Composite joining system, composite joining method, and composite joining structure

Abstract

Provided is a system, etc., with which it is possible to reduce the likelihood of occurrence of rupturing in a layered metal foil when joining the layered metal foil and a metal material. A layered metal foil W1 is ultrasonically joined by using ultrasonic vibration, whereby a recessed part Tij serving as an ultrasonic joining mark is formed in a designated region of the layered metal foil Ｗ1. Furthermore, the recessed part Tij of the layered metal foil W1, which is arranged so as to be superposed on a metal material W2, is irradiated with a laser beam LB, whereby the layered metal foil W1 and the metal material W2 are joined.

Description

Composite bonding system, composite bonding method, and composite bonding structure

[0001] This invention relates to a technique for joining multiple workpieces by a combination of ultrasonic bonding and laser welding.

[0002] Laser welding has been proposed for joining laminated metal foils (e.g., aluminum foil, aluminum alloy foil, copper foil, or copper alloy foil, etc.) (see, for example, Patent Document 1). The joined metal foils are used, for example, as electrodes in lithium-ion batteries, and efforts are being made to increase the thickness of the laminated metal foil, i.e., the number of metal foils constituting the laminated metal foil, in order to improve the conductivity of the electrodes. Furthermore, as shown in Figure 15, laser welding is also used to attach a metal material W2 constituting a current collector or terminal to the laminated metal foil W1 constituting the electrode.

[0003] Japanese Patent Publication No. 2024-097640

[0004] However, stress may remain between the bead Bd, which is a laser welding mark formed on the laminated metal foil W1, and its adjacent location, and a fracture Rp may occur in the laminated metal foil W1, as shown in Figure 15.

[0005] Therefore, the present invention aims to provide a system that can reduce the probability of breakage occurring in laminated metal foil when joining laminated metal foil and metal materials, as well as a current collection structure in a secondary battery, etc.

[0006] The present invention provides a composite bonding system comprising: an ultrasonic bonding device that bonds a laminated metal foil in a designated region by propagating ultrasonic vibrations induced in an ultrasonic vibration element to the designated region of the laminated metal foil via an ultrasonic bonding tip; and a laser welding device that welds the laminated metal foil bonded by the ultrasonic bonding device to a metal material using laser light in at least one of the designated region of the laminated metal foil and an adjacent region of the designated region.

[0007] In the composite joining system of the present invention, the laser welding apparatus is configured to irradiate the overlapping region of the laminated metal foil, which is arranged to overlap the metal material in at least one of the designated region and an adjacent region of the designated region, with laser light to weld the laminated metal foil and the metal material.

[0008] The composite bonding method of the present invention includes an ultrasonic bonding step of bonding a laminated metal foil in a designated region by propagating ultrasonic vibrations induced in an ultrasonic vibration element to the designated region of the laminated metal foil via an ultrasonic bonding tip, and a laser welding step of welding the laminated metal foil bonded in the ultrasonic bonding step to a metal material using laser light in at least one of the designated region of the laminated metal foil and an adjacent region of the designated region.

[0009] The composite bonding structure of the present invention has composite ultrasonic welding marks formed in a designated area of ​​the laminated metal foil, and laser welding marks formed in at least one of the designated area and an adjacent area.

[0010] According to the composite bonding system and composite bonding method of the said configuration, laminated metal foils are ultrasonically bonded using ultrasonic vibrations, thereby forming ultrasonic bonding marks in a designated area of ​​the laminated metal foil. Furthermore, by irradiating at least a portion of the designated area of ​​the laminated metal foil placed on a metal material with laser light, the laminated metal foil and the metal material constituting the current collector are bonded. Although stress due to solidification occurs near the laser welding marks (or beads), the laser output is adjusted to make the size of the melting target area or irradiation area smaller than the size of the designated area. As a result, the effect of solidification shrinkage is confined to the ultrasonic bonding marks, and the stress acts not on the individual metal foils, but on the aggregate of multiple ultrasonically bonded metal foils (ultrasonic bonding marks). Therefore, according to the composite bonding system and composite bonding method of the said configuration, and furthermore, the composite bonded structure of the said configuration manufactured therefrom, the probability of fracture due to the stress in the laminated metal foil is reduced.

