WO2023085336A1 - Welding method, welding device, and metal laminate - Google Patents

Abstract

This welding method is for welding together, for example, a plurality of metallic foils and a metallic member having a first surface facing a first direction, and comprises: a step for retaining the metallic member and the metallic foils in a state where the metallic foils are layered in the first direction on the first surface; and a step for emitting a laser beam on a second surface of the metallic foils located on the side opposite to the metallic member in the first direction. In the step for emitting the laser beam, the laser beam is emitted in such a manner as not to cause the metallic foils to form any wrinkles that protrude in the first direction beyond a prescribed height. Said prescribed height may be set at 0.2 [mm].

Description

Welding method, welding apparatus, and metal laminate

The present invention relates to a welding method, a welding device, and a metal laminate.

Conventionally, a battery is known in which a plurality of tabs and terminals are joined by laser welding (for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2020-4643

As a result of intensive research by the inventors, it has been found that, in this type of laser welding, if laser welding is not performed under appropriate conditions, a gap is generated between the metal foil as the tab and the metal member as the terminal, and some It has been found that the metal foil may be cut, making it difficult to ensure continuity between at least some of the tabs and the terminals.

Therefore, one of the objects of the present invention is to provide a novel improvement that can suppress, for example, the formation of gaps between a plurality of metal foils and a metal member and the cutting of a part of the metal foils. a welding method, a welding apparatus, and obtaining a metal laminate.

In the welding method of the present invention, for example, a metal member having a first surface facing a first direction and a plurality of metal foils are stacked on the first surface in the first direction. and irradiating a second surface of the plurality of metal foils opposite to the metal member in the first direction with a laser beam, wherein the metal member and the plurality of wherein, in the step of irradiating the metal foil with the laser beam, the laser beam is irradiated in a state in which wrinkles exceeding a predetermined height projecting in the first direction of the metal foil do not occur. .

In the welding method, the predetermined height may be 0.2 [mm].

In the welding method, in the step of irradiating the laser beam, wrinkles exceeding the predetermined height protruding in the first direction of the metal foil do not occur as the metal foil expands due to the irradiation of the laser beam. Laser light irradiation may be performed.

In the welding method, in the step of irradiating the laser light, the laser light irradiation may be performed multiple times.

In the welding method, in the step of irradiating the laser beam, the irradiation of the laser beam a plurality of times includes a first scan for scanning the spot of the laser beam in a predetermined section on the second surface, and a scan following the first scan. and a second scan of scanning a spot of laser light in a predetermined section on the second surface, and the end point of the first scan and the start point of the second scan may be separated from each other.

In the welding method, the start point of the first scan and the end point of the second scan may overlap.

In the welding method, the start point of the first scan and the start point of the second scan may overlap.

In the welding method, in the step of irradiating the laser beam, each irradiation of the laser beam is carried out between the end portion held by the holding mechanism of the metal member and the plurality of metal foils and the irradiation center of the current irradiation. The distance in the second direction intersecting the first direction between, or the irradiation center and the current irradiation at the location where the metal member and the plurality of metal foils are welded and fixed by previous irradiation in multiple irradiations may be performed so that the distance in the second direction between the irradiation center of is 3 [mm] or less.

In the welding method, in the step of irradiating the laser light, a position closer to the end held by the holding mechanism between the metal member and the plurality of metal foils is first irradiated with the laser light, and the end is held by the holding mechanism. Irradiation of the laser light to a position farther from the position may be performed later.

In the welding method, in the step of irradiating the laser beam, the plurality of irradiations of the laser beam include the first irradiation of the laser beam and the irradiation of the laser beam which is performed after the first irradiation and is farther from the end than the first irradiation. A second irradiation with a longer scanning length than the first irradiation may be included, which is irradiation of the position with a laser beam.

In the welding method, in the step of irradiating the laser beam, two mutually separated ends of the laminate including the metal member and the plurality of metal foils are respectively held by the holding mechanism, and the plurality of laser beams are emitted from the holding mechanism. The first irradiation of the laser beam to a plurality of locations away from each of the two ends, and a position between the two ends and between the first irradiation of at least two locations and a second irradiation of the laser light to the.

In the welding method, the scanning length of the second irradiation may be longer than the scanning length of the first irradiation at the at least two locations between which the second irradiation is located.

In the welding method, in the step of irradiating the laser beam, the laser beam irradiation may be performed a plurality of times so as to partially overlap each other to form a massive welded portion.

In the welding method, in the step of holding the metal member and the plurality of metal foils, the plurality of metal foils and the plurality of metal foils are respectively held in the first direction. In the step of holding by a plurality of holding mechanisms separated in a second direction intersecting the first direction and irradiating the laser beam, the plurality of holding mechanisms separated in the second direction In between, the second surface may be irradiated with the laser light.

In the welding method, the distance between the plurality of holding mechanisms in the second direction may be 2 [mm] or more.

In the welding method, at least one of the plurality of holding mechanisms is separated from the laminate including the metal member and the plurality of metal foils in the second direction by the two holding members. Even if the absolute value of the difference between the thickness of the laminate in the first direction and the thickness of the intervening member in the first direction is 0.5 [mm] or less good.

In the welding method, in the step of irradiating the laser beam, the laser beam comprises a first laser beam that forms a first spot on the second surface and a second laser beam that forms a second spot on the second surface. and laser light.

In the welding method, the wavelength of the first laser beam may be 800 [nm] or more and 1200 [nm] or less, and the wavelength of the second laser beam may be 550 [nm] or less.

In the welding method, the wavelength of the second laser light may be 400 [nm] or more and 500 [nm] or less.

In the welding method, in the step of irradiating the laser beam, on the second surface, a first spot formed on the second surface by the first laser beam and the second spot formed on the second surface by the second laser beam. A second spot formed on the surface may at least partially overlap.

In the welding method, the metal foil may be made of a copper-based material.

For example, the welding device of the present invention includes a metal member having a first surface facing a first direction, and a plurality of metal foils, the plurality of metal foils being stacked on the first surface in the first direction. A welding device for welding in a state in which a laser beam is output from a light source, and the laser beam output from the light source is directed to a second side of the plurality of metal foils opposite to the metal member in the first direction. An optical head that irradiates on two sides, and a welding device in which the metal member and the plurality of metal foils are held in a state in which wrinkles exceeding a predetermined height protruding in the first direction of the metal foils do not occur. .

The welding device may include a holding mechanism that holds the metal member and the plurality of metal foils in a state in which wrinkles exceeding a predetermined height projecting in the first direction of the metal foils do not occur.

In the welding device, the optical head irradiates the laser beam under conditions that do not cause wrinkles exceeding the predetermined height protruding in the first direction in the metal foil as the metal foil expands due to the irradiation of the laser beam. may be performed.

