Joining method, method for manufacturing cooler, method for manufacturing semiconductor device, cooler, and semiconductor device

Abstract

This joining method includes the following steps. A brazing material (12) and a material (13) to be joined are arranged on a base part (1). The base part (1) and the material (13) to be joined are joined by heating the brazing material (12) at a temperature equal to or higher than a melting point of the brazing material (12) and less than a melting point of the base part (1). The base part (1) contains aluminum. The brazing material (12) contains aluminum and silicon. The material (13) to be joined includes a first layer (31) and a second layer (32). The first layer (31) contains nickel. The second layer (32) is provided on the first layer (31). The second layer (32) contains copper. In the step for arranging the brazing material (12) and the material (13) to be joined, the brazing material (12) is arranged between the base part (1) and the first layer (31).

Description

Bonding method, manufacturing method of cooler, manufacturing method of semiconductor device, cooler and semiconductor device

[0001] The present disclosure relates to a bonding method, a method for manufacturing a cooler, a method for manufacturing a semiconductor device, a cooler, and a semiconductor device.

[0002] Aluminum-containing components are prone to forming dense oxide films, which means that they have poor solder wettability, making it difficult to join other components to aluminum-containing components using soldering.

[0003] Japanese Patent Laid-Open Publication No. 2014-227579 (Patent Document 1) describes, as an example of an aluminum alloy member, an aluminum alloy member having a base member made of an aluminum alloy and a soldering surface portion for soldering another member to the base member. The soldering surface portion is composed of a brazing filler metal layer joined to the surface of the base member and a nickel foil layer brazed to the brazing filler metal layer.

[0004] Japanese Patent Application Laid-Open No. 2014-227579

[0005] Nickel may have poor solder wettability. Specifically, the solder wettability of nickel may be poor depending on the solder composition and the atmosphere inside the furnace during soldering. As a result, when nickel is joined to a component containing aluminum, the solder wettability of the component containing aluminum may not be improved.

[0006] The present disclosure has been made in consideration of the above, and its purpose is to provide a joining method, a manufacturing method of a cooler, a manufacturing method of a semiconductor device, a cooler, and a semiconductor device that can improve the solder wettability of a component containing aluminum.

[0007] The joining method according to the present disclosure includes the following steps: A brazing filler metal and a workpiece are placed on a base portion; The base portion and the workpiece are joined by heating the brazing filler metal at a temperature equal to or higher than the melting point of the brazing filler metal and lower than the melting point of the base portion; The base portion includes aluminum; The brazing filler metal includes aluminum and silicon; The workpiece has a first layer and a second layer; The first layer includes nickel; The second layer is disposed on the first layer; The second layer includes copper; In the step of placing the brazing filler metal and the workpiece, the brazing filler metal is placed between the base portion and the first layer.

[0008] According to the bonding method of the present disclosure, a second layer containing copper is bonded to a base portion containing aluminum. Copper has a wide range of soldering conditions under which it exhibits good solder wettability. Therefore, it is possible to provide a bonding method, a manufacturing method for a cooler, a manufacturing method for a semiconductor device, a cooler, and a semiconductor device that can improve the solder wettability of aluminum-containing members.

[0009] FIG. 1 is a schematic cross-sectional view showing the configuration of a cooler according to embodiment 1. FIG. 2 is an enlarged schematic cross-sectional view showing region II of FIG. 1. FIG. 3 is a schematic cross-sectional view showing the configuration of a semiconductor device according to embodiment 1. FIG. 4 is a flow chart showing a joining method according to embodiment 1. FIG. 5 is a schematic cross-sectional view showing a step of arranging a brazing filler metal and a material to be joined on a base portion. FIG. 6 is a flow chart showing a manufacturing method of a cooler according to embodiment 1. FIG. 7 is a schematic cross-sectional view showing a step of arranging a brazing filler metal and a material to be joined on a base portion in the manufacturing method of a cooler according to embodiment 1. FIG. 8 is an exploded schematic view showing the configuration of a fin member. FIG. 9 is a flow chart showing a manufacturing method of a semiconductor device according to embodiment 1. FIG. 10 is a schematic cross-sectional view showing a joining method according to embodiment 2. FIG. 11 is a schematic cross-sectional view showing a joining method according to embodiment 3. FIG. 12 is a schematic cross-sectional view showing a joining method according to embodiment 4. FIG. 13 is a schematic plan view showing a joining method according to embodiment 4. FIG. 14 is a schematic cross-sectional view showing a joining method according to embodiment 5. FIG. 15 is a schematic perspective view showing the configuration of materials to be joined according to embodiment 5. FIG. 16 is a schematic cross-sectional view showing a joining method according to embodiment 6. FIG. 17 is a schematic cross-sectional view showing a joining method according to embodiment 7. FIG. 18 is a schematic cross-sectional view showing a joining method according to embodiment 8. 13 is a cross-sectional view schematically illustrating a state after a step of placing a brazing filler metal and a workpiece to be joined on a base portion in a joining method according to a ninth embodiment. FIG. 14 is a plan view schematically illustrating the configuration of the workpiece to be joined according to the ninth embodiment. FIG. 15 is a cross-sectional view schematically illustrating a step of joining the base portion and the workpiece to be joined according to the ninth embodiment. FIG. 16 is a cross-sectional view schematically illustrating a modification of the joining method according to the ninth embodiment. FIG. 17 is a flow chart generally illustrating a joining method according to a tenth embodiment. FIG. 18 is a bottom view schematically illustrating the configuration of the first layer according to the tenth embodiment. FIG. 19 is a cross-sectional view generally illustrating a state in which an anti-wetting agent has been applied to the first layer. FIG. 19 is a flow chart generally illustrating a method for manufacturing a cooler and a method for manufacturing a semiconductor device according to an eleventh embodiment. FIG. 19 is a cross-sectional view generally illustrating a step of performing blasting on the surface of the second layer. FIG. 20 is an enlarged cross-sectional view generally illustrating the configuration of a cooler according to the eleventh embodiment. FIG. 21 is an enlarged cross-sectional view generally illustrating the configuration of a semiconductor device according to the eleventh embodiment.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and the description thereof will not be repeated.

[0011] First Embodiment <Configuration of Cooler> First, the configuration of a cooler 100 according to the first embodiment will be described with reference to Figures 1 and 2. As shown in Figure 1, the cooler 100 mainly includes a base portion 1, a joining portion 2, a portion to be joined 3, fins 5, and a jacket 6. The cooler 100 is a type of heat exchanger.

[0012] The base portion 1 has, for example, a flat plate shape. The base portion 1 has a first surface 41 and a second surface 42. The first surface 41 has, for example, a planar shape. The second surface 42 is provided on the opposite side of the first surface 41. The direction from the second surface 42 toward the first surface 41 is defined as a first direction 101.

[0013] The base portion 1 contains aluminum (Al). The material constituting the base portion 1 may be aluminum or an aluminum alloy containing aluminum as a main component. Specifically, the material constituting the base portion 1 may be pure aluminum, a 1000 series aluminum alloy, or a 3000 series aluminum alloy. The 1000 series aluminum alloy and the 3000 series aluminum alloy are materials specified in JIS (Japanese Industrial Standards) H4000:2014.

[0014] The weight content of aluminum in base portion 1 may be, for example, 90% or more, 95% or more, 99% or more, or 99.9% or more. The weight content of a material in a member is the value obtained by dividing the weight of the material by the weight of the member.

[0015] The joint 2 is joined to the base portion 1. Specifically, the joint 2 is joined to the base portion 1 at the first surface 41. The joint 2 is provided in a first direction 101 relative to the base portion 1.

[0016] The joint 2 contains aluminum and silicon (Si). The joint 2 is made of, for example, aluminum, silicon, and unavoidable impurities. The joint 2 is made of, for example, an Al-Si aluminum alloy.

[0017] The weight content of silicon in the bonding portion 2 is, for example, 4% or more and 12% or less. The weight content of silicon in the bonding portion 2 is desirably 6% or more and 9% or less. The weight content of aluminum in the bonding portion 2 may be lower than the weight content of aluminum in the base portion 1.

[0018] The bonded portion 3 is provided above the bonding portion 2. From another perspective, the bonding portion 2 is provided between the base portion 1 and the bonded portion 3. The bonded portion 3 has a first layer 31 and a second layer 32.

[0019] The first layer 31 is provided above the bonding portion 2. The first layer 31 contains nickel. The first layer 31 may be made of pure nickel. Specifically, the weight content of nickel in the first layer 31 may be, for example, 99% or more. The first layer 31 may contain at least one of the elements contained in the bonding portion 2 and at least one of the elements contained in the second layer 32 described below. Specifically, the first layer 31 may contain, for example, at least one of aluminum and silicon. The first layer 31 may also contain copper (Cu).

[0020] The second layer 32 is provided on the first layer 31. In this specification, "provided on" includes a case where two objects are in direct contact with each other and a case where another object is provided between the two objects so as to be in contact with each of the two objects, and the two objects are separated by the other object. In the cooler 100 according to the first embodiment, the second layer 32 is in contact with the first layer 31.

[0021] The second layer 32 is bonded to the first layer 31. Specifically, the second layer 32 is bonded to the first layer 31 by, for example, rolling. From another perspective, the bonded portion 3 is, for example, a clad material. The second layer 32 is provided in the first direction 101 relative to the first layer 31. The second layer 32 is a portion to which another component, such as a semiconductor chip 9 (see FIG. 3 ), described below, is bonded by, for example, soldering.

[0022] The second layer 32 contains copper. The second layer 32 may be made of pure copper. Specifically, the weight content of copper in the second layer 32 may be, for example, 99% or more. The second layer 32 may contain at least one of the elements contained in the first layer 31. Specifically, the second layer 32 may contain, for example, nickel.

[0023] 2 , the cooler 100 has a compound portion 4. The compound portion 4 is connected to each of the joining portion 2 and the joined portion 3. Specifically, the compound portion 4 is connected to the first layer 31. The compound portion 4 is provided in a first direction 101 with respect to the joining portion 2.

