Method for manufacturing a heat exchanger, a heat exchanger, and a method for joining aluminum materials.

Abstract

Provided is a bonding method for aluminum materials, wherein: a plurality of cladding members (10a, 10b) made of aluminum materials are prepared, each cladding member having layered therein an aluminum or aluminum alloy core material (11) and an aluminum-alloy brazing material (12) containing 4-12 mass% of Si; and, in a decompressed inert gas atmosphere, the plurality of cladding members (10a, 10b) are brazed together without using flux, with brazing material surfaces (13) of the cladding members facing each other.

Description

[Technical Field]

[0001] The present disclosure relates to ,heat a method for manufacturing a heat exchanger, a heat exchanger, and a method for joining aluminum materials. [Background Art]

[0002] Since an aluminum material is covered with a strong oxide film, joining is difficult. Therefore, in ordinary brazing, a method using a non-corrosive flux in a nitrogen atmosphere is common.

[0003] A strong oxide film exists on the surface of an aluminum material, which inhibits the wetting of the brazing filler metal. When flux is applied, the flux destroys the oxide film, so that favorable brazing is achieved. That is, it is a common belief that flux is essential for brazing aluminum materials in an ordinary nitrogen atmosphere.

[0004] In addition to the above, Patent Document 1 describes a method for joining aluminum materials by interposing an insert material made of a eutectic alloy with hypereutectic silicon and applying two-stage pressure. [Prior Art Literature] [Patent Literature]

[0005] [Patent Document 1] Japanese Patent Publication No. Sho 59-48714 [Summary of the Invention] [Problem to be Solved by the Invention]

[0006] In a brazing method using flux, there are problems that a flux application step is required, and flux residue remains after brazing.

[0007] Further, in the joining method of Patent Document 1, there are problems that it is difficult to manufacture the insert material, the material cost is high, and two-stage pressurization is required.

[0008] This disclosure has been made in view of the above circumstances and aims to provide a method for joining aluminum materials, a method for manufacturing a heat exchanger, a pressurizing device, a brazed joint, and a heat exchanger, which enable the brazing of aluminum materials in a non-reduced pressure inert gas atmosphere without using flux or expensive insert materials. [Means for solving the problem]

[0009] To achieve the above objectives, this disclosure Heat exchanger manufacturing method The present invention relates to a method for manufacturing a heat exchanger in which multiple clad materials are joined by a method for joining aluminum materials, wherein multiple clad materials are prepared by laminating a core material of pure aluminum or an aluminum alloy and a brazing material of an aluminum alloy containing 4 to 12 mass% of Si, and the multiple clad materials are joined by fluxless brazing in a non-reduced pressure inert gas atmosphere with the brazing material surfaces of the multiple clad materials facing each other, and the multiple clad materials are joined by a method for joining aluminum materials, wherein multiple clad materials In some or all of these processes, a step is taken to form holes by press working, and multiple clad materials are brazed together while leaving burrs or sharp edges formed on the clad material by press working. ru. [Effects of the Invention]

[0010] Book According to the disclosure, it is possible to braze aluminum materials in a non-reduced pressure inert gas atmosphere without using flux or expensive insert materials. [Brief explanation of the drawing]

[0011] [Figure 1] Schematic cross-sectional view of a brazed joint in Embodiment 1 of this disclosure [Figure 2] Schematic cross-sectional view of a brazed joint of three or more layers in Embodiment 3 of this disclosure [Figure 3] Schematic diagram of a heat exchanger in Embodiment 4 of the present disclosure [Figure 4] Schematic diagram of a semiconductor device in Embodiment 5 of the present disclosure [Figure 5] (a) to (c) Diagrams showing the manufacturing process of a semiconductor device in Embodiment 5 of this disclosure. [Figure 6]A diagram illustrating the brazing method in Embodiment 6 of the present disclosure [Figure 7] A diagram illustrating the brazing method in Embodiment 7 of the present disclosure [Figure 8] A diagram illustrating the brazing method in Embodiment 8 of the present disclosure [Figure 9] Cross-sectional structure of a brazed joined body in an example of the present disclosure [Figure 10] Cross-sectional structure of a corner portion of a brazed joined body in an example of the present disclosure [Figure 11] Cross-sectional structure of a brazed joined body in a comparative example of the present disclosure DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, specific embodiments of a method for joining aluminum materials, a method for manufacturing a heat exchanger, a pressurizing device, a brazed joined body, and a heat exchanger according to the present disclosure will be described with reference to the accompanying drawings. The present disclosure is not limited to the following embodiments.

[0013] Embodiment 1. A method for joining aluminum materials according to Embodiment 1 will be described with reference to FIG. 1. In the present disclosure, the term "aluminum material" refers to a member formed of pure aluminum or an aluminum alloy, and a member formed of any combination thereof. In each of the following embodiments, a core material, a brazing filler metal, and a cladding material are all included in aluminum materials.

