Copper-based sheet material and its manufacturing method

Abstract

To provide a copper plate material which is less likely to occur internal defect during laser welding and is therefore excellent in laser weldability, and a method for producing the copper plate material.SOLUTION: Each of copper plate materials 11a and 11b is comprised of a copper material having an alloy composition including Cu of 90 mass% or more. The maximum height (Rz) served as a parameter showing a surface roughness measured in a width direction orthogonal to the rolling direction is 0.30 μm or more and 2.50 μm or less; an arithmetic average roughness (Ra) is 0.10 μm or more and 0.50 μm or less; when Gs1 (60°) denotes a glossiness when irradiating the surface at an incidence angle of 60° in a direction parallel to the rolling direction with light and Gs2 (60°) denotes a glossiness when irradiating the surface in the width direction with the light, a glossiness Gs1 (60°) is 450 or less; and a ratio (Gs1(60°) / Gs2(60°) to the glossiness Gs2 (60°) is 1.0 or more and 2.0 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a copper-based sheet material and a method for producing the same, and more particularly to a copper-based sheet material suitable for use as a heat dissipation member or terminal material for electric and electronic devices, and a method for producing the same. [Background technology]

[0002] In recent years, the amount of heat generated by electrical and electronic devices has been increasing due to their increasingly sophisticated functionality and performance. Furthermore, as electrical and electronic devices become smaller, the density of heat generated increases, making it increasingly important to cool the generated heat. One example of a component for cooling the generated heat is a vapor chamber, which is a planar heat pipe. It is desirable to use a copper-based material (copper or copper alloy) with high thermal conductivity as the material for the vapor chamber.

[0003] The vapor chamber has an airtight structure formed by joining two stacked plates at their outer peripheries to form an internal space into which a working fluid is poured, and then the plates are sealed under reduced pressure. Examples of such joining methods include laser welding, diffusion bonding, brazing, and TIG welding.

[0004] When these are joined by diffusion bonding or brazing, the weld is formed by melting the material at a high temperature and then resolidifying it. This makes it difficult to heat treat only the weld, and the periphery of the weld must also be heat treated. In this case, the periphery of the weld softens, similar to when annealing plate materials, resulting in a problem of lower strength than the plate materials before joining. When the strength of the plate materials decreases, the plate materials become more susceptible to deformation.

[0005] To address this issue, Patent Document 1 discloses a method for manufacturing a vapor chamber by joining multiple parts by diffusion bonding or brazing, in which a precipitation-hardened copper alloy is used as the material for the housing, and this is aged to precipitation harden it, thereby improving the strength of the housing.

[0006] On the other hand, laser welding achieves this by melting only the joint area and then re-solidifying it, which prevents softening except at the joint area and the surrounding affected area. Furthermore, the heat-affected zone can be made narrower than with TIG welding, making it a suitable joining method for processing tiny parts such as vapor chambers.

[0007] In this regard, Patent Document 2 discloses a copper alloy material for resistance material that is likely to give an accurate measured value in electrical resistivity measurement and has good laser weldability when a specific parameter related to surface roughness is within a predetermined range when a roughness curve in a direction perpendicular to the rolling direction is obtained for the surface of a plate material by a contact surface roughness measurement method.

[0008] Furthermore, Patent Document 3 discloses a copper or copper alloy strip for a vapor chamber having a surface maximum height roughness Rz of 1.5 μm or less, an arithmetic mean roughness Ra of 0.15 μm or less, and a residual stress of 50 MPa or less. Patent Document 3 also discloses a method for manufacturing a vapor chamber by joining multiple components by diffusion bonding or brazing, in which the surface roughness, residual stress, and warpage of the plate material used for the housing are within specific ranges to provide sufficient bonding strength when joining the plate materials, thereby suppressing leakage of the working fluid held inside the vapor chamber when the internal pressure fluctuates due to evaporation or condensation of the working fluid. It also discloses that this technology suppresses warpage of the plate material when reducing the plate material's thickness in the etching process or when stamping the plate material in the press process, thereby improving productivity in the etching and press processes. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2017 / 164013 [Patent Document 2] Patent No. 6382479 [Patent Document 3] Patent No. 6166414 Summary of the Invention [Problem to be solved by the invention]

[0010] However, the technology of Patent Document 1 requires the use of a precipitation-hardening copper alloy, and has the problem that it cannot be applied to non-precipitation-hardening copper alloys or pure copper. Furthermore, the technology of Patent Document 1 requires aging treatment, which increases the number of steps, resulting in a decrease in productivity. For this reason, it is desirable to increase the strength of the weld by a method other than the method of precipitation-hardening a precipitation-hardening copper alloy through aging treatment.

[0011] The problem of reduced strength of the welded joints described above is not limited to vapor chambers, but also exists in other electrical and electronic devices such as bus bars.

[0012] Furthermore, the technology of Patent Document 2 specifies the surface roughness of the plate material in order to improve the laser weldability and the measurement accuracy of the electrical resistivity, but does not take into consideration factors other than surface roughness that may affect laser welding, such as warpage of the plate material, irregularities such as oil pits formed during rolling, and impurities on the plate material surface.

[0013] Furthermore, the technology of Patent Document 3 specifies the surface roughness, residual stress, and warpage of plate materials for a housing formed by joining multiple components by diffusion bonding or brazing. However, these surface roughness, residual stress, and warpage of plate materials are specified from the perspective of adhesion between plate materials, wettability and spreadability of brazing filler during brazing, and suppression of deformation of the plate materials during pressing and etching processes, and are not specified with consideration given to laser weldability. Furthermore, the technology of Patent Document 3 does not take into account the effect on laser welding of impurities on the surface of the plate materials, such as oil pits formed during rolling.

[0014] Therefore, the present invention has been made in consideration of the above problems, and an object of the present invention is to provide a copper-based sheet material that is less likely to have internal defects during laser welding and has excellent laser weldability, and a method for manufacturing the same. [Means for solving the problem]

[0015] The present inventors have discovered that, in a sheet material made of a copper-based material having an alloy composition containing 90% by mass or more of Cu, when the maximum height (Rz) and arithmetic mean roughness (Ra), which are parameters representing surface roughness measured in the width direction, which is the direction perpendicular to the rolling direction, are within predetermined ranges, and when the gloss when light is irradiated on the surface of the copper-based material at an incident angle of 60° in a direction parallel to the rolling direction is defined as Gs1 (60°), and the gloss when light is irradiated in the width direction is defined as Gs2 (60°), internal defects such as voids are less likely to occur at the joining surfaces and joints between copper-based sheet materials to be joined by laser welding, and as a result, laser weldability is significantly improved, which led to the completion of the present invention.