[0024] The compound portion 4 contains at least one of the elements contained in the bonding portion 2 and at least one of the elements contained in the first layer 31. Specifically, the compound portion 4 contains, for example, aluminum and nickel (Ni). The compound portion 4 is formed of, for example, an Al-Ni intermetallic compound. The compound portion 4 may also contain silicon. From another perspective, the compound portion 4 may also contain a compound of silicon and nickel. As shown in FIG. 2 , the thickness of the bonding portion 2 and the compound portion 4 in the first direction 101 is defined as a first thickness H1. The first thickness H1 is, for example, 0.1 mm or less.

[0025] The bonded portion 3 is provided in the first direction 101 relative to the compound portion 4. From another perspective, the compound portion 4 is provided between the bonding portion 2 and the bonded portion 3. The bonded portion 3 is separated from the bonding portion 2 by the compound portion 4. In other words, the bonded portion 3 is spaced apart from the bonding portion 2. The compound portion 4 and the bonding portion 2 bond the bonded portion 3 and the base portion 1 together.

[0026] The first layer 31 has a third surface 43. At the third surface 43, the first layer 31 is continuous with the compound portion 4. From another perspective, the third surface 43 is an interface between the first layer 31 and the compound portion 4. The first layer 31 is provided between the second layer 32 and the compound portion 4. The thickness of the first layer 31 in the first direction 101 is a seventh thickness H7.

[0027] The second layer 32 has a fifth surface 45, a sixth surface 46, a first side surface 21, and a second side surface 22. The second layer 32 is bonded to the first layer 31 at the fifth surface 45. From another perspective, the fifth surface 45 is the interface between the second layer 32 and the first layer 31. The thickness of the second layer 32 in the first direction 101 is defined as an eighth thickness H8. The eighth thickness H8 is at least twice the seventh thickness H7.

[0028] The sixth surface 46 is provided on the opposite side of the fifth surface 45. The sixth surface 46 is, for example, planar. The sixth surface 46 is a surface to which other components, such as a semiconductor chip 9 (see FIG. 3 ), described below, are soldered. The first side surface 21 is continuous with both the fifth surface 45 and the sixth surface 46. The first side surface 21 is spaced apart from the first layer 31. The second side surface 22 is provided on the opposite side of the first side surface 21. The second side surface 22 is continuous with both the fifth surface 45 and the sixth surface 46. The second side surface 22 is spaced apart from the first layer 31.

[0029] As shown in Fig. 2, the thickness of the bonded portion 3 in the first direction 101 is set to a second thickness H2. The second thickness H2 is, for example, 300 µm or less. The base portion 1, the bonding portion 2, the compound portion 4, and the bonded portion 3 constitute a bonded structure 10. Fig. 2 shows the configuration of the bonded structure 10 according to the first embodiment.

[0030] 1, the fins 5 are bonded to the base portion 1. Specifically, the fins 5 are bonded to the base portion 1 at the second surface 42. The fins 5 are provided on the opposite side of the base portion 1 from the bonded portion 3. The fins 5 are configured to cool other components bonded to the second layer 32 by transferring heat to a coolant (not shown) and dissipating the heat. A flow path 90 is provided in the fins 5. The flow path 90 is a portion through which the coolant flows.

[0031] The fin 5 has a plurality of plate portions 8. The fin 5 is formed by stacking the plurality of plate portions 8 along the first direction 101. Two adjacent plate portions 8 are bonded to each other. The plate portions 8 have a bonded layer 82 and a bonding layer 81. The bonded layer 82 is made of, for example, an aluminum alloy containing aluminum as a main component. The bonded layer 82 is made of, for example, a 3000 series aluminum alloy.

[0032] The bonding layer 81 is provided in the first direction 101 relative to the bonded layer 82. The bonding layer 81 bonds two adjacent plate portions 8 together. The bonding layer 81 in contact with the base portion 1 bonds the base portion 1 to the fins 5. The bonding layer 81 contains aluminum and silicon. The bonding layer 81 is made of, for example, an Al-Si aluminum alloy.

[0033] As shown in Fig. 1 , the jacket 6 is joined to the base portion 1. The jacket 6 surrounds the fins 5. The jacket 6 is, for example, spaced apart from the fins 5. The jacket 6 and the base portion 1 define a space 91. The space 91 is provided between the jacket 6 and the fins 5. The space 91 is connected to a flow path 90.

[0034] The jacket 6 has a main body 60, a first pipe 61, and a second pipe 62. The main body 60 is joined to the base 1. The main body 60 surrounds the fins 5. The main body 60 has a cylindrical shape. The material constituting the main body 60 may be, for example, pure aluminum or an aluminum alloy containing aluminum as a main component.

[0035] The first pipe 61 is attached to the main body 60. An inlet passage 92 is provided in the first pipe 61. The inlet passage 92 is connected to the space 91. The inlet passage 92 is a flow path through which the refrigerant flowing into the flow path 90 flows.

[0036] The second pipe 62 is attached to the main body 60. An outflow path 93 is provided in the second pipe 62. The outflow path 93 is connected to the space 91. The outflow path 93 is a flow path through which the refrigerant flowing out from the flow path 90 flows.

[0037] <Configuration of Semiconductor Device> Next, the configuration of the semiconductor device 200 according to the first embodiment will be described with reference to FIG. 3 . As shown in FIG. 3 , the semiconductor device 200 includes a cooler 100 and a semiconductor chip 9. The configuration of the cooler 100 shown in FIG. 3 is substantially the same as the configuration of the cooler 100 shown in FIG. 1 . The semiconductor chip 9 is bonded to the second layer 32. Specifically, the semiconductor chip 9 is bonded to the second layer 32 at the sixth surface 46 using, for example, solder (not shown). From another perspective, the semiconductor device 200 includes a chip bonding layer (not shown) that bonds the semiconductor chip 9 to the second layer 32. The semiconductor chip 9 may be bonded to the second layer 32 by sintering silver (not shown) or copper (not shown) disposed between the semiconductor chip 9 and the second layer 32.

[0038] <Bonding Method> Next, a bonding method according to the first embodiment will be described with reference to Figures 4 and 5. The bonding method is used, for example, to bond the bonded portion 3 and the base portion 1 in the manufacture of the cooler 100 shown in Figure 1. From another perspective, the bonding method is a method for manufacturing the bonded structure 10 (see Figure 2). Note that the bonding method may be used for a method other than the manufacture of the cooler 100.

[0039] As shown in FIG. 4, the joining method according to the first embodiment mainly includes a step (S10) of placing a brazing filler metal and a workpiece on a base portion, and a step (S20) of joining the base portion and the workpiece by heating the brazing filler metal.

[0040] First, a step (S10) of placing the brazing filler metal and the materials to be joined on the base is performed. Specifically, as shown in FIG. 5 , the base 1 is prepared. The base 1 has, for example, a flat plate shape. The base 1 has a first surface 41 and a second surface 42. The first surface 41 has, for example, a planar shape. The second surface 42 is provided on the opposite side of the first surface 41. The direction from the second surface 42 toward the first surface 41 is a first direction 101.

[0041] The base portion 1 contains aluminum. The material constituting the base portion 1 may be aluminum or an aluminum alloy containing aluminum as a main component. Specifically, the material constituting the base portion 1 may be pure aluminum, a 1000 series aluminum alloy, or a 3000 series aluminum alloy. The weight content of aluminum in the base portion 1 may be, for example, 95% or more, 99% or more, or 99.9% or more.

[0042] Next, a flux (not shown) is supplied to the first surface 41. The flux is not particularly limited, but is preferably a non-corrosive flux such as an Al-K (potassium)-F (fluorine) based flux or an Al-Cs (cesium)-F based flux. The flux is, for example, in a paste form.

[0043] Next, the brazing filler metal 12 is placed on the base portion 1. Specifically, the brazing filler metal 12 is placed on the portion of the first surface 41 to which the flux has been supplied. From another perspective, the flux is located between the base portion 1 and the brazing filler metal 12. The brazing filler metal 12 is placed in the first direction 101 relative to the base portion 1.

[0044] The brazing filler metal 12 contains aluminum and silicon. The brazing filler metal 12 is made of, for example, aluminum, silicon, and inevitable impurities. The brazing filler metal 12 is made of, for example, an Al-Si aluminum alloy. The weight content of silicon in the brazing filler metal 12 is, for example, 4% or more and 12% or less. The weight content of silicon in the brazing filler metal 12 is preferably 6% or more and 9% or less.

[0045] The brazing filler metal 12 has a third thickness H3 in the first direction 101. The third thickness H3 is preferably 0.01 mm or more and 0.1 mm or less. The brazing filler metal 12 has a foil shape, for example.

[0046] Next, flux (not shown) is supplied onto the brazing filler metal 12. The workpiece 13 is placed on the portion of the brazing filler metal 12 to which the flux has been supplied. The flux is located between the brazing filler metal 12 and the workpiece 13. The workpiece 13 is placed in the first direction 101 relative to the brazing filler metal 12. The thickness of the workpiece 13 in the first direction 101 is set to a fourth thickness H4. The fourth thickness H4 is preferably 20 μm or more and 300 μm or less.

[0047] The workpiece 13 has a first layer 31 and a second layer 32. The first layer 31 contacts the flux supplied on the brazing material 12. The first layer 31 is located on the brazing material 12. From another perspective, the brazing material 12 is disposed between the base portion 1 and the first layer 31. The flux is located between the brazing material 12 and the first layer 31.

[0048] The first layer 31 contains nickel. The first layer 31 is made of, for example, pure nickel. The weight content of nickel in the first layer 31 is, for example, 99% or more. The thickness of the first layer 31 in the first direction 101 is set to a fifth thickness H5. It is desirable that the fifth thickness H5 be 10 μm or more.

[0049] The second layer 32 is provided on the first layer 31. The first layer 31 and the second layer 32 are bonded together by, for example, rolling. From another perspective, the bonded material 13 is a clad material. The second layer 32 is a portion to which another member, such as a semiconductor chip 9 (see FIG. 3), is bonded.

[0050] The second layer 32 contains copper. The second layer 32 is made of, for example, pure copper. The weight content of copper in the second layer 32 is 99.9% or more. The thickness of the second layer 32 in the first direction 101 is set to a sixth thickness H6. The sixth thickness H6 is preferably 10 μm or more. The sixth thickness H6 is, for example, twice or more the fifth thickness H5. In this way, the brazing filler metal 12 and the workpiece 13 are arranged on the base portion 1.

