JP7609652B2 - Method for joining copper alloy sheets and joined body of copper alloy sheets - Google Patents

Description

The present invention relates to a method for joining copper alloy sheets and a joined body of copper alloy sheets.

Generally, when joining copper alloy sheets together, joining methods such as brazing and crimping are used. However, these joining methods have low productivity and lead to high production costs. In contrast, a joining method in which copper alloy sheets are laser welded together can achieve high productivity while keeping costs down.

As a technique for welding copper alloy sheets together using a laser, Patent Document 1 shows that two or more fiber laser beams having the same focused beam diameter are irradiated onto the parts to be welded so that the center-to-center distance between the irradiated parts of each fiber laser beam is 0.7 or less of the focused beam diameter.

JP 2014-161863 A

However, copper alloy sheets have high thermal conductivity and low absorption of laser light, making it difficult to provide a stable heat input. In particular, when laser welding thin copper alloy sheets, defects such as poor penetration and burn-through due to reflections are likely to occur, making it difficult to achieve a reliable joint.

Furthermore, when laser welding copper alloy sheets containing low-boiling point elements such as zinc, magnesium or phosphorus, the sudden heat input can cause the low-boiling point elements to evaporate and the molten metal to be blown away, which can lead to defects such as burn-through and a decrease in quality.

The present invention aims to provide a method for joining copper alloy sheets that can be laser-welded to join copper alloy sheets with high reliability, and a joint of copper alloy sheets that is joined with high reliability.

The present invention comprises the following configurations.
(1) A method for joining a plurality of copper alloy plates by laser welding, comprising the steps of:
A step of stacking and arranging a plurality of the copper alloy plates containing at least one component having a boiling point lower than the melting point of copper;
a laser welding process in which a laser beam is irradiated along a welding direction to an irradiated portion where the copper alloy plates are overlapped with each other, thereby joining the plurality of copper alloy plates;
Including,
In the laser welding step,
The laser beam is scanned in the welding direction while being moved a plurality of times in a width direction intersecting the welding direction.
A method for joining copper alloy plates.
(2) A joint of copper alloy plates in which a plurality of copper alloy plates are overlapped and joined by welding at the overlapping portions,
The overlapping portion is provided with a welded portion formed by solidifying molten metal, penetrating from the front to the back,
The welded portion has a width dimension on the back side that is 80% or more of the width dimension on the front side.
Copper alloy plate joint.

According to the present invention, copper alloy plates can be laser welded together with high reliability.

FIG. 2 is a perspective view showing how copper alloy plates are laser-welded together. FIG. 1 is a schematic perspective view showing a laser irradiation device. FIG. 2 is a schematic plan view of copper alloy sheets with overlapping edges showing laser welding. FIG. 2 is a cross-sectional view of a joint in a joint formed by joining copper alloy plates together. 1A and 1B are diagrams showing the state of a joint of a joint formed by joining copper alloy plates together, in which (A) is a schematic plan view of the laser light irradiated side, and (B) is a schematic plan view of the side opposite to the laser light irradiated side. FIG. 11 is a schematic plan view of copper alloy sheets with overlapping edges, illustrating another laser welding process. 1A and 1B are diagrams showing the state of a joint of a joint formed by joining copper alloy plates together, in which (A) is a schematic plan view of the laser light irradiated side, and (B) is a schematic plan view of the side opposite to the laser light irradiated side. 1A is an image of the side irradiated with laser light, FIG. 1B is an image of the side opposite to the side irradiated with laser light, and FIG. 1C is an image of a cross section at a joint. 13A is an image of the side irradiated with the laser light, FIG. 13B is an image of the side opposite to the side irradiated with the laser light, and FIG. 13C is an image of a cross section at the joint. 13A is an image of the side irradiated with laser light, (B) is an image of the side opposite to the side irradiated with laser light, and (C) is an image of a cross section at the joint.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view showing how copper alloy plates 11 and 13 are laser-welded to each other.

As shown in FIG. 1, the method for joining copper alloy plates according to this embodiment is a method for joining multiple copper alloy plates 11, 13 by laser welding. In this example, the joining of two copper alloy plates 11, 13 is illustrated.

The copper alloy plates 11 and 13, which are the objects to be joined, are overlapped at their respective portions, and these overlapping portions become the irradiated portions 15. Then, the irradiated portions 15 are irradiated with laser light L by the laser irradiation device 100, and are laser welded and joined together.