[0016] (1) A copper-based sheet material made of a copper-based material having an alloy composition containing 90% by mass or more of Cu, wherein the copper-based sheet material has a maximum height (Rz), a parameter representing surface roughness measured in the width direction, which is a direction perpendicular to the rolling direction, in the range of 0.30 μm to 2.50 μm, and an arithmetic mean roughness (Ra), in the range of 0.10 μm to 0.50 μm. When the gloss when light is irradiated to the surface of the copper-based sheet material at an incident angle of 60° in a direction parallel to the rolling direction is defined as Gs1(60°), and the gloss when light is irradiated in the width direction is defined as Gs2(60°), the gloss Gs1(60°) is 450 or less, and the ratio of the gloss Gs1(60°) to the gloss Gs2(60°) (Gs1(60°) / Gs2(60°) ratio) is 1.0 or more and 2.0 or less. (2) The copper-based sheet material according to (1) above, wherein the gloss values ​​when light is irradiated onto the surface of the copper-based sheet material in a direction parallel to the rolling direction at incident angles of 45° and 75° are Gs1(45°) and Gs1(75°), respectively, have a value of parameter A calculated by the following formula (I) in the range of 0.5 to 1.2. A=[Gs1(60°)-Gs1(45°)] / [Gs1(75°)-Gs1(60°)] Formula (I) (3) The copper-based sheet material according to (1) or (2) above, wherein the thickness of the oxide film formed on the surface of the copper-based sheet material is in the range of 20 Å to 500 Å. (4) A copper-based member integrally formed by joining at least two copper-based plate materials according to any one of (1) to (3) above by a laser welding method. (5) A method for producing a copper-based sheet material according to any one of (1) to (3) above, comprising the steps of: casting a copper-based material (step 1), homogenizing heat treatment (step 2), hot rolling (step 3), cooling (step 4), facing (step 5), first cold rolling (step 6), first heat treatment (step 7), second cold rolling (step 8), third cold rolling (step 9), temper annealing (step 10), shape correction (step 11), and rust prevention treatment (step 12) in that order; and in the second cold rolling (step 8), the diameter of the work roll is set to 150 mm or less, and the surface roughness of the work roll is set to 150 mm or less. A method for producing a copper-based sheet material, wherein the arithmetic mean roughness (Ra) is set to a range of 0.01 μm or more and 0.05 μm or less, the rolling reduction per pass is 10% or more, and the total rolling reduction is 20% or more, and in the third cold rolling step [step 9], the diameter of the work roll is 150 mm or less, the arithmetic mean roughness (Ra) of the work roll surface is set to a range of 0.10 μm or more and 0.50 μm or less, the rolling reduction per pass is 10% or more, and the total rolling reduction is 25% or more, and the surface of the copper-based sheet material after the shape correction step [step 11] is controlled so that the steepness, which is a parameter of flatness measured along the rolling direction, is 0.5% or less. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a copper-based sheet material that is less likely to develop internal defects during laser welding and has excellent laser weldability, and a method for producing the same. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic perspective view of two copper-based plate materials that are overlapped and linearly joined together. [Figure 2] FIG. 2 is a diagram showing a schematic configuration of a glossiness measuring device. [Figure 3]FIG. 3 is an optical microscope photograph of the cross section of the copper-based sheet material of Inventive Example 12, in which two copper-based sheets were overlapped and joined by laser welding. [Figure 4] Figure 4 shows optical microscope photographs of the cross-section of the copper-based sheet material of Comparative Example 16, when two copper-based sheets were overlapped and joined by laser welding. Figure 4(a) is the optical microscope photograph before image conversion, and Figure 4(b) is a photograph showing the image after the color tone of the image of Figure 4(a) was converted by black and white binarization processing. DETAILED DESCRIPTION OF THE INVENTION

[0019] Next, an embodiment of the present invention will be described. The following description is an example of an embodiment of the present invention and does not limit the scope of the claims.

[0020] The copper-based sheet material according to the present invention is a copper-based sheet material made of a copper-based material having an alloy composition containing 90% by mass or more of Cu, and the copper-based sheet material has a maximum height (Rz), which is a parameter representing surface roughness measured in the width direction, which is a direction perpendicular to the rolling direction, in the range of 0.30 μm to 2.50 μm, and an arithmetic mean roughness (Ra), which is a parameter representing surface roughness measured in the width direction, which is a direction perpendicular to the rolling direction, in the range of 0.10 μm to 0.50 μm. When the gloss when light is irradiated to the surface of the copper-based sheet material at an incident angle of 60° in a direction parallel to the rolling direction is defined as Gs1(60°), and the gloss when light is irradiated in the width direction is defined as Gs2(60°), the gloss Gs1(60°) is 450 or less, and the ratio of the gloss Gs1(60°) to the gloss Gs2(60°) (Gs1(60°) / Gs2(60°) ratio) is 1.0 or more and 2.0 or less.

[0021] Here, by setting the maximum height (Rz) along the width direction on the surface of the copper-based plate material to a range of 0.30 μm or more and 2.50 μm or less, and the arithmetic mean roughness (Ra) to a range of 0.10 μm or more and 0.50 μm or less, when the copper-based plate materials 11a, 11b are overlapped in the thickness direction as shown in Figure 1, the adhesion between the overlapping copper-based plate materials 11a, 11b is improved, and the plate surfaces of the copper-based plate materials 11a, 11b become appropriately rough, making them easier to heat by the laser L during laser welding, so internal defects such as voids are less likely to occur at the joint surfaces and joints between the copper-based plate materials joined by laser welding. Furthermore, by setting the gloss Gs1(60°) of the copper-based sheet material to 450 or less and the Gs1(60°) / Gs2(60°) ratio to be in the range of 1.0 or more and 2.0 or less, the reflection of the laser L is reduced, making it easier to heat, and the anisotropy of the gloss is reduced, improving the uniformity of heating by the laser L, making it even less likely for internal defects to occur in the joining surfaces and joints formed by laser welding. Therefore, by using the copper-based sheet material of the present invention, internal defects are less likely to occur in the joining surfaces and joints formed by laser welding, and therefore laser weldability, i.e., joint strength after laser welding, can be significantly improved.

[0022] [1] Alloy composition of copper-based sheet materials The copper-based sheet material of the present invention is made of a copper-based material having an alloy composition containing 90% by mass or more of Cu. Cu inherently has high thermal conductivity, but as the amount of added elements increases and as second phases appear, the thermal conductivity tends to decrease. In this regard, the copper-based sheet material of this embodiment contains 90% by mass or more of Cu, which prevents the decrease in thermal conductivity, resulting in a sheet material with high thermal conductivity suitable for use in electrical and electronic devices, such as heat dissipation and cooling components.

[0023] Here, the copper-based material having an alloy composition containing 90% or more by mass of Cu is not particularly limited as long as it is a plate material containing 90% or more by mass of Cu, and may be pure Cu or any Cu alloy.

[0024] (1) When the plate material is pure Cu Among these, when the copper-based material constituting the copper-based sheet material is pure Cu, it preferably has a composition containing 99.96 mass% or more of Cu, with inevitable impurities such as Cd, Mg, Pb, Sn, Cr, Bi, Se, and Te totaling 5 mass ppm or less, and Ag and O each being 400 mass ppm or less. Pure Cu has excellent thermal conductivity, and therefore can exhibit particularly excellent performance as a heat dissipation and cooling material. Examples of so-called pure Cu include electrolytic copper, oxygen-free copper (OFC), and TPC.

[0025] (2) When the plate material is a Cu alloy Furthermore, when the copper-based material constituting the copper-based sheet material is a Cu alloy, it is preferable that the copper alloy contains 90 mass% or more of Cu and has a composition containing one or more elements selected from Ag, Fe, Ni, Co, Si, Cr, Sn, Zn, Mg, and P.