[0011] Diagram illustrating the configuration of a composite bonding system as one embodiment of the present invention. Diagram illustrating the configuration of an ultrasonic bonding tip. Flowchart of the ultrasonic bonding process. Flowchart of the laser welding process. Photograph of ultrasonically bonded laminated metal foil. Partial cross-sectional photograph of ultrasonically bonded laminated metal foil. Partial configuration diagram of a composite bonding structure. Diagram illustrating the configuration of a composite bonding structure as a first embodiment. Diagram illustrating the configuration of a composite bonding structure as a second embodiment. Bottom view of a horn tip in another embodiment. Side view of a horn tip in another embodiment. Diagram illustrating the configuration of ultrasonic bonding marks formed on laminated metal foil in another embodiment. Diagram illustrating the configuration of a composite bonding structure in another embodiment. Diagram illustrating one aspect of laser welding. Diagram illustrating another aspect of laser welding. Exemplary configuration diagram of a composite bonding structure. Bottom view of a horn tip in yet another embodiment. Side view of a horn tip in yet another embodiment. Diagram illustrating the configuration of ultrasonic bonding marks formed on laminated metal foil in yet another embodiment. Diagram illustrating the configuration of a composite bonding structure in yet another embodiment. Partial cross-sectional photographs of laminated metal foil and metal material laser-welded by the prior art.

[0012] (Configuration of the composite bonding system) The composite bonding system shown in Figure 1, as one embodiment of the present invention, comprises an ultrasonic bonding device 1 and a laser welding device 2.

[0013] (Configuration of the ultrasonic bonding apparatus) As shown in Figure 1, the ultrasonic bonding apparatus 1 comprises an ultrasonic vibrating element 10, a horn tip 140 (ultrasonic bonding tip), an anvil 118, a control device 120, a high-frequency power supply 121, a translational drive device 122, a state sensor 124, and an interface device 126. The ultrasonic vibrating element 10 comprises a substantially cylindrical first vibrating element 111, a substantially cylindrical, substantially cylindrical, or substantially bottomed cylindrical intermediate vibrating element 110, and a substantially cylindrical or substantially bottomed cylindrical second vibrating element 112.

[0014] The first vibration element 111 and the intermediate vibration element 110 are coaxially connected by a mechanical coupling mechanism (such as a bolt and / or clamp mechanism) in the middle abdomen or intermediate part of the ultrasonic vibration element 10. The intermediate vibration element 110 and the second vibration element 112 are coaxially connected by a mechanical coupling mechanism in the middle abdomen of the ultrasonic vibration element 10. The first vibration element 111, the intermediate vibration element 110, and the second vibration element 112 may be integrally formed instead of being mechanically connected.

[0015] The intermediate vibration element 110 may be a component of the first vibration element 111. That is, the first vibration element 111 may be composed of two vibration elements. In this case, the first vibration element 111 and the intermediate vibration element 110 may be integrally formed instead of being mechanically connected. The intermediate vibration element 110 may be a component of the second vibration element 112. That is, the second vibration element 112 may be composed of two vibration elements. In this case, the second vibration element 112 and the intermediate vibration element 110 may be integrally formed instead of being mechanically connected.

[0016] As shown in FIG. 1, a piezoelectric body 1112 whose axial direction is the piezoelectric polarization direction is provided in the first vibration element 111.

[0017] As shown in Figure 1, the intermediate vibration element 110 has a substantially annular plate-shaped intermediate flange 102 that extends radially around its entire circumference at an intermediate position in its axial direction. The intermediate vibration element 110 is configured to be clamped or supported around its entire circumference by a clamping mechanism (not shown) at least at the intermediate flange 102. The intermediate flange 102 may be omitted if it is ensured that the intermediate vibration element 110 is supported by a mechanical support mechanism. As shown in Figure 1, the intermediate vibration element 110 is substantially cylindrical with an outer diameter that is substantially constant in the axial direction behind the intermediate flange 102 (to the left in Figure 1). As shown in Figure 1, the intermediate vibration element 110 is substantially cylindrical (a substantially frustoconical shape and a substantially cylindrical shape connected coaxially) with an outer diameter that is continuously reduced towards the tip partway through, after which it has a substantially constant outer diameter in front of the intermediate flange 102 (to the right in Figure 1).