FIG. 2 is a schematic perspective view showing the laser irradiation device 100. As shown in FIG.
2, the laser irradiation device 100 that irradiates the irradiated portion 15 with the laser light L is equipped with a galvanometer scanner unit, and has a galvanometer mirror 101 and an fθ lens 103. In this laser irradiation device 100, a fiber laser output from a fiber laser oscillator (not shown) is reflected by the galvanometer mirror 101, and is condensed through the fθ lens 103 to irradiate the irradiated portion 15. According to this laser irradiation device 100, the laser light L can be scanned at high speed and with high accuracy by controlling the angle of the galvanometer mirror 101 attached to the rotating shaft.

The copper alloy sheets 11, 13 to be joined together are sheets made of a copper alloy containing at least one component with a boiling point lower than the melting point of copper (Cu). The component contained in the copper alloy sheets 11, 13 and having a boiling point lower than the melting point of copper (Cu) is zinc (Zn), magnesium (Mg) or phosphorus (P). These copper alloy sheets 11, 13 are thin sheets having a thickness of 0.1 mm to 1.0 mm. The thickness of each copper alloy sheet 11, 13 may be the same, or one may be thicker than the other.

Next, a method for joining copper alloy sheets according to this embodiment will be described.
Fig. 3 is a schematic plan view of the copper alloy sheets 11 and 13 with their edges overlapped, showing how they are laser welded. Fig. 4 is a cross-sectional view of a joint in a joint 25 in which the copper alloy sheets 11 and 13 are joined together. Fig. 5 is a view showing the state of the joint in the joint 25 in which the copper alloy sheets 11 and 13 are joined together.

(Placement process)
As shown in Fig. 3, the copper alloy sheets 11 and 13 to be joined are arranged so as to overlap each other. In this example, the edges of the copper alloy sheets 11 and 13 are overlapped. In this way, the copper alloy sheets 11 and 13 are provided with an irradiated portion 15 consisting of the overlapped portions.

(Laser welding process)
Next, the laser irradiation device 100 irradiates the irradiated portion 15 of the copper alloy plates 11 and 13 with laser light L, and scans the irradiated portion 15 along a welding direction A from one end 15a to the other end 15b.

At this time, the laser irradiation device 100 is subjected to a wobbling operation, so that the laser light L is periodically rotated while being scanned in the welding direction A. Then, the laser light L is irradiated to the irradiated portion 15 in a spiral shape such that the spirals R overlap each other along the welding direction A. As a result, the laser light L scans the irradiated portion 15 in the welding direction A while moving multiple times with a rotation diameter D in the width direction intersecting the welding direction A. As a result, the irradiated portions 15 of the copper alloy plates 11, 13 are heated in stages by the laser light L and welded.

When the laser irradiation device 100 is wobbled in this way to perform laser welding, as shown in FIG. 4, the irradiated areas of the copper alloy plates 11, 13 melt and fuse together at the joint, and melt all the way to the back surface of the copper alloy plate 13 on the side opposite to the side irradiated with the laser light L. The molten areas then cool, solidify, and harden to form a weld 21, joining the copper alloy plates 11, 13, and a joint 25 of these copper alloy plates 11, 13 is obtained.

In the welded portion 21 of the joint 25 of the copper alloy plates 11 and 13, a bead Ba is formed on the side irradiated with the laser light L, and a bead Bb is formed on the side opposite the side irradiated with the laser light L. The width dimension WBb of the bead Bb formed on the side opposite the side irradiated with the laser light L is 80% or more of the width dimension WBa of the bead Ba formed on the surface of the copper alloy plate 11 on the side irradiated with the laser light L.

As shown in FIG. 5A, by rotating the laser light L, multiple annular weld marks MRa are formed in the bead Ba on the side of the joint 25 where the laser light L is irradiated, so that they are connected in the welding direction A. Similarly, as shown in FIG. 5B, by rotating the laser light L, multiple annular weld marks MRb are formed in the bead Bb on the opposite side of the joint 25 from the side where the laser light L is irradiated, so that they are connected in the welding direction A.

