 14 and the silver paste 16′, and this gap acts as a flow path for the gas generated during sintering of the silver paste 16′, promoting desolvent removal and allowing the sintering to proceed uniformly, which is thought to enable good bonding even when heated at a temperature lower than 400°C. When metal base plate 14 and metal heat sink 18 are made of aluminum, they are preferably made of pure aluminum (preferably with an aluminum purity of 99.0% or more, more preferably 99.5% or more). When metal base plate 14 and metal heat sink 18 are made of an aluminum alloy, they are preferably an aluminum alloy containing 0.15% by mass or less of Si, 1.2 to 1.7% by mass of Fe, 0.05% by mass or less of Cu, 0.05% by mass or less of Mn, Mg, Cr, Zn, Ga, V, Ni, B, and Zr each in a total amount of 0.15% by mass or less, with the remainder being Al and unavoidable impurities.

[0022] As a pretreatment for the blasting treatment, the bonding surface (blasted surface) between the metal base plate 14 and the metal heat sink plate 18 may be chemically polished with an alkaline chemical such as a sodium hydroxide solution, and as a posttreatment for the blasting treatment, the bonding surface (blasted surface) between the metal base plate 14 and the metal heat sink plate 18 may be immersed in a nitric acid solution. Chemical polishing with a sodium hydroxide solution is preferably performed by immersing the metal base plate 14 and the metal heat sink plate 18 in a sodium hydroxide solution containing 1 to 5 mass% sodium hydroxide at 20 to 60°C for 10 to 60 seconds. Immersion in a nitric acid solution is preferably performed by immersing the metal base plate 14 and the metal heat sink plate 18 in a nitric acid solution containing 55 to 70 mass% nitric acid at 20 to 40°C for 10 to 60 seconds. The blasting treatment is preferably performed by wet blasting, in which an abrasive slurry containing fine particles in a liquid is sprayed onto the surface of the metal plate. The processing conditions for the wet blasting device are an air pressure of 0.1 to 1 MPa, a processing speed of 1 to 20 m / sec, a projection distance of 10 to 40 mm, and a projection angle of 70 to 90°, and an abrasive slurry containing 15 to 20 volume % abrasive grains made of melamine resin in water can be used.

[0023] The sintering of the silver in the silver paste 16' is preferably carried out by heating the metal base plate 14 while applying pressure to the metal heat sink 18. The sintering temperature is preferably lower than 400°C (more preferably 350°C or lower), and preferably comprises a first heating step at a temperature of 60°C or higher but lower than 120°C, a second heating step at a temperature of 120°C or higher but lower than 190°C, a third heating step at a temperature of 190°C or higher but lower than 300°C, and a fourth heating step at a temperature of 300°C or higher but lower than 400°C. The sintering is preferably carried out at a temperature lower than 400°C for 30 to 120 minutes, with the heating times for the first to third heating steps being 5 to 20 minutes and the heating time for the fourth heating step being 30 to 120 minutes. The pressure applied during the sintering is preferably 0.5 to 4 MPa, more preferably 1 to 3 MPa.

[0024] Alternatively, the silver paste 16' may contain silver particles that can be sintered at a temperature lower than 400°C (preferably at a temperature of 350°C or lower). For example, the average primary particle size (D 50 A bonding material in which silver particles having a diameter (cumulative 50 mass % particle diameter measured by laser diffraction) of 0.1 to 10 μm are dispersed in a dispersion medium can be used.

[0025] In an embodiment of the method for manufacturing a heat dissipation structure according to the present invention, even when the silver in the silver paste 16' is sintered at a low pressure of approximately 0.5 to 4 MPa (preferably 1 to 3 MPa) and heated at a temperature of 250°C or higher but lower than 400°C, the metal base plate 14 can be bonded to the metal heat dissipation plate 18 made of aluminum or an aluminum alloy with sufficient bonding strength (with almost no bonding defects such as voids in the bonding portion).