[0018] As shown in Figure 1, the second vibration element 112 is provided with a frequency adjustment element 1120, which is a roughly regular octagon with rounded corners, extending radially around its entire circumference at an intermediate position in its axial direction. The frequency adjustment element 1120 adjusts the resonance frequencies of the longitudinal and torsional vibration components of the ultrasonic vibration.

[0019] As shown in Figure 1, the second vibration element 112 has a plurality of slits 1124 formed on its outer surface behind the frequency adjustment element 1120. The plurality of slits 1124 may also be formed on the outer surface of the second vibration element 112 in front of the frequency adjustment element 1120. The slits 1124 extend diagonally when viewed from the side of the second vibration element 112, or extend axially while being displaced in the circumferential direction in phase. The N (N = 2, 3, ...) slits 1124 may be arranged to have N rotational symmetry about the central axis of the second vibration element 112 (for example, N = 8, 12, or 16).

[0020] As shown in FIG. 1, the second vibrating element 112 is provided at the tip position in its axial direction with a substantially regular octagonal tip portion 1126 having rounded corners and projecting radially over the entire circumference. Holes 1128 (or through holes) are formed at a plurality of circumferentially spaced locations in the tip portion 1126. The N (N = 2, 3,...) holes 1128 may be arranged so as to have N-fold rotational symmetry (e.g., N = 4) about the central axis of the second vibrating element 112. Threads are provided on the inner surface of the holes 1128.

[0021] As shown in FIG. 2, the horn tip 140 has a plurality of convex portions 142 at least the tip portion of which locally projects from the end face of a substantially rectangular parallelepiped-shaped base and abuts against the laminated metal foil W1. Based on the end face of the base of the horn tip 140, it is preferable that the protruding amount or height of the convex portion 142 is equal to or greater than the total thickness of the plurality of metal foils constituting the laminated metal foil W1. In the example of FIG. 2, at least the tip portion of the base of the horn tip 140 is substantially rectangular columnar, but at least the tip portion of the base of the horn tip 140 may have various shapes such as substantially cylindrical, substantially elliptical columnar, substantially square columnar, substantially frustum of a cone-shaped, substantially frustum of a pyramid-shaped, etc. The shape of the end face of the base of the horn tip 140 may be variously changed in addition to being substantially rectangular, such as substantially circular, substantially elliptical, substantially triangular, substantially trapezoidal, substantially parallelogram-shaped, substantially regular polygonal, etc. In the example of FIG. 2, the convex portion 142 is substantially frustum of a cone-shaped, but the convex portion 142 may have various shapes such as substantially frustum of a pyramid-shaped, substantially conical, substantially pyramid-shaped, substantially hemispherical, substantially semi-elliptical spherical, substantially columnar, etc. In the example of FIG. 2, 14 convex portions 142 are arranged like a 2 (y direction) × 7 (x direction) matrix or square lattice, but the number of the convex portions 142 may be less than or more than 14, and in addition to various regular arrangement modes such as triangular lattice-shaped, kagome lattice-shaped, etc., the convex portions 142 may be arranged according to an irregular arrangement mode. The plurality of convex portions 142 may be constituted by one pair or a plurality of pairs of convex portions 142 arranged with point symmetry with respect to the center of the end face of the base of the horn tip 140. The plurality of convex portions 142 may be constituted by one pair or a plurality of pairs of convex portions 142 arranged with line symmetry with respect to the center line of the end face of the base of the horn tip 140.

[0022] As shown in Figure 1, the male thread at the base end of the horn tip 140 is screwed into the female thread in the hole 1128 at the tip 1126 of the second vibrating element 112, thereby detachably fixing the horn tip 140 to the second vibrating element 112. By preparing horn tips 140 of various shapes, the horn tip 140 can be appropriately replaced depending on the type of metal to be joined.

[0023] The male thread of the balancer, which adjusts the phase difference between longitudinal and torsional vibrations at the tip 1126 of the second vibrating element 112, and consequently at the horn tip 140, may be screwed into the female thread of the hole 1128, thereby allowing the balancer to be detachably fixed to the tip 1126 of the second vibrating element 112.

[0024] The anvil 118 is positioned perpendicularly to the tip of the horn tip 140. Multiple laminated metal foils W1 are placed on the upper surface of the anvil 118 as workpieces. The anvil 118 may be configured to be passively or actively displaced vertically in response to the pressure exerted by the horn tip 140 via the laminated metal foils W1.