[0014] As shown in FIG. 1, clad materials 10a and 10b each obtained by laminating an Al-Si based brazing filler metal 12 on a core material 11 are arranged such that their brazing filler metal faces face each other. Thereafter, the clad materials 10a and 10b in a laminated state are heated to a temperature equal to or higher than the melting point of the brazing filler metal while being pressurized. Thereby, for the reason described below, the clad materials 10a and 10b of aluminum materials can be brazed without flux even in a non-reduced pressure inert gas atmosphere.

[0015] (Material) Clad materials 10a and 10b obtained by cladding a brazing filler metal 12 on a core material 11 are used. The clad materials 10a and 10b have the same configuration as each other.

[0016] A general aluminum-based material can be used for the core material 11. For example, pure aluminum or an aluminum alloy such as a 1000 series or 3000 series aluminum alloy can be used.

[0017] It is desirable that the brazing filler metal is formed of an Al-Si based alloy having a composition in which Si is 4 to 12% by mass, and the balance is Al and unavoidable impurities. If the Si content is 4% by mass or more, the melting point of the brazing filler metal can be sufficiently lowered than that of the core material to be brazed, and reliable brazing can be achieved. On the other hand, if the Si content exceeds 12% by mass, the effect of lowering the melting point of the brazing filler metal is small. In addition, if the Si content exceeds 12% by mass, the material becomes hard, which makes it difficult to manufacture the clad material. Furthermore, in order to improve wettability, the brazing filler metal may contain bismuth and lithium in addition to Si.

[0018] When joining two clad materials to each other, the brazing filler metal may be clad on one side or may be clad on both sides. In both cases of single-sided cladding and double-sided cladding, the clad materials are arranged with the brazing filler metal layers facing each other.

[0019] Regarding the thickness of the brazing filler metal, it is desirably 0.01 to 0.1 mm. When the thickness of the brazing filler metal is less than 0.01 mm, the amount of the brazing filler metal that melts and flows during brazing is insufficient. Therefore, the gap between the core materials cannot be filled, and there is a risk that voids remain after brazing. On the other hand, when the thickness of the brazing filler metal exceeds 0.1 mm, there is a risk that excess brazing filler metal erodes the core material or excess brazing filler metal protrudes from the side surface of the clad material. However, the protruding brazing filler metal can also be removed by cutting after brazing. In addition, when erosion becomes a problem, lowering the temperature during brazing or reducing the Si content in the brazing filler metal is also effective as a countermeasure.

[0020] (Arrangement of Materials) Using two clad materials 10a and 10b, the brazing surfaces 13, which are the outer surfaces of the brazing materials 12 of each material, are stacked facing each other to form a laminate. That is, the structure is, from top to bottom, core material 11, brazing material 12, brazing material 12, and core material 11. In the following explanation, the brazing surface refers to the same surface as the brazing surface 13.

[0021] No flux is supplied between the cladding materials 10a and 10b. More preferably, the laminate is compressed with a force of 10 kPa or more using a jig. Compression is expected to fill the voids at the joint interface.

[0022] (Atmosphere and temperature) The laminated members described above are heated in a furnace under a non-reduced, inert atmosphere, such as a nitrogen atmosphere, to a temperature range above the solidus temperature of the brazing material 12 and below 640°C. After being held in the heated state for a certain period of time, they are cooled to room temperature. If the temperature is below the solidus temperature of the brazing material 12, the brazing material 12 will not melt, and therefore joining will not be achieved. It is preferable to keep the maximum temperature below 640°C to prevent the melting of the core material. Furthermore, it is desirable that the maximum temperature be above the liquidus temperature of the brazing material. This is to increase the fluidity of the brazing material and to promote the breakdown of the oxide film on the brazing material.

[0023] Nitrogen, argon, etc., can be used as the inert gas. The oxygen concentration of the atmosphere should preferably be 500 ppm or less. If the oxygen concentration of the atmosphere exceeds 500 ppm, oxidation of the brazed material will proceed more easily.

[0024] Furthermore, it is preferable that the initial oxide film on the surfaces of the clad materials 10a and 10b be thin. If possible, it is desirable to remove the oxide film by washing before joining. By joining according to the above procedure, the clad materials are joined together, and the brazed joint 100 is formed.

[0025] Next, we will explain why brazing is achieved without flux in this embodiment.

[0026] First, let's explain the standard method of aluminum brazing. In standard brazing, the common method involves using a non-corrosive flux in a nitrogen atmosphere. In this method, the non-corrosive flux is applied to the aluminum material, and then the material is heated to approximately 600°C to achieve brazing. The purpose of applying the flux is to break down the oxide film on the aluminum material. A strong oxide film exists on the surface of the aluminum material, inhibiting the wetting of the brazing material. Therefore, by applying the flux, the flux breaks down the oxide film, resulting in good brazing. In other words, it is generally accepted that flux is essential for brazing aluminum material in a standard nitrogen atmosphere.