[0026] The reasons for limiting the composition of the copper-based material when the copper-based material constituting the copper-based sheet material is a Cu alloy will be explained below.

[0027] (Ag: 0.05% by mass to 5.00% by mass) Ag (silver) is a component that has the effect of improving heat resistance, and to exhibit this effect, the Ag content is preferably 0.05% by mass or more. Although there is no particular need to set an upper limit for the Ag content, since Ag is expensive, it is preferable to set the upper limit to 5.00% by mass from the viewpoint of material costs.

[0028] (Fe:0.05 mass%~0.50 mass%) Iron (Fe) is a component that improves product properties such as electrical conductivity, strength, stress relaxation properties, and plating properties. To achieve this effect, the Fe content is preferably 0.05% by mass or more. However, even if the Fe content exceeds 0.50% by mass, no further improvement can be expected, and electrical conductivity and thermal conductivity tend to decrease. For this reason, the Fe content is preferably 0.05% to 0.50% by mass.

[0029] (Ni: 0.05% by mass to 5.00% by mass) Ni (nickel) precipitates finely in the Cu matrix as second-phase particles consisting of either a simple substance or a compound with Si, with sizes ranging from about 50 to 500 nm. These precipitates suppress dislocation movement, resulting in precipitation hardening. Furthermore, they suppress grain growth, resulting in finer crystal grains, thereby increasing material strength and enhancing rebending resistance. To achieve these effects, the Ni content is preferably 0.05% by mass or more. However, if the Ni content exceeds 5.00% by mass, significant decreases in electrical and thermal conductivity occur. Therefore, the upper limit of the Ni content is preferably 5.00% by mass.

[0030] (Co:0.05 mass%~2.00 mass%) Cobalt (Co) precipitates finely in the Cu matrix as second-phase particles consisting of either a simple substance or a compound with Si, typically measuring approximately 50 to 500 nm in size. These precipitates suppress dislocation movement, resulting in precipitation hardening. Furthermore, they suppress grain growth, resulting in finer crystal grains, increasing material strength and enhancing rebending resistance. To achieve these effects, the Co content is preferably 0.05% by mass or more. However, a Co content exceeding 2.00% by mass significantly reduces electrical and thermal conductivity, so the Co content is preferably 2.00% by mass or less.

[0031] (Si:0.05 mass%~1.10 mass%) Silicon (Si) is an important component that precipitates finely in the Cu matrix as second-phase particle precipitates composed of compounds together with Co and Cr. These precipitates suppress dislocation movement, resulting in precipitation hardening. Furthermore, they suppress grain growth and refine the crystal grains, thereby increasing the material strength. To achieve this effect, the Si content is preferably 0.05% by mass or more. On the other hand, if the Si content exceeds 1.10% by mass, the electrical conductivity decreases significantly, making it impossible to achieve an electrical conductivity of more than 30% IACS. Therefore, the upper limit of the Si content is preferably 1.10% by mass.

[0032] (Cr:0.05 mass%~0.50 mass%) Cr (chromium) is a component that precipitates finely in the Cu matrix (matrix) as a compound or as an element, for example, in the form of precipitates with a size of about 50 nm to 500 nm. These precipitates suppress dislocation movement, resulting in precipitation hardening. Furthermore, they suppress grain growth, resulting in finer crystal grains, thereby increasing material strength and improving rebending resistance. To achieve this effect, the Cr content is preferably 0.05% by mass or more. Furthermore, if the Cr content exceeds 0.50% by mass, significant decreases in electrical and thermal conductivity occur. Therefore, the Cr content is preferably 0.05% to 0.50% by mass.

[0033] (Sn: 0.05% by mass to 9.50% by mass) Sn (tin) is a component that dissolves in the Cu matrix and contributes to improving the strength of the Cu alloy, and the Sn content is preferably 0.05% by mass or more. On the other hand, if the Sn content exceeds 9.50% by mass, embrittlement is likely to occur. Therefore, the Sn content is preferably 0.05% to 9.50% by mass. Furthermore, since the inclusion of Sn tends to reduce electrical conductivity and thermal conductivity, in order to prevent a decrease in electrical conductivity and thermal conductivity, the Sn content is more preferably 0.05% to 0.50% by mass.

[0034] (Zn: 0.05% by mass to 0.50% by mass) Zn (zinc) is a component that not only provides excellent rebending workability but also improves the adhesion and migration properties of Sn plating and solder plating. To achieve this effect, the Zn content is preferably 0.05% by mass or more. On the other hand, if the Zn content exceeds 0.50% by mass, electrical conductivity and thermal conductivity tend to decrease. For this reason, the Zn content is preferably 0.05% to 0.50% by mass.

[0035] (Mg:0.01 mass%~0.50 mass%) Mg (magnesium) is a component that has the effect of improving stress relaxation resistance. To achieve this effect, the Mg content is preferably 0.01% by mass or more. On the other hand, if the Mg content exceeds 0.50% by mass, electrical conductivity and thermal conductivity tend to decrease. For this reason, the Mg content is preferably 0.01% to 0.50% by mass.

[0036] (P:0.01~0.50% by mass) P (phosphorus) not only serves as a deoxidizer for Cu alloys, but also precipitates as a compound in the form of fine precipitates with sizes of approximately 20 to 500 nm. These precipitates suppress dislocation movement, resulting in precipitation hardening. Furthermore, grain growth is suppressed, resulting in finer crystal grains, thereby increasing material strength. To achieve this effect, the P content is preferably 0.01% by mass or more. On the other hand, if the P content exceeds 0.50% by mass, cracks tend to occur more easily during hot working when forming a sheet material. For this reason, the P content is set to 0.01% by mass to 0.50% by mass.

[0037] (balance: Cu and unavoidable impurities) The Cu alloy constituting the copper-based sheet material has an alloy composition consisting of the above-mentioned components, with the remainder being Cu (copper) and inevitable impurities. The term "unavoidable impurities" as used herein generally refers to impurities present in the raw materials of metal products or unavoidably mixed in during the manufacturing process. These impurities are essentially unnecessary but are tolerated in trace amounts because they do not affect the properties of the metal product. Examples of inevitable impurities include tin (Sn) and oxygen (O). The upper limit of the content of these components can be, for example, 0.05% by mass for each of the above components, or 0.20% by mass for the total amount of the above components.

[0038] [2] Surface properties of copper-based sheet materials The copper-based sheet material of the present invention has a maximum height (Rz), a parameter representing surface roughness measured in the width direction, which is perpendicular to the rolling direction, in the range of 0.30 μm to 2.50 μm, and an arithmetic mean roughness (Ra) in the range of 0.10 μm to 0.50 μm. In particular, if the maximum height (Rz) exceeds 2.50 μm or the arithmetic mean roughness (Ra) exceeds 0.50 μm, internal defects occur and weldability deteriorates when multiple copper-based sheets are overlapped in the thickness direction and laser welded. This is thought to be because the rough surface of the sheets reduces the adhesion between the sheets, resulting in voids between the sheets during laser welding. On the other hand, even if the maximum height (Rz) is less than 0.30 μm or the arithmetic mean roughness (Ra) is less than 0.10 μm, internal defects occur and weldability deteriorates when multiple copper-based sheets are overlapped in the thickness direction and laser welded. This is thought to be because the surface of the copper-based sheet material becomes too smooth, making it easier for the laser irradiated during laser welding to be reflected, resulting in insufficient heat input by the laser. In particular, the surface roughness measured in the width direction of the copper-based sheet material preferably has a maximum height (Rz) of 0.40 μm or more or 2.40 μm or less, and also preferably has an arithmetic mean roughness (Ra) of 0.15 μm or more or 0.40 μm or less.