[0051] After the brazing filler metal 12 and the workpieces 13 are placed on the base portion 1, pressure may be applied to the base portion 1, the brazing filler metal 12, and the workpieces 13 in a direction parallel to the first direction 101, for example, using a jig (not shown). The magnitude of the pressure is, for example, 10 kPa or more. This forces out the flux between the base portion 1 and the brazing filler metal 12, thereby bringing the base portion 1 and the brazing filler metal 12 into closer contact with each other. This forces out the flux between the brazing filler metal 12 and the workpieces 13, thereby bringing the brazing filler metal 12 and the workpieces 13 into closer contact with each other.

[0052] Next, a step (S20) is performed in which the base portion and the workpieces are joined by heating the brazing filler metal. Specifically, the base portion 1, the brazing filler metal 12, and the workpieces 13 are first placed inside a furnace (not shown). The inside of the furnace is an inert gas atmosphere. Specifically, the inside of the furnace is, for example, a nitrogen atmosphere or an argon atmosphere. The oxygen concentration inside the furnace is preferably 500 ppm or less. This prevents the brazing filler metal 12 from oxidizing when heated. The inside of the furnace is not depressurized. Therefore, the time required to join the base portion 1 and the workpieces 13 is shorter than when the inside of the furnace is depressurized.

[0053] Next, the base portion 1, the brazing filler metal 12, and the workpieces 13 are heated inside the furnace. The temperature inside the furnace is equal to or higher than the melting point of the brazing filler metal 12 and lower than the melting point of the base portion 1. In other words, the temperature to which the brazing filler metal 12 is heated is equal to or higher than the melting point of the brazing filler metal 12 and lower than the melting point of the base portion 1. In this specification, the "melting point" of the alloy material refers to the solidus temperature.

[0054] The temperature to which the brazing filler metal 12 is heated is preferably, for example, 640°C or lower. This can prevent the base portion 1 from melting. The temperature to which the brazing filler metal 12 is heated is preferably equal to or higher than the solidus temperature of the brazing filler metal 12 and equal to or lower than the liquidus temperature of the brazing filler metal 12. This can prevent the fluidity of the brazing filler metal 12 from becoming excessively high. As a result, it can prevent the brazing filler metal 12 from flowing out from between the base portion 1 and the workpiece 13.

[0055] The brazing filler metal 12 is melted by heating the base 1, the brazing filler metal 12, and the workpieces 13. Specifically, the brazing filler metal 12 is brought into a state in which, for example, a solid phase and a liquid phase coexist by heating the base 1, the brazing filler metal 12, and the workpieces 13. The nickel contained in the first layer 31 diffuses into the molten brazing filler metal 12.

[0056] Next, the base portion 1, the brazing filler metal 12, and the workpieces 13 are cooled. The molten brazing filler metal 12 solidifies. This bonds the base portion 1 and the workpieces 13 together. From another perspective, the bonded structure 10 shown in FIG. 2 is produced. As shown in FIGS. 2 and 5, a portion of the brazing filler metal 12 becomes the bonded portion 2. The remaining portion of the brazing filler metal 12 becomes the compound portion 4. Specifically, the portion of the brazing filler metal 12 into which the nickel contained in the first layer 31 has diffused becomes the compound portion 4. In this way, the base portion 1 and the workpieces 13 are bonded together.

[0057] The relationship between each part before and after the step (S20) of joining the base part and the workpiece by heating the brazing filler metal will be described. As shown in Figures 2 and 5, the joining part 2 is made of the brazing filler metal 12. The compound part 4 is made of the brazing filler metal 12 and the first layer 31.

[0058] <Method of Manufacturing Cooler> Next, a method of manufacturing the cooler 100 according to the first embodiment will be described with reference to Figs. 6 to 8. The method of manufacturing the cooler 100 according to the first embodiment uses the joining method according to the first embodiment described above. The method of manufacturing the cooler 100 according to the first embodiment differs from the joining method according to the first embodiment mainly in that the fins 5 and the jacket 6 are joined to the base portion 1. The following description will focus on the differences from the configuration of the joining method according to the first embodiment.

[0059] As shown in FIG. 6, the manufacturing method of the cooler 100 according to the first embodiment mainly includes, for example, a step (S10) of placing a brazing filler metal and a material to be joined on a base portion, a step (S20) of joining the base portion and the material to be joined by heating the brazing filler metal, and a step (S30) of joining a jacket to the base portion.

[0060] 7 , in the step (S10) of placing the brazing filler metal and the workpiece on the base portion, fin member 15 is placed on the opposite side of base portion 1 from workpiece 13. Fin member 15 contacts base portion 1 at second surface 42. Flux may or may not be supplied between fin member 15 and base portion 1.

[0061] The fin member 15 has a plurality of plate materials 18. A flow path 90 is provided in the fin member 15. The fin member 15 is configured by stacking a plurality of plate materials 18 along a first direction 101. Flux may or may not be supplied between two adjacent plate materials 18. Each of the plurality of plate materials 18 has a bonded layer 82 and a brazing material layer 86.

[0062] The bonded layer 82 is made of, for example, an aluminum alloy containing aluminum as a main component. The bonded layer 82 is made of, for example, a 3000-series aluminum alloy. The brazing filler metal layer 86 contains aluminum and silicon. The brazing filler metal layer 86 is made of, for example, an Al-Si-based aluminum alloy. The brazing filler metal layer 86 is bonded to the bonded layer 82. Specifically, the brazing filler metal layer 86 is bonded to the bonded layer 82 by, for example, rolling. From another perspective, the plate material 18 is a clad material.

[0063] As shown in Fig. 8, holes 98 are provided in the plurality of plate materials 18. The holes 98 provided in the plurality of plate materials 18 are connected together to form the flow path 90 (see Fig. 7). When viewed in the first direction 101, the minimum width of the hole 98 is, for example, about 0.2 mm.

[0064] After the brazing filler metal 12 and the workpieces 13 are placed on the base portion 1, a pressure may be applied to the base portion 1, the brazing filler metal 12, the workpieces 13, and the fin member 15 in a direction parallel to the first direction 101, for example, using a jig (not shown). The magnitude of the pressure is, for example, 10 kPa or more. This causes the two adjacent plate materials 18 to adhere to each other. The base portion 1 and the fin member 15 also adhere to each other.

[0065] In the step (S20) of joining the base portion and the workpieces by heating the brazing filler metal, the base portion 1, the brazing filler metal 12, the workpieces 13, and the fin member 15 are placed inside a furnace (not shown). Inside the furnace, the base portion 1, the brazing filler metal 12, the workpieces 13, and the fin member 15 are heated. As a result, the fin member 15 is heated together with the brazing filler metal 12. The brazing filler metal layer 86 of the fin member 15 melts. Specifically, by heating the base portion 1, the brazing filler metal 12, the workpieces 13, and the fin member 15, the brazing filler metal 12 enters a state in which, for example, a solid phase and a liquid phase coexist.

[0066] Next, the base portion 1, brazing material 12, workpiece 13, and fin member 15 are cooled. The molten brazing material layer 86 solidifies. This bonds the fin member 15 to the base portion 1. Two adjacent workpiece layers 82 are bonded to each other. The brazing material layer 86 becomes the bonding layer 81 (see FIG. 1). The fin member 15 becomes the fin 5 (see FIG. 1). In this way, the fin member 15 is bonded to the base portion 1 by heating the brazing material 12 and the fin member 15.

[0067] The relationship between the components before and after the step (S20) of joining the base and the workpiece by heating the brazing material will be described. As shown in Figures 1 and 7, the fin 5 is formed of a fin member 15. The joining layer 81 is formed of a brazing material layer 86.

[0068] Next, a step (S30) of joining the jacket to the base portion is carried out. Specifically, the jacket 6 is arranged on the opposite side of the base portion 1 from the portion to be joined 3. The jacket 6 has a main body portion 60, a first pipe 61, and a second pipe 62. The main body portion 60 is joined to the base portion 1. The main body portion 60 surrounds the fins 5. The main body portion 60 has a cylindrical shape. The main body portion 60 may be made of, for example, pure aluminum, or may be made of an aluminum alloy containing aluminum as a main component.

[0069] Next, the jacket 6 is joined to the base portion 1 at the second surface 42 using a fastening method such as mechanical fastening, welding, brazing, or solid-state bonding. In this manner, the cooler 100 (see FIG. 1 ) according to the first embodiment is manufactured.

[0070] <Method for Manufacturing Semiconductor Device> Next, a method for manufacturing the semiconductor device 200 according to the first embodiment will be described with reference to FIG. 9 . As shown in FIG. 9 , the method for manufacturing the semiconductor device 200 according to the first embodiment includes a step (S50) of preparing a cooler and a step (S60) of bonding a semiconductor chip to the second layer. First, the step (S50) of preparing a cooler is performed. Specifically, the cooler 100 (see FIG. 1 ) is prepared using the method for manufacturing the cooler 100 described above.

[0071] Next, a step (S60) of bonding the semiconductor chip to the second layer is performed. Specifically, the semiconductor chip 9 is bonded to the second layer 32 at the sixth surface 46 using, for example, solder. A chip bonding layer 94 (see FIG. 29 ) is formed between the semiconductor chip 9 and the second layer 32. In this manner, the semiconductor device 200 (see FIG. 3 ) is manufactured. The semiconductor chip 9 may be bonded to the second layer 32 by sintering silver or copper disposed between the semiconductor chip 9 and the second layer 32.

[0072] The effects of the cooler 100, the semiconductor device 200, the bonding method, the method for manufacturing the cooler 100, and the method for manufacturing the semiconductor device 200 according to the first embodiment will be described.

[0073] Aluminum-containing components are prone to the formation of dense oxide films. Therefore, aluminum-containing components have poor solder wettability. To improve the solder wettability of aluminum-containing components, nickel is sometimes joined to the aluminum-containing components. However, nickel may have poor solder wettability. Specifically, the solder wettability of nickel may be poor depending on the solder composition and the atmosphere inside the furnace during soldering.