For example, the welding device of the present invention includes a metal member having a first surface facing a first direction, and a plurality of metal foils, the plurality of metal foils being stacked on the first surface in the first direction. A welding device for welding in a state in which a light source for outputting a laser beam and a second laser beam output from the light source are provided on a second side of the plurality of metal foils opposite to the metal member in the first direction. an optical head that irradiates the surface, a sensor that detects the height of wrinkles protruding in the first direction of the plurality of metal foils, and a height of the wrinkles detected by the sensor that is equal to or less than a predetermined value. and a controller for controlling operation of the light source.

The metal laminate of the present invention is, for example, a metal laminate in which a metal member having a first surface facing a first direction and a plurality of metal foils are welded together, At least one weld that penetrates the plurality of metal foils and reaches the metal member from a second surface opposite to the metal member in one direction, and on the second surface, the The distance between the center of irradiation at the welded portion and the pinching mark formed by pinching the metal laminate between the pinching members or the center of irradiation at another welded portion is 3 mm or less.

According to the present invention, for example, a novel and improved welding method that can suppress the formation of gaps between a plurality of metal foils and metal members and the cutting of some metal foils. Devices and metal laminates can be obtained.

FIG. 1 is an exemplary schematic configuration diagram of a laser welding device according to the first embodiment. FIG. 2 is an exemplary and schematic cross-sectional view of a metal laminate as an object to be processed by the laser welding apparatus of the embodiment. FIG. 3 is an exemplary and schematic cross-sectional view of a battery including a metal laminate as an object to be processed by the laser welding apparatus of the embodiment. FIG. 4 is an exemplary schematic diagram showing a beam (spot) of a laser beam formed on the surface of a metal laminate as an object to be processed by the laser welding apparatus of the embodiment. FIG. 5 is a graph showing the light absorptance of each metal material with respect to the wavelength of the irradiated laser light. FIG. 6 is a flow chart showing an example of a procedure of a welding method using the laser welding device of the embodiment. FIG. 7 is an exemplary and schematic cross-sectional view showing a part of the metal laminate to be processed by the laser welding apparatus of the embodiment, and is a cross-sectional view when a preferable bonding state is obtained. FIG. 8 is an exemplary and schematic cross-sectional view showing a part of the metal laminate as a processing target of the laser welding apparatus of the embodiment, in which a gap is generated between the metal member and the plurality of metal foils. FIG. 5 is a cross-sectional view when an unfavorable bonding state is obtained; FIG. 9 is an exemplary and schematic cross-sectional view showing a part of the metal laminate as a processing target of the laser welding apparatus of the embodiment, in which a part of the metal foil is cut and an unfavorable joining state is obtained. FIG. 10 is a cross-sectional view when the FIG. 10 is an exemplary schematic plan view showing an example of a welded portion and a welding procedure on the surface of a metal laminate to be processed by the laser welding apparatus of the embodiment. FIG. 11 is an exemplary schematic plan view showing an example of a welded portion and a welding procedure on the surface of a metal laminate to be processed by the laser welding apparatus of the embodiment. FIG. 12 is an exemplary schematic plan view showing an example of a welded portion and a welding procedure on the surface of a metal laminate to be processed by the laser welding apparatus of the embodiment. FIG. 13 is an exemplary schematic plan view showing an example of a welded portion and a welding procedure on the surface of a metal laminate to be processed by the laser welding apparatus of the embodiment. FIG. 14 is an exemplary schematic plan view showing an example of a welded portion and a welding procedure on the surface of a metal laminate to be processed by the laser welding apparatus of the embodiment. FIG. 15 is an exemplary schematic plan view showing an example of a welded portion and a welding procedure on the surface of a metal laminate to be processed by the laser welding apparatus of the embodiment. FIG. 16 is an exemplary schematic plan view showing an example of a welded portion and a welding procedure on the surface of a metal laminate to be processed by the laser welding apparatus of the embodiment. FIG. 17 is an exemplary schematic plan view showing an example of a welded portion and a welding procedure on the surface of a metal laminate to be processed by the laser welding apparatus of the embodiment. FIG. 18 is an exemplary and schematic plan view showing an example of welding sites and welding procedures on the surface of a metal laminate to be processed by the laser welding apparatus of the embodiment. FIG. 19 is an exemplary schematic configuration diagram of the laser welding device of the second embodiment. FIG. 20 is an explanatory diagram showing the concept of the principle of the diffractive optical element included in the laser welding device of the second embodiment. FIG. 21 is an exemplary schematic configuration diagram of a laser welding device according to the third embodiment.

Exemplary embodiments of the present invention are disclosed below. The configurations of the embodiments shown below and the actions and results (effects) brought about by the configurations are examples. The present invention can be realized by configurations other than those disclosed in the following embodiments. Moreover, according to the present invention, it is possible to obtain at least one of various effects (including derivative effects) obtained by the configuration.

The embodiments shown below have similar configurations. Therefore, according to the configuration of each embodiment, similar actions and effects based on the similar configuration can be obtained. Moreover, below, while the same code|symbol is provided to those same structures, the overlapping description may be abbreviate|omitted.

Also, in each figure, the X direction is indicated by an arrow X, the Y direction is indicated by an arrow Y, and the Z direction is indicated by an arrow Z. The X-, Y-, and Z-directions intersect and are orthogonal to each other. Also, the scanning direction SD is represented by an arrow SD. The Z direction is the normal direction of the surface Wa (machined surface, welded surface) of the workpiece W, the thickness direction of the metal foil 12 , and the stacking direction of the metal foil 12 and the metal laminate 10 .

Also, in this specification, ordinal numbers are given for convenience to distinguish directions, processes, laser beams, spots, parts, members, sites, etc., and do not indicate priority or order.

[First embodiment]
FIG. 1 is a schematic configuration diagram of a laser welding device 100 of the first embodiment. As shown in FIG. 1, the laser welding device 100 includes a laser device 111, a laser device 112, an optical head 120, an optical fiber 130, a sensor 140, and a control device 150. Laser welding device 100 is an example of a welding device.

The laser devices 111 and 112 each have a laser oscillator, and are configured to output laser light with a power of, for example, several kW. The laser devices 111 and 112 emit laser light with a wavelength of 380 [nm] or more and 1200 [nm] or less. The laser devices 111 and 112 internally have laser light sources such as fiber lasers, semiconductor lasers (elements), YAG lasers, and disk lasers. The laser devices 111 and 112 may be configured to output multimode laser light with a power of several kW as the total output of a plurality of light sources.

The laser device 111 outputs a first laser beam with a wavelength of 800 [nm] or more and 1200 [nm] or less. Laser device 111 is an example of a first laser device. As an example, the laser device 111 has a fiber laser or a semiconductor laser (element) as a laser light source. The laser oscillator included in the laser device 111 is an example of a light source and can also be called a first laser oscillator.

On the other hand, the laser device 112 outputs a second laser beam with a wavelength of 550 [nm] or less. Laser device 112 is an example of a second laser device. As an example, the laser device 112 has a semiconductor laser (element) as a laser light source. The laser device 112 preferably outputs a second laser beam with a wavelength of 400 [nm] or more and 500 [nm] or less. The laser oscillator included in the laser device 112 is an example of a light source and can also be called a second laser oscillator.