[0039] Here, the maximum height (Rz) and arithmetic mean roughness (Ra), which represent the surface roughness of copper-based sheet material, can be determined by measuring the surface roughness using a method (contact surface roughness measurement method) that conforms to the method specified in JIS B0601 (2001), obtaining a roughness curve along the width direction perpendicular to the rolling direction, and then determining the maximum height (Rz) and arithmetic mean roughness (Ra) from the roughness curve.

[0040] Furthermore, in the copper-based sheet material of the present invention, when light is irradiated at an incident angle of 60° to the surface in a direction parallel to the rolling direction, Gs1(60°) is the gloss, and when light is irradiated in the width direction, which is a direction perpendicular to the rolling direction, Gs2(60°) is the gloss. The gloss Gs1(60°) is 450 or less, and the ratio of the gloss Gs1(60°) to the gloss Gs2(60°) (Gs1(60°) / Gs2(60°) ratio) is in the range of 1.0 to 2.0. Here, the Gs1(60°) / Gs2(60°) ratio is preferably in the range of 1.0 to 1.7. In particular, when Gs1(60°) exceeds 450, internal defects occur during laser welding of multiple copper-based sheets, resulting in reduced weldability. This is thought to be because excessive gloss makes the laser irradiated during laser welding more likely to be reflected, resulting in insufficient heat input by the laser. Furthermore, when the Gs1(60°) / Gs2(60°) ratio exceeds 2.0, internal defects occur and weldability deteriorates when multiple copper-based sheets are laser welded together. In this case, it is thought that the increase in gloss anisotropy causes the heat input from the laser when sweeping the laser to become uneven on the surface of the copper-based sheets, making it more likely for internal defects to occur.

[0041] Furthermore, in the copper-based sheet material of the present invention, when the gloss levels when light is irradiated to the surface in a direction parallel to the rolling direction at incident angles of 45° and 75° to the surface are Gs1(45°) and Gs1(75°), respectively, it is preferable that the value of parameter A calculated by the following formula (I) is in the range of 0.5 to 1.2. A=[Gs1(60°)-Gs1(45°)] / [Gs1(75°)-Gs1(60°)] Formula (I) In measuring gloss, the JIS standard (JIS Z8741 (1997)) specifies incident angles of 20°, 45°, 60°, 75°, and 85°. However, because gloss is nearly directly proportional to the angle, gloss is typically measured at 60°. However, the copper-based sheet material of the present invention is affected by surface roughness and slight warping of the sheet material, so gloss is not perfectly proportional to the angle. Therefore, the present inventors evaluated laser weldability using gloss measured at various incident angles and found that, within the above-mentioned ranges of surface roughness and gloss, the closer the ratio [Gs1(60°) - Gs1(45°)] / [Gs1(75°) - Gs1(60°)] is to 1, i.e., the closer the gloss and angle are to a proportional relationship, the better the laser weldability. This is thought to be because when the glossiness and the angle are nearly proportional, the effects of surface roughness and slight warping of the plate material are reduced, and as a result, the heating of the copper-based plate material during laser welding is carried out in a nearly uniform manner.

[0042] Here, as shown in FIG. 2(a), the gloss value Gs1(θ1) of the copper-based sheet material can be determined by measuring the intensity of specularly reflected light reflected at a reflection angle θ2 when incident light I is incident on the surface of the copper-based sheet material 11 at an incident angle θ1 along the rolling direction x using a light receiver 21. Also, as shown in FIG. 2(b), the gloss value Gs2(θ1) of the copper-based sheet material can be determined by measuring the intensity of specularly reflected light reflected at a reflection angle θ2' when incident light I is incident on the surface of the copper-based sheet material 11 at an incident angle θ1' along the width direction y using a light receiver 21. The gloss value can be calculated from the intensity of specularly reflected light according to the above-mentioned JIS Z8741 standard, using a gloss value calculation means 22 such as a computer.

[0043] The copper-based sheet material of the present invention preferably has an oxide film formed on the surface of the copper-based sheet material with a thickness in the range of 20 Å to 500 Å. When the surface roughness and gloss are within the above-mentioned ranges, excellent laser weldability can be obtained by having the oxide film thickness of the copper-based sheet material in the range of 20 Å to 500 Å. In particular, it is believed that when the oxide film thickness of the copper-based sheet material is 20 Å or more, the wettability of the surface of the copper-based sheet material to copper (alloy) is reduced, making it difficult for the melted portion to flow from the joining interface of the copper-based sheet material to the sheet surface during laser welding. Furthermore, when the oxide film thickness exceeds 500 Å, the laser weldability is reduced. This is believed to be due to the large amount of impurities contained in the oxide film diffusing into the welded portion.

[0044] [3] Shape of copper-based sheet material The "sheet material" as used herein refers to a material that has been processed into a predetermined shape, such as a plate, strip, or foil, and has a predetermined thickness, and in a broad sense includes strip materials. The thickness of the copper-based sheet material in the present invention is not particularly limited, but is preferably in the range of 0.05 mm to 2.0 mm, and more preferably in the range of 0.1 mm to 1.0 mm.

[0045] [4] Laser welding of copper-based components Fig. 1 is a schematic perspective view of a copper-based member 10 formed by linearly laser welding two overlapping copper-based plates 11a and 11b. The copper-based member 10 of the present invention is formed by joining at least two of the above-mentioned copper-based plates 11a and 11b together by a laser welding method. In particular, the embodiment shown in Fig. 1 has a welded portion 13 that integrates the overlapping copper-based plates 11a and 11b, and this portion is joined by laser welding using a laser L.

[0046] Here, laser welding is a welding method that uses a highly directional and highly focused wavelength of light collected by a lens, resulting in a laser beam with an extremely high energy density as a heat source. By adjusting the output of the laser beam, it is possible to achieve penetration welding with a narrow width relative to the depth. Furthermore, laser beams can be focused much more narrowly than the arc used in arc welding. The energy densified by the collecting lens makes it possible to use a laser welding device to perform localized welding and join materials with different melting points. Laser welding is also suitable for fine welding because it has little thermal impact due to welding, produces a thin weld pattern, and does not generate processing reaction forces.

[0047] The laser used for laser welding can be appropriately selected from known welding lasers. Examples of lasers include CO2 lasers, Nd:YAG lasers, semiconductor lasers, and fiber lasers. Fiber lasers are preferable in terms of output and focusing of laser light. Other configurations of the laser welding device can be selected from any conventionally known configurations.

[0048] In order to prevent oxidation caused by heating by the laser beam, it is preferable to supply an inert gas, such as nitrogen, argon, or helium, to the vicinity of the laser beam irradiated portion of the laser welding device.