[0074] According to the joining method of the present disclosure, a brazing filler metal 12 and a workpiece 13 are placed on a base portion 1. The base portion 1 and the workpiece 13 are joined together. The base portion 1 contains aluminum. The workpiece 13 has a second layer 32. The second layer 32 contains copper. Copper has a wide range of soldering conditions under which it exhibits good solder wettability. Therefore, a part with good solder wettability can be provided in a member (aluminum-containing member) composed of the base portion 1, brazing filler metal 12, and workpiece 13. This improves the solder wettability of the aluminum-containing member.

[0075] When brazing copper to aluminum, the aluminum, copper, and brazing filler metal are typically heated to 600°C, at which point the Al-Si brazing filler metal melts. In this case, if the copper and Al-Si brazing filler metal come into contact during heating, a Cu-Al eutectic structure may be formed. The melting point of the Cu-Al eutectic structure is approximately 540°C. That is, the melting point of this eutectic structure is lower than the heating temperature used in the brazing described above. Therefore, the eutectic structure may melt during the brazing described above. As a result, the aluminum and copper base materials may melt and deform.

[0076] According to the joining method of the first embodiment, the base portion 1 contains aluminum. The first layer 31 contains nickel. The second layer 32 contains copper. The second layer 32 is provided on the first layer 31. In the step (S10) of placing the brazing filler metal and the materials to be joined on the base portion, the brazing filler metal 12 is placed between the base portion 1 and the first layer 31. This prevents the second layer 32 from coming into contact with the brazing filler metal 12 when the brazing filler metal 12 is heated. This prevents the formation of a Cu-Al eutectic structure. Therefore, the second layer 32 can be joined to the base portion 1 while preventing melting and deformation of the base portion 1 and the second layer 32.

[0077] According to the joining method of the first embodiment, in the step (S10) of placing the brazing filler metal and the workpiece on the base portion, the brazing filler metal 12 is placed between the base portion 1 and the first layer 31. Therefore, when joining the base portion 1 and the workpiece 13, the nickel contained in the first layer 31 diffuses into the brazing filler metal 12. This forms an Al-Ni intermetallic compound. The strength of the Al-Ni intermetallic compound is high. Therefore, the base portion 1 and the workpiece 13 can be joined more firmly.

[0078] According to the joining method of the first embodiment, the weight content of silicon in the brazing filler metal 12 is 4% or more. This allows the melting point of the brazing filler metal 12 to be sufficiently lower than the melting point of the base portion 1 and the melting point of the joined material 13. Therefore, when joining the base portion 1 and the joined material 13, it is possible to prevent the base portion 1 and the joined material 13 from melting.

[0079] If the weight content of silicon in the brazing filler metal 12 is greater than 12%, the brazing filler metal 12 becomes excessively hard. This makes it difficult to manufacture the brazing filler metal 12. According to the joining method of embodiment 1, the weight content of silicon in the brazing filler metal 12 is 12% or less. This prevents the brazing filler metal 12 from becoming excessively hard. As a result, it is possible to prevent the brazing filler metal 12 from becoming difficult to manufacture.

[0080] The molten brazing filler metal 12 may wet and spread onto the side surfaces of the workpieces 13. Therefore, the molten brazing filler metal 12 may come into contact with the second layer 32. This may result in the formation of a Cu-Al eutectic structure. According to the joining method of embodiment 1, the weight content of silicon in the brazing filler metal 12 may be 9% or less. This sufficiently reduces the fluidity of the molten brazing filler metal 12. This more effectively prevents the molten brazing filler metal 12 from coming into contact with the second layer 32. As a result, the formation of a Cu-Al eutectic structure may be suppressed.

[0081] If the fluidity of the brazing filler metal 12 is sufficiently high, it is possible to prevent voids from being generated in the joint 2. According to the joining method of the first embodiment, the weight content of silicon in the brazing filler metal 12 may be 6% or more. This makes it possible to sufficiently increase the fluidity of the brazing filler metal 12. As a result, it is possible to more effectively prevent voids from being generated in the joint 2.

[0082] If the thickness (third thickness H3) of the brazing filler metal 12 in the first direction 101 is excessively small, the volume of the molten brazing filler metal 12 becomes excessively small when joining the base portion 1 and the workpiece 13. Therefore, the molten brazing filler metal 12 may not be used to sufficiently fill the gap between the base portion 1 and the workpiece 13. This may leave a gap between the base portion 1 and the workpiece 13. As a result, the reliability of the joint between the base portion 1 and the workpiece 13 decreases. According to the joining method of embodiment 1, the third thickness H3 is 0.01 mm or more. Therefore, the volume of the molten brazing filler metal 12 can be prevented from becoming excessively small. This can prevent a decrease in the reliability of the joint between the base portion 1 and the workpiece 13.

[0083] If the third thickness H3 is excessively large, the volume of the molten brazing filler metal 12 becomes excessively large when joining the base portion 1 and the workpiece 13. Therefore, excessive flow of the molten brazing filler metal 12 may cause wear (erosion) of the base portion 1 and the workpiece 13, or the molten brazing filler metal 12 may flow excessively out from between the base portion 1 and the workpiece 13. Furthermore, if the volume of the molten brazing filler metal 12 is excessively large, nickel is excessively diffused from the first layer 31 to the brazing filler metal 12. This causes excessive growth of Al-Ni intermetallic compounds. Excessive growth of Al-Ni intermetallic compounds may reduce the strength of the joint between the base portion 1 and the workpiece 13. As a result, the reliability of the joint between the base portion 1 and the workpiece 13 decreases.

[0084] According to the joining method of the first embodiment, the third thickness H3 is 0.1 mm or less, which prevents the volume of the molten brazing material 12 from becoming excessively large, thereby preventing a decrease in the reliability of the joining between the base portion 1 and the workpiece 13.

[0085] According to the joining method of the first embodiment, the thickness (fourth thickness H4) of the workpieces 13 in the first direction 101 is 20 μm or more and 300 μm or less. When the fourth thickness H4 is 20 μm or more, the workpieces 13 can be prevented from melting when the brazing filler metal 12 is heated. When the fourth thickness H4 is 300 μm or less, the thermal stress caused by the difference in thermal expansion coefficient between the base portion 1 and the workpieces 13 can be reduced.

[0086] According to the joining method of the first embodiment, the thickness (fifth thickness H5) of the first layer 31 in the first direction 101 is 10 μm or more, which can prevent the first layer 31 from dissolving into the brazing filler metal 12 and disappearing when the brazing filler metal 12 is heated.

[0087] According to the joining method of the first embodiment, the thickness (sixth thickness H6) of the second layer 32 in the first direction 101 is 10 μm or more. This makes it possible to prevent nickel from appearing on the surface of the second layer 32 due to diffusion of nickel contained in the first layer 31 inside the second layer 32 when the brazing filler metal 12 is heated.

[0088] According to the manufacturing method of cooler 100 according to the first embodiment, in the step (S20) of joining the base portion and the workpiece by heating the brazing filler metal, fin member 15 is heated together with brazing filler metal 12. Therefore, by heating once, base portion 1 can be joined to fin member 15 while joining base portion 1 to workpiece 3. This allows the time required to manufacture cooler 100 to be shortened.

[0089] According to the manufacturing method of the semiconductor device 200 of the first embodiment, the cooler 100 of the first embodiment is prepared. The semiconductor chip 9 is bonded to the second layer 32. Compared to aluminum, copper has good solder wettability. Therefore, the semiconductor chip 9 can be bonded more easily than when the semiconductor chip 9 is bonded to a member containing aluminum.

[0090] According to the cooler 100 of the first embodiment, the to-be-joined portion 3 is provided above the joining portion 2. The to-be-joined portion 3 has a first layer 31 and a second layer 32. The second layer 32 is provided on the first layer 31. The second layer 32 contains copper. Copper has a wide range of soldering conditions under which it exhibits good solder wettability. Therefore, in the member (member containing aluminum) formed by the base portion 1, the joining portion 2, and the to-be-joined portion 3, a portion with good solder wettability can be provided. As a result, the solder wettability of the member containing aluminum can be improved.

[0091] According to the cooler 100 of embodiment 1, the compound portion 4 is provided between the joining portion 2 and the joined portion 3. The compound portion 4 is continuous with both the joining portion 2 and the joined portion 3. The joining portion 2 contains aluminum. The first layer 31 contains nickel. The compound portion 4 contains at least one of the elements contained in the joining portion 2 and at least one of the elements contained in the first layer 31. Therefore, a compound is formed in the compound portion 4. This can increase the strength of the bond between the base portion 1 and the joined portion 3.

[0092] The semiconductor device 200 according to the first embodiment includes the cooler 100 according to the first embodiment and a semiconductor chip 9. The semiconductor chip 9 is bonded to the second layer 32. Therefore, the reliability of the bond between the cooler 100 and the semiconductor chip 9 can be improved compared to when the semiconductor chip 9 is bonded to aluminum.

[0093] (Variation of First Embodiment) In the above description of the joining method, the brazing filler metal 12 is in foil form, but the form of the brazing filler metal 12 is not particularly limited. The brazing filler metal 12 may be in granular or paste form. When the brazing filler metal 12 is in paste form, a solvent and flux are mixed into the brazing filler metal 12. When the brazing filler metal 12 is in paste form and a flux is mixed into the brazing filler metal 12, it is not necessary to supply flux between the base portion 1 and the brazing filler metal 12 and between the brazing filler metal 12 and the joined material 13.

[0094] The area of ​​the brazing filler metal 12 as viewed in the first direction 101 may be smaller than the area of ​​the workpieces 13. This makes it possible to prevent the volume of the molten brazing filler metal 12 from becoming excessively large.