In this way, according to the method for joining copper alloy sheets of the present invention, when the overlapping portion of the copper alloy sheets 11 and 13 is irradiated with the laser light L along the welding direction A, the laser light L is moved multiple times in the width direction intersecting with the welding direction A while being scanned in the welding direction A. This allows the irradiated portion 15 consisting of the overlapping portion of the copper alloy sheets 11 and 13 to be heated and welded stepwise by the laser light L. In other words, since the heat input can be finely controlled, it is possible to suppress the occurrence of welding defects such as blowholes, cracks, or burn-through due to the sudden evaporation of the alloy composition while suppressing poor penetration due to reflection, etc. In addition, by suppressing rapid heating and cooling, the occurrence of cracks can be reduced. In other words, the copper alloy sheets 11 and 13, which have high thermal conductivity and low absorptance of the laser light L, and therefore are difficult to apply stable heat input to, can be laser welded and joined with high reliability.

Therefore, even if the copper alloy sheet contains components with a boiling point lower than the melting point of copper, such as zinc, magnesium, or phosphorus, the occurrence of welding defects caused by the sudden evaporation of these alloy components can be suppressed, and copper alloy sheets can be laser welded together with high reliability.

In particular, by scanning the laser light L in the welding direction A while periodically moving it in the width direction intersecting the welding direction, it is possible to ensure that the molten metal has time to solidify and to promote the escape of air bubbles that have formed in the molten metal.

Specifically, by wobbling the laser light L and rotating the irradiation position while scanning it in the welding direction A, the heat input to the welding point can be controlled more precisely, and a sufficient amount of heat input can be ensured while suppressing the sudden evaporation of the alloy composition.

As a result, even if the copper alloy plates 11 and 13 to be joined are thin plates with a thickness of 0.1 mm to 1.0 mm, they can be laser welded together with high reliability.

The joined copper alloy sheets 25 obtained by the joining method of the present invention have a weld 21 that penetrates the overlapping portion of the multiple copper alloy sheets 11, 13 from front to back. The weld 21 has a width dimension WBb on the back side that is 80% or more of the width dimension WBa on the front side. Therefore, a joined copper alloy sheet 25 is obtained in which the overlapping portions of the multiple copper alloy sheets 11, 13 are joined in a well-balanced manner with high strength by the weld 21.

In addition, since the beads Ba, Bb on the front and back of the welded portion 21 have multiple annular weld marks MRa, MRb that are connected in the welding direction A, by irradiating the laser light L in a wobbling manner, it is possible to confirm that the joint 25 is welded and joined in a balanced manner with high strength, making quality control easier.

The above joining method is suitable for manufacturing a vapor chamber with a hollow space formed inside, for example, by stacking a flat copper alloy plate on a concave copper alloy plate and laser welding the outer periphery to join them.

In the above example, the joining of two copper alloy plates 11 and 13 was described, but the present invention is not limited to this embodiment and can also be applied to the joining of three or more copper alloy plates.

In the above example, the laser irradiation device 100 was subjected to a wobbling operation in the laser welding process, but the laser light L may be scanned in the welding direction A while moving multiple times in the width direction intersecting with the welding direction A by a weaving operation other than the wobbling operation.

Specifically, as shown in FIG. 6, in the laser welding process, the laser irradiation device 100 is operated in a weaving manner, so that the laser light L periodically moves back and forth in a width direction intersecting with the welding direction A, with a width dimension W. In this case as well, the irradiated portions 15 of the copper alloy plates 11 and 13 are gradually heated and welded by the laser light L.

In this way, even when laser welding is performed by performing the weaving operation of the laser irradiation device 100, the irradiated portion of the copper alloy plates 11, 13 melts and fuses together at the joint, and melts all the way to the back surface of the copper alloy plate 13 on the side opposite to the side irradiated with the laser light L (see FIG. 4). Then, this molten portion cools and solidifies and hardens to form a weld 21, joining the copper alloy plates 11, 13, and a joint 25 of these copper alloy plates 11, 13 is obtained.

And even in the welded portion 21 of the joint 25 of the copper alloy plates 11 and 13, the width dimension WBb of the bead Bb formed on the side opposite to the side irradiated with the laser light L is 80% or more of the width dimension WBa of the bead Ba formed on the surface of the copper alloy plate 11 on the side irradiated with the laser light L.

Furthermore, as shown in FIG. 7A, a wavy weld mark MWa is formed along the welding direction A in the bead Ba on the side of the joint 25 where the laser light L is irradiated by the laser light L, by moving the laser light L back and forth in a direction intersecting the welding direction A. Similarly, as shown in FIG. 7B, a wavy weld mark MWb is formed along the welding direction A in the bead Bb on the opposite side of the joint 25 from the side where the laser light L is irradiated by the laser light L, by moving the laser light L back and forth in a direction intersecting the welding direction A.