[0027] Next, the process of the fluxless brazing method of this disclosure will be described. As shown schematically in Figure 1, clad materials 10a and 10b are brazed without flux with their brazing surfaces 13 facing each other. Oxide films are present on the brazing surfaces 13 of the clad materials 10a and 10b. However, these oxide films are destroyed and separated when the brazing material melts, making joining possible. Since the oxide films on both opposing brazing surfaces 13 are destroyed, a good bond is achieved.

[0028] Embodiment 2. In Embodiment 2, clad materials 10a and 10b are brazed, in which the amount of Mg in the brazing material 12 of Embodiment 1 is reduced to less than 0.1% by mass. Except for the reduction in the amount of Mg in the brazing material 12, it is the same as Embodiment 1.

[0029] Reducing the amount of Mg in the brazing material has two effects. The first effect is the suppression of contamination of the brazing furnace. When the brazing material melts, metal vapor is generated. If the brazing material contains Mg, Mg vapor is generated at this time, which may contaminate the inside of the brazing furnace. By reducing the amount of Mg to less than 0.1 mass%, the amount of Mg evaporation is extremely small, eliminating concerns about furnace contamination.

[0030] The second effect is the suppression of brazing defects. In a typical brazing furnace, aluminum materials are brazed using the flux mentioned earlier. Since the flux melts and evaporates during brazing, the flux is present in the atmosphere of a typical brazing furnace. If the brazing material contains Mg, the Mg may react with the flux, potentially inhibiting brazing. This is because fluorine or potassium in the flux reacts with magnesium to form potassium-fluorine-magnesium compounds. Potassium-fluorine-magnesium compounds inhibit the wetting of the brazing material. Therefore, the formation of these compounds may reduce the bonding strength. By limiting the amount of Mg to less than 0.1% by mass, the reaction between the brazing material and the flux can be avoided.

[0031] Embodiment 3. In Embodiment 3, a laminate of three or more layers of aluminum material is brazed together.

[0032] Figure 2 shows a schematic cross-sectional view of the brazed joint 200 in Embodiment 3. In Figure 2, as an example, a laminate of outer cladding material 23a, inner cladding material 24, and outer cladding material 23b is shown from top to bottom.

[0033] In the case of three or more layers, one or more internal cladding materials 24 other than the outermost cladding materials 23a and 23b located on the outermost surface must be double-sided cladding materials. This is because the brazing materials of adjacent cladding materials must be positioned facing each other. The outer cladding materials 23a and 23b may be single-sided cladding materials as shown in the figure, or they may be double-sided cladding materials.

[0034] In the case of double-sided clad materials, the thickness of the brazing material is preferably 0.01 to 0.1 mm. Here, the thickness of the brazing material in the case of double-sided clad materials refers to the thickness of each brazing material 22 placed on each surface of the core material 21. In addition, in order to prevent misalignment of the laminate, alignment grooves may be provided on each of the clad materials 23a, 23b, and 24, or alignment jigs may be used.

[0035] By adopting the configuration of Embodiment 3, it is possible to easily form a brazed joint with more layers.

[0036] Embodiment 4. Embodiment 4 shows an example of application to a heat exchanger. However, the products and locations to which the method of this disclosure can be applied are not limited to those shown.

[0037] First, the configuration of the heat exchanger 300 will be explained using the schematic diagram in Figure 3. The header 35 of the heat exchanger 300 is composed of, for example, 10 layers of external cladding material 31a, 31b and internal cladding material 32a, 32b, 32c, 32d, 32e, 32f, 32g, 32h. All of these cladding materials are formed from the aluminum material described in Embodiment 1 or Embodiment 2.

[0038] The two outer cladding layers 31a and 31b located on the outermost surface may be single-sided or double-sided cladding. The eight inner cladding layers 32a, 32b, 32c, 32d, 32e, 32f, 32g, and 32h located inside the outermost surface are all double-sided cladding.

[0039] The outer cladding materials 31a, 31b and the inner cladding materials 32a to 32h are drilled with holes as needed. The holes can be circular, oval, or of other shapes. By stacking these cladding materials, the holes in adjacent cladding materials are connected. The connection of multiple holes forms a refrigerant flow path inside the header 35. The minimum width of the holes for the flow path is, for example, about 0.2 mm.

[0040] The thickness of the outer cladding materials 31a, 31b and the inner cladding materials 32a to 32h is, for example, about 0.2 to 1 mm. The thickness, width, and length of these cladding materials do not all need to be the same.

[0041] Next, the brazing method in this embodiment will be described.

[0042] First, before brazing, the outer cladding materials 31a, 31b and the inner cladding materials 32a to 32h are laminated in the shape shown in Figure 3. It is desirable that each cladding material has a mechanism for alignment. At this time, flux application is not necessary.

[0043] Furthermore, it is desirable to apply pressure to the laminated structure using a jig after lamination. This pressure is applied, for example, by sandwiching the laminated structure between plate jigs from above and below and tightening it with screws. Other components may be joined to the laminated structure by brazing or other methods.