[0095] In the above description of the manufacturing method of the cooler 100, a configuration in which the step (S30) of joining the jacket to the base portion is performed after the step (S20) of joining the base portion and the workpiece by heating the brazing filler metal is described. However, the manufacturing method of the cooler 100 according to the present disclosure is not limited to the above configuration. The jacket 6 may be joined to the base portion 1 together with the workpiece 13 and the fin member 15. Specifically, in the step (S10) of placing the brazing filler metal and the workpiece on the base portion, the jacket 6 may be placed together with the fin member 15 on the opposite side of the base portion 1 from the workpiece 13. The fin member 15 may be sandwiched between the jacket 6 and the base portion 1. In the step (S20) of joining the base portion and the workpiece by heating the brazing filler metal, the fin member 15 and the jacket 6 may be heated together with the brazing filler metal 12, thereby joining the fin member 15 and the jacket 6 to the base portion 1. This reduces the time required to manufacture the cooler 100. In the cooler 100, the fins 5 and the jacket 6 may be in contact with each other.

[0096] In the manufacturing method of the cooler 100, a positioning mechanism may be provided for each of the base portion 1, the brazing filler metal 12, the workpieces 13, the fin members 15, and the jacket 6. This reduces the time required to position each of the base portion 1, the brazing filler metal 12, the workpieces 13, the fin members 15, and the jacket 6.

[0097] Second Embodiment Next, the configuration of a joining method according to a second embodiment will be described with reference to Figure 10. The joining method according to the second embodiment differs from the joining method according to the first embodiment mainly in that the brazing filler metal 12 contains magnesium (Mg), but is otherwise substantially the same as the joining method according to the first embodiment. The following description will focus on the differences from the joining method according to the first embodiment.

[0098] 10 , the brazing filler metal 12 may contain magnesium. The brazing filler metal 12 is made of, for example, an Al-Si-Mg aluminum alloy. The weight content of magnesium in the brazing filler metal 12 is, for example, 0.1% or more and 5% or less. In the joining method according to the second embodiment, no flux is supplied between the base portion 1 and the brazing filler metal 12 and between the brazing filler metal 12 and the workpiece 13.

[0099] The oxide film formed on the aluminum surface inhibits wetting of the molten brazing filler metal 12. In this case, it becomes difficult to join the base portion 1 and the workpiece 13 without using flux. According to the joining method of the second embodiment, the brazing filler metal 12 contains magnesium. When the brazing filler metal 12 is heated, the magnesium reduces the aluminum oxide film and the nickel oxide film, thereby removing them. This allows the molten brazing filler metal 12 to easily wet and spread over the base portion 1 without supplying flux between the base portion 1 and the brazing filler metal 12 and between the brazing filler metal 12 and the workpiece 13. This shortens the time required to join the base portion 1 and the workpiece 13 compared to when flux is supplied between the base portion 1 and the brazing filler metal 12 and between the brazing filler metal 12 and the workpiece 13.

[0100] If the weight content of magnesium in the brazing filler metal 12 is excessively low, the aluminum oxide film and the nickel oxide film cannot be sufficiently removed. On the other hand, if the weight content of magnesium in the brazing filler metal 12 is excessively high, the brazing filler metal 12 becomes excessively hard. Therefore, rolling the brazing filler metal 12 becomes difficult. As a result, manufacturing the brazing filler metal 12 becomes difficult. According to the joining method of embodiment 2, the weight content of magnesium in the brazing filler metal 12 is 0.1% or more and 5% or less. Therefore, the aluminum oxide film and the nickel oxide film can be sufficiently removed while preventing the brazing filler metal 12 from becoming excessively hard.

[0101] If an excessive amount of flux is supplied between the base portion 1 and the brazing filler metal 12 and between the brazing filler metal 12 and the workpiece 13, the fluidity of the molten brazing filler metal 12 may become excessively high. In this case, the molten brazing filler metal 12 may excessively wet and spread, causing the molten brazing filler metal 12 to come into contact with the second layer 32. According to the joining method of embodiment 2, the base portion 1 and the workpiece 13 can be joined without using flux. This prevents the fluidity of the molten brazing filler metal 12 from becoming excessively high. This prevents the molten brazing filler metal 12 from coming into contact with the second layer 32.

[0102] Before the step (S10) of placing the brazing filler metal and the workpieces on the base portion, the base portion 1, the brazing filler metal 12, and the workpieces 13 may be cleaned by pickling or the like. This makes it possible to thin the oxide films on the base portion 1, the brazing filler metal 12, and the workpieces 13.

[0103] Third Embodiment Next, the configuration of a joining method according to a third embodiment will be described with reference to Figure 11. The joining method according to the third embodiment differs from the joining method according to the first embodiment mainly in that the base portion 1 contains magnesium, but is otherwise substantially the same as the joining method according to the first embodiment. The following description will focus on the differences from the joining method according to the first embodiment.

[0104] 11 , the base portion 1 may contain magnesium. The base portion 1 is made of, for example, an Al-Si-Mg aluminum alloy. The base portion 1 is made of, for example, a 6000 series aluminum alloy. The 6000 series aluminum alloy is a material specified in JIS H4000:2014. The weight content of magnesium in the base portion 1 is, for example, 0.1% or more and 5% or less. In the joining method according to the third embodiment, no flux is supplied between the base portion 1 and the brazing filler metal 12 and between the brazing filler metal 12 and the workpiece 13.

[0105] According to the joining method of the third embodiment, the base portion 1 contains magnesium. Therefore, when the brazing filler metal 12 is heated, the magnesium contained in the base portion 1 diffuses into the brazing filler metal 12. This makes it possible to remove the oxide films of aluminum and nickel. As a result, the same effects as those of the joining method of the second embodiment can be obtained.

[0106] 12 and 13, the configuration of a joining method according to a fourth embodiment will be described. The joining method according to the fourth embodiment differs from the joining method according to the first embodiment mainly in that a groove is provided in the base portion 1, but in other respects, the joining method according to the fourth embodiment is substantially the same as the joining method according to the first embodiment. The following description will focus on the differences from the joining method according to the first embodiment. Note that FIG. 13 shows the configuration of the base portion 1 and the workpieces 13 as viewed in the direction from the workpieces 13 toward the base portion 1.

[0107] 12 , the first surface 41 may have a first surface portion 51 and a second surface portion 52. For example, the second surface portion 52 is spaced apart from the first surface portion 51. In the first direction 101, the second surface portion 52 is provided at substantially the same position as the first surface portion 51.

[0108] The base portion 1 may have a bottom surface 19, a first side wall surface 27, and a second side wall surface 28. In the first direction 101, the bottom surface 19 is provided between the first surface 41 and the second surface 42. The first side wall surface 27 is continuous with both the first surface portion 51 and the bottom surface 19. The second side wall surface 28 is continuous with both the second surface portion 52 and the bottom surface 19. The first side wall surface 27, the second side wall surface 28, and the bottom surface 19 form a groove 99. In other words, the groove 99 is provided in the base portion 1. Specifically, the groove 99 is provided in the first surface 41.

[0109] 13 , when viewed in a direction from the workpieces 13 toward the base portion 1, the groove 99 surrounds the workpieces 13 and the brazing filler metal 12 (see FIG. 12 ). When viewed in a direction from the workpieces 13 toward the base portion 1, the second side wall surface 28 surrounds the workpieces 13 and the brazing filler metal 12. When viewed in a direction from the workpieces 13 toward the base portion 1, the first side wall surface 27 surrounds the second side wall surface 28. When viewed in a direction from the workpieces 13 toward the base portion 1, the first surface portion 51 surrounds the second surface portion 52.

[0110] The molten brazing filler metal 12 wets and spreads on aluminum more easily than on Ni. Therefore, in the step (S20) of joining the base portion and the workpiece by heating the brazing filler metal, the molten brazing filler metal 12 wets and spreads on the surface of the base portion 1, and the molten brazing filler metal 12 flows into the grooves 99.

[0111] If the volume of the brazing filler metal 12 is excessively large, part of the molten brazing filler metal 12 will flow out from between the workpieces 13 and the base portion 1. The flowing brazing filler metal 12 will wet and spread on the side surfaces of the workpieces 13, which may cause contact between the molten brazing filler metal 12 and the second layer 32. According to the joining method of embodiment 4, a groove 99 is provided in the base portion 1. Part of the molten brazing filler metal 12 flows into the groove 99. Therefore, even if the molten brazing filler metal 12 flows out from between the workpieces 13 and the base portion 1, it is possible to prevent the molten brazing filler metal 12 from wetting and spreading on the side surfaces of the workpieces 13. As a result, it is possible to prevent contact between the molten brazing filler metal 12 and the second layer 32.

[0112] 14 and 15, the configuration of a bonding method according to embodiment 5 will be described. The bonding method according to embodiment 5 differs from the bonding method according to embodiment 1 mainly in that a portion of the second layer 32 is embedded in the first layer 31, but is otherwise substantially the same as the bonding method according to embodiment 1. The following description will focus on the differences from the bonding method according to embodiment 1.

[0113] 14 and 15 , a part of the second layer 32 may be embedded in the first layer 31. The workpiece 13 is, for example, an Invar clad material. The first layer 31 has a seventh surface 47 and an eighth surface 48.

[0114] The seventh surface 47 is provided on the opposite side of the third surface 43. In the first direction 101, the seventh surface 47 may be located at substantially the same position as the sixth surface 46. The eighth surface 48 is provided on the opposite side of the third surface 43 of the second layer 32. The eighth surface 48 is spaced apart from the seventh surface 47. In the first direction 101, the seventh surface 47 may be located at substantially the same position as the sixth surface 46. The first side surface 21 of the second layer 32 is covered by the first layer 31. The second side surface 22 of the second layer 32 is covered by the first layer 31.

[0115] As shown in FIG. 15 , the second layer 32 has a third side surface 23. The third side surface 23 is continuous with each of the sixth surface 46, the third surface 43 (see FIG. 14 ), the first side surface 21 (see FIG. 14 ), and the second side surface 22 (see FIG. 14 ). The third side surface 23 is exposed from, for example, the first layer 31. In other words, the third side surface 23 is not covered by the first layer 31. As shown in FIG. 15 , the direction perpendicular to the third side surface 23 is defined as a second direction 102. The second direction 102 is substantially perpendicular to the first direction 101. The second layer 32 extends along the second direction 102.