[0049] [5] An example of a manufacturing method for copper-based sheet materials The above-mentioned copper-based sheet material can be realized by controlling the alloy composition and the manufacturing process in combination, and the manufacturing process is not particularly limited. Among them, the following method can be mentioned as an example of a manufacturing process that can obtain a copper-based sheet material having such high laser weldability.

[0050] In one example of the method for producing a copper-based sheet material of the present invention, a copper-based material having substantially the same alloy composition as the copper-based sheet material described above is subjected to at least the following steps in sequence: casting (step 1), homogenizing heat treatment (step 2), hot rolling (step 3), cooling (step 4), facing (step 5), first cold rolling (step 6), first heat treatment (step 7), second cold rolling (step 8), third cold rolling (step 9), temper annealing (step 10), shape correction (step 11), and rust prevention treatment (step 12). In the second cold rolling (step 8), the diameter of the work roll is 150 mm or less, the arithmetic mean roughness (Ra) of the work roll surface is 0.01 μm to 0.05 μm, the rolling reduction per pass is 10% or more, and the total rolling reduction is 20% or more. In the third cold rolling step [step 9], the work roll diameter is set to 150 mm or less, the arithmetic mean roughness (Ra) of the work roll surface is set to 0.10 μm or more and 0.50 μm or less, the rolling reduction per pass is set to 10% or more, and the total rolling reduction is set to 25% or more. In addition, the surface of the copper-based sheet material after the shape correction step [step 11] is controlled so that the steepness, which is a parameter of flatness measured along the rolling direction, is 0.5% or less.

[0051] (i) Casting process [Process 1] In the casting process [Step 1], a copper-based material (copper material or copper alloy material) having the above-described alloy composition is melted and cast to produce an ingot of a predetermined shape (e.g., 300 mm thick, 500 mm wide, and 3000 mm long). In the casting process [Step 1], the copper-based material is preferably melted and cast in an inert gas atmosphere such as nitrogen or in a vacuum using a high-frequency melting furnace. Note that the alloy composition of the copper-based material may not necessarily be completely identical to that of the copper-based sheet material produced due to the addition of certain components that adhere to or volatilize the melting furnace during each manufacturing process, but the copper-based material has substantially the same alloy composition as that of the copper-based sheet material.

[0052] (ii) Homogenization heat treatment process [Process 2] The homogenization heat treatment step [Step 2] is a step in which heat treatment is performed on the ingot after the casting step [Step 1]. The homogenization heat treatment step [Step 2] is performed to homogenize the metal structure of the ingot and promote the formation of a fibrous second phase in a subsequent step. The conditions for the homogenization heat treatment are not particularly limited as long as they are commonly used conditions. An example of the conditions for the homogenization heat treatment is a holding temperature in the range of 700°C to 1000°C and a holding time in the range of 0.1 to 10 hours.

[0053] (iii) Hot rolling process [Process 3] The hot rolling step (step 3) is a step in which the ingot that has been subjected to the homogenization heat treatment is hot rolled until it reaches a predetermined thickness to produce a hot-rolled material. In the hot rolling step (step 3), for example, it is preferable to set the rolling temperature to 500°C or higher and the total reduction rate (total rolling processing rate) to 90% or higher.

[0054] Here, the "rolling reduction" (rolling processing rate) is a value obtained by subtracting the cross-sectional area after rolling from the cross-sectional area before rolling, dividing the value by the cross-sectional area before rolling, and multiplying the result by 100, expressed as a percentage, and is expressed by the following formula. [Rolling reduction] = {([Cross-sectional area before rolling] - [Cross-sectional area after rolling]) / [Cross-sectional area before rolling]} x 100 (%)

[0055] (iv) Water cooling process [Process 4] The water cooling step is a step of cooling the hot-rolled material after the hot rolling step [step 3]. Here, the cooling means in the cooling step is not particularly limited, but from the viewpoint of preventing the coarsening of crystal grains, it is preferable to make the cooling rate as high as possible. For example, by cooling the hot-rolled material by water cooling, the hot-rolled material can be cooled at a high cooling rate of, for example, 50°C / second or more, which makes it possible to prevent the coarsening of crystal grains.

[0056] (v) Facing process [Process 5] The facing process [Step 5] is a process of scraping off the surface of the hot-rolled material after the cooling process [Step 4]. By performing the facing process, it is possible to remove the oxide film and defects on the surface that occurred in the hot-rolling process [Step 3]. The conditions for the facing process are not particularly limited as long as they are commonly used conditions. The amount of material scraped off from the surface of the hot-rolled material can be adjusted appropriately based on the conditions of the hot-rolling process [Step 3], and can be, for example, about 0.5 mm to 4 mm from each of the front and back sides of the hot-rolled material.

[0057] (vi) First cold rolling process [Process 6] The first cold rolling step [step 6] is a step in which the hot-rolled material after the facing step is cold-rolled at an arbitrary rolling reduction ratio according to the product plate thickness. The rolling conditions in the first cold rolling step [step 6] require a total reduction ratio of 70% or more in order to refine the crystal grains contained in the cold-rolled material after the first heat treatment step [step 7] described below. On the other hand, if the total reduction ratio is too large, it becomes difficult to increase the rolling reduction ratio in the third cold rolling step [step 9] described below, so it is preferable to set the total reduction ratio to 95% or less.

[0058] (vii) First heat treatment step [Step 7] The first heat treatment step [step 7] is a step in which the cold-rolled material after the first cold rolling step [step 6] is subjected to heat treatment once or multiple times depending on the alloy composition.

[0059] The conditions for the heat treatment in the first heat treatment step [Step 7] can be, for example, an ultimate temperature in the range of 350°C to 600°C, and a holding time at this ultimate temperature in the range of 0.1 to 10 hours.

[0060] Here, when the copper-based material is made of a precipitation-type alloy such as a Corson copper alloy or a chromium-based copper alloy, the first heat treatment step [Step 7] can be performed to dissolve the precipitates or increase the amount of precipitation by solution treatment and aging heat treatment. In particular, when the copper-based material is made of a chromium-based copper alloy, the first heat treatment step [Step 7] may be performed to increase the amount of precipitates by aging heat treatment.

[0061] When the copper-based material is a precipitation-type alloy, the first heat treatment step [step 7] can be performed, for example, by a two-stage heat treatment (heat treatment condition 1). In the first heat treatment under heat treatment condition 1, the ultimate temperature can be in the range of 700°C to 900°C, the holding time at this temperature can be in the range of 5 seconds to 1000 seconds, and the cooling rate after the first heat treatment can be in the range of 10°C / second to 500°C / second. In the second heat treatment under heat treatment condition 1, the ultimate temperature can be in the range of 300°C to 600°C, and the holding time at this temperature can be in the range of 0.1 hours to 10 hours. The cooling rate after the second heat treatment is not particularly limited.

[0062] Furthermore, when the copper-based material is composed of a precipitation-type alloy, the first heat treatment step [Step 7] can also be performed, for example, by performing only the second heat treatment step of the first and second heat treatment steps described above (heat treatment condition 2).

[0063] On the other hand, when the copper-based material is made of pure copper or phosphor bronze alloy, the first heat treatment step [Step 7] can be carried out to soften the copper-based material by intermediate annealing.