[0044] In the example shown in Figure 3, the refrigerant inlet 33 and refrigerant outlet 34 are attached to the laminate. The refrigerant inlet 33 and refrigerant outlet 34 each have a brazing layer and can be brazed to the laminate.

[0045] The heat exchanger components arranged as described above are heated in a furnace with an inert atmosphere, such as a nitrogen atmosphere, to a temperature range above the melting point of the brazing material and below 640°C. After being held in the heated state for a certain period of time, they are cooled to room temperature. The maximum temperature reached during heating is preferably just above the liquidus temperature of the brazing material. Therefore, it is preferable to stop heating and start cooling when the temperature just above the liquidus temperature is reached. It is preferable to keep the maximum temperature below 640°C to prevent melting and deformation of the aluminum plate material.

[0046] The heat exchanger 300 is manufactured by the method described above. By adopting the aluminum material joining method of this disclosure, the heat exchanger 300 can be easily manufactured using clad aluminum material.

[0047] Embodiment 5. Embodiment 5 shows examples of application to a cooler, which is a type of heat exchanger, and to a semiconductor device. However, the products and applications to which the method of this disclosure can be applied are not limited to those shown.

[0048] The configuration of the cooler and semiconductor device will be described below. Figure 4 is a schematic diagram of the cooler 410 and the semiconductor device 400 equipped with the cooler 410.

[0049] The cooler 410 comprises fins 41 and a jacket 44 covering the fins 41. The method for manufacturing the fins 41 is the same as the method for manufacturing the heat exchanger in Embodiment 4. Holes that serve as refrigerant passages are provided in each of the laminated cladding materials as needed. The fins 41 brazed in this method may be joined to other aluminum materials. Joining methods include brazing, welding, and solid-state bonding.

[0050] The brazed fins 41 are further covered externally by a box-shaped jacket 44. The jacket 44 is manufactured from, for example, aluminum. The fins and jacket are attached by fastening methods such as mechanical fastening, welding, brazing, or solid-state bonding.

[0051] The jacket 44 can be further fitted with piping for the refrigerant 48, including a refrigerant inlet 46 and a refrigerant outlet 47, as well as other components. The refrigerant 48 flows into the cooler 410 through the refrigerant inlet 46, flows through the internal flow path of the cooler 410, and is then discharged to the outside through the refrigerant outlet 47.

[0052] Furthermore, a semiconductor chip 45 is bonded to the cooler 410, which is an integrated unit of fins 41 and jacket 44, to form a semiconductor device 400. In Figure 4, the semiconductor chip 45 is mounted on an external cladding material 42a.

[0053] Figures 5(a) to 5(c) show the manufacturing process of the semiconductor device 400. First, as shown in Figures 4 and 5(a), internal cladding materials 43a, 43b, 43c, 43d, 43e, 43f, 43g, and 43h are layered between external cladding materials 42a and 42b in order from top to bottom, and fins 41 are formed by brazing. The brazing method is the same as in Embodiment 4. Holes are provided in each cladding material as needed to serve as coolant channels.

[0054] As shown in Figure 5(b), the jacket 44 has a refrigerant inlet 46 and a refrigerant outlet 47 pre-attached to it. Then, the outer cladding material 42a of the fins 41 is placed on the jacket 44 and the fins 41 and jacket 44 are fastened together. After that, as shown in Figure 5(c), the semiconductor chip 45 is placed on the outer cladding material 42a of the fins 41 and joined to the outer cladding material 42a. Soldering is used to join the semiconductor chip 45, for example. At this time, plating may be applied to the soldering surface in order to improve the wettability of the solder to the aluminum outer cladding material 42a. Nickel plating or copper plating can be used for the plating. In addition, the semiconductor chip 45 can also be joined by silver sintering, for example.

[0055] The semiconductor device 400 is manufactured by the method described above. By adopting the aluminum material joining method of this disclosure, the semiconductor device 400 can be easily manufactured using aluminum clad material.

[0056] Embodiment 6. When laminating and brazing clad materials, the plate thickness may decrease before and after brazing due to pressure from above and below. This is because when the brazing material melts, it is pushed out from the joint into the flow path, and the plate thickness decreases by the amount of the discharged brazing material. In addition, the discharge of brazing material may narrow the flow path. If the plate thickness decreases or the brazing material is discharged, the flow path of the fins narrows, which can lead to increased refrigerant pressure loss. This increased pressure loss leads to an increased load on the water pump. Therefore, in embodiments 6 to 8, brazing is performed in a manner that suppresses the reduction in plate thickness before and after brazing.

[0057] Figure 6 shows a schematic diagram of a pressurizing jig 710 for applying pressure from above to a laminate 700 made of stacked clad materials. The pressurizing jig 710 comprises a pressurizing base 711, a stopper 712, and a pressurizing section 713.

[0058] The pressurizing platform 711 is a platform on which the laminated body 700 to be pressed is placed.

[0059] The pressurizing section 713 is positioned to press the laminate 700 from above, creating pressure between it and the pressurizing base 711. The pressurizing section 713 is sized to cover the entire upper surface of the laminate 700 and at least a portion of the upper surface of the stopper 712.