[0116] According to the joining method of the fifth embodiment, a part of the second layer 32 is embedded in the first layer 31. Therefore, when the molten brazing filler metal 12 wets and spreads on the side surface of the workpiece 13, it is possible to lengthen the distance over which the molten brazing filler metal 12 must wet and spread before it comes into contact with the second layer 32. This makes it possible to prevent the molten brazing filler metal 12 and the second layer 32 from coming into contact with each other.

[0117] Note that both ends of the workpieces 13 in the second direction 102 may be bent toward the first direction 101. From another perspective, both ends of the workpieces 13 in the second direction 102 may be bent so that the third side surface 23 is positioned in the first direction 101 with respect to the sixth surface 46. This makes it possible to more effectively prevent the molten brazing material 12 and the second layer 32 from coming into contact with each other.

[0118] Sixth Embodiment Next, the configuration of a joining method according to a sixth embodiment will be described with reference to Fig. 16. The joining method according to the sixth embodiment differs from the joining method according to the second embodiment mainly in that the workpieces 13 and the brazing filler metal 12 are integrally formed, but in other respects it is substantially the same as the joining method according to the second embodiment. The following description will focus on the differences from the joining method according to the second embodiment.

[0119] 16 , in the step (S10) of placing the brazing filler metal and the materials to be joined on the base portion, materials to be joined 13 and brazing filler metal 12 may be formed integrally. From another perspective, materials to be joined 13 and brazing filler metal 12 may constitute a structure 50.

[0120] The workpieces 13 and the brazing filler metal 12 are joined by, for example, rolling. From another perspective, the structure 50 is a clad material. In the step (S10) of arranging the brazing filler metal and the workpieces on the base portion, the structure 50 is arranged on the base portion 1, whereby the brazing filler metal 12 and the workpieces 13 are arranged on the base portion 1.

[0121] According to the joining method of the sixth embodiment, workpiece 13 and brazing filler metal 12 are integrally formed. This makes it easier to arrange brazing filler metal 12 and workpiece 13 in the step (S10) of arranging the brazing filler metal and workpiece 13 on the base portion. This reduces the time required to join base portion 1 and workpiece 13 together.

[0122] Seventh Embodiment Next, the configuration of a joining method according to a seventh embodiment will be described with reference to Figure 17. The joining method according to the seventh embodiment differs from the joining method according to the second embodiment mainly in that the base portion 1 and the brazing filler metal 12 are integrally formed, but in other respects, the joining method according to the seventh embodiment is substantially the same as the joining method according to the second embodiment. The following description will focus on the differences from the joining method according to the second embodiment.

[0123] 17 , in the step (S10) of placing the brazing filler metal and the workpiece on the base portion, the base portion 1 and the brazing filler metal 12 may be integrally formed. From another perspective, the base portion 1 and the brazing filler metal 12 may form a base structure 70. The base portion 1 and the brazing filler metal 12 are joined by, for example, rolling. The brazing filler metal 12 covers, for example, the first surface 41.

[0124] In the step (S10) of arranging the brazing filler metal and the materials to be joined on the base portion, a base structure 70 is prepared. Materials to be joined 13 are placed on the base structure 70. Note that in the step (S10) of arranging the brazing filler metal and the materials to be joined on the base portion, a portion of the brazing filler metal 12 may be removed using a processing method such as cutting.

[0125] According to the joining method of the seventh embodiment, base portion 1 and brazing filler metal 12 are integrally formed. This makes it easier to arrange brazing filler metal 12 in the step (S10) of arranging the brazing filler metal and the workpieces on the base portion. This reduces the time required to join base portion 1 and workpieces 13 together.

[0126] Eighth Embodiment Next, the configuration of a joining method according to an eighth embodiment will be described with reference to Figure 18. The joining method according to the eighth embodiment differs from the joining method according to the first embodiment mainly in that the workpieces 13 have a third layer, but is otherwise substantially the same as the joining method according to the first embodiment. The following description will focus on the differences from the joining method according to the first embodiment.

[0127] 18 , the workpiece 13 may have a third layer 33. The third layer 33 is provided on the first layer 31. The third layer 33 is in contact with each of the first layer 31 and the second layer 32. The third layer 33 is provided between the first layer 31 and the second layer 32. From another perspective, the second layer 32 is separated from the first layer 31 by the third layer 33. The third layer 33 may be joined to each of the first layer 31 and the second layer 32 by rolling. The third layer 33 contains titanium (Ti). The third layer 33 is made of, for example, pure titanium. The weight content of titanium in the third layer 33 may be, for example, 99% or more.

[0128] In the step (S20) of joining the base portion and the workpiece by heating the brazing filler metal, the first layer 31 and the second layer 32 are also heated together with the brazing filler metal 12. Therefore, when the first layer 31 and the second layer 32 are in contact with each other, the nickel contained in the first layer 31 diffuses into the second layer 32. Similarly, the copper contained in the second layer 32 diffuses into the first layer 31.

[0129] In the step (S20) of joining the base portion and the workpiece by heating the brazing filler metal, if the heating time is excessively long and the thickness (fifth thickness H5) of the first layer 31 is excessively thin, copper diffused into the first layer 31 may come into contact with the brazing filler metal 12. This results in the formation of an Al-Cu eutectic structure. The melting point of the Al-Cu eutectic structure is lower than both the melting point of the brazing filler metal 12 and the melting point of the base portion 1. This may cause the base portion 1 to melt and deform. Furthermore, nickel diffused into the second layer 32 may appear on the surface of the second layer 32. This may result in a deterioration in the solderability of the second layer 32.

[0130] According to the joining method of the eighth embodiment, the workpiece 13 has a third layer 33. The third layer 33 is provided between the first layer 31 and the second layer 32. The third layer 33 contains titanium. Therefore, the third layer 33 can suppress the diffusion of copper and nickel between the first layer 31 and the second layer 32. This can suppress the melting and deformation of the base portion 1 while suppressing the deterioration of the solderability of the second layer 32.

[0131] 19 to 22, the configuration of a joining method according to embodiment 9 will be described. The joining method according to embodiment 9 differs from the joining method according to embodiment 1 mainly in that the outer periphery of the workpiece 13 is bent, but in other respects it is substantially the same as the joining method according to embodiment 1. The following description will focus on the differences from the joining method according to embodiment 1.

[0132] 19 and 20 , the workpiece 13 is made up of a central portion 16 and an outer peripheral portion 17. The outer peripheral portion 17 surrounds the central portion 16. The outer peripheral portion 17 is continuous with the central portion 16. Each of the central portion 16 and the outer peripheral portion 17 is made up of a first layer 31 and a second layer 32.

[0133] 19 , before the step (S20) of joining the base portion and the workpiece by heating the brazing material, the central portion 16 is in contact with the brazing material 12. The outer periphery portion 17 is spaced apart from the brazing material 12. The outer periphery portion 17 is bent in the first direction 101 relative to the central portion 16. From another perspective, the outer periphery portion 17 is raised. The outer periphery portion 17 is inclined in the first direction 101 relative to the central portion 16. The distance between the outer periphery portion 17 and the base portion 1 in the first direction 101 increases with increasing distance from the central portion 16.

[0134] As shown in FIG. 21 , because outer peripheral portion 17 is inclined in first direction 101 with respect to central portion 16, in the step (S20) of joining the base portion and the workpiece by heating the brazing filler metal, molten brazing filler metal 12 flows into the space between outer peripheral portion 17 and base portion 1. As a result, a fillet 96 is formed in molten brazing filler metal 12. The capillary force acting on molten brazing filler metal 12 is reduced. This makes it difficult for molten brazing filler metal 12 to flow. This prevents the brazing filler metal 12 from flowing out from between base portion 1 and the workpiece 13. This also prevents molten brazing filler metal 12 from contacting second layer 32. This prevents erosion of second layer 32 caused by contact between molten brazing filler metal 12 and second layer 32.

[0135] When the workpieces 13 are formed by punching out a clad material by press working, sagging and burrs due to the press working are formed on the outer peripheral edge of the workpieces 13. The outer peripheral portion 17 may be formed by the portion where the sagging and burrs are formed.

[0136] As shown in Fig. 22 , outer peripheral portion 17 may be folded back. Outer peripheral portion 17 may be in contact with a portion of second layer 32 in central portion 16. Specifically, the portion of second layer 32 in outer peripheral portion 17 may be in contact with the portion of second layer 32 in central portion 16. The portion of second layer 32 in outer peripheral portion 17 faces the portion of second layer 32 in central portion 16. Second layer 32 is surrounded by first layer 31. Fig. 22 shows a state after the step (S10) of placing the brazing filler metal and the materials to be joined on the base portion.

[0137] Tenth Embodiment Next, the configuration of a bonding method according to a tenth embodiment will be described with reference to Figures 23 to 25. The bonding method according to the tenth embodiment differs from the bonding method according to the first embodiment mainly in that an anti-wetting agent is applied to the first layer 31, but is substantially the same as the bonding method according to the first embodiment in other respects. The following description will focus on the differences from the bonding method according to the first embodiment.

[0138] 23 , the joining method according to the tenth embodiment includes a step (S15) of applying an anti-wetting agent to the first layer. The step (S15) of applying an anti-wetting agent to the first layer is performed, for example, after the step (S10) of placing the brazing filler metal and the workpieces on the base and before the step (S20) of joining the base and the workpieces by heating the brazing filler metal.

[0139] 24 and 25 , the third surface 43 is composed of a bonding region 35 and a non-bonding region 36. The bonding region 35 is a region that comes into contact with the brazing material 12. The non-bonding region 36 is a region to which an anti-wetting agent 39, which will be described later, is applied. The non-bonding region 36 is continuous with the bonding region 35. The non-bonding region 36 surrounds the bonding region 35. The non-bonding region 36 is located on the outer periphery of the third surface 43. The first layer 31 has a first outer peripheral side surface 37. The first outer peripheral side surface 37 is continuous with the non-bonding region 36. The first outer peripheral side surface 37 has an annular shape.

[0140] 25 , the second layer 32 has a second outer peripheral side surface 38. The second outer peripheral side surface 38 is annular. The second outer peripheral side surface 38 includes the first side surface 21 and the second side surface 22 (see FIG. 2 ). The second outer peripheral side surface 38 is continuous with each of the fifth surface 45 and the sixth surface 46.