The optical fiber 130 guides the laser beams output from the laser devices 111 and 112 to the optical head 120, respectively.

The optical head 120 is an optical device for irradiating the object W to be processed with laser light input from the laser devices 111 and 112 . The optical head 120 includes a collimating lens 121, a condensing lens 122, a mirror 123, and a filter . Collimating lens 121, condensing lens 122, mirror 123, and filter 124 may also be referred to as optics.

The optical head 120 is configured to be able to change its relative position with respect to the processing target W in order to scan the laser light L while irradiating the surface Wa of the processing target W with the laser light L. Relative movement between the optical head 120 and the workpiece W can be realized by moving the optical head 120, moving the workpiece W, or moving both the optical head 120 and the workpiece W.

Note that the optical head 120 may be configured to be able to scan the surface Wa with the laser light L by having a galvanometer scanner or the like (not shown).

The collimating lenses 121 (121-1, 121-2) collimate the laser light input via the optical fiber 130, respectively. The collimated laser light becomes parallel light.

The mirror 123 reflects the first laser light collimated by the collimating lens 121-1. The first laser beam reflected by the mirror 123 travels in the opposite direction of the Z direction and travels toward the filter 124 . Note that the mirror 123 is not necessary in the configuration in which the first laser light is input so as to travel in the direction opposite to the Z direction in the optical head 120 .

The filter 124 is a high-pass filter that transmits the first laser beam and reflects the second laser beam without transmitting it. The first laser beam passes through the filter 124 and travels in the opposite direction of the Z direction to the condenser lens 122 . On the other hand, the filter 124 reflects the second laser beam collimated by the collimating lens 121-2. The second laser beam reflected by the filter 124 travels in the opposite direction of the Z direction and travels toward the condenser lens 122 .

The condensing lens 122 converges the first laser beam and the second laser beam as parallel light, and irradiates the object W to be processed as laser light L (output light). That is, the optical head 120 outputs the laser beam L substantially along the direction opposite to the Z direction, and irradiates the workpiece W with the laser beam.

The object W to be processed is a metal laminate 10 in which a metal member 11 and a plurality of metal foils 12 are laminated in the Z direction. The metal laminate 10 has a metal member 11 , a plurality of metal foils 12 and welded portions 14 . The welded portion 14 mechanically and electrically connects the metal member 11 and the plurality of metal foils 12 . The metal member 11, the plurality of metal foils 12, and the welded portion 14 are all conductors, and are all made of a copper-based material such as copper or a copper alloy. The welded portion 14 mechanically and electrically connects the metal member 11 and the plurality of metal foils 12 . Note that the metal member 11, the plurality of metal foils 12, and the welded portion 14 may not be made of a copper-based material.

The sensor 140 can detect wrinkles as unevenness on the surface Wa, and is, for example, a non-contact camera, a laser displacement meter, or the like.

Based on the detection result of the sensor 140 in the step of irradiating the laser light L, the control device 150 stops the laser devices 111 and 112, for example, when the height of wrinkles from the surface Wa exceeds a predetermined value. Also, the operation of the laser devices 111 and 112 can be controlled by, for example, reducing the output of the laser devices 111 and 112 .

FIG. 2 is a cross-sectional view of the metal laminate 10. FIG. The metal member 11 has a plate-like shape extending across the Z direction. However, the metal member 11 is not limited to a plate-like member. In addition, the plurality of metal foils 12 are stacked in the Z direction on the end surface 11a of the metal member 11 in the Z direction, that is, on the end surface 11a facing the Z direction. The laser light L output from the optical head 120 is irradiated onto the surfaces Wa of the plurality of metal foils 12 on the side opposite to the metal member 11 in the Z direction. The Z direction is an example of a first direction. The end surface 11a is an example of a first surface. Further, the surface Wa is an example of the second surface, and can also be referred to as a laser beam L irradiation surface. The back surface Wb is the surface of the metal laminate 10 opposite to the front surface Wa in the Z direction.

When the metal laminate 10 is laser-welded by the laser welding apparatus 100, as shown in FIG. It is set in a posture in which the normal direction of the surface Wa is substantially parallel to the Z direction. That is, laser welding is performed in a state in which the metal laminate 10 is held by a plurality of holding mechanisms 210 as shown in FIG.

The holding mechanism 210 has two clamping members 211a and 211b spaced apart from each other in the Z direction. The clamping members 211a and 211b are pressed by a pressing mechanism (not shown) with an appropriate pressing force toward each other in the Z direction. In the example of FIG. 2, the ends of the metal laminate 10 in the Y direction and in the opposite direction to the Y direction are held in the Z direction by holding members 211a and 211b of two holding mechanisms 210, respectively. Each of the holding mechanisms 210 also holds a spacer 220 spaced apart from the metal laminate 10 in a direction crossing the Z direction together with the metal laminate 10 . That is, in each holding mechanism 210, the holding members 211a and 211b hold the metal laminate 10 and the spacer 220 therebetween. Spacer 220 is an example of an intervening member. Also, the direction crossing the Z direction is an example of the second direction.

In such a configuration, the inventors found that if the difference between the Z-direction thickness T1 of the metal laminate 10 and the Z-direction thickness T2 of the spacer 220 is too large, the metal foil 12 wrinkles on the surface Wa. It was found that the wrinkles caused welding defects. From this point of view, the absolute value of the difference between the thickness T1 and the thickness T2 is preferably 0.5 [mm] or less.

By such irradiation of the laser beam L, the welded portion 14 extends from the surface Wa in the direction opposite to the Z direction. The direction opposite to the Z-direction may also be referred to as the depth direction of weld 14 . In addition, the laser beam L is scanned on the surface Wa in a direction that intersects the Z direction (scanning direction SD, see FIG. 7, etc.), so that the welded portion 14 has a cross-sectional shape substantially similar to that of FIG. It will also extend to SD.

FIG. 3 is a cross-sectional view of a battery 1 as an electrical product having a metal laminate 10. FIG. A battery 1 is one application example of the metal laminate 10 . In this case, the metal laminate 10 is an example of an electrical component as a conductor, and an example of an electrical component included in an electrical product. An electrical component may also be referred to as a component part of an electrical product.