[0060] The stopper 712 is a member that locks the movement of the pressurizing section 713 during pressurization, and sets the total plate thickness of the pressurized laminate 700 to the pressurizing height H2 shown in the figure. The stopper 712 is placed on the pressurizing base 711, sandwiching or surrounding the laminate 700. The stopper 712 has a flat upper surface having a pressurizing height H2 from the upper surface of the pressurizing base 711.

[0061] The pressurized height H2 is lower than the height H1 in the lamination direction, which is the total plate thickness of the laminate 700 before brazing. More specifically, the pressurized height H2 is preferably an arbitrary value between 90% and 100% of the height H1 before pressurization, depending on the type and size of the laminate 700. If it is less than 90% of the height H1, the flow path of the fins may become narrow. If it is 100% or more of the height H1, the bonding may be insufficient. In this embodiment, the pressurized height H2 is 95% of the height H1.

[0062] The materials used for each part of the pressurizing jig 710 should preferably be stainless steel or carbon to prevent adhesion with the aluminum material.

[0063] Before brazing, the laminate 700 is placed on the pressurizing jig 710 as shown in Figure 6. When the pressurizing part 713 is used to press the laminate 700 downward with a pressure P, the laminate 700 is compressed from above and below. As a result, the height H1 of the laminate 700 decreases. When the height H1 becomes equal to the pressurizing height H2 of the stopper 712, the pressurizing part 713 hits the stopper 712 and locks in place. If brazing is performed in this state, the height of the laminate 700 after brazing will not decrease further from the pressurizing height H2.

[0064] Brazing a laminate of clad material requires a jig for applying pressure. With the configuration of Embodiment 6, simply adding a stopper 712 to an existing jig provides the effect of suppressing the reduction in plate thickness.

[0065] Embodiment 7. Figure 7 shows the lamination configuration of the clad material 10a and clad material 10b shown in Figure 1 of Embodiment 1. This differs from Embodiment 1 in that the clad material 10a has multiple press holes 14, which serve as the refrigerant flow paths, formed by press processing.

[0066] When the press hole 14 is processed by press working, a burr or sharp edge 15 is formed, as shown in the enlarged section of Figure 7. The burr or sharp edge 15 creates a space between the clad material 10a and the overlapping clad material 10a. The burr or sharp edge 15 is composed of the core material 11 and the brazing material 12 shown in Figure 1, and does not melt immediately even when the brazing material melts.

[0067] The height of the burrs or edges 15 should preferably be 5 μm or more, and less than the thickness of the brazing material 12 layer of the clad material 10a before brazing. If the height of the burrs or edges 15 is 5 μm or less, the effect of suppressing the reduction in plate thickness becomes extremely small. Also, if the burrs or edges 15 are higher than the brazing material 12 layer, contact between the clad material 10a and the clad material 10a during brazing may be hindered, potentially resulting in joint defects.

[0068] In Embodiment 7, burrs or sharp edges 15 that are inevitably formed during press working are utilized. Therefore, no additional components are required, and the effect of suppressing a reduction in plate thickness is obtained.

[0069] Embodiment 8. Figure 8 shows the configuration of clad material 10a and clad material 10b before brazing. In Embodiment 8, a spacer 720 is inserted between adjacent clad material 10a and clad material 10b.

[0070] The spacer 720 is formed in a granular shape. The cross-sectional shape of the spacer 720 is not specified. For example, it may be round or square. The height of the spacer 720 should be 5 μm or more, taking into account the total plate thickness after brazing, and preferably smaller than the thickness of each brazing material 12 layer of clad material 10a and clad material 10b before brazing. If the height of the spacer 720 is greater than the thickness of the brazing material 12 layer, a gap will be created between clad material 10a and clad material 10b, and joining will not be achieved.

[0071] The material of the spacer 720 should preferably not melt even at the brazing temperature of 600°C. For example, carbon, ceramic, or a metal with a melting point higher than 600°C can be used. Pure aluminum is also acceptable. The melting point of pure aluminum is approximately 660°C, and it will not melt at the brazing temperature. Using pure aluminum has the advantage that it does not leave any joint defects because its material is similar to that of the cladding material.

[0072] When spacers 720 are distributed between clad material 10a and clad material 10b and brazed, the spacers 720 do not melt even if the brazing material 12 melts. As a result, the spacers 720 maintain the space between clad material 10a and clad material 10b. Therefore, the effect of suppressing the reduction in plate thickness can also be obtained with Embodiment 8. [Examples]

[0073] The embodiments of this disclosure will be described below in comparison with comparative examples. These embodiments represent one aspect of the disclosure, and the disclosure is not limited thereto.

[0074] First, two clad materials were prepared. The thickness of the clad material was 0.3 mm. The thickness of the brazing material within the clad material was 0.03 mm. The core material of the clad material was A3003. The brazing material was an Al-Si alloy, with a Si content of 7% by mass. In addition, holes simulating refrigerant flow paths were made in a portion of the clad material.