[0141] As shown in FIG. 25 , in the step (S15) of applying an anti-wetting agent to the first layer, an anti-wetting agent 39 is applied to at least a portion of the non-bonding region 36. The surface of the anti-wetting agent 39 is less susceptible to wetting and spreading of the molten brazing filler metal 12. From another perspective, the wettability of the surface of the anti-wetting agent 39 with the molten brazing filler metal 12 is lower than the wettability of the third surface 43 with the molten brazing filler metal 12. The anti-wetting agent 39 prevents the molten brazing filler metal 12 from wetting and spreading. The anti-wetting agent 39 is also referred to as a stop-off agent. The anti-wetting agent 39 is composed of, for example, at least one of oxide particles and ceramics, and a binder (solvent).

[0142] The anti-wetting agent 39 may be applied to the entire non-bonded region 36. The anti-wetting agent 39 may be applied to the first outer peripheral side surface 37, the second outer peripheral side surface 38, or the outer peripheral end of the sixth surface 46.

[0143] Before the step (S20) of joining the base portion and the workpiece by heating the brazing material, the joining region 35 is in contact with the brazing material 12. The joining region 35 and the brazing material 12 are in contact without an anti-wetting agent 39 therebetween. The brazing material 12 is surrounded by the anti-wetting agent 39. The non-joining region 36 is spaced apart from the brazing material 12.

[0144] In a cross section parallel to the first direction 101, the width of the workpieces 13 to be joined is greater than the width of the brazing filler metal 12. When viewed in the direction opposite to the first direction 101, the brazing filler metal 12 overlaps the workpieces 13 to be joined.

[0145] According to the joining method of the tenth embodiment, an anti-wetting agent 39 is applied to the non-joining region 36 of the first layer 31. Therefore, in the step (S20) of joining the base portion and the workpiece by heating the brazing filler metal, the anti-wetting agent 39 prevents the molten brazing filler metal 12 from wetting and spreading over the surface of the first layer 31. This makes it possible to prevent the molten brazing filler metal 12 from contacting the second layer 32. Therefore, it is possible to prevent erosion of the second layer 32 caused by contact between the molten brazing filler metal 12 and the second layer 32.

[0146] The step (S15) of applying an anti-wetting agent to the first layer may be performed before the step (S10) of placing the brazing filler metal and the workpieces on the base portion. The step (S15) of applying an anti-wetting agent to the first layer may be performed before the step (S20) of joining the base portion and the workpieces by heating the brazing filler metal.

[0147] Embodiment 11 Next, the configuration of a manufacturing method for a cooler according to embodiment 11 will be described using Figures 26 and 27. The manufacturing method for a cooler according to embodiment 11 differs from the manufacturing method for a cooler according to embodiment 1 mainly in that a blast treatment is performed on the surface of the second layer 32, but is substantially the same as the manufacturing method for a cooler according to embodiment 1 in other respects. The following description will focus on the differences from the manufacturing method for a cooler according to embodiment 1.

[0148] 26 , the method for manufacturing cooler 100 according to the eleventh embodiment includes a step (S25) of performing blasting on the surface of the second layer. Similarly, the method for manufacturing semiconductor device 200 according to the eleventh embodiment includes a step (S25) of performing blasting on the surface of the second layer.

[0149] The step (S25) of blasting the surface of the second layer is carried out after the step (S20) of joining the base portion and the material to be joined, for example, by heating the brazing material, and before the step (S30) of joining the jacket to the base portion.

[0150] As shown in Figure 27, in the step (S25) of blasting the surface of the second layer, the sixth surface 46 is blasted. The blasting is a processing process in which hard fine particles are collided with an object to perform the processing. Specifically, fine particles 95 are projected onto the sixth surface 46. The fine particles 95 collide with the sixth surface 46, slightly scraping the sixth surface 46. This may result in the formation of minute irregularities (not shown) on the sixth surface 46.

[0151] The blasting process may be either wet blasting or dry blasting. When wet blasting is used, the number of particles 95 embedded in the sixth surface 46 can be reduced. The material constituting the particles 95 may be, for example, a metal such as iron, stainless steel, aluminum, or copper, or may be ceramic, glass, or dry ice. When the particles 95 are made of dry ice, the particles 95 can be prevented from remaining on the sixth surface 46.

[0152] The glossiness of the sixth surface 46 before the step (S25) of blasting the surface of the second layer is lower than the glossiness of the sixth surface 46 before the step (S25) of blasting the surface of the second layer. Note that the step (S25) of blasting the surface of the second layer may be performed after the step (S30) of joining the jacket to the base portion. The blasting may be performed on the surface of the second layer 32. The surface of the second layer 32 is the surface of the second layer 32 that is not covered by the first layer 31 or the third layer 33 (see FIG. 18 ).

[0153] Next, the configuration of a cooler 100 according to embodiment 11 will be described with reference to Fig. 28 . As shown in Fig. 28 , according to the cooler 100 according to embodiment 11, the surface of the second layer 32 is subjected to blasting. Specifically, the sixth surface 46 is subjected to blasting. The sixth surface 46 may have minute irregularities.

[0154] The cooler 100 may have fine particles 95. The fine particles 95 are located on the sixth surface 46. The fine particles 95 are embedded in the second layer 32 at the sixth surface 46. The fine particles 95 are the fine particles 95 used in the blasting process in the step (S25) of performing the blasting process on the surface of the second layer.

[0155] Next, the configuration of a semiconductor device 200 according to an eleventh embodiment will be described with reference to Fig. 29. As shown in Fig. 29, the semiconductor device 200 according to the eleventh embodiment has, for example, a particle 95. The particle 95 is located on the sixth surface 46. The particle 95 is embedded in the second layer 32 at the sixth surface 46.

[0156] The particles 95 are located between the second layer 32 and the semiconductor chip 9. Specifically, the particles 95 are located between the second layer 32 and the chip bonding layer 94. The sixth surface 46 is subjected to a blasting treatment. The sixth surface 46 may have minute irregularities. Each of the first side surface 21 and the second side surface 22 may be subjected to a blasting treatment.

[0157] Next, the effects of the manufacturing method of the cooler 100 according to the eleventh embodiment will be described.

[0158] In the step (S20) of joining the base portion and the workpiece by heating the brazing filler metal, the second layer 32 is heated to a high temperature. This may cause the surface of the second layer 32 to oxidize or discolor. Furthermore, in the process of manufacturing the cooler 100, the surface of the second layer 32 may be pressed using a jig or the like. In this case, marks from the jig may remain on the surface of the second layer 32, or the surface of the second layer 32 may be contaminated due to contact with the jig.

[0159] The manufacturing method of the cooler 100 according to the eleventh embodiment includes a step (S25) of blasting the surface of the second layer 32 after the step (S20) of joining the base portion and the workpiece by heating the brazing filler metal. Therefore, the blasting can remove oxides and foreign matter present on the surface of the second layer 32. This can make the surface condition of the second layer 32 more uniform. This can make it easier to solder other components to the second layer 32.

[0160] The manufacturing method of the semiconductor device 200 according to the eleventh embodiment includes a step (S25) of blasting the surface of the second layer 32 after the step (S20) of joining the base portion and the workpiece by heating the brazing filler metal. This makes it possible to make the surface condition of the second layer 32 more uniform, as described above. This improves the reliability of the joining between the semiconductor chip 9 and the second layer 32.

[0161] In the above description of the manufacturing method of the cooler 100, a configuration using the bonding method according to the first embodiment has been described. However, the manufacturing method of the cooler 100 according to the present disclosure may also use the bonding methods according to each of the second to tenth embodiments. In the manufacturing method of the cooler 100, when the bonding method according to the second embodiment is used, the compound portion 4 may contain magnesium. The compound portion 4 may contain a compound of magnesium and nickel. Similarly, in the manufacturing method of the cooler 100, when the bonding method according to the third embodiment is used, the compound portion 4 may contain magnesium. The compound portion 4 may contain a compound of magnesium and nickel.

[0162] The embodiments disclosed herein are to be considered as illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the above description, and is intended to include meanings equivalent to the claims and all modifications within the scope thereof.