The battery 1 shown in FIG. 3 is, for example, a laminated lithium ion battery cell. The battery 1 has two film-like exterior materials 20 . A storage chamber 20 a is formed between the two exterior materials 20 . A plurality of flat positive electrode materials 13p, a plurality of flat negative electrode materials 13m, and a plurality of flat separators 15 are accommodated in the storage chamber 20a. In the housing chamber 20a, the positive electrode material 13p and the negative electrode material 13m are alternately stacked with the separator 15 interposed therebetween. A metal foil 12 extends from each of the plurality of positive electrode materials 13p and the plurality of negative electrode materials 13m. In the example of FIG. 3, the plurality of metal foils 12 extending from each of the positive electrode materials 13p are overlapped on the metal member 11 at the opposite end of the battery 1 in the Y direction, and the metal member 11 and the plurality of metal foils 12 A metal laminate 10 welded with a metal foil 12 is provided. On the positive electrode side, only a portion of the metal member 11 is exposed outside the exterior material 20, and the other portion of the metal member 11, the plurality of metal foils 12, and the welded portion 14 are exposed outside the exterior material 20. not. Metal member 11 constitutes a positive electrode terminal of battery 1 . On the other hand, the plurality of metal foils 12 extending from each of the negative electrode materials 13m are overlapped on the metal member 11 at the Y-direction end of the battery 1, and the metal member 11 and the plurality of metal foils 12 are overlapped at the end. A welded metal laminate 10 is provided. Also on the negative electrode side, only a portion of the metal member 11 is exposed outside the exterior material 20, and the other portion of the metal member 11, the plurality of metal foils 12, and the welded portion 14 are exposed outside the exterior material 20. not. Metal member 11 constitutes a negative electrode terminal of battery 1 .

As shown in FIG. 3 , each metal laminate 10 is sandwiched between two exterior materials 20 . Airtightness or liquidtightness is ensured between the metal laminate 10 and the exterior material 20 by a sealing material or the like. For this reason, it is preferable that the surface Wa and the rear surface Wb of the metal laminate 10 have as little, as little, or no unevenness as possible. In this regard, according to the welding method of the present embodiment, as will be described in detail later, it is possible to suppress the occurrence of welding defects, so that unevenness of the surface Wa due to welding defects can be reduced. Therefore, the metal laminate 10 welded by the welding method of this embodiment is suitable for the negative electrode terminal of the battery 1 . A negative terminal is an example of an electrical component. The metal laminate 10 or the metal member 11 can also be called an electrode tab or a tab. Moreover, the metal member 11 can also be called a conductive member.

FIG. 4 is a schematic diagram showing a beam (spot) of the laser light L irradiated onto the surface Wa. The beam of the laser light L includes the first laser light beam B1 output from the laser device 111 and the second laser light beam B2 output from the laser device 112 . Each of the beams B1 and B2 has, for example, a Gaussian-shaped power distribution in the radial direction of the cross section perpendicular to the optical axis direction of the beam. However, the power distributions of beam B1 and beam B2 are not limited to Gaussian shapes. In each drawing, such as FIG. 4, in which the beams B1 and B2 are represented by circles, the diameter of the circle representing the beams B1 and B2 is the beam diameter of each beam B1 and B2. The beam diameter of each of the beams B1 and B2 is defined as the diameter of the region including the peak of the beam and having an intensity of 1/e2 or ^more of the peak intensity. Although not shown, in the case of a non-circular beam, the beam diameter can be defined as the length of the region in which the intensity is 1/ ^e2 or more of the peak intensity in the direction perpendicular to the scanning direction SD. A beam diameter on the surface Wa is called a spot diameter.

As shown in FIG. 4, in this embodiment, as an example, the beam of the laser light L is such that the beam B1 of the first laser light and the beam B2 of the second laser light overlap on the surface Wa, and the beam B2 is It is formed so that it is larger (broader) than the beam B1, and the outer edge B2a of the beam B2 surrounds the outer edge B1a of the beam B1. In this case, the spot diameter D2 of the beam B2 is larger than the spot diameter D1 of the beam B1. On the surface Wa, the beam B1 is an example of a first spot and the beam B2 is an example of a second spot.

Further, in the present embodiment, as shown in FIG. 4, on the surface Wa, the beam (spot) of the laser light L has a point-symmetrical shape with respect to the center point C. Therefore, in an arbitrary scanning direction SD , the spot shape will be the same. Therefore, when a moving mechanism for relatively moving the optical head 120 and the workpiece W for scanning the surface Wa of the laser beam L is provided, the moving mechanism should have at least a relatively translatable mechanism. In some cases, the relatively rotatable mechanism can be omitted.

[Wavelength and light absorption rate]
Here, the light absorptivity of the metal material will be described. FIG. 5 is a graph showing the light absorptance of each metal material with respect to the wavelength of the laser light L to be irradiated. The horizontal axis of the graph in FIG. 5 is the wavelength, and the vertical axis is the absorptance. FIG. 5 shows the relationship between wavelength and absorptance for aluminum (Al), copper (Cu), gold (Au), nickel (Ni), silver (Ag), tantalum (Ta), and titanium (Ti). It is shown.

Although the characteristics differ depending on the material, for each metal shown in FIG. 5, blue or green laser light (second laser It can be seen that the energy absorption rate is higher when light is used. This feature becomes remarkable in copper (Cu), gold (Au), and the like.

When the laser beam is irradiated onto the workpiece W, which has a relatively low absorptance with respect to the wavelength used, most of the light energy is reflected and does not affect the workpiece W as heat. Therefore, a relatively high power must be applied to obtain a sufficiently deep melted region. In that case, energy is suddenly applied to the center of the beam, causing sublimation and forming a keyhole.

On the other hand, when laser light is applied to the processing target W, which has a relatively high absorption rate for the wavelength used, most of the input energy is absorbed by the processing target W and converted into heat energy. In other words, since it is not necessary to apply excessive power, the melting is of the thermal conduction type without the formation of keyholes.

In this embodiment, the wavelength of the first laser beam, the wavelength of the second laser beam, and the wavelength of the workpiece W are adjusted so that the absorptance of the workpiece W for the second laser beam is higher than the absorptivity for the first laser beam. A material is selected. In this case, when the scanning direction is the scanning direction SD shown in FIG. A second laser beam is irradiated by a region B2f located in front of SD in FIG. 5 of the beam B2 of the second laser beam. After that, the portion to be welded is irradiated with the beam B1 of the first laser beam, and then the beam B2 of the second laser beam is irradiated with the second laser beam again by the region B2b located behind in the scanning direction SD. be.

Therefore, in the welded part, first, a heat-conducting melted region is generated by irradiation of the second laser beam, which has a high absorptivity in the region B2f. After that, a deeper keyhole-type melted region is generated in the welded portion by the irradiation of the first laser beam. In this case, since the heat-conducting melted region is formed in advance in the welded portion, the required depth is obtained by the lower power first laser beam compared to the case where the heat-conducting melted region is not formed. fused regions can be formed. Furthermore, after that, the welded portion changes its molten state due to the irradiation of the second laser beam, which has a high absorptivity in the region B2b. From this point of view, the wavelength of the second laser light is preferably 550 [nm] or less, more preferably 500 [nm] or less.

In addition, experimental research by the inventors has confirmed that welding defects such as spatter and blowholes can be reduced in welding by irradiation of the beam of laser light L as shown in FIG. This is because the molten pool of the workpiece W formed by the beams B2 and B1 is more stabilized by preheating the workpiece W by the area B2f of the beam B2 before the beam B1 arrives. We can assume that there is.