[0025] The high-frequency power supply unit 121 is configured to excite the first vibrating element 111 in the axial direction by applying a high-frequency AC voltage to the piezoelectric body 1112 of the first vibrating element 111 in accordance with the power supplied from a commercial power source (not shown). The translational drive unit 122 is equipped with a pressure block and is configured to apply pressure from the horn tip 140 to the laminated metal foil W1 by displacing a support mechanism such as a clamp mechanism that supports the intermediate vibrating element 110 with the pressure block. The state sensor 124 includes a stroke sensor that outputs a signal corresponding to the amount of displacement of the pressure block constituting the translational drive unit 122, as well as an amplitude sensor that outputs a signal corresponding to the amplitude of the horn tip 140 (corresponding to a specified parameter). The amplitude sensor may be a sensor module composed of an imaging device and equipment that calculates the amplitude by analyzing the image acquired through the imaging device.

[0026] As specified parameters that change according to the progress of bonding of the laminated metal foil W1 and, by extension, the multiple metal foils constituting it, in addition to the amplitude A of the horn tip 140, the axial displacement, displacement velocity and / or displacement acceleration of the vibration element (for example, the second vibration element 12) may also be measured as specified parameters.

[0027] The interface device 126 is configured, for example, as a display, and displays or outputs on the display the displacement amount and / or pressure time series of the pressurizing block in response to the output signal of the state sensor 124. The display may be configured as a touch panel display and may be configured to accept setting operations to allow the user to directly or indirectly specify parameters, such as one of a plurality of bonding modes that define the time series pattern of the target pressure.

[0028] The control device 120 is composed of a microcomputer, and by extension, an arithmetic processing unit (CPU, microprocessor, processor core, etc.) and a storage device (ROM, RAM, etc.). The control device 120 is configured to control the displacement operation of the pressure block by the translation drive device 122 based on the time series of the displacement amount of the pressure block, which is represented by the output signal of the stroke sensor that constitutes the state sensor 124. The control device 120 is configured to control the power supplied to the piezoelectric body 1112 based on the amplitude of the horn tip 140 (corresponding to a specified parameter), which is represented by the output signal of the amplitude sensor that constitutes the state sensor 124, and thereby control the ultrasonic vibration power of the vibration elements (first vibration element 111, intermediate vibration element 110, and second vibration element 112) and the ultrasonic vibration power of the horn tip 140. As a state sensor 124, a pressure sensor is provided that outputs a signal corresponding to the pressure acting on the intermediate vibration element 110 from the pressurizing block of the translational drive device 122 (up to the pressure applied by the horn tip 140 to the laminated metal foil W1). Based on the output signal of the pressure sensor, the control device 120 may control the time series of the pressure to be constant or controlled in a specified manner.

[0029] (Configuration of the laser welding apparatus) As shown in Figure 1, the laser welding apparatus 2 is configured such that the laser light LB emitted in the laser oscillator 20 is irradiated from the output head 24 via the optical cable 22. The laser welding apparatus 2 further includes an optical system control device 220, a camera 222, and a relative displacement mechanism 240. The optical system control device 240 may be composed of a common processing unit with the control device 120. The relative displacement mechanism 240 is composed of a translational drive mechanism such as an xy stage or an xyz stage and, if necessary, a tilting drive mechanism. The anvil 18 may constitute the relative displacement mechanism 240.

[0030] The optical system control device 220 identifies a designated area based on an image of the laminated metal foil W1 and / or metal material W2 ultrasonically bonded in that area, captured by the camera 222. The "area" such as the designated area is identified by a set of three-dimensional coordinate values ​​(x, y, z) representing the position in real space. Then, the optical system control device 220 identifies the designated area and / or at least a part of the area adjacent to the designated area as the welding target area. The optical system control device 220 adjusts the relative position between the emission head 24 and the target object by driving the relative displacement mechanism 240 in order to adjust the irradiation position of the laser beam LB on the target object (metal material W2 and / or the ultrasonically bonded laminated metal foil W1 placed on top of the metal material W2). The optical system control device 220 controls the operation of the laser oscillator 20 or the operation of the light-shielding plates that constitute the optical system so that the laser beam LB is irradiated onto the target object at a timing when the irradiation position of the laser beam LB scans the welding target area or is included in the welding target area, and the irradiation of the laser beam LB is stopped at other timings.