[0075] Subsequently, two clad materials were laminated, and the laminate was pressed with a load of 1 MPa using a pressure jig to apply force to the overlapping section. No flux was applied between the two clad materials. The laminate in the above configuration was heated to 620°C in a furnace under a nitrogen atmosphere to obtain a brazed joint 500.

[0076] Subsequently, the brazed joint 500 was cut in the middle to obtain a cross-section. After polishing and etching this cross-section, the cross-sectional structure was observed with an optical microscope. The observed image is shown in Figure 9.

[0077] As can be seen from the observation image in Figure 9, two clad materials 50a and 50b were brazed together. Clad material 50a is clad with a core material 51a and brazing material 56a. Clad material 50b is clad with a core material 51b and brazing material 56b. A region 53 with a high Si concentration is formed near the center of the brazing bond layer 52 where brazing material 56a and brazing material 56b are joined. It was confirmed that the region 53 with a high Si concentration extends discretely in the in-plane direction. This is a characteristic structure that resulted from brazing the brazing materials 56a and 56b of the two clad materials 50a and 50b facing each other.

[0078] Figure 10 shows the cross-sectional structure of the region where the hole 54 of the brazed joint 500 is located. Observation of the corner 55 formed by the side surface of the hole 54 in the lower core material 51b and the lower surface of the upper core material 51a revealed that no fillet had been formed.

[0079] In typical aluminum brazing, flux is used. As a result, the flux, which melts before the brazing material, destroys the oxide film on both the aluminum and the brazing material, allowing the brazing material to wet and spread. Consequently, the brazing material cross-links at the corners, forming fillets.

[0080] In contrast, in this embodiment, the oxide film on each brazing material, including brazing material 56c that flowed to the side of the hole 54, is destroyed by the melting of brazing materials 56a and 56b. However, the oxide film is not completely removed to the same extent as when flux is used. Therefore, the wettability of each brazing material is worse than when flux is used. As a result, it is thought that the brazing material could not crosslink at the corners, and fillets could not be formed.

[0081] As a comparative example, two single-sided clad materials 60a and 60b, each 2 mm thick, were brazed together with their brazing surfaces facing each other to produce a brazed joint 600. Clad material 60a consists of a core material 61a and brazing material 66a. Clad material 60b consists of a core material 61b and brazing material 66b. The materials of each part are the same as those of the brazed joint 500. The thickness of the brazing materials 66a and 66b in the comparative example clad materials 60a and 60b is 0.2 mm, respectively.

[0082] As shown in the cross-sectional structure of Figure 11, in the comparative example brazed joint 600, a joint layer 62 of brazing materials 66a and 66b is formed. Next to the joint layer 62, an erosion area 67 was formed where the core materials 61a and 61b were gouged out by erosion. This is thought to be the result of excessive thickness of brazing materials 66a and 66b, i.e., excessive amount of brazing material, causing a large amount of Si in the brazing materials 66a and 66b to diffuse into the core materials 61a and 61b. Therefore, it was found that if there is too much brazing material 66a and 66b, erosion of the core materials 61a and 61b progresses significantly.

[0083] Although the present disclosure has been described above based on embodiments, the present disclosure is not limited to the embodiments and modifications described above, and various modifications and applications are possible.

[0084] Figure 1 shows a cross-section of a single-sided clad material. Alternatively, two double-sided clad materials may form a brazed joint.

[0085] In addition to the refrigerant inlet 33, refrigerant outlet 34, etc., shown in each of the above embodiments, any other components can be attached to the brazed joint as needed for the device.

[0086] In embodiments 4 to 8, the holes in each cladding material may be processed during the manufacturing process of the heat exchanger, or the cladding material with the holes already processed may be prepared in advance.

[0087] In Embodiment 8, the spacer 720 may be granular or, for example, foil-shaped. The thickness of the foil is equivalent to the height of the granular spacer 720.

[0088] As described above, the aluminum joining method, heat exchanger manufacturing method, pressurizing device, brazed joint, and heat exchanger are not limited to the embodiments described above, and can be modified and substituted in various ways. Various forms of this disclosure are described below as appendices.

[0089] (Note) (Note 1) Multiple clad aluminum materials are prepared, each consisting of a core made of pure aluminum or an aluminum alloy and a brazing material made of an aluminum alloy containing 4-12 mass% Si. The aforementioned multiple clad materials are brazed together in a fluxless manner in a non-reduced pressure inert gas atmosphere, with their brazing surfaces facing each other. Methods for joining aluminum materials.

[0090] (Note 2) The Mg content in the aforementioned brazing material is kept below 0.1% by mass. The method for joining aluminum materials as described in Appendix 1.

[0091] (Note 3) The thickness of the brazing material is 0.01 to 0.1 mm. The method for joining aluminum materials as described in Appendix 1.

[0092] (Note 4) In the brazing process described above, the multiple cladding materials are heated to a temperature above the liquidus temperature of the brazing material. The method for joining aluminum materials as described in Appendix 1.