Furthermore, according to experimental research by the inventors, when the temperature of the metal foil 12 becomes higher than the temperature of the metal member 11 due to the irradiation of the laser light L, the plurality of metal foils 12 expands due to thermal expansion and separates from the metal member 11. As a result, gaps are formed between the metal foils 12 and the metal members 11 , and only the metal foils 12 are welded or between the metal foils 12 and the metal members 11 . It was found that there are cases where welding is performed with a gap left open. Furthermore, the inventors have found that welding with such a gap can be prevented by setting appropriate conditions. The suitable conditions will be described later.

[Welding method]
FIG. 6 is a flow chart showing an example of a laser welding method by the laser welding device 100. As shown in FIG. As shown in FIG. 6, first, as shown in FIG. 2, the metal laminate 10 is held by two holding mechanisms 210, and set in a state in which the surface Wa is irradiated with the laser light L (S1 ). In the state shown in FIG. 2 by S1, the surface Wa is irradiated with a laser beam from the optical head 120 (S2). When the irradiation of all the irradiation points on the surface Wa is completed (Yes in S3), the irradiation of the laser beam L is terminated, and when the irradiation of all the irradiation points on the surface Wa is not completed (in S3 No), S2 is executed. That is, when the irradiation of the laser beam L is performed on a plurality of locations on the surface Wa, S2 is executed a plurality of times. In each time of S2, the laser light L may be irradiated at a fixed point on the surface Wa, that is, spot-irradiated, or may be scanned along the surface Wa in a scanning direction SD that intersects the Z direction. . In S2, the portion irradiated with the laser light L melts and then solidifies as the temperature drops, thereby welding the metal member 11 and the plurality of metal foils 12 together, and the metal laminate 10 is integrated. (solidification step). In the solidification process, cooling of the metal laminate 10 may be natural cooling or forced cooling using a cooling mechanism.

[Cross section of weld]
FIG. 7 is a cross-sectional view (a photographic image of a cross section) of the metal laminate 10 including the welded portion 14 when a preferable bonding state is obtained. As shown in FIG. 7, in a preferable bonded state, the welded portion 14 penetrates the plurality of metal foils 12 from the surface Wa in the direction opposite to the Z direction, reaches the inside of the metal member 11, and reaches the inside of the metal member 11. is eating into

The inventors, through repeated experimental research, found that an unfavorable bonding state as shown in Fig. 8 may be obtained. FIG. 8 shows a state in which a gap G is formed between a plurality of metal foils 12 and the metal member 11. As shown in FIG. The plurality of metal foils 12 are thermally expanded by being heated by the irradiation of the laser light L. As shown in FIG. In this case, since the metal member 11 is adjacent to the plurality of metal foils 12 in the direction opposite to the Z direction, the plurality of metal foils 12 are buckled according to the elongation, and the gap G is generated. If the gap G in this case becomes large, as shown in FIG. An unfavorable bonding state is obtained in which the two are not mechanically and electrically connected to each other.

According to the intensive research of the inventors, on the surface Wa of the metal foil 12, wrinkles do not occur, or even if wrinkles occur, the height of the wrinkles, that is, the general portion of the surface Wa (wrinkles occur) It has been found that the gap G shown in FIG. 8 does not occur unless the height of the wrinkles in the Z direction from the flat portion where the surface is not flat does not exceed 0.2 [mm]. In addition, the inventors' intensive research has revealed that the wrinkles, regardless of thermal expansion, also cause the same gap G even when they are generated before the laser beam L is applied in the set state. bottom. That is, it was found that the holding mechanism 210 needs to hold the metal laminate 10 in a state in which wrinkles with a height in the Z direction exceeding 0.2 [mm] do not occur.

In addition, the inventors have also discovered through repeated experimental research that an unfavorable bonding state as shown in FIG. 9 may be obtained. FIG. 9 shows a state in which a part of the metal foils 12 located near the ends in the Z direction is cut. Since the metal foil 12 is thin by itself, in a state in which the plurality of metal foils 12 are likely to come apart, depending on the irradiation intensity of the laser beam L, some of the metal foils 12 may be cut as shown in FIG. An unfavorable bonding state is obtained in which the metal foil 12 is not mechanically and electrically connected to the metal member 11 . Hereinafter, this phenomenon will be referred to as partial cutting S.

[Welding conditions]
As a result of extensive studies by the inventors, it was found that by irradiating the laser beam L so as to satisfy the following conditions (1) to (4), the unfavorable bonding state shown in FIGS. However, it was found that a preferable bonded state as shown in FIG. 7 was obtained.

(1) The irradiation time of the laser light L is set to a predetermined time or less, or the scanning length ls (see FIG. 12) of the laser light L is set to a predetermined length or less.
As a result, it has been found that the gap G and the partial cut S can be suppressed. It is considered that this is because gaps G and partial cuts S can be suppressed by suppressing local increases in irradiation energy. As an example, the metal laminate 10 includes 50 metal foils 12 made of a copper-based material having a thickness of 8 [μm] and metal members 11 made of a copper-based material having a thickness of 1 [mm]. , the holding mechanism 210 is fixed so that the distance in the direction intersecting the Z direction is 3 [mm], and the wavelength is 1070 [nm] and the output power is 800 [W]. When laser light L including a laser light and a second laser light having a wavelength of 450 [nm] and an output power of 500 [W] is irradiated onto the surface Wa (hereinafter referred to as condition A), the laser light It was found that the irradiation time of L is preferably 0.1 [s] or less. Further, according to such a point of view, the irradiation of the laser beam L may be performed, for example, at a plurality of locations on the surface Wa, at positions separated from each other on the surface Wa, or at a plurality of times. It can be said that it is preferable to execute. In this case, an appropriate time interval may be provided between multiple locations and multiple times of irradiation. However, as a result of repeated experimental research by the inventors, this condition (1) is a condition determined according to specific specifications, and the irradiation time and scanning length of each welding portion are different from each other. It was found that the larger the volume of the laminate 10 or the plurality of metal foils 12 and the larger the area of the surface Wa, the longer the length can be set.

(2) When performing multiple irradiations of the laser light L, the position of the end point of the previous irradiation and the position of the start point of the next irradiation are separated from each other in two successive irradiations.
As a result, it has been found that the gap G and the partial cut S can be suppressed. This is also considered to be because the gap G and the partial cutting S can be suppressed by suppressing the local increase in the irradiation energy, as in (1). As an example, in the case of the above condition A, the position of the end point of the irradiation performed first and the position of the start point of the irradiation performed next are 2 [ mm] or more has been found to be preferable. However, as a result of repeated experimental research by the inventors, this condition (2) is a condition determined according to specific specifications, and the length of the interval between the previous end point and the current start point is , the larger the volume of the metal laminate 10 or the plurality of metal foils 12 and the larger the area of the surface Wa, the shorter it can be set.