In this case, too, by weaving and periodically moving the irradiation position in the width direction intersecting with the welding direction A while scanning in the welding direction A, the heat input to the welded area can be controlled more precisely, and a sufficient amount of heat input can be ensured while suppressing the rapid evaporation of the alloy composition.

The welded portion 21 of the resulting joint 25 of copper alloy plates has a width dimension WBb on the back side that is 80% or more of the width dimension WBa on the front side. Therefore, a joint 25 is obtained in which the overlapping portions of multiple copper alloy plates 11, 13 are joined in a well-balanced manner with high strength by the welded portion 21.

In addition, the beads Ba, Bb on the front and back of the welded portion 21 have wavy weld marks MWa, MWb along the welding direction A. By irradiating the weaving laser light L, it can be confirmed that the joint 25 is welded and joined in a balanced manner with high strength, making quality control easier.

Two copper alloy sheets 11 and 13 with the same composition and thickness were stacked together and laser welded using a laser irradiation device equipped with a galvano scanner unit to produce a joint. The front, back and cross section of the welded part of the joint were observed and evaluated. The copper alloy sheets 11 and 13 were made of (Ni,Fe)-P-based copper alloy with a thickness of 0.15 mm.

<Welding conditions>
Example 1
Laser welding was performed in one direction while performing a wobbling motion at a laser output of 3.8 kW and a scanning speed of 10 m/min. The wobbling motion had a rotation diameter of 0.6 mm and a rotation frequency of 250 Hz.
(Comparative Example 1)
Laser welding was performed linearly along one welding direction at a laser output of 4.7 kW and a scanning speed of 20 m/min.
(Comparative Example 2)
Laser welding was performed linearly along one welding direction at a laser output of 4.5 kW and a scanning speed of 20 m/min.

<Evaluation Results>
8 to 10 are images showing the evaluation results of Example 1, Comparative Example 1, and Comparative Example 2. In each figure, (A) is an image of the side irradiated with the laser light, (B) is an image of the side opposite to the side irradiated with the laser light, and (C) is an image of a cross section at the joint.

Example 1
In Example 1, as shown in Fig. 8A, a bead Ba was formed on the surface of the copper alloy plate 11 on the side irradiated with the laser light, and multiple annular weld marks MRa were formed on this bead Ba by rotating the laser light. Also, as shown in Fig. 8B, a bead Bb was formed on the surface of the copper alloy plate 13 on the side opposite to the side irradiated with the laser light, and multiple annular weld marks MRb were also formed on this bead Bb by rotating the laser light. Also, there was no sign of burn-through on the beads Ba and Bb.

In Example 1, as shown in FIG. 8C, a weld 21 was formed that penetrated the joint between the copper alloy plates 11 and 13 in the thickness direction. In this weld 21, the width dimension WBa of the bead Ba formed on the copper alloy plate 11 side was 0.80 mm, and the width dimension WBb of the bead Bb formed on the copper alloy plate 13 side was 0.69 mm. Therefore, the width dimension WBb of the bead Bb was 86% of the width dimension WBa of the bead Ba. In other words, the width dimension WBb was 80% or more of the width dimension WBa, and the weld 21 was formed without bias in the copper alloy plates 11 and 13.

(Comparative Example 1)
In Comparative Example 1, as shown in Fig. 9A, a linear bead Ba was formed along the scanning direction of the laser light on the surface of the copper alloy plate 11 on the side irradiated with the laser light. Also, as shown in Fig. 9B, a linear bead Bb was formed along the scanning direction of the laser light on the surface of the copper alloy plate 13 on the opposite side to the side irradiated with the laser light. However, these beads Ba and Bb were melted through, probably due to the sudden input of heat by the laser light (part F in Fig. 9A and Fig. 9B).

In Comparative Example 1, as shown in FIG. 9C, a weld 21 was formed at the joint between the copper alloy plates 11 and 13, penetrating the joint in the thickness direction. In this weld 21, the width dimension WBa of the bead Ba formed on the copper alloy plate 11 side was 0.66 mm, and the width dimension WBb of the bead Bb formed on the copper alloy plate 13 side was 0.48 mm. Therefore, the width dimension WBb of the bead Bb was 72% of the width dimension WBa of the bead Ba. In other words, the width dimension WBb was less than 80% of the width dimension WBa, and the weld 21 was formed unevenly at the joint between the copper alloy plates 11 and 13.