[0093] (Note 5) The cladding materials are pressed together with a pressure of 10 kPa or more, and the brazing materials are brazed together while their surfaces are in contact with each other. The method for joining aluminum materials as described in Appendix 1.

[0094] (Note 6) A step of joining a plurality of stacked clad materials to form a fin using the aluminum material joining method described in any one of Appendix 1 to 5, The process includes fastening the fin and the jacket covering the fin together. A method for manufacturing a heat exchanger.

[0095] (Note 7) A method for manufacturing a heat exchanger, comprising joining a plurality of stacked cladding materials by a method for joining aluminum materials described in any one of Appendix 1 to 5, The process of forming holes in some or all of the aforementioned multiple cladding materials, The process includes stacking the aforementioned multiple cladding materials to connect the holes and form a refrigerant flow path, A method for manufacturing a heat exchanger.

[0096] (Note 8) A method for manufacturing a heat exchanger, comprising joining a plurality of stacked cladding materials by a method for joining aluminum materials described in any one of Appendix 1 to 5, A step of preparing the clad material in which some or all of the plurality of pieces have holes formed in them, The process includes stacking the aforementioned multiple cladding materials to connect the holes and form a refrigerant flow path, A method for manufacturing a heat exchanger.

[0097] (Note 9) A method for manufacturing a heat exchanger, comprising joining a plurality of stacked cladding materials by a method for joining aluminum materials described in any one of Appendix 1 to 5, Using a pressurizing device for applying pressure to the aforementioned multiple cladding materials in the stacking direction, The pressurizing device is configured to hold a laminate in which the multiple cladding materials are stacked together. The laminate is pressed in the stacking direction, The height of the pressurized laminate in the stacking direction is set to a pressurized height of 90% or more and less than 100% of the height before pressurization. A method for manufacturing a heat exchanger.

[0098] (Note 10) A pressurizing device used in the manufacturing method of the heat exchanger described in Appendix 9, A pressure platform on which the laminate is placed in the stacking direction, A pressing section that presses the laminate between itself and the pressing platform in the stacking direction, The system includes a stopper that locks the movement of the pressurizing part during pressurization and sets the height of the pressurized laminate to the pressurized height. Pressurizing device.

[0099] (Note 11) A method for manufacturing a heat exchanger, comprising joining a plurality of stacked cladding materials by a method for joining aluminum materials described in any one of Appendix 1 to 5, A step of forming holes in some or all of the aforementioned multiple clad materials by press working, The multiple clad materials are brazed together while leaving the burrs or sharp edges formed on the clad material during the aforementioned press working. A method for manufacturing a heat exchanger.

[0100] (Note 12) A method for manufacturing a heat exchanger, comprising joining a plurality of stacked cladding materials by a method for joining aluminum materials described in any one of Appendix 1 to 5, A spacer is placed between two adjacent clad materials and brazed. A method for manufacturing a heat exchanger.

[0101] (Note 13) Multiple clad materials, each comprising a core material of pure aluminum or an aluminum alloy and a brazing material of an aluminum alloy containing Si, are joined together with their respective brazing materials facing each other. In the brazed joint between the aforementioned brazing materials, the structure has regions with high Si concentration that extend discretely in the in-plane direction. Brazed joint.

[0102] (Note 14) A heat exchanger comprising a brazed joint as described in Appendix 13, Some or all of the aforementioned multiple cladding materials are each provided with holes, The holes in the stacked cladding materials are connected to form a refrigerant flow path. heat exchanger.

[0103] This invention allows for various embodiments and modifications without departing from the broad spirit and scope of the invention. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of the invention. In other words, the scope of the invention is indicated not by the embodiments, but by the claims. Various modifications made within the scope of the claims and the equivalent scope of the meaning of the invention are considered to be within the scope of this invention.

[0104] This application is based on Japanese Patent Application No. 2022-212193, filed on 28 December 2022. The entire specification, claims, and drawings of Japanese Patent Application No. 2022-212193 are incorporated herein by reference. [Industrial applicability]

[0105] The present invention can be suitably employed, for example, in the manufacture of heat exchangers. [Explanation of Symbols]

[0106] 10a, 10b Cladding material, 11, 21 Core material, 12, 22 Brazing material, 13 Brazing material surface, 14 Pressed hole, 15 Burr or flash, 23a, 23b, 31a, 31b, 42a, 42b Outer cladding material, 24, 32a, 32b, 32c, 32d, 32e, 32f, 32g, 32h, 43a, 43b, 43c, 43d, 43e, 43f, 43g, 43h Inner cladding material, 33, 46 Refrigerant inlet, 34, 47 Refrigerant outlet, 35 Header, 41 Fin, 44 Jacket, 45 Semiconductor chip, 48 Refrigerant, 50a, 50b, 60a, 60b Cladding material, 51a, 51b, 61a, 61b Core material, 52, 62 53 Bonding layer, 54 High Si concentration region, 54 Hole, 55 Corner section, 56a, 56b, 56c, 66a, 66b Brazing material, 67 Erosion section 100, 200, 500, 600 Brazed joint, 300 Heat exchanger, 400 Semiconductor device, 410 Cooler, 700 Laminate, 710 Pressurizing jig (pressurizing device), 711 Pressurizing stand, 712 Stopper, 713 Pressurizing section, 720 Spacer.