(3) Make the distances d1 and d2 (see FIGS. 10 and 12) from the fixed position to the irradiation site less than or equal to a predetermined length.
It has been found that this can suppress the partial cutting S. This is because the longer the distances d1 and d2 in the line of sight in the direction opposite to the Z direction, the weaker the holding force on the metal foil 12 becomes and the easier it is for the metal foil 12 to move independently, and the easier it is for the metal foil 12 to move away from the molten pool during welding. This is considered to be because Here, the fixed position is the end portion 10e (see FIGS. 2 and 10) held by the holding mechanism 210 of the metal laminate 10, or the plurality of metal foils 12 in the previous irradiation when multiple irradiations are performed. and the metal member 11 are welded and fixed (14 (P1), etc., see FIG. 12). In addition, the distance d1 is the distance between the edge 10e and the current irradiation center in the direction intersecting the Z direction, and the distance d2 is the distance between the irradiation center of the previous fixed location and the current irradiation center intersecting the Z direction. is the distance in the direction. As an example, in the case of condition A, it has been found that the distances d1 and d2 are preferably 3 [mm] or less. Note that the irradiation site may also be referred to as an irradiation area, an irradiation range, or an irradiation position.

(4) The distance Dw (see FIGS. 2 and 10) of the plurality of holding mechanisms 210 in the direction crossing the Z direction is set to a predetermined length or longer.
It has been found that the gap G can be suppressed by this. It is considered that this is because the shorter the distance Dw in the line of sight opposite to the Z direction, the greater the amount of bending in the Z direction due to the extension of the plurality of metal foils 12 . As an example, in the case of condition A, it was found that the distance Dw is preferably 2 [mm] or more.

[Specific examples of welding parts and welding procedures]
10 to 18 are plan views of the metal laminate 10 showing examples of welding sites (irradiation sites) and welding procedures (irradiation procedures) that satisfy the above conditions (1) to (4). 10 to 18, the metal laminate 10 is sandwiched by a plurality of (two in this embodiment) holding mechanisms 210 spaced apart in the Y direction, as shown in FIG. In each holding mechanism 210, two holding members 211a and 211b are arranged in the Z direction. Therefore, the end 10e of the metal laminate 10 on the front surface Wa and the end 10e of the metal laminate 10 on the back surface Wb are aligned in the Z direction. Also, as shown in FIGS. 10 to 18, the ends 10e spaced apart in the Y direction extend in the X direction and are substantially parallel to each other. 2 and 10 to 18 and after removing the holding mechanism 210, clamping members 211a and 211b are provided on the front surface Wa and the back surface Wb of the metal laminate 10 corresponding to the end portion 10e. A level difference or a concave groove is generated as a pressing mark (not shown) caused by being sandwiched by the two. The press trace is formed in a linear shape extending in the X direction. Press marks may also be referred to as pinch marks.

In the example of FIG. 10, the metal laminate 10 is irradiated with spots of the laser beam L in the order of irradiation sites P1, P2, and P3 (welding sites), thereby forming a plurality of (three) welds 14. be done. Each of the irradiation sites P1 to P3 extends for a predetermined length in the X direction at a substantially central portion in the Y direction between two ends 10e separated from each other in the Y direction. The dashed arrow in the figure indicates the scanning direction of the spot of the laser light L on the surface Wa. Here, the irradiation site P2 is located in the opposite direction in the X direction to the irradiation site P1, and the irradiation site P3 is located in the opposite direction in the X direction to the irradiation site P2. Also, the spots are scanned in the X direction at each of the irradiation sites P1 to P3. Therefore, the start point p2s of the irradiation site P2 is separated from the end point p1e of the previous irradiation site P1, and the start point p3s of the irradiation site P3 is separated from the end point p2e of the previous irradiation site P2. In this manner, by separating the start point of the current irradiation from the end point of the previous irradiation in each of the irradiation sites P1 to P3, the energy given to the metal laminate 10 by the laser light L is suppressed from locally increasing. However, the extension of the plurality of metal foils 12 and the bending (buckling) in the Z direction due to the extension are locally increased, thereby suppressing the occurrence of partial cutting S of the metal foils 12 . Note that although the previous irradiation start point (for example, start point p1s) and the current irradiation end point (for example, end point p2e) overlap each other in the example of FIG. 10, they do not necessarily overlap. In this case, the irradiation on the irradiation site P1 is an example of the first scan, and the irradiation on the irradiation site P2 is an example of the second scan.

In the example of FIG. 11, similarly to the example of FIG. 10, the metal laminate 10 is irradiated with the spot of the laser beam L in order of the irradiation sites P1, P2, and P3, thereby welding at a plurality of sites (three sites). A portion 14 is formed. However, in the example of FIG. 11, the scanning direction, start point p3s and end point p3e at the irradiation site P3 are reversed from the example of FIG. 10, and the start point p2s and the start point p3s overlap. However, in this case as well, the start point of the current irradiation can be separated from the end point of the previous irradiation in each of the irradiation sites P1 to P3, thereby obtaining the same effect as in the example of FIG. In this case, the irradiation on the irradiation site P2 is an example of the first scan, and the irradiation on the irradiation site P3 is an example of the second scan.

In the example of FIG. 12, the metal laminate 10 is irradiated with spots of the laser beam L in the order of irradiation sites P1, P2, P3, P4, and P5, thereby forming a plurality of (five) welds 14. be done. Note that the spots of the laser light L are not scanned at the irradiation sites P1 to P4, but are fixed point irradiation. In the example of FIG. 12, compared to FIGS. 10 and 11, the distance Dw between the two holding mechanisms 210 is longer, so the bending amount (buckling amount) in the Z direction due to the extension of the plurality of metal foils 12 is reduced. This makes it difficult for the gap G to occur. However, as in the examples of FIGS. 10 and 11, if the central position in the Y direction between the end portions 10e is irradiated, the distance from the fixed position to the irradiation site becomes long, and partial cutting S is likely to occur. Therefore, in the example of FIG. 12, first, the laser beam L is irradiated at the irradiation sites P1 to P4 having a smaller distance d1 from the end 10e, and the irradiation sites P1 to P4 are solidified to form the welded portion 14. With the irradiation sites P1 to P4 at fixed positions, the laser light L is irradiated onto the irradiation site P5 at a distance d2 from the irradiation sites P1 to P4. By setting the irradiation site and the irradiation procedure in this way, welding is performed while suppressing the distance from the fixed position to each irradiation site from becoming long and suppressing partial cutting S due to wrinkles for a wider range of the surface Wa. be able to. Also, as shown in FIG. 12, the scanning length ls of the irradiation site P5 is longer than the scanning lengths of the irradiation sites P1 to P4 in FIGS. Thus, the longer the distance Dw between the holding mechanisms 210 and the larger the area of the surface Wa, that is, the larger the volume of the metal laminate 10 and the plurality of metal foils 12, the more the occurrence of the gap G and the partial cut S is suppressed. However, the scan length can be set longer. This means that the irradiation time and scanning length at each irradiation site can be set longer as long as the conditions (3) and (4) are satisfied. In this case, the irradiation of the irradiation sites P1 to P4 is an example of the first irradiation, and the irradiation of the irradiation site P5 is an example of the second irradiation.

In the example of FIG. 13, the metal laminate 10 is irradiated with spots of the laser beam L in the order of the irradiation sites P1, P2, P3, P4, P5, P6, and P7, thereby welding at a plurality of sites (seven sites). A portion 14 is formed. In the example of FIG. 13, the number of irradiated regions is increased compared to the example of FIG. As shown in FIGS. 12 and 13, the number and arrangement of irradiation sites can be set arbitrarily within the range satisfying the above conditions (1) to (4). In this case, the irradiation of the irradiation sites P1 to P6 is an example of the first irradiation, and the irradiation of the irradiation site P7 is an example of the second irradiation.

In the example of FIG. 14, the metal laminate 10 is irradiated with spots of the laser beam L in the order of irradiation sites P1, P2, P3, P4, and P5, thereby forming a plurality of (five) welded portions 14. be done. In the example of FIG. 14, the spot of the laser light L is scanned at each of the irradiation sites P1 to P5. As shown in FIGS. 12 and 14, the scanning length of each irradiated portion can be arbitrarily set within the range satisfying the above conditions (1) to (4).

In the example of FIG. 15, the metal laminate 10 is irradiated with spots of the laser beam L in the order of the irradiation sites P1, P2, P3, P4, and P5, thereby forming a plurality of (five) welds 14. be done. In the example of FIG. 15, the scanning direction is along the Y direction at each of the irradiation sites P1 to P5. In this manner, the scanning direction of each irradiation site can be arbitrarily set within the range satisfying the above conditions (1) to (4). Note that the order of a plurality of irradiation sites and the scanning direction can be arbitrarily set within the range satisfying the above conditions (1) to (4), and are not limited to the example in FIG.

In the examples of FIGS. 16 and 18, the metal laminate 10 is irradiated with spots of the laser beam L in the order of irradiation sites P11 to P13, P21 to P23, and P31 to P33, thereby forming welded portions 14 at a plurality of locations. be done. In addition, in the example of FIG. 17, the spot of the laser light L is also irradiated to the irradiation sites P41 to P43 and P51 to P53. As in the examples of FIGS. 16 to 18, a plurality of adjacent irradiation sites may be set so as to be slightly shifted and arranged so as to partially overlap each other. As a result, a massive welded portion is formed by gathering a plurality of welded portions 14 .

As described above, in the welding method using the laser welding apparatus 100 of the present embodiment, for example, in the step of irradiating the surface Wa of the metal laminate 10 with the laser beam L, the surface Wa is irradiated in the Z direction. The laser light L is irradiated in a state in which wrinkles exceeding a predetermined height are not generated. According to such a configuration and method, for example, gaps G and partial cuts S caused by wrinkles can be suppressed, and a higher quality metal laminate 10 can be formed.

[Second embodiment]
FIG. 19 is a schematic configuration diagram of a laser welding device 100A of the second embodiment. In this embodiment, the optical head 120 has a DOE 125 between the collimating lens 121-1 and the mirror 123. FIG. Except for this point, the laser welding device 100A has the same configuration as the laser welding device 100 of the first embodiment.

The DOE 125 shapes the shape of the beam B1 of the first laser light (hereinafter referred to as beam shape). As conceptually illustrated in FIG. 20, the DOE 125 has, for example, a structure in which a plurality of diffraction gratings 125a with different periods are superimposed. The DOE 125 can shape the beam shape by bending or superimposing the parallel beams in the direction affected by each diffraction grating 125a. DOE 125 may also be referred to as a beam shaper.

The optical head 120 includes a beam shaper provided after the collimating lens 121-2 for adjusting the beam shape of the second laser beam, and a filter 124 provided after the beam shape of the first laser beam and the second laser beam. It may also have a beam shaper or the like that adjusts. By appropriately adjusting the beam shape of the laser light L using the beam shaper, it is possible to further suppress the occurrence of spatters and blowholes during welding.

[Third Embodiment]
FIG. 21 is a schematic configuration diagram of a laser welding device 100B of the third embodiment. In this embodiment, the optical head 120 has a galvanometer scanner 126 between the filter 124 and the condenser lens 122 . Except for this point, the laser welding device 100B has the same configuration as the laser welding device 100 of the first embodiment.

The galvanometer scanner 126 has two mirrors 126a and 126b, and by controlling the angles of the two mirrors 126a and 126b, the irradiated portion of the laser beam L can be detected without moving the optical head 120. It is a device that can be moved and scanned with a laser beam L. FIG. The angles of the mirrors 126a and 126b are changed by, for example, motors (not shown). Such a configuration eliminates the need for a mechanism for moving the optical head 120 and the workpiece W relative to each other, and provides an advantage that, for example, the device configuration can be made smaller.

Although the embodiment of the present invention has been illustrated above, the above embodiment is an example and is not intended to limit the scope of the invention. The above embodiments can be implemented in various other forms, and various omissions, replacements, combinations, and modifications can be made without departing from the scope of the invention. In addition, specifications such as each configuration and shape (structure, type, direction, model, size, length, width, thickness, height, number, arrangement, position, material, etc.) may be changed as appropriate. can be implemented.

For example, the present invention can be applied to lithium-ion battery cells with configurations different from those of the above embodiments, and can also be applied to batteries other than lithium-ion battery cells.

Further, when scanning the laser beam, the surface area of the molten pool may be adjusted by performing scanning by known wobbling, weaving, output modulation, or the like.

In addition, a surface layer made of other substances may be formed on the surface of the metal foil or metal member.

The present invention can be used for welding methods, welding equipment, and metal laminates.

DESCRIPTION OF SYMBOLS 1... Battery 10... Metal laminate 10e... End part 11... Metal member 11a... End surface (first surface)
DESCRIPTION OF SYMBOLS 12... Metal foil 13p... Positive electrode material 13m... Negative electrode material 14... Welding part 15... Separator 20... Exterior material 20a... Storage chambers 100, 100A, 100B... Laser welding apparatus (welding apparatus)
111... Laser device (light source)
112... Laser device (light source)
120... Optical head 121, 121-1, 121-2... Collimating lens 122... Collecting lens 123... Mirror 124... Filter 125... DOE (diffractive optical element)
DESCRIPTION OF SYMBOLS 125a... Diffraction grating 126... Galvano scanner 126a, 126b... Mirror 130... Optical fiber 140... Sensor 150... Control device 210... Holding mechanism 211a, 211b... Clamping member 220... Spacer (intervening member)
B1... Beam (first spot)
B1a... Outer edge B2... Beam (second spot)
B2a... outer edge B2b... area B2f... area C... center point D1... spot diameter (outer diameter)
D2...Spot diameter (outer diameter)
d1, d2 --- distance Dw --- distance G --- gap L --- laser light p1e, p2e, p3e --- end point p1s, p2s, p3s --- start point P1-P7, P11-P13, P21-P23, P31-P33, P41-P43, P51 ~ P53 ... Irradiation part S ... Partial cutting SD ... Scanning direction T1, T2 ... Thickness W ... Processing object Wa ... Surface (second surface)
Wb Back surface X Direction Y Direction Z Direction (first direction)

Claims (26)

1. holding a metal member having a first surface facing a first direction and a plurality of metal foils in a state in which the plurality of metal foils are stacked on the first surface in the first direction;
   a step of irradiating a second surface of the plurality of metal foils opposite to the metal member in the first direction with a laser beam;
   A welding method for welding the metal member and the plurality of metal foils,
   The welding method, wherein in the step of irradiating the laser light, the laser light is radiated in a state in which wrinkles exceeding a predetermined height projecting in the first direction of the metal foil do not occur.
2. The welding method according to claim 1, wherein the predetermined height is 0.2 [mm].
3. In the step of irradiating the laser light, the laser light irradiation is performed under conditions in which wrinkles exceeding the predetermined height protruding in the first direction of the metal foil do not occur as the metal foil expands due to the irradiation of the laser light. The welding method according to claim 1 or 2, wherein
4. The welding method according to claim 1, wherein in the step of irradiating the laser light, the laser light irradiation is performed multiple times.
5. In the step of irradiating the laser beam, the irradiation of the laser beam a plurality of times includes a first scan for scanning a laser beam spot in a predetermined section on the second surface, and a laser beam spot next to the first scan. in a predetermined section on the second surface, and the end point of the first scan and the start point of the second scan are separated from each other.
6. The welding method according to claim 5, wherein the start point of the first scan and the end point of the second scan overlap.
7. The welding method according to claim 5, wherein the starting point of the first scanning and the starting point of the second scanning overlap.
8. In the step of irradiating the laser beam, each irradiation of the laser beam is performed between the end held by the holding mechanism of the metal member and the plurality of metal foils and the irradiation center of the current irradiation. A distance in a second direction that intersects the direction, or between the irradiation center at the location where the metal member and the plurality of metal foils are welded and fixed by previous irradiation in multiple irradiations and the irradiation center of the current irradiation The welding method according to claim 4, wherein the distance in said second direction is 3 mm or less.
9. In the step of irradiating the laser light, a position closer to the end held by the holding mechanism of the metal member and the plurality of metal foils is first irradiated with the laser light, and a position farther from the end is irradiated with the laser light. 5. The welding method according to claim 4, wherein irradiation with laser light is performed later.
10. In the step of irradiating the laser light, the multiple irradiations of the laser light are performed after the first irradiation of the laser light and the laser light for a position farther from the end than the first irradiation. and a second irradiation having a longer scan length than the first irradiation.
11. In the step of irradiating the laser light,
    two mutually separated ends of a laminate including the metal member and the plurality of metal foils are held by the holding mechanism;
    The multiple irradiations of the laser light include the first irradiation of the laser light to a plurality of positions away from each of the two ends, and the first irradiation of the at least two positions between the two ends. and a second irradiation of the laser light to an intervening position.
12. The welding method according to claim 11, wherein the scan length of said second exposure is longer than the scan length of said first exposure at said at least two locations between which said second exposure is located.
13. In the step of irradiating the laser light, the multiple irradiations of the laser light are performed so as to partially overlap each other,
    5. The welding method of claim 4, forming a bulk weld.
14. In the step of holding the metal member and the plurality of metal foils, two holding members for holding the plurality of metal foils and the metal members in the first direction, respectively. held by a plurality of holding mechanisms separated in a second direction intersecting the first direction,
    The welding method according to claim 1, wherein in the step of irradiating said laser beam, said laser beam is radiated onto said second surface between a plurality of holding mechanisms separated in said second direction.
15. The welding method according to claim 14, wherein the distance between the plurality of holding mechanisms in the second direction is 2 [mm] or more.
16. At least one of the plurality of holding mechanisms includes a layered body including the metal member and the plurality of metal foils and an intervening member spaced apart from the layered body in the second direction by the two holding members, sandwiching the
    The welding method according to claim 14 or 15, wherein the absolute value of the difference between the thickness of the laminate in the first direction and the thickness of the intervening member in the first direction is 0.5 [mm] or less. .
17. In the step of irradiating the laser beam, the laser beam is composed of a first laser beam that forms a first spot on the second surface and a second laser beam that forms a second spot on the second surface. 2. The welding method of claim 1, comprising:
18. The welding method according to claim 17, wherein the first laser light has a wavelength of 800 [nm] or more and 1200 [nm] or less, and the second laser light has a wavelength of 550 [nm] or less.
19. The welding method according to claim 18, wherein the second laser beam has a wavelength of 400 [nm] or more and 500 [nm] or less.
20. In the step of irradiating the laser beam, on the second surface, a first spot formed on the second surface by the first laser beam and a spot formed on the second surface by the second laser beam The welding method according to any one of claims 17 to 19, wherein the second spot at least partially overlaps.
21. The welding method according to claim 1, wherein the metal foil is made of a copper-based material.
22. A welding device that welds a metal member having a first surface facing a first direction and a plurality of metal foils in a state in which the plurality of metal foils are stacked on the first surface in the first direction. hand,
    a light source that outputs laser light;
    an optical head that irradiates a laser beam output from the light source onto a second surface of the plurality of metal foils opposite to the metal member in the first direction;
    The welding device, wherein the metal member and the plurality of metal foils are held in a state in which wrinkles exceeding a predetermined height projecting in the first direction of the metal foils do not occur.
23. The welding device according to claim 22, comprising a holding mechanism that holds the metal member and the plurality of metal foils in a state in which wrinkles exceeding a predetermined height projecting in the first direction of the metal foils do not occur.
24. 3. The optical head irradiates the laser beam under conditions in which wrinkles exceeding the predetermined height protruding in the first direction of the metal foil do not occur as the metal foil extends due to the irradiation of the laser beam. 24. The welding device according to 22 or 23.
25. A welding device that welds a metal member having a first surface facing a first direction and a plurality of metal foils in a state in which the plurality of metal foils are stacked on the first surface in the first direction. hand,
    a light source that outputs laser light;
    an optical head that irradiates a laser beam output from the light source onto a second surface of the plurality of metal foils opposite to the metal member in the first direction;
    a sensor that detects the height of wrinkles protruding in the first direction of the plurality of metal foils;
    a control device for controlling the operation of the light source so that the height of the wrinkles detected by the sensor is equal to or less than a predetermined value;
    Welding equipment with
26. A metal laminate in which a metal member having a first surface facing a first direction and a plurality of metal foils are welded together,
    Having at least one weld that penetrates the plurality of metal foils and reaches the metal member from a second surface opposite to the metal member in the first direction of the plurality of metal foils,
    On the second surface, the distance between the center of irradiation in the welded portion and the pinching mark where the metal laminate is pinched by a pinching member or the center of irradiation in another welded portion is 3 mm or less. body.

Images