(Comparative Example 2)
In Comparative Example 2, as shown in Fig. 10A, a linear bead Ba was formed along the scanning direction of the laser light on the surface of the copper alloy plate 11 on the side irradiated with the laser light. However, as shown in Fig. 10B, no bead Bb was formed on the surface of the copper alloy plate 13 on the opposite side to the side irradiated with the laser light.

In Comparative Example 2, as shown in FIG. 10(C), a weld 21 was formed in the copper alloy plate 11 on the side irradiated with the laser light at the joint between the copper alloy plates 11 and 13. However, perhaps due to insufficient output of the laser light L, this weld 21 barely reached the copper alloy plate 13 and was not melted into the copper alloy plate 13.

As such, the present invention is not limited to the above-described embodiment, and the invention also contemplates the mutual combination of the various components of the embodiment, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known technology, and these are included in the scope of the protection sought.

As described above, the present specification discloses the following:
(1) A method for joining a plurality of copper alloy plates by laser welding, comprising the steps of:
A step of stacking and arranging a plurality of the copper alloy plates containing at least one component having a boiling point lower than the melting point of copper;
a laser welding process in which a laser beam is irradiated along a welding direction to an irradiated portion where the copper alloy plates are overlapped with each other, thereby joining the plurality of copper alloy plates;
Including,
In the laser welding step,
The method for joining copper alloy sheets includes scanning the laser light in the welding direction while moving the laser light multiple times in a width direction intersecting the welding direction.
According to the method for joining copper alloy sheets having this configuration, when the overlapping portions of the copper alloy sheets are irradiated with a laser beam along the welding direction, the laser beam is moved multiple times in the width direction intersecting with the welding direction while being scanned in the welding direction. This allows the overlapping portions of the copper alloy sheets to be heated and welded stepwise by the laser beam. In other words, since the heat input can be finely controlled, it is possible to suppress the occurrence of welding defects such as blowholes, cracks, or burn-through caused by the rapid evaporation of the alloy composition while suppressing poor penetration caused by reflection, etc. In addition, by suppressing rapid heating and cooling, it is possible to reduce the occurrence of cracks. In other words, it is possible to laser-weld and join copper alloy sheets, which have high thermal conductivity and low laser beam absorption rate, to which stable heat input is difficult to apply, with high reliability.

(2) The method for joining copper alloy sheets according to (1), wherein the component having a boiling point lower than the melting point of copper contained in the copper alloy sheets is zinc, magnesium or phosphorus.
According to the method for joining copper alloy sheets having this configuration, the occurrence of welding defects due to the sudden evaporation of alloy components such as zinc, magnesium, or phosphorus can be suppressed, and copper alloy sheets can be joined by laser welding with high reliability.

(3) The method for joining copper alloy sheets according to (1) or (2), wherein in the laser welding step, the laser light is scanned in the welding direction while being periodically moved in a width direction intersecting the welding direction.
According to the method for joining copper alloy sheets having this configuration, the laser light is periodically moved in the width direction intersecting the welding direction while being scanned in the welding direction, thereby ensuring time for the molten metal to solidify and promoting the escape of bubbles generated in the molten metal.

(4) The method for joining copper alloy plates according to any one of (1) to (3), wherein in the laser welding step, the laser light is wobbled to rotate an irradiation position while scanning in the welding direction.
According to the method for joining copper alloy sheets having this configuration, the laser light is wobbled and rotated to scan the irradiation position in the welding direction, thereby making it possible to more precisely control the heat input to the welding point and ensure a sufficient amount of heat input while suppressing rapid evaporation of the alloy composition.

(5) In the laser welding step, the laser beam is woven to periodically move an irradiation position in a width direction intersecting the welding direction while scanning the laser beam in the welding direction. The method for joining copper alloy plates according to any one of (1) to (3).
According to the method for joining copper alloy sheets having this configuration, by weaving and periodically moving the irradiation position in the width direction intersecting the welding direction while scanning it in the welding direction, the heat input to the welding point can be controlled more finely, and a sufficient amount of heat input can be secured while suppressing rapid evaporation of the alloy composition.

(6) The method for joining copper alloy sheets according to any one of (1) to (5), wherein the copper alloy sheets to be joined together are thin sheets having a thickness of 0.1 mm to 1.0 mm.
According to the method for joining copper alloy sheets having this configuration, even if the copper alloy sheets to be joined are thin sheets having a thickness of 0.1 mm to 1.0 mm, they can be joined by laser welding with high reliability.