Claims

1. Multiple clad aluminum materials are prepared, each consisting of a core made of pure aluminum or an aluminum alloy and a brazing material made of an aluminum alloy containing 4 to 12 mass% Si. A method for joining aluminum materials, wherein a plurality of clad materials are joined by a fluxless brazing method in which the brazing surfaces of the plurality of clad materials are faced to each other and brazed in a non-reduced inert gas atmosphere, wherein a plurality of stacked clad materials are joined by this method, A step of forming holes in some or all of the aforementioned multiple clad materials by press working, The multiple clad materials are brazed together while leaving the burrs or sharp edges formed on the clad material during the aforementioned press working. A method for manufacturing a heat exchanger.

2. Multiple clad aluminum materials are prepared, each consisting of a core made of pure aluminum or an aluminum alloy and a brazing material made of an aluminum alloy containing 4 to 12 mass% Si. A method for joining aluminum materials, wherein a plurality of clad materials are joined by a fluxless brazing method in which the brazing surfaces of the plurality of clad materials are faced to each other and brazed in a non-reduced inert gas atmosphere, wherein a plurality of stacked clad materials are joined by this method, A spacer is placed between two adjacent clad materials and brazed. A method for manufacturing a heat exchanger.

3. The Mg content in the brazing material is kept below 0.1% by mass. A method for manufacturing a heat exchanger according to claim 1 or 2.

4. The thickness of the brazing material is 0.01 to 0.1 mm. A method for manufacturing a heat exchanger according to claim 1 or 2.

5. In the brazing process described above, the multiple cladding materials are heated to a temperature above the liquidus temperature of the brazing material. A method for manufacturing a heat exchanger according to claim 1 or 2.

6. The clad materials are pressed together with a pressure of 10 kPa or more, and the brazing materials are brazed together while their surfaces are in contact. A method for manufacturing a heat exchanger according to claim 1 or 2.

7. The structure comprises a laminate of multiple cladding materials of aluminum, each including a core material of pure aluminum or an aluminum alloy and a brazing material of an aluminum alloy containing 4 to 12 mass% of Si. The aforementioned multiple clad materials are joined together by the aforementioned brazing material. Some or all of the aforementioned multiple cladding materials are provided with holes in which burrs or sharp edges are formed. heat exchanger.

8. The Mg content in the brazing material is kept below 0.1% by mass. The heat exchanger according to claim 7.

9. A process for preparing multiple clad aluminum materials, each consisting of a core made of pure aluminum or an aluminum alloy and a brazing material made of an aluminum alloy containing 4 to 12 mass% Si, A step of forming holes in some or all of the aforementioned multiple clad materials by press working, A step of laminating the multiple clad materials while leaving burrs or sharp edges formed on the clad material during the aforementioned press working, The process comprises a step of fluxless brazing the aforementioned plurality of cladding materials in a non-reduced pressure inert gas atmosphere. Methods for joining aluminum materials.

10. The Mg content in the brazing material is kept below 0.1% by mass. The method for joining aluminum materials according to claim 9.

11. The thickness of the brazing material is 0.01 to 0.1 mm. The method for joining aluminum materials according to claim 9.

12. In the brazing process described above, the multiple cladding materials are heated to a temperature above the liquidus temperature of the brazing material. The method for joining aluminum materials according to claim 9.

13. The aforementioned cladding materials are pressed together with a pressure of 10 kPa or more, and brazed together while their brazing surfaces are in contact with each other. The method for joining aluminum materials according to claim 9.

14. A method for manufacturing a heat exchanger, comprising joining a plurality of stacked cladding materials by a method for joining aluminum materials according to any one of claims 9 to 13.

15. A step of joining a plurality of stacked cladding materials to form a fin using the aluminum material joining method described in any one of claims 9 to 13, The process includes fastening the fin and the jacket covering the fin together. A method for manufacturing a heat exchanger.

16. A method for manufacturing a heat exchanger, comprising joining a plurality of stacked cladding materials by the aluminum material joining method described in any one of claims 9 to 13, The process of forming holes in some or all of the aforementioned multiple cladding materials, The process includes stacking the aforementioned multiple cladding materials to connect the holes and form a refrigerant flow path, A method for manufacturing a heat exchanger.

17. A method for manufacturing a heat exchanger, comprising joining a plurality of stacked cladding materials by the aluminum material joining method described in any one of claims 9 to 13, A step of preparing the clad material in which some or all of the plurality of pieces have holes formed in them, The process includes stacking the aforementioned multiple cladding materials to connect the holes and form a refrigerant flow path, A method for manufacturing a heat exchanger.

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