[0031] (Composite bonding method) A composite bonding method as one embodiment of the present invention includes an ultrasonic bonding step performed using an ultrasonic bonding apparatus 1 and a laser welding step performed using a laser welding apparatus 2.

[0032] (Ultrasonic Bonding Process) The procedure for the ultrasonic bonding process will be explained using the flowchart in Figure 3. The laminated metal foil W1 is placed on the anvil 18. The laminated metal foil W1 may be composed of various metal foils such as aluminum foil, aluminum alloy foil, copper foil, copper alloy foil, nickel foil, nickel alloy foil, and gold foil. The thickness of the metal foil (e.g., 5 to 250 μm) and the number of foils (e.g., 10 to 200) may be varied. For example, the laminated metal foil W1 is composed of 60 layers of aluminum foil with a thickness of 12 μm.

[0033] The translational drive device 122 drives the ultrasonic vibration element 10 and the horn tip 140 to approach the laminated metal foil W1 from above (Figure 3 / STEP 112). The x and y positions of the horn tip 140 are adjusted so that when the horn tip 140 descends, it comes into contact with a designated area (ultrasonic bonding target area) of the laminated metal foil W1.

[0034] Furthermore, it is determined whether the horn tip 140 contacts a designated area of ​​the laminated metal foil W1 from above and whether the pressure P received from the laminated metal foil W1 is equal to or greater than the first designated pressure P1 (Figure 3 / STEP 114). The pressure P received by the horn tip 140 from the laminated metal foil W1 is measured based on the output signal of the pressure sensor constituting the state sensor 124. When the tip of the horn tip 140 is separated from the workpiece W1, P = 0. When the tip of the horn tip 140 contacts the laminated metal foil W1 placed on the anvil 18, it receives a reaction force and P > 0.

[0035] If the determination result is negative (Figure 3 / STEP 114...NO), the translational drive device 122 drives the ultrasonic vibration element 10 and the tip of the horn tip 140 to approach the laminated metal foil W1 (Figure 3 / Coupler X1 → STEP 112). This adjusts the position of the horn tip 140, and consequently the static pressure applied to the laminated metal foil W1 from the tip of the horn tip 140, so that it falls within the specified static pressure range (for example, 200N to 800N).

[0036] If the determination result is positive (Figure 3 / STEP 114...YES), ultrasonic vibration is generated in the ultrasonic vibration element 10 (Figure 3 / STEP 116). Specifically, in response to power being supplied to the high-frequency power supply device 121 from a commercial power source (not shown) via a slip ring or the like, the high-frequency power supply device 121 applies a high-frequency AC voltage to the piezoelectric body 112 of the first vibration element 111. As a result, the first vibration element 111 vibrates in its axial direction at, for example, about 20 kHz, generating ultrasonic vibration. The ultrasonic vibration is transmitted from the first vibration element 111 to the intermediate vibration element 110 in its axial direction, and the amplitude of the ultrasonic vibration is amplified. Furthermore, the amplified ultrasonic vibration is transmitted from the intermediate vibration element 110 to the second vibration element 112 in its axial direction.

[0037] In this way, a portion of the longitudinal vibration component (the axial component of the second vibration element 112) of the ultrasonic vibration transmitted to the second vibration element 112 is converted into a torsional vibration component by the multiple slits 1124 formed on the outer surface of the second vibration element 112. The combined vibration resulting from the combination of the longitudinal vibration component and the torsional vibration component is then transmitted to the horn tip 140 fixed to the tip of the second vibration element 112.

[0038] In response, the horn tip 140 displaces or vibrates so as to trace a circular or elliptical orbit in a plane perpendicular to the contact direction of the laminated metal foil W1. As a result, the amplitude and ultrasonic vibration power of the horn tip 140 gradually increase from the vibration start time t=t0. At this time, impurities on the contact surfaces between the metal foils constituting the laminated metal foil W1 are removed, and plastic deformation of the contact surfaces of the metal foils constituting the laminated metal foil W1 may be promoted. Then, after the rate of increase of the amplitude and ultrasonic vibration power of the horn tip 140 decreases significantly at time t=t1, the amplitude and ultrasonic vibration power of the horn tip 140 gradually increase. This is because oxide films and the like of the metal constituting the bonding surface of the metal foils of the laminated metal foil W1 are removed, clean and activated metal atoms appear on the bonding surface, the motion of the atoms becomes more active due to the temperature rise caused by frictional heat, and mutual attractive forces between atoms are generated.