[0064] When the copper-based material is made of pure copper or a phosphorus bronze alloy, the first heat treatment step [Step 7] can be performed, for example, by a single heat treatment (heat treatment condition 3). The heat treatment under heat treatment condition 3 can achieve a temperature in the range of 300°C to 700°C, and a holding time at this temperature in the range of 5 seconds to 10 hours.

[0065] Furthermore, when the copper-based material is made of oxygen-free copper, the first heat treatment step [step 7] can be carried out to remove distortion by intermediate annealing.

[0066] (viii) Second cold rolling process [Process 8] The second cold rolling step [Step 8] is a step in which the cold-rolled material after the first heat treatment step [Step 7] is further cold-rolled using work rolls. In the second cold rolling step [Step 8], the diameter of the work rolls is 150 mm or less, the arithmetic mean roughness (Ra) of the work roll surface is in the range of 0.01 μm to 0.05 μm, the rolling reduction (processing rate) per pass is 10% or more, and the total rolling reduction (total processing rate) is 20% or more. By smoothing the surface of the cold-rolled material within the above conditions in the second cold rolling step [Step 8], the desired surface roughness and gloss can be obtained in the subsequent third cold rolling step [Step 9].

[0067] In particular, by setting the diameter of the work rolls used in the second cold rolling step [step 8] to 150 mm or less, more preferably 120 mm, it is possible to suppress oil pits and increase the reduction per pass. On the other hand, the lower limit of the diameter of the work rolls used in the second cold rolling step [step 8] is preferably 30 mm or more, from the viewpoint of preventing deterioration of the rolling shape.

[0068] Furthermore, by setting the arithmetic mean roughness (Ra) of the work roll surface used in the second cold rolling step [Step 8] to a range of 0.01 μm or more and 0.05 μm or less, a smooth surface can be obtained, making it possible to achieve the desired surface properties in the third cold rolling step [Step 9] described below.

[0069] In the second cold rolling step [step 8], the reduction rate (processing rate) per pass is preferably 10% or more, and more preferably 15% or more. On the other hand, the upper limit of the reduction rate (processing rate) per pass in the second cold rolling step [step 8] may be set to 50% or less, taking into account the limitations of the rolling mill.

[0070] The total reduction rate (total processing rate) in the second cold rolling step (step 8) is preferably 20% or more, and more preferably 30% or more. On the other hand, the upper limit of the total reduction rate (total processing rate) in the second cold rolling step (step 8) may be 80% or less.

[0071] (ix) Third cold rolling process [Process 9] The third cold rolling step [step 9] is a step in which the cold-rolled material obtained after the second cold rolling step [step 8] is further cold-rolled using work rolls. In the third cold rolling step [step 9], the diameter of the work roll is 150 mm or less, the arithmetic mean roughness (Ra) of the work roll surface is in the range of 0.10 μm to 0.50 μm, the rolling reduction (processing rate) per pass is 10% or more, and the total rolling reduction (total processing rate) is 25% or more. In the third cold rolling step [step 9], the surface of the cold-rolled material is smoothed under the above conditions, thereby achieving the desired surface roughness and gloss in the resulting copper-based sheet material. On the other hand, if rolling is performed outside the above conditions, the desired surface properties cannot be obtained, resulting in insufficient laser weldability.

[0072] In particular, by setting the diameter of the work rolls used in the third cold rolling step [step 9] to 150 mm or less, more preferably 120 mm, it is possible to suppress oil pits and increase the reduction per pass. On the other hand, the lower limit of the diameter of the work rolls used in the second cold rolling step [step 8] is preferably 30 mm or more, from the viewpoint of preventing deterioration of the rolling shape.

[0073] Furthermore, by setting the arithmetic mean roughness (Ra) of the work roll surface used in the third cold rolling step [step 9] to a range of 0.10 μm or more and 0.50 μm or less, more preferably 0.15 μm or more and 0.50 μm or less, the desired surface roughness and gloss can be obtained.

[0074] In the third cold rolling step [step 9], the reduction rate (processing rate) per pass is preferably 10% or more, and more preferably 15% or more. On the other hand, the upper limit of the reduction rate (processing rate) per pass in the third cold rolling step [step 9] may be set to 50% or less, taking into account the limitations of the rolling mill.

[0075] The total reduction rate (total processing rate) in the third cold rolling step (step 9) is preferably 25% or more, and more preferably 30% or more. On the other hand, the upper limit of the total reduction rate (total processing rate) in the third cold rolling step (step 9) may be 80% or less.

[0076] (x) Temperature annealing process [Process 10] The temper annealing step (Step 10) is a step in which the rolled material after the third cold rolling step (Step 9) is subjected to a heat treatment according to the alloy composition. By performing the temper annealing step (Step 10), the rolled material can be tempered. Here, the conditions for the heat treatment in the temper annealing step (Step 10) can be, for example, an ultimate temperature in the range of 200°C to 500°C, and a holding time at this ultimate temperature in the range of 10 seconds to 500 seconds.

[0077] (xi) Shape correction process [Process 11] In the shape correction process [Step 11], a tension leveler is used to correct the shape of the copper-based sheet material after the temper annealing process [Step 10], more specifically, the warpage and elongation along the rolling direction and width direction. Here, it is preferable to control the surface of the copper-based sheet material (corrected material) after the shape correction process [Step 11] so that the steepness, which is a parameter of flatness measured along the rolling direction, is 0.5% or less. This can suppress the anisotropy of the gloss on the surface of the copper-based sheet material and the decrease in parameter A calculated by the above-mentioned formula (I). Furthermore, it can also prevent the formation of gaps between the sheets when laser-bonding copper-based sheets, which can lead to a decrease in laser bondability.

[0078] (xii) Rust prevention treatment process [Process 12] In the rust prevention treatment step (step 12), the rolled material after the shape correction step (step 11) is subjected to rust prevention treatment. This makes it difficult for an oxide film to form on the surface of the rolled material, making it less likely that impurities from the oxide film will get mixed into the weld, which would cause a decrease in weldability.

[0079] The rust prevention treatment step [Step 12] can be performed using known rust prevention means for pure copper materials or copper alloy materials, but among them, rust prevention treatment using benzotriazole or its derivatives is preferred from the viewpoint of providing excellent rust prevention effect by reaction with Cu. Note that the rolled material to be subjected to the rust prevention treatment step [Step 12] is preferably degreased after the above-mentioned shape correction step [Step 11].

[0080] [6] Uses of copper-based sheet materials The copper-based sheet material of the present invention is suitable for use as a heat dissipation member or terminal material for electric and electronic devices, etc. More specifically, it is suitable for use in electric and electronic devices that require miniaturization and high integration, such as home game consoles, medical devices, workstations, servers, personal computers, car navigation systems, mobile phones, robot connectors, battery terminals, jacks, relays, switches, autofocus camera modules, and lead frames.

[0081] In particular, when the copper-based sheet material of the present invention is used as a structural material for heat dissipation components such as vapor chambers, the sheets can be joined at their outer peripheries with high laser weldability when stacked, making it difficult for the working fluid sealed in the internal space of the heat dissipation component to leak. As a result, it is possible to suppress a decrease in the thermal conductivity of the vapor chamber, and it is possible to exhibit excellent effects in suppressing product deterioration and extending the lifespan of the product.