(7) A joint of copper alloy plates in which a plurality of copper alloy plates are overlapped and joined by welding at the overlapping portions,
The overlapping portion is provided with a welded portion formed by solidifying molten metal, penetrating from the front to the back,
A joint of copper alloy plates, wherein the welded portion has a width dimension on the back side that is 80% or more of the width dimension on the front side.
According to the joined body of copper alloy sheets having this configuration, the overlapping portions of the copper alloy sheets have a welded portion penetrating from the front to the back. The width dimension of the welded portion on the back side is 80% or more of the width dimension on the front side. Therefore, a joined body in which the overlapping portions of the copper alloy sheets are joined in a well-balanced manner with high strength by the welded portion can be obtained.

(8) A bead is formed on the front and back of the weld along the welding direction,
The joined body of copper alloy sheets according to (7), wherein each of the beads has a plurality of annular weld marks formed in a continuous manner in the welding direction.
According to the joined copper alloy plates having this configuration, the beads on the front and back of the welded portion have a plurality of annular weld marks that are continuous in the welding direction. Therefore, for example, by irradiating the welded portion with a wobbling laser beam, it is possible to confirm that the joined body is welded with high strength in a balanced manner, which makes it easy to control the quality.

(9) A bead is formed on the front and back of the weld along the welding direction,
The joined body of copper alloy sheets according to (7), wherein each of the beads has a wavy weld mark formed along the welding direction.
In the joined copper alloy sheets having this configuration, the beads on the front and back sides of the welded portion have wavy weld marks along the welding direction. Therefore, for example, by irradiating the weaving laser light, it can be confirmed that the joined sheet is welded with high strength in a balanced manner, and quality control becomes easy.

11, 13 Copper alloy plate 15 Irradiated part 21 Welded part 25 Joint A Welding direction Ba, Bb Bead L Laser light WBa, WBb Width dimension MRa, MRb Annular weld mark MWa, MWb Wavy weld mark

Claims (9)

A method for joining copper alloy plates by laser welding a plurality of copper alloy plates together, comprising the steps of:
A step of stacking and arranging a plurality of the copper alloy plates containing at least one component having a boiling point lower than the melting point of copper ;
a laser welding process in which a laser beam is irradiated along a welding direction to an irradiated portion where the copper alloy plates are overlapped with each other, thereby joining the plurality of copper alloy plates;
Including,
In the laser welding step,
The laser beam is moved a plurality of times in a width direction intersecting the welding direction while being scanned in the welding direction, so that a welded portion in which molten metal is solidified is provided in a portion where the plurality of copper alloy sheets are overlapped, penetrating from the front to the back, and the width dimension of the welded portion on the back side is set to 80% or more of the width dimension on the front side in the width direction .
A method for joining copper alloy plates. The component having a boiling point lower than the melting point of copper contained in the copper alloy plate is zinc, magnesium or phosphorus.
The method for joining copper alloy sheets according to claim 1. In the laser welding step, the laser light is scanned in the welding direction while being periodically moved in the width direction .
The method for joining copper alloy sheets according to claim 1 or 2. In the laser welding step, the laser light is wobbled to rotate an irradiation position while scanning in the welding direction.
The method for joining copper alloy sheets according to any one of claims 1 to 3. In the laser welding step, the laser light is weaved to periodically move an irradiation position in a width direction intersecting the welding direction while scanning the laser light in the welding direction.
The method for joining copper alloy sheets according to any one of claims 1 to 3. The copper alloy plates to be joined together are thin plates having a thickness of 0.1 mm to 1.0 mm;
The method for joining copper alloy sheets according to any one of claims 1 to 5. A joint of copper alloy plates in which a plurality of copper alloy plates containing at least one component having a boiling point lower than the melting point of copper are overlapped with each other and overlapping portions are welded to each other ,
The overlapping portion is provided with a laser welded portion formed by solidifying molten metal, penetrating from the front to the back,
The laser welded portion has a width dimension on the back side in a width direction intersecting with the welding direction on the front side that is 80% or more of the width dimension in the width direction on the back side.
Copper alloy plate joint. Beads are formed on the front and back of the laser welded portion along the welding direction,
Each of the beads has a plurality of annular weld marks formed in a continuous manner in the welding direction.
A joined body of copper alloy sheets according to claim 7. Beads are formed on the front and back of the laser welded portion along the welding direction,
Each of the beads has a wavy weld mark formed along the welding direction.
A joined body of copper alloy sheets according to claim 7.

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