[0039] In this process, the amount of pressure applied to the laminated metal foil W1 by the horn tip 140 and / or the static pressure applied to the laminated metal foil W1 are adjusted while ultrasonic composite vibrations are applied to the laminated metal foil W1. As a result, the multiple metal foils constituting the laminated metal foil W1 are solid-state bonded together.

[0040] It is determined whether the time derivative δA of the amplitude A of the horn tip 140 (= current amplitude A(k) - previous amplitude A(k-1)) is negative and whether the amplitude A is less than or equal to the reference amplitude A0 (Figure 3 / STEP 118). The amplitude sensor constituting the state sensor 124 optically measures the amplitude A at a specified location on the horn tip 140 (for example, a location with a relatively large amplitude). Instead of this determination process, it may be determined whether the amplitude A has decreased by the reference amplitude A0 (or a reference ratio based on the maximum value) with respect to the maximum value at which the amplitude A began to decrease. For example, the reference amplitude A0 may be directly or indirectly specified by the user through a touch panel display constituting the interface device 126, such as one of several junction modes that define the reference amplitude A0.

[0041] In addition to the amplitude A of the horn tip 140, the axial displacement, displacement velocity, and / or displacement acceleration of the ultrasonic vibration element 10 (for example, the second vibration element 12) may be measured as values ​​of specified parameters that change according to the progress of bonding of the laminated metal foil W1.

[0042] If the determination result is negative (Figure 3 / STEP 118...NO), ultrasonic vibrations are continuously generated in the vibrating element (Figure 3 / Coupler X2 → STEP 116). On the other hand, if the determination result is positive (Figure 3 / STEP 118...YES), the translational drive device 122 moves the ultrasonic vibrating element 10 and the horn tip 140 so as to move away from the laminated metal foil W1 (Figure 3 / STEP 122).

[0043] Furthermore, it is determined whether the pressure P that the horn tip 140 receives from the laminated metal foil W1 has become less than or equal to the second specified pressure P2 (Figure 3 / STEP 124). The second specified pressure P2 is set to a value smaller than the first specified pressure P1, for example, 0 or a very small value.

[0044] If the determination result is negative (Figure 3 / STEP 124...NO), the translational drive device 122 moves the ultrasonic vibration element 10 and the horn tip 140 so that they are separated from the laminated metal foil W1 (Figure 3 / coupler X4 → STEP 122). This adjusts the z-direction position of the horn tip 140, and consequently the static pressure applied to the laminated metal foil W1 from the tip of the horn tip 140, to decrease.

[0045] If the determination result is positive (Figure 3 / STEP 124...YES), the generation of ultrasonic vibration in the ultrasonic vibration element 10 is stopped (Figure 3 / STEP 126). For example, after time t=t2 when the amplitude of the horn tip 140 changes from increasing to decreasing and becomes less than or equal to the reference amplitude A0, the ultrasonic power of the horn tip 140 is controlled to become 0 with a slight response delay, and the series of ultrasonic bonding processes is stopped.

[0046] As a result of the ultrasonic bonding process, as shown in Figure 5, the laminated metal foil W1 has recesses T as ultrasonic bonding marks in designated areas located at positions corresponding to the positions of each of the multiple protrusions 142 at the tip of the horn tip 140. 11 ~T 17 , T 21 ~T 27 A recess T is formed. As shown in Figure 6, the laminated metal foil W1 is formed in the recess T ij At (i=1,2,j=1,2,...,7), the metal foils are pressed into a roughly conical or frustoconical shape, and the multiple metal foils constituting the laminated metal foil W1 are solid-state bonded in the designated area. As shown in Figure 5, in plan view, the recess T ij Each of these is approximately circular or approximately elliptic with an ellipticity close to 1, and its aspect ratio (size in the x-direction / size in the y-direction) is, for example, in the range of 0.90 to 1.10, 0.92 to 1.08, or 0.95 to 1.05. This is because, when ultrasonic composite vibrations are transmitted from the ultrasonic vibration element 10 to the horn tip 140, the tip of the horn tip 140 is displaced to follow an approximately circular or approximately elliptic orbit rather than a linear orbit.