[0026] In this specification, the terms "arithmetic mean roughness Ra" and "ten-point mean roughness Rz" refer to the arithmetic mean roughness Ra and ten-point mean roughness Rz calculated based on JIS B0601 (2001), respectively. [Example]

[0027] Hereinafter, examples of the method for manufacturing a heat dissipation structure according to the present invention will be described in detail.

[0028] [Example] Using the so-called molten metal bonding method, a metal-ceramic bonding substrate was prepared in which a metal circuit plate 12 made of pure aluminum (A1050) and having a roughly rectangular planar shape of 27 mm x 27 mm x 1 mm was directly bonded to one surface of a ceramic substrate 10 having a roughly rectangular planar shape of 30 mm x 30 mm x 0.635 mm, and one surface of a metal base plate 14 made of pure aluminum (A1050) and having a roughly rectangular planar shape of 27 mm x 27 mm x 1 mm was directly bonded to the other surface, and a metal heat sink 18 made of pure aluminum (A1050) and having a roughly rectangular planar shape of 40 mm x 40 mm x 3 mm was also prepared.

[0029] Next, the other surface of metal base plate 14 and one surface of metal heat sink plate 18 were chemically polished by immersing them in a 3% sodium hydroxide aqueous solution at room temperature for 30 seconds, then the surfaces were wet-blasted using a wet blasting device (Model NFR-737 manufactured by Maco Corporation) to roughen them, and then immersed in a 65.7% nitric acid aqueous solution for 30 seconds to perform surface treatment on the other surface of metal base plate 14 and one surface of metal heat sink plate 18. The treatment conditions for the wet blasting device were an air pressure of 0.2 MPa, a treatment speed of 10 m / s, a projection distance of 20 mm, and a projection angle of 90°, and an abrasive slurry containing 18 volume % melamine resin #80 / 100 with a grain size of 0.125 to 0.177 mm in water as abrasive grains. For the other surface of metal base plate 14 and one surface of metal heat sink 18 after this surface treatment, the line roughness measurement function of an ultra-deep surface profile measuring microscope (VK-8500 manufactured by Keyence Corporation) was used to measure the line roughness along any straight line 100 μm long parallel to one side of any 100 μm × 100 μm square area on the other surface of metal base plate 14 and one surface of metal heat sink 18. From the results, the surface roughness (arithmetic mean roughness Ra and ten-point mean roughness Rz) was calculated based on JIS B0601 (2001). As a result, the arithmetic mean roughness Ra of the other surface of metal base plate 14 and one surface of metal heat sink 18 after surface treatment was 2.4 μm, and the ten-point mean roughness Rz was 12 μm.

[0030] In addition, the average primary particle size (D 50 A silver paste was prepared by mixing flake silver particles having a diameter (cumulative 50% by volume particle diameter) of 6 μm with an ether-based solvent (CELTOL IA manufactured by Daicel Corporation) at a mass ratio (flake silver particles:ether-based solvent) of 13:1.

[0031] Next, the above silver paste 16' was applied to a thickness of 100 μm in 36 spaced-apart application areas (36 (= 6 columns × 6 rows) (approximately rectangular application areas with b = 4 mm) spaced apart so that the spacing between adjacent rows and columns was a = 2 mm) on one side of the surface-treated metal heat sink 18 (as shown in Figure 3), and a metal-ceramic bonding substrate was placed on top so that the other side of the surface-treated metal base plate 14 abutted against it.The metal-ceramic bonding substrate was then preheated in air at 80°C for 20 minutes, 120°C for 20 minutes, and 190°C for 20 minutes while applying a pressure of 2 MPa, and then heated at 300°C for 60 minutes, thereby bonding the other side of the metal base plate 14 to one side of the metal heat sink 18, and a heat dissipation structure was produced in which a metal-ceramic bonding substrate was bonded to the metal heat sink 18.

[0032] The heat dissipation structure produced in this manner was cut into pieces measuring 5 mm x 5 mm (as shown in Figure 4), yielding samples 1 to 15. Using a shear strength measuring device (SPST2000N manufactured by Adwells Co., Ltd.), the force at which the metal base plate 14 peeled off from the metal heat dissipation plate 18 was measured, and the shear strength (bonding strength) was calculated to be 15.8 to 22.6 MPa, indicating that all samples were very firmly bonded.

[0033] [Comparative Example] A heat dissipation structure in which a metal-ceramic bonding substrate was bonded to a metal heat dissipation plate 18 was produced in the same manner as in the example, except that the silver paste 20' was applied to a roughly rectangular coating area measuring 35 mm x 35 mm (as shown in Figure 5) on one side of the surface-treated metal heat dissipation plate 18. The shear strength (bonding strength) of the heat dissipation structure thus produced was determined by the same method as in the example, and it was found to be 0 to 20.4 MPa, with some portions not being bonded at all. [Explanation of symbols]

[0034] 10 Ceramic substrate 12 Metal circuit board 14 Metal base plate 16 Silver bonding layer 16' Silver Paste 18 Metal heat sink 20' Silver Paste

Claims

1. A method for manufacturing a heat dissipation structure, comprising: preparing a metal-ceramic bonding substrate having a metal circuit plate made of aluminum or an aluminum alloy bonded to one surface of a ceramic substrate and one surface of a metal base plate made of aluminum or an aluminum alloy bonded to the other surface; preparing a metal heat sink made of aluminum or an aluminum alloy; surface treating one surface of the metal heat sink by blasting to roughen the surface; applying silver paste to a plurality of spaced-apart application areas on one surface of the metal heat sink; placing the metal base plate so that the other surface of the metal base plate abuts on the silver paste; sintering the silver in the silver paste to form a silver bonding layer; and bonding the metal base plate to one surface of the metal heat sink by means of the silver bonding layer.

2. The method for manufacturing a heat dissipation structure according to claim 1 , wherein each of the plurality of coated areas is surrounded by a non-coated area on one side of the metal heat sink where the silver paste is not coated.

3. The method for manufacturing a heat dissipation structure according to claim 2 , wherein the non-coated areas are arranged in a grid pattern on one surface of the metal heat dissipation plate.

4. The method for manufacturing a heat dissipation structure according to claim 3 , wherein each of the plurality of coating areas is a rectangular area.

5. 2. The method for manufacturing a heat dissipation structure according to claim 1, wherein the blasting treatment makes the arithmetic mean roughness Ra of one surface of the metal heat dissipation plate 1.7 [mu]m or more.

6. 2. The method for manufacturing a heat dissipation structure according to claim 1, wherein the blasting treatment makes the ten-point mean roughness Rz of one surface of the metal heat dissipation plate 8 [mu]m or more.

7. The method for manufacturing a heat dissipation structure according to claim 1 , wherein the sintering is performed by heating the second metal while applying pressure to the metal heat dissipation plate.

8. The method for manufacturing a heat dissipation structure according to claim 7, wherein the heating is performed at a temperature of less than 400°C.

9. 8. The method for manufacturing a heat dissipation structure according to claim 7, characterized in that the heating comprises a first heating step of heating at a temperature of 60°C or higher and lower than 120°C, a second heating step of heating at a temperature of 120°C or higher and lower than 190°C, a third heating step of heating at a temperature of 190°C or higher and lower than 300°C, and a fourth heating step of heating at a temperature of 300°C or higher and lower than 400°C.

10. 2. The method for manufacturing a heat dissipation structure according to claim 1, wherein one surface of the metal heat dissipation plate is chemically polished with an aqueous solution of sodium hydroxide as a pretreatment for the blasting treatment.

11. 2. The method for manufacturing a heat dissipation structure according to claim 1, wherein one surface of the metal heat dissipation plate is immersed in an aqueous nitric acid solution as a post-treatment of the blasting treatment.

12. 2. The method for manufacturing a heat dissipation structure according to claim 1, wherein the metal heat dissipation plate and the metal base plate are made of pure aluminum having an aluminum purity of 99.0% or more.

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