[0163] Various aspects of the present disclosure are described below as appendices. (Appendix 1) A joining method comprising the steps of: placing a brazing filler metal and materials to be joined on a base portion; and joining the base portion and the materials to be joined by heating the brazing filler metal at a temperature equal to or higher than the melting point of the brazing filler metal and lower than the melting point of the base portion, wherein the base portion includes aluminum, the brazing filler metal includes aluminum and silicon, and the materials to be joined have a first layer including nickel and a second layer provided on the first layer and including copper, wherein the brazing filler metal is placed between the base portion and the first layer in the step of placing the brazing filler metal and the materials to be joined. (Appendix 2) The joining method according to Appendix 1, wherein the brazing filler metal includes aluminum, silicon, and magnesium, and wherein the brazing filler metal is heated in an inert gas atmosphere in the step of joining the base portion and the materials to be joined by heating the brazing filler metal at a temperature equal to or higher than the melting point of the brazing filler metal and lower than the melting point of the base portion. (Supplementary Note 3) The joining method according to Supplementary Note 1, wherein the base portion contains magnesium, and in the step of joining the base portion and the workpieces by heating the brazing filler metal at a temperature equal to or higher than the melting point of the brazing filler metal and lower than the melting point of the base portion, the brazing filler metal is heated in an inert gas atmosphere. (Supplementary Note 4) The joining method according to any one of Supplementary Notes 1 to 3, wherein a thickness of the second layer is at least twice the thickness of the first layer. (Supplementary Note 5) The joining method according to any one of Supplementary Notes 1 to 4, wherein a groove is provided in the base portion, and in the step of joining the base portion and the workpieces by heating the brazing filler metal at a temperature equal to or higher than the melting point of the brazing filler metal and lower than the melting point of the base portion, a portion of the molten brazing filler metal flows into the groove. (Appendix 6) The joining method according to any one of Appendices 1 to 5, wherein the workpieces are composed of a central portion and an outer peripheral portion surrounding the central portion, and before a step of joining the base portion and the workpieces by heating the brazing material at a temperature equal to or higher than the melting point of the brazing material and lower than the melting point of the base portion, the central portion is in contact with the brazing material, and the outer peripheral portion is bent relative to the central portion in a direction from the base portion toward the brazing material.(Supplementary Note 7) The bonding method according to any one of Supplementary Notes 1 to 6, wherein the first layer has a third surface constituted by a bonding region and a non-bonding region continuous with the bonding region, and before a step of bonding the base portion and the workpieces by heating the brazing filler metal at a temperature equal to or higher than the melting point of the brazing filler metal and lower than the melting point of the base portion, the bonding region is in contact with the brazing filler metal and the non-bonding region is spaced from the brazing filler metal, and the method further comprises a step of applying an anti-wetting agent to the non-bonding region before a step of bonding the base portion and the workpieces by heating the brazing filler metal at a temperature equal to or higher than the melting point of the brazing filler metal and lower than the melting point of the base portion. (Supplementary Note 8) The bonding method according to any one of Supplementary Notes 1 to 7, wherein a portion of the second layer is embedded in the first layer. (Supplementary Note 9) The joining method according to any one of Supplementary Notes 1 to 8, wherein in the step of placing the brazing filler metal and the materials to be joined on the base portion, the materials to be joined and the brazing filler metal are integrally formed. (Supplementary Note 10) The joining method according to any one of Supplementary Notes 1 to 8, wherein in the step of placing the brazing filler metal and the materials to be joined on the base portion, the base portion and the brazing filler metal are integrally formed. (Supplementary Note 11) The joining method according to any one of Supplementary Notes 1 to 10, wherein the materials to be joined have a third layer provided between the first layer and the second layer, and the third layer contains titanium. (Appendix 12) A method for manufacturing a cooler using the joining method described in any one of Appendix 1 to Appendix 11, wherein in the step of placing the brazing filler metal and the material to be joined on the base portion, a fin member is placed on the opposite side of the base portion from the material to be joined, and in the step of joining the base portion and the material to be joined by heating the brazing filler metal at a temperature equal to or higher than the melting point of the brazing filler metal and lower than the melting point of the base portion, the fin member is heated together with the brazing filler metal to join the fin member to the base portion.(Supplementary Note 13) The method for manufacturing a cooler according to Supplementary Note 12, further comprising the step of blasting a surface of the second layer after the step of joining the base portion and the workpiece by heating the brazing filler metal at a temperature equal to or higher than the melting point of the brazing filler metal and lower than the melting point of the base portion. (Supplementary Note 14) A method for manufacturing a semiconductor device, comprising the steps of preparing a cooler using the method for manufacturing a cooler according to Supplementary Note 12 or Supplementary Note 13, and joining a semiconductor chip to the second layer of the cooler. (Supplementary Note 15) A cooler comprising: a base portion containing aluminum; a bonding portion bonded to the base portion; a bonded portion provided above the bonding portion; a compound portion provided between the bonding portion and the bonded portion and connected to each of the bonding portion and the bonded portion; and a fin bonded to the base portion and provided on the opposite side of the bonded portion with respect to the base portion, wherein the bonding portion contains aluminum and silicon, and the bonded portion comprises: a first layer connected to the compound portion and containing nickel, and a second layer provided on the first layer and containing copper, and the compound portion contains at least one element contained in the bonding portion and at least one element contained in the first layer. (Supplementary Note 16) The cooler according to Supplementary Note 15, wherein a surface of the second layer is blasted. (Supplementary Note 17) A semiconductor device comprising: the cooler according to Supplementary Note 15 or Supplementary Note 16; and a semiconductor chip bonded to the second layer. (Supplementary Note 18) The semiconductor device according to Supplementary Note 17, further comprising fine particles for blasting, the second layer having a sixth surface to which the semiconductor chip is bonded, and the fine particles located on the sixth surface.

[0164] 1 Base portion, 2 Bonding portion, 3 Bonded portion, 4 Compound portion, 5 Fin, 6 Jacket, 8 Plate portion, 9 Semiconductor chip, 10 Bonded structure, 12 Brazing material, 13 Bonded material, 15 Fin member, 16 Central portion, 17 Outer periphery, 18 Plate material, 19 Bottom surface, 21 First side surface, 22 Second side surface, 23 Third side surface, 27 First side wall surface, 28 Second side wall surface, 31 First layer, 32 Second layer, 33 Third layer, 35 Bonding region, 36 Non-bonding region, 37 First outer peripheral side surface, 38 Second outer peripheral side surface, 39 Anti-wetting agent, 41 First surface, 42 Second surface, 43 Third surface, 45 Fifth surface, 46 Sixth surface, 47 Seventh surface, 48 Eighth surface, 50 Structure, 51 First surface portion, 52 Second surface portion, 60 Main body portion, 61 First piping, 62 Second piping, 70 Base structure, 81 Bonding layer, 82 Bonded layer, 86 Brazing material layer, 90 Flow path, 91 Space, 92 Inflow path, 93 Outflow path, 94 Chip bonding layer, 95 Fine particles, 96 Fillet, 98 Hole, 99 Groove, 100 Cooler, 101 First direction, 102 Second direction, 200 Semiconductor device, H1 First thickness, H2 Second thickness, H3 Third thickness, H4 Fourth thickness, H5 Fifth thickness, H6 Sixth thickness, H7 Seventh thickness, H8 Eighth thickness.

Claims

1. A joining method comprising the steps of: placing a brazing material and materials to be joined on a base portion; and joining the base portion and the materials to be joined by heating the brazing material at a temperature equal to or higher than the melting point of the brazing material and lower than the melting point of the base portion, wherein the base portion contains aluminum, the brazing material contains aluminum and silicon, and the materials to be joined have a first layer containing nickel and a second layer provided on the first layer and containing copper, and wherein in the step of placing the brazing material and the materials to be joined, the brazing material is placed between the base portion and the first layer.

2. The joining method according to claim 1, wherein the brazing filler metal contains aluminum, silicon and magnesium, and in the process of joining the base portion and the joined material by heating the brazing filler metal at a temperature equal to or higher than the melting point of the brazing filler metal and lower than the melting point of the base portion, the brazing filler metal is heated in an inert gas atmosphere.

3. The joining method according to claim 1, wherein the base portion contains magnesium, and in the process of joining the base portion and the workpiece by heating the brazing material at a temperature equal to or higher than the melting point of the brazing material and lower than the melting point of the base portion, the brazing material is heated in an inert gas atmosphere.

4. The bonding method according to claim 1, wherein the thickness of said second layer is at least twice the thickness of said first layer.

5. A joining method as claimed in any one of claims 1 to 4, wherein a groove is provided in the base portion, and in a process of joining the base portion and the material to be joined by heating the brazing material at a temperature equal to or higher than the melting point of the brazing material and lower than the melting point of the base portion, a portion of the molten brazing material flows into the groove.

6. A joining method according to any one of claims 1 to 4, wherein the workpieces are composed of a central portion and an outer peripheral portion surrounding the central portion, and prior to a process of joining the base portion and the workpieces by heating the brazing material at a temperature equal to or higher than the melting point of the brazing material and lower than the melting point of the base portion, the central portion is in contact with the brazing material, and the outer peripheral portion is bent relative to the central portion in a direction from the base portion toward the brazing material.

7. A joining method according to any one of claims 1 to 4, wherein the first layer has a third surface constituted by a joining region and a non-joining region continuous with the joining region, and wherein, prior to a step of joining the base portion and the workpieces by heating the brazing material at a temperature equal to or higher than the melting point of the brazing material and lower than the melting point of the base portion, the joining region is in contact with the brazing material and the non-joining region is spaced apart from the brazing material, and further comprising a step of applying an anti-wetting agent to the non-joining region prior to a step of joining the base portion and the workpieces by heating the brazing material at a temperature equal to or higher than the melting point of the brazing material and lower than the melting point of the base portion.

8. A bonding method according to any one of claims 1 to 4, wherein a portion of the second layer is embedded in the first layer.

9. A joining method according to any one of claims 1 to 4, wherein in the step of placing the brazing material and the material to be joined on the base portion, the material to be joined and the brazing material are formed integrally.

10. A joining method according to any one of claims 1 to 4, wherein in the step of placing the brazing material and the workpiece on the base portion, the base portion and the brazing material are formed integrally.

11. A joining method according to any one of claims 1 to 4, wherein the materials to be joined have a third layer provided between the first layer and the second layer, and the third layer contains titanium.

12. A method for manufacturing a cooler using the joining method described in any one of claims 1 to 4, wherein in the step of placing the brazing filler metal and the material to be joined on the base portion, a fin member is placed on the opposite side of the base portion to the material to be joined, and in the step of joining the base portion and the material to be joined by heating the brazing filler metal at a temperature equal to or higher than the melting point of the brazing filler metal and lower than the melting point of the base portion, the fin member is heated together with the brazing filler metal to join the fin member to the base portion.

13. A method for manufacturing a cooler as described in claim 12, further comprising a step of blasting the surface of the second layer after a step of joining the base portion and the material to be joined by heating the brazing material at a temperature equal to or higher than the melting point of the brazing material and lower than the melting point of the base portion.

14. A method for manufacturing a semiconductor device, comprising the steps of: preparing a cooler using the method for manufacturing a cooler according to claim 12; and bonding a semiconductor chip to the second layer of the cooler.

15. A cooler comprising: a base portion comprising aluminum; a joining portion joined to the base portion; a joined portion provided above the joining portion; a compound portion provided between the joining portion and the joined portion and connected to each of the joining portion and the joined portion; and a fin joined to the base portion and provided on the opposite side of the joined portion with respect to the base portion, wherein the joining portion comprises aluminum and silicon, the joined portion comprises: a first layer connected to the compound portion and comprising nickel, and a second layer provided on the first layer and comprising copper, and the compound portion contains at least one of the elements contained in the joining portion and at least one of the elements contained in the first layer.

16. The cooler of claim 15, wherein the surface of the second layer is blasted.

17. A semiconductor device comprising the cooler according to claim 15 or 16, and a semiconductor chip bonded to the second layer.

18. The semiconductor device according to claim 17, further comprising fine particles for blasting, the second layer having a sixth surface to which the semiconductor chip is bonded, and the fine particles being located on the sixth surface.

Images