[0047] (Laser Welding Process) The procedure of the laser welding process will be described using the flowchart of FIG. 4. First, on the second workpiece or the metal material W2 placed and fixed on a table (e.g., an xy table), the laminated metal foil W1 ultrasonically joined as described above is arranged so as to overlap the designated area where the recesses T 11 ~T 17 、T 21 ~T 27 are formed. The metal material W2 may be composed of various metals such as aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, etc. The metal material W2 may be, for example, a metal plate with a thickness of 0.5 to 1.5 mm. The metal material W2 may be composed of, for example, an aluminum plate with a thickness of 1 μm. The metal material W2 may be another laminated metal foil W1 ultrasonically joined as described above.

[0048] The operation of the relative displacement mechanism 240 is controlled by the optical system control device 220, whereby the relative positions with respect to the emission head 24, the laminated metal foil W1, and the metal material W2 are adjusted (FIG. 4 / STEP142). Then, by the laser welding device 2, the recess T ij formed in the designated area of the ultrasonically joined laminated metal foil W1, preferably the center thereof, is irradiated with laser light LB (FIG. 4 / STEP144). As a result, the laminated metal foil W1 and the metal material W2 are locally welded at the bottom (center) of the recess T ij . In order to avoid the uneven distribution of residual stress caused by the temperature change of the local welding part of the laminated metal foil W1, the irradiation order of the laser light LB with respect to the recess T ij may be adjusted. In the example of FIG. 2, for example, T 11 →T 27 →T 21 →T 17 →T 12 →T 26 →T 22 →T 16 →T 13 →T 25 →T 23 →T 15 →T 14 →T 24 in this order, T 11 →T 17 →T21 →T 27 →T 12 →T 16 →T 22 →T 26 →T 13 →T 15 →T 23 →T 25 →T 14 →T 24 In that order, each recess T ij A laser beam LB may be irradiated onto the metal, and local welding between the laminated metal foil W1 and the metal material W2 may be performed sequentially. That is, a pair of recesses T corresponding to each of the pair of convex portions 142 are arranged to have point symmetry with respect to the center of the substantially rectangular end face of the base of the horn tip 140. ij In this process, the laminated metal foil W1 and the metal material W2 may be locally welded in order. A pair of recesses T corresponding to each of the pair of convex portions 142 are arranged to have line symmetry with respect to the center line of the substantially rectangular end face of the base of the horn tip 140. ij In this configuration, the laminated metal foil W1 and the metal material W2 may be locally welded in that order.

[0049] Furthermore, the recess T to be welded ij (Partial or all unwelded recess T) ij The presence or absence of ) is determined (Figure 4 / STEP 146). Recess T to be welded ij If it is determined that there is a problem (Figure 4 / STEP 146...YES), the processes from the relative position adjustment process for the injection head 24, laminated metal foil W1, and metal material W2 (Figure 4 / STEP 142) onward are repeatedly executed.

[0050] And the recess T to be welded ij If it is determined that there is no [unclear] (Figure 4 / STEP 146...NO), the laser welding process is terminated. As a result, a recess T, which is an ultrasonic bonding mark, is formed in the laminated metal foil W1, as schematically shown in Figure 7. ij At the bottom (center), the composite bonded structure W0, in which the laminated metal foil W1 and the metal material W2 are joined, is cleaned. The recess T, which is an ultrasonic bonding mark formed in the laminated metal foil W1, is cleaned. ij At the bottom (center), there is a bead Bd as a laser welding mark. ijIt is formed.

[0051] (Effects) According to the composite bonding system and composite bonding method of the said configuration, the laminated metal foil W1 is ultrasonically bonded using ultrasonic composite vibration, thereby forming a recess T as an ultrasonic bonding mark. ij The recess T is formed in the laminated metal foil W1 (see Figures 5 and 6). Furthermore, the recess T of the laminated metal foil W1 placed on the metal material W2 is formed in the laminated metal foil W1. ij When laser light LB is irradiated onto the material, the laminated metal foil W1 and the metal material W2 are joined together. The bead Bd is the laser welding mark. ij Although stress remains in the laminated metal foil W1 in the vicinity of this point, this stress acts not on the individual metal foils, but on the aggregate of multiple ultrasonically bonded metal foils. Therefore, