Plate material, joined body, method for joining plate material, and method for manufacturing plate material

Abstract

The invention provides a plate material, a joined body formed by joining a plate material to a plate material on the joined side, a method for joining the plate material, and a method for manufacturing the plate material, wherein the output range of laser light for welding can be widened, and stable welding construction can be performed; the joined body is formed by joining the plate material to the plate material on the joined side. A sheet material which is laser-welded by overlapping with a member on the side to be joined that is composed of copper or a copper alloy, and which is composed of copper or a copper alloy, the sheet material having a roughened surface in at least a portion thereof, the roughened surface having an arithmetic average roughness (Ra) of 4 [mu] m or more and a maximum height roughness (Rz) of 20 [mu] m or more.

Description

Technical Field

[0001] The present invention relates to a plate material, a joined body, a method for joining plate materials, and a method for manufacturing a plate material. Background Art

[0002] For example, when copper alloy plates are joined together to make heat dissipation components such as vapor chambers, electronic components, etc., the copper alloy plates are often joined together by brazing or riveting. However, these joining methods have the disadvantages of low productivity and high equipment costs. In contrast, according to the joining method of laser welding copper alloy plates together, high-speed welding can be performed to obtain high productivity.

[0003] Patent Document 1 discloses a heat spreader in which light is irradiated from one plate-like member side of a container having a cavity and the outer periphery is sealed by welding. The plate-like member on the other side of the container is thickened so that light does not penetrate in the plate thickness direction, thereby reducing the energy density of light and suppressing the heat generated during welding. As a result, it is described that the strain of the container is reduced and pinholes can be prevented from being generated in the molten portion.

[0004] In addition, Patent Document 2 shows that a surface layer composed of a metal material such as nickel having a high laser absorption rate and a higher fracture strength than metal materials is formed on the surface of one of the overlapping metal components, and laser is irradiated from the surface layer to form a resolidified portion from the surface of the surface layer to the inside of the metal component, thereby joining the metal components on both sides.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2018 / 147283

[0008] Patent Document 2: International Publication No. 2012 / 124255 Summary of the invention

[0009] Problems to be solved by the invention

[0010] Laser welding can be performed at high speed, so the productivity is high, and it is gaining more and more attention as a joining method for sealing the gap between plates. In addition, the copper or copper alloy plates used for heat dissipation components are thinned from the perspective of miniaturization and lightness, such as seeking a total wall thickness of less than 0.3 mm. In addition, as a characteristic of copper, it is known that the absorption rate of laser light is low in a solid state, and the absorption rate of laser light increases sharply when it becomes a molten state. Therefore, when copper or copper alloy plates are joined to each other by laser welding, the molten pool is unstable and defects such as pores are easily generated. In particular, defects such as burn-through may occur in thinner plates.

[0011] The occurrence of defects such as pores and burn-through cannot be fully suppressed by only increasing the thickness of a portion of the plate when laser welding thin copper or copper alloy plates to each other as in Patent Document 1, or forming a surface layer on the laser irradiated surface as in Patent Document 2. In addition, in Patent Document 1, the weight increases because the plate thickness at the molten portion of the other plate-like member is increased. In addition, in Patent Document 2, it is difficult to join components that cannot be plated with a surface layer.

[0012] Therefore, an object of the present invention is to provide a plate material that can expand the output range of a laser suitable for welding and can stably perform welding, a joint body formed by joining the plate material to a joined side member, a plate material joining method, and a plate material manufacturing method.

[0013] Solutions to Solve Problems

[0014] The present invention is constituted by the following structure.

[0015] (1) A plate material composed of copper or a copper alloy, which is overlapped with a joined side member composed of copper or a copper alloy and laser welded thereto, wherein:

[0016] The plate has a roughened surface at least in part,

[0017] The roughened surface has an arithmetic mean roughness Ra of 4 μm or more and a maximum height roughness Rz of 20 μm or more.

[0018] (2) A conjugate, wherein:

[0019] The joined body includes the plate material described in (1) and a joined side member joined to the plate material.

[0020] (3) A method for joining plates, wherein:

[0021] The plate described in (1) is overlapped with the side member to be joined,

[0022] The plate material is laser-welded to the joined side member by irradiating the plate material with laser light along the roughened surface formed on the plate material.

[0023] (4) A method for manufacturing a plate material, the plate material being overlapped with a joined side member being made of copper or a copper alloy and being laser welded and being made of copper or a copper alloy, wherein:

[0024] The irradiated portion irradiated with laser light during laser welding is roughened by rolling or pressing to have an arithmetic mean roughness Ra of 4 μm or more and a maximum height roughness Rz of 20 μm or more.

[0025] Effects of the Invention

[0026] According to the present invention, when laser welding copper or copper alloys, the output range of the laser light suitable for welding can be expanded, and stable welding can be performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a perspective view schematically showing a state of laser welding a plate material and a side member to be joined.

[0028] Figure 2 It is an enlarged photograph showing the roughened surface of the plate materials of Test Examples 1 to 4 and an explanatory diagram showing the surface roughness.

[0029] Figure 3 This is a graph showing the output range of the laser light in which welding can be performed when the plate material of each test example is joined to the joined side member.

[0030] Figure 4 This is an enlarged photograph of the irradiated portion when irradiated with laser light having an output exceeding 2.6 kW.

[0031] Figure 5 This is an enlarged photograph of the irradiated portion when irradiated with laser light having an output of less than 1.8 kW. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0033] Figure 1 It is a perspective view schematically showing a state of laser welding the plate material 11 and the joined side member 13 .

[0034] The plate 11 of this embodiment is joined to the joined side member 13 by laser welding. The joined side member 13 shown here is explained as a plate made of the same material as the plate 11, and is therefore also referred to as a "joined side plate". The plate 11 and the joined side plate 13 each partially overlap each other, and the overlapping portion becomes the irradiated portion 15 of the laser L. Then, by irradiating the irradiated portion 15 with the laser L using the laser irradiation device 100, the plate 11 and the joined side plate 13 are laser welded. The laser L is irradiated to at least a portion of the above-mentioned irradiated portion 15, and does not exceed the irradiated portion 15.

[0035] The plate 11 and the plate 13 on the joined side are made of copper or a copper alloy. In the case of a copper alloy, components contained in copper (Cu) include tin (Sn), nickel (Ni), zinc (Zn), magnesium (Mg), phosphorus (P), etc. The plate 11 and the plate 13 on the joined side shown here are thin plates with a thickness of 0.10 mm to 1.0 mm. The plate thickness of the plate 11 and the plate 13 on the joined side may be equal, or one may be thicker than the other.

[0036] The plate 11 has a roughened surface 21 at least in a portion. In the present embodiment, the roughened surface 21 is formed at a position of the plate 11 corresponding to the irradiated portion 15. The roughened surface 21 is formed along the scanning direction A of the laser, and is preferably formed over the entire area of ​​the irradiated portion 15. The shape and size of the range in which the roughened surface 21 is formed are not particularly limited. The roughened surface 21 may be formed at least in a portion of the plate 11, and in the present embodiment, in the irradiated portion 15.

[0037] As the laser irradiation device 100 for irradiating the laser light L to the irradiated portion 15, a laser irradiation device having a galvano scanner unit can be exemplified. In the laser irradiation device 100 having a galvano scanner unit, the laser light from the fiber laser oscillator is reflected by a galvano mirror, and is focused by a lens to irradiate the irradiated portion 15. According to the laser irradiation device 100, by controlling the angle of the galvano mirror attached to the rotating shaft, the laser light L can be scanned at high speed and high precision. However, the laser irradiation device 100 is not limited thereto, and may be an irradiation device of another type.

[0038] Next, the procedure of the joining method of laser welding the plate material 11 and the plate material 13 to be joined according to the present embodiment will be described.

[0039] (Roughening treatment)

[0040] First, a roughened surface 21 is formed on the plate 11. The roughened surface 21 can be formed, for example, by a stamping process using a conventional stamping die. In this case, a roughened surface equivalent to the roughened surface 21 to be formed is formed on the stamping die, and the plate 11 is pressed against the stamping die, so that the roughened surface is transferred to the surface 21 on at least a portion of the plate 11. In addition, the roughened surface 21 can also be formed by rolling a roller having a surface with projections and depressions formed by sandblasting or the like on the surface of the plate 11. The roughening method of the surface 21 shown here is an example, and the roughening method is not particularly limited.

[0041] The roughened surface 21 is processed to have an arithmetic mean roughness Ra of 4 μm or more and a maximum height roughness Rz of 20 μm or more. The arithmetic mean roughness Ra and the maximum height roughness Rz are values ​​in accordance with JIS B 0601, etc. By having an arithmetic mean roughness Ra of 4 μm or more and a maximum height roughness Rz of 20 μm or more, the entire surface of the roughened surface 21 includes unevenness having a size greater than a specified value on average.

[0042] (Laser welding)

[0043] Next, the plate 11 having the roughened surface 21 is overlapped with the plate 13 on the joined side. Then, the laser light L emitted from the laser irradiation device 100 is scanned from one end 15a to the other end 15b of the irradiated portion 15 of the plate 11 overlapping with the joined side plate 13. Thus, the laser light L is irradiated to the irradiated portion 15 along the scanning direction A, and a weld bead 23 formed by laser welding the plate 11 and the joined side plate 13 is formed.

[0044] When laser welding is performed using the laser light L of the laser irradiation device 100, the irradiated portion of the laser light L in the joint portion (irradiated portion 15) where the plate 11 and the plate 13 on the joined side are joined is melted, and the back surface of the plate 13 on the joined side opposite to the irradiated side of the laser light L is melted. The molten portion is cooled, solidified, and hardened, thereby continuously forming a weld bead 23 along the scanning direction A. Thus, a joint body 25 in which the plate 11 and the plate 13 on the joined side are well joined is obtained.

[0045] As described above, the plate 11 of this structure forms a roughened surface 21 in at least a portion. In the roughened surface 21, the absorption rate of the laser L is improved, and the irradiated portion 15 can be partially melted with a lower power of the laser L than when the surface is not roughened. Therefore, the output range of the laser suitable for welding is widened, and more stable welding can be performed. As a result, the plate and the plate on the joined side can be reliably joined while the generation of defects such as pores and burn-through can be fully suppressed, while laser welding can be smoothly performed. In addition, high-quality laser welding can be performed even at low output, which can increase the freedom of choice of equipment.

[0046] Here, the improvement in the absorption rate of the laser light L can be estimated as follows.

[0047] In copper or copper alloy, the absorption rate of laser in the solid state is as low as 5% or less, but it increases sharply to more than several tens of% when it becomes a molten state. Therefore, once melted, the molten pool is unstable, and defects such as sputtering and pores are easily generated, and burn-through is easily generated in thin-walled plates. However, by forming a roughened surface 21 in advance on the plate 11 as described above, and irradiating the surface 21 with laser L, the rapid melting is suppressed. That is, in the irradiation range of laser L, the surface of the plate 11 has a roughness accompanied by tiny bumps, and the thinner wall thickness of the protruding tiny bumps is mixedly configured. As a result, the heat input in the irradiation area of ​​laser L starts to melt from the thin-walled part under the action of heat conduction, and heat conducts toward the surrounding of the formed molten pool. As a result, a larger range than the laser irradiation area is heated. In the molten part, the energy absorption of laser L is improved, but combined with the heat diffusion to the surroundings, the rapid melting progress is suppressed. Therefore, even if the output of the laser L is low, melting will begin, and even if the output is high, excessive heat input is suppressed by heat diffusion of the portion that starts melting first. In this way, the output range of the laser suitable for welding can be expanded.

[0048] In addition, the roughened surface 21 is provided to extend along the laser scanning direction A, so that continuous laser welding can be performed along the roughened surface 21. As a result, a high-quality joint 25 is obtained in which the plate 11 and the plate 13 on the joined side are joined by a homogeneous weld bead 23. In addition, the plate 11 and the plate 13 on the joined side can be joined well while suppressing burn-through. In addition, by forming the continuous weld bead 23, high sealing performance of the joint surface is exerted.

[0049] The manufacturing process of the plate 11 includes a process of roughening the irradiated portion for irradiating the laser L during laser welding by rolling or stamping to form a surface 21 with an arithmetic mean roughness Ra of 4 μm or more and a maximum height roughness Rz of 20 μm or more.

[0050] According to the manufacturing method of the plate 11, the roughened surface 21 is formed by rolling or punching, so that a manufacturing line including ordinary rolling or punching can be used, and manufacturing can be performed at a reduced manufacturing cost. It should be noted that the roughening treatment may also be performed by other methods such as etching.

[0051] Example

[0052] Figure 2The diagram is an enlarged photograph of the roughened surface 21 of the plate 11 of Test Examples 1 to 4 and an explanatory diagram of the surface roughness. The enlarged photograph and the surface roughness of Test Example 1 show the results of the plate 11 in a mirror-like state without surface roughening. The plate 11 is a copper alloy thin plate with a thickness of 0.2 mm, and the welding speed is 10 mpm.

[0053] The roughened surface of Test Example 2 showed a fine dull texture morphology, the roughened surface of Test Example 3 showed a coarse dull texture morphology, and the roughened surface of Test Example 4 showed a convex circular scratch morphology.

[0054] The roughened surface of each test example can be formed by, for example, rolling, stamping, etc. The roughened surface of Test Examples 2 and 3 is formed by transferring the shape of the roller surface whose surface roughness is adjusted. In addition, the roughened surface of Test Example 4 is formed by providing tiny circular depressions on the roller surface and transferring the shape thereof.

[0055] And, in Figure 2 , the arithmetic mean roughness Ra and the maximum height roughness Rz of each test example are also shown. The arithmetic mean roughness Ra and the maximum height roughness Rz will be described later.

[0056] Figure 3 This is a graph showing the output range of the laser beam in which welding can be performed when the plate material 11 of each test example is joined to the plate material 13 on the joining side.

[0057] Figure 3 It is shown that the output range of the laser suitable for welding in Test Examples 2 to 4 is expanded, especially on the low output side, compared with Test Example 1. That is, the plate 11 having the roughened surface 21 can be joined even with a laser of a lower output level than the plate not having the roughened surface 21. In particular, in Test Example 2, the output range of the laser suitable for welding is expanded by about 1.5 times compared with Test Example 1.

[0058] like Figure 2 As shown, Test Examples 2 to 4 have larger arithmetic mean roughness Ra and maximum height roughness Rz than Test Example 1. Therefore, it is estimated that the absorption rate of the laser light L is improved in the roughened surface 21. Thus, even a laser light with a relatively low output level can partially melt the irradiated portion 15, so the output range of the laser light suitable for welding is widened, and stable welding construction can be performed.

[0059] As described above, the arithmetic mean roughness Ra of the roughened surface 21 is 4 μm or more and the maximum height roughness Rz is 20 μm or more, so that the absorption rate of the laser light L can be improved. In addition, the arithmetic mean roughness Ra is preferably 10 μm or less, and the maximum height roughness Rz is preferably 35 μm or less. By setting the arithmetic mean roughness Ra and the maximum height roughness Rz to the above ranges, the output range of the laser light suitable for welding can be reliably widened, especially toward the low output side.

[0060] Here, the surface roughness of the roughened surface 21 is specified by the arithmetic mean roughness Ra and the maximum height roughness Rz for the following reasons. When the arithmetic mean roughness Ra has a specified value, there are bumps on the surface, but the arithmetic mean roughness Ra is a value averaged over the entire surface to be calculated, so there is a situation where the convexity larger than the average value and the concavity lower than the average value cancel each other out and the value becomes smaller. Therefore, by adding the maximum height roughness Rz to the conditions, the condition of the minimum bumps and concavities that scatter the laser on the entire surface is ensured. However, if the arithmetic mean roughness Ra and the maximum height roughness Rz are too large, it is difficult to obtain good bonding depending on the state of the plate surface. Therefore, it is preferred to set the upper limit of the arithmetic mean roughness Ra to 30 μm and the upper limit of the maximum height roughness Rz to 100 μm.

[0061] Figure 4 This is an enlarged photograph of the irradiated portion when irradiated with a laser having an output exceeding 2.6 kW. Figure 3 When the laser is irradiated with a large output in the laser output range suitable for welding shown, burn-through portions are generated in both the plate 11 and the plate 13 on the joined side in the irradiated portion.

[0062] Figure 5 This is an enlarged photograph of the irradiated portion when irradiated with a laser having an output of less than 1.8 kW. Figure 3 When the laser is irradiated with a small output within the output range of the laser suitable for welding, the laser does not penetrate the plate material 13 on the joining side in the irradiated portion, and a sufficient joining strength cannot be obtained.

[0063] In addition, the laser welding performed by laser scanning can select at least one of line welding, spot welding, and spiral welding. Laser welding can also be performed by applying the laser from the laser irradiation device 100 to the Figure 1In addition to line welding in which the laser is irradiated while scanning in a straight line or a curved line as shown in the figure, spot welding in which the laser is stopped at a predetermined position and irradiated. In addition, the laser welding can also be spiral welding in which the laser is irradiated while scanning in a spiral, circular, triangular, etc. The scanning form of the laser can be appropriately selected according to the type of the plate 11 and the plate 13 on the joined side, the size and shape of the irradiated portion 15, and the joining form.

[0064] The beam spot diameter of the laser used here is preferably 0.1 mm to 0.7 mm, and particularly preferably 0.3 mm. When the beam spot diameter is within this range, the effect of preventing the above-mentioned burn-through and laser non-penetration becomes significant. In addition, the welding speed is preferably 2 mpm to 20 mpm.

[0065] Thus, the present invention is not limited to the above-mentioned embodiments, and the combination of the structures of the embodiments and the changes and applications made by those skilled in the art based on the description in the specification and known technologies are also intended by the present invention and are included in the scope of the protection requested.

[0066] For example, the member 13 to be joined is not limited to a thin plate, and may be a thick member. In this case, the output of the laser beam is expanded toward the low output side by providing a roughened surface on the plate to be joined.

[0067] As described above, the following matters are disclosed in this specification.

[0068] (1) A plate material composed of copper or a copper alloy, which is overlapped with a joined side member composed of copper or a copper alloy and laser welded thereto, wherein:

[0069] The plate has a roughened surface at least in part,

[0070] The roughened surface has an arithmetic mean roughness Ra of 4 μm or more and a maximum height roughness Rz of 20 μm or more.

[0071] According to the plate, the absorption rate of the laser is improved in the roughened surface of the plate, so that the irradiated portion can be melted even with a lower laser output than when the surface is not roughened. Thus, the laser output range that can be welded is widened, and stable welding construction can be performed.

[0072] (2) The plate material according to (1), wherein:

[0073] The roughened surface is formed along the scanning direction of the laser.

[0074] According to the plate material, the roughened surface is formed along the scanning direction of the laser, so that the laser welding can be continuously performed along the roughened surface. Thus, a homogeneous and continuous weld bead is formed, and high-quality joining can be achieved. In addition, high sealing performance is achieved in the joint surface.

[0075] (3) The plate material according to (1) or (2), wherein:

[0076] The arithmetic mean roughness Ra is 10 μm or less.

[0077] According to this plate material, the output range suitable for welding is reliably widened toward the low output side.

[0078] (4) The plate material according to any one of (1) to (3), wherein:

[0079] The maximum height roughness Rz is 35 μm or less.

[0080] According to this plate material, the output range suitable for welding is reliably widened toward the low output side.

[0081] (5) A conjugate, wherein:

[0082] The joined body includes the plate material according to any one of (1) to (4) and a joined side member joined to the plate material.

[0083] According to this joined body, the plate material and the joined side member are laser welded at the roughened surfaces, thereby obtaining a joined body in which the plate material and the joined side member are joined with high quality.

[0084] (6) A method for joining plates, wherein:

[0085] Overlapping the plate material described in any one of (1) to (4) with the side member to be joined,

[0086] The plate material is laser-welded to the joined side member by irradiating the plate material with laser light along the roughened surface formed on the plate material.

[0087] According to this method of joining plate materials, the plate materials and the joined side member can be joined well while suppressing burn-through.

[0088] (7) The method for joining plate materials according to (6), wherein:

[0089] The laser welding is at least any one of line welding, spot welding, and spiral welding.

[0090] According to this method of joining plate materials, it is possible to select optimal laser welding according to the form of joining.

[0091] (8) A method for manufacturing a plate material, the plate material being overlapped with a joined side member being made of copper or a copper alloy and being laser welded and being made of copper or a copper alloy, wherein:

[0092] The irradiated portion irradiated with laser light during laser welding is roughened by rolling or pressing to have an arithmetic mean roughness Ra of 4 μm or more and a maximum height roughness Rz of 20 μm or more.

[0093] According to this method of manufacturing a plate material, a production line including ordinary rolling and pressing can be utilized, and production can be performed while suppressing the production cost.

[0094] It should be noted that the present application is based on the Japanese patent application (Japanese Patent Application No. 2022-081520) filed on May 18, 2022, and the contents thereof are incorporated herein by reference.

[0095] Description of Reference Numerals

[0096] 11. Plate

[0097] 13 Joined side member

[0098] 15 Irradiated part

[0099] 21 Roughened surface

[0100] 23 weld bead

[0101] 25 Conjugate

[0102] 100 Laser irradiation device

[0103] A Scan direction

[0104] L Laser.

Claims

1. A plate material composed of copper or a copper alloy, which is overlapped with a joined side member composed of copper or a copper alloy and is laser welded, wherein: The plate has a roughened surface at least in part, The roughened surface has an arithmetic mean roughness Ra of 4 μm or more and a maximum height roughness Rz of 20 μm or more.

2. The sheet material according to claim 1, wherein: The roughened surface is formed along the scanning direction of the laser.

3. The sheet material according to claim 1, wherein: The arithmetic mean roughness Ra is 10 μm or less.

4. The sheet material according to claim 2, wherein: The arithmetic mean roughness Ra is 10 μm or less.

5. The sheet material according to any one of claims 1 to 4, wherein: The maximum height roughness Rz is 35 μm or less.

6. A conjugate, wherein: The joined body includes the plate material according to any one of claims 1 to 4 and a joined side member joined to the plate material.

7. A conjugate, wherein: The joined body includes the plate material according to claim 5 and a joined side member joined to the plate material.

8. A method for joining plates, wherein: The plate material according to any one of claims 1 to 4 is overlapped with the side member to be joined, The plate material is laser-welded to the joined side member by irradiating the plate material with laser light along the roughened surface formed on the plate material.

9. A method for joining plates, wherein: The plate material according to claim 5 is overlapped with the side member to be joined, The plate material is laser-welded to the joined side member by irradiating the plate material with laser light along the roughened surface formed on the plate material.

10. The method for joining plates according to claim 8, wherein: The laser welding is at least any one of line welding, spot welding, and spiral welding.

11. The method for joining plates according to claim 9, wherein: The laser welding is at least any one of line welding, spot welding, and spiral welding.

12. A method for manufacturing a plate material, the plate material being overlapped with a joined side member being composed of copper or a copper alloy and being laser welded and being composed of copper or a copper alloy, wherein: The irradiated portion irradiated with laser light during laser welding is roughened by rolling or pressing to have an arithmetic mean roughness Ra of 4 μm or more and a maximum height roughness Rz of 20 μm or more.

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