[0082] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, but includes all aspects encompassed by the concept of the present invention and the scope of the claims, and can be modified in various ways within the scope of the present invention. [Example]

[0083] Next, in order to further clarify the effects of the present invention, examples of the present invention and comparative examples will be described, but the present invention is not limited to these examples of the present invention.

[0084] (Invention Examples 1 to 17 and Comparative Examples 1 to 18) Various copper-based materials (copper materials or copper alloy materials) having the alloy compositions shown in Tables 1 and 3 were melted and cooled in a nitrogen atmosphere to obtain ingots through a casting process [Step 1]. The ingots were then subjected to a homogenization heat treatment process [Step 2] in which heat treatment was performed at a holding temperature of 700°C to 1000°C for 2 hours, and then to a hot rolling process [Step 3] in which the ingots were rolled in the longitudinal direction at a rolling temperature of 500°C or higher with a total reduction of 90% or more, to obtain hot-rolled materials. This was followed by a cooling process [Step 4] in which the ingots were cooled to room temperature by water cooling.

[0085] After the cooling process [Step 4], the hot-rolled material was subjected to a facing process [Step 5] in which approximately 1 to 3 mm was removed from both the front and back surfaces to remove the oxide film on the surface.Then, the first cold rolling process [Step 6] was carried out, in which the material was rolled so that the longitudinal direction was the rolling direction, under conditions where the total reduction ratio was 90% or more.

[0086] Among these, for Inventive Examples 1 to 5 and 11 and Comparative Examples 2 to 6 and 11, the first heat treatment step [Step 7] was carried out in which heat treatment was carried out twice at the ultimate temperature and for the holding time that satisfied the heat treatment condition 1 described above.

[0087] In addition, for Inventive Examples 6, 8, and 9 and Comparative Examples 8, 9, and 10, the first heat treatment step [Step 7] was carried out in which a single heat treatment was carried out at an ultimate temperature and for a holding time that satisfied the above-mentioned heat treatment condition 2.

[0088] In addition, for Inventive Examples 7, 10, 12 to 17 and Comparative Examples 1, 7, 12 to 18, the first heat treatment step [step 7] was carried out in which a single heat treatment was carried out at an ultimate temperature and for a holding time that satisfied the heat treatment condition 3 described above.

[0089] After the first heat treatment step [step 7], the second cold rolling step [step 8] was carried out in which the longitudinal direction was the rolling direction under the conditions of the work roll diameter, arithmetic mean roughness (Ra) of the work roll surface, minimum reduction rate per pass, and total reduction rate shown in Tables 1 and 3.

[0090] The rolled material after the second cold rolling process [Step 8] was further subjected to a third cold rolling process [Step 9] in which the longitudinal direction was the rolling direction under the conditions of the work roll diameter, arithmetic mean roughness (Ra) of the work roll surface, minimum reduction rate per pass, and total reduction rate listed in Tables 1 and 3.

[0091] After the third cold rolling step [step 9], the rolled material was subjected to a temper annealing step [step 10] in which heat treatment was performed at an ultimate temperature of 300 ° C and a holding time of 50 seconds, and then a shape correction step [step 11] was performed using a tension leveler to correct warpage and elongation along the rolling direction and width direction of the copper-based sheet material. After that, a rust prevention treatment step [step 12] was performed on the surface of the degreased copper-based sheet material using benzotriazole or its derivative to produce the copper-based sheet material of the present invention. Here, the steepness, which is a parameter of flatness measured along the rolling direction immediately after the shape correction step [step 11], was the value shown in Tables 1 and 3.

[0092] In Tables 1 and 3, constituent elements other than copper (Cu) are listed as optional added elements. In Table 1, a horizontal line (-) is entered in the column for elements not included in the alloy composition of copper-based materials, indicating that the corresponding element is not included, or if it is included, it is below the detection limit.

[0093] [Various measurement and evaluation methods] The copper-based sheet materials according to the above-mentioned invention examples and comparative examples were used to carry out the following characteristic evaluations. The evaluation conditions for each characteristic were as follows.

[0094] [1] Measurement of surface roughness of copper-based plate materials The surface roughness of the copper-based sheet material was measured using a method (contact surface roughness measurement method) in accordance with the method specified in JIS B0601 (2001), and a roughness curve was obtained along the width direction, which is perpendicular to the rolling direction. The maximum height (Rz) and arithmetic mean roughness (Ra) were calculated from the roughness curve. The results are shown in Tables 2 and 4.

[0095] [2] Measurement of gloss of copper-based sheet materials The gloss of the copper-based sheet material was measured using a gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "PG-1M") conforming to JIS Z8741. As shown in Figure 2(a), incident light I was incident on the surface of the copper-based sheet material 11 at angles of incidence of 45°, 60°, and 75° along the rolling direction x. The intensity of the specularly reflected light reflected at a reflection angle θ2 was measured with a photodetector 21, resulting in gloss Gs1(45°), Gs1(60°), and Gs1(75°). Furthermore, as shown in Figure 2(b), incident light I was incident on the surface of the copper-based sheet material 11 at an angle of incidence of 60° along the width direction y. The intensity of the specularly reflected light reflected at a reflection angle θ2' was measured with a photodetector 21, resulting in gloss Gs2(60°). Then, from the obtained gloss values, the Gs1(60°) / Gs2(60°) ratio and the parameter A calculated by the above formula (I) were obtained. The results are shown in Tables 2 and 4.

[0096] [3] Measurement of oxide film thickness on copper-based sheet materials A test piece 25 mm wide and 50 mm long was taken so that the rolling direction of the copper-based plate material was the longitudinal direction. 2 The remaining parts were covered with resin, and the thickness of the oxide film was measured by cathodic reduction. A 0.1KCl solution was used as the electrolyte, and after thoroughly removing dissolved oxygen by passing N2 gas through it, the sample was immersed in the solution and simultaneously subjected to reduction by passing an electric current. The solution temperature was maintained at 25°C, and the cathodic current density was 0.1mA / cm. 2 The reduction yielded a cathodic reduction curve, from which the thickness of the oxide film was determined.

[0097] There are two types of copper oxide: cupric oxide (CuO) and cuprous oxide (Cu2O), which differ in the valence of copper (Cu 2+ and Cu + ) Furthermore, when the copper-based sheet material is made of a copper alloy, oxides containing copper and alloying elements may be formed in addition to copper oxides. Therefore, in this application, the thickness of the oxide film was determined assuming that all copper oxides were Cu2O. The results are shown in Tables 2 and 4.

[0098] [4] Measurement of the steepness of the surface of the copper-based plate material after the shape correction process [Process 11] For copper-based sheet material (sheet width length (300 mm or more), length in the rolling direction 1000 mm), the steepness in the rolling direction was measured using a non-contact three-dimensional measuring machine in accordance with the Japan Copper and Brass Association technical standard JCBA-T326-2014 (Method for measuring flatness of copper and copper alloy sheet strips). Measurements were taken at a total of 20 locations at 25 mm intervals centered on the center part in the width direction, and it was determined that the laser weldability was good when the maximum value was 0.5% or less.

[0099] Here, the steepness was calculated by (h / w) × 100(%), where w is the distance from one trough to the next in the wave profile in the rolling direction, and h is the distance from a line drawn between the troughs to the crest of the wave. The results are shown in Tables 2 and 4.

[0100] [5] Evaluation of laser weldability For the copper-based sheet materials of the present invention and comparative examples, two 1 mm thick copper-based sheets were stacked together, and laser welding was performed by irradiating the surfaces of the overlapping portions with a laser beam having a wavelength ranging from 800 nm to 1200 nm at an output of 6 kW and sweeping the beam at a speed of 4 m / min. To prevent oxidation due to heating by the laser beam, nitrogen was supplied as an inert gas, and welding was performed in a nitrogen atmosphere. After welding, the sheets were cut perpendicular to the laser sweep direction, and the resulting cross sections were filled with resin, wet polished, and etched, and then observed under an optical microscope.

[0101] Furthermore, optical microscope photographs of the welded copper-based sheet materials were subjected to binarization analysis (Image-J). When the maximum defect size was φ50 μm or less and the defect area ratio was 1% or less, the weldability of the copper-based sheet material was evaluated as excellent and rated as "◎". When the maximum defect size was φ50 μm or less and the defect area ratio was greater than 1% and less than 5%, the weldability of the copper-based sheet material was evaluated as acceptable and rated as "○". On the other hand, when the maximum defect size exceeded φ50 μm or the defect area ratio exceeded 5%, the weldability of the copper-based sheet material was evaluated as unacceptable and rated as "×". The results are shown in Tables 2 and 4.

[0102] 3 and 4 show optical microscope photographs of the cross-sections of two copper-based sheets of copper-based sheet material of Example 12 of the present invention and Comparative Example 16, which were overlapped and joined by laser welding. In Fig. 4, Fig. 4(a) is an optical microscope photograph before image conversion, and Fig. 4(b) is a photograph showing the image after the color tone of the image of Fig. 4(a) was converted by black and white binarization processing.

[0103] [Table 1]

[0104] [Table 2]

[0105] [Table 3]

[0106] [Table 4]

[0107] From the results in Tables 1 to 4, the copper-based sheet materials of Examples 1 to 17 of the present invention have alloy compositions within the appropriate range of the present invention, a maximum height (Rz) along the width direction in the range of 0.30 μm or more and 2.50 μm or less, an arithmetic mean roughness (Ra) along the width direction in the range of 0.10 μm or more and 0.50 μm or less, a gloss Gs1(60°) of 450 or less, and a Gs1(60°) / Gs2(60°) ratio in the range of 1.0 or more and 2.0 or less, and the laser weldability was also evaluated as "◎" or "◯".

[0108] Therefore, the copper-based sheet materials of Examples 1 to 17 of the present invention met the requirements for maximum height (Rz), arithmetic mean roughness (Ra), gloss Gs1 (60°) and Gs1 (60°) / Gs2 (60°) ratio, and therefore also had excellent laser weldability.

[0109] On the other hand, the copper-based sheet materials of Comparative Examples 1 to 18 all had at least one of the requirements of maximum height (Rz), arithmetic mean roughness (Ra), gloss Gs1 (60°) and Gs1 (60°) / Gs2 (60°) ratio outside the appropriate range of the present invention, and therefore the evaluation of laser weldability did not reach an acceptable level. [Explanation of symbols]

[0110] 10 Copper-based materials 11, 11a, 11b Copper plate material 13 Welded parts 21 Receiver 22 Gloss value calculation method I incident light L laser light x rolling direction y width direction

Claims

1. Pure copper having a composition containing 99.96 mass% or more of Cu, the total content of Cd, Mg, Pb, Sn, Cr, Bi, Se and Te being 5 mass ppm or less, the content of Ag being 400 mass ppm or less, and the content of O being 400 mass ppm or less, or 1. A copper-based sheet material made of a copper alloy having an alloy composition containing one or more selected from Ag in a range of 0.05 mass% to 5.00 mass% or less, Fe in a range of 0.05 mass% to 0.50 mass% or less, Ni in a range of 0.05 mass% to 5.00 mass% or less, Si in a range of 0.05 mass% to 1.10 mass% or less, Cr in a range of 0.05 mass% to 0.50 mass% or less, Sn in a range of 0.05 mass% to 9.50 mass% or less, Zn in a range of 0.05 mass% to 0.50 mass% or less, Mg in a range of 0.01 mass% to 0.50 mass% or less, and P in a range of 0.01 mass% to 0.50 mass% or less, with the balance being Cu and unavoidable impurities, The copper-based sheet material has a maximum height (Rz), which is a parameter representing surface roughness measured in a width direction that is a direction perpendicular to the rolling direction, in the range of 0.30 μm or more and 2.50 μm or less, and an arithmetic mean roughness (Ra), which is a parameter representing surface roughness measured in a width direction that is a direction perpendicular to the rolling direction, in the range of 0.10 μm or more and 0.50 μm or less, When the glossiness when light is irradiated in a direction parallel to the rolling direction at an incident angle of 60° with respect to the surface of the copper-based sheet material is Gs1 (60°), and the glossiness when light is irradiated in the width direction is Gs2 (60°), The glossiness Gs1 (60 °) is 168 or more and 450 or less, and the ratio to the glossiness Gs2 (60 °) (Gs1 (60 °) / Gs2 (60 °) ratio) is 1.0 or more and 2.0 or less. A copper-based sheet material.

2. When the gloss levels when light is irradiated to the surface of the copper-based sheet material at incident angles of 45° and 75° in a direction parallel to the rolling direction are Gs1 (45°) and Gs1 (75°), respectively, The copper-based sheet material according to claim 1, wherein the value of parameter A calculated by the following formula (I) is in the range of 0.5 to 1.

2. A = [Gs1 (60°) - Gs1 (45°)] / [Gs1 (75°) - Gs1 (60°)] Formula (I)

3. 3. The copper-based sheet material according to claim 1, wherein the thickness of the oxide film formed on the surface of the copper-based sheet material is in the range of 20 Å to 500 Å.

4. A copper-based member formed integrally by joining at least two of the copper-based plate materials according to any one of claims 1 to 3 together by laser welding.

5. A method for producing a copper-based sheet material according to any one of claims 1 to 3, The copper-based material is subjected to at least a casting step [step 1], a homogenizing heat treatment step [step 2], a hot rolling step [step 3], a cooling step [step 4], a facing step [step 5], a first cold rolling step [step 6], a first heat treatment step [step 7], a second cold rolling step [step 8], a third cold rolling step [step 9], a temper annealing step [step 10], a shape correction step [step 11], and a rust prevention treatment step [step 12] in this order; In the second cold rolling step [step 8], the diameter of the work roll is 150 mm or less, the arithmetic mean roughness (Ra) of the work roll surface is in the range of 0.01 μm or more and 0.05 μm or less, the rolling reduction per pass is 10% or more, and the total rolling reduction is 20% or more, In the third cold rolling step [step 9], the diameter of the work roll is 150 mm or less, the arithmetic mean roughness (Ra) of the work roll surface is in the range of 0.10 μm or more and 0.50 μm or less, the rolling reduction per pass is 10% or more, and the total rolling reduction is 25% or more, A method for producing a copper-based sheet material, wherein the surface of the copper-based sheet material after the shape correction step [step 11] is controlled so that the steepness, which is a parameter of flatness measured along the rolling direction, is 0.5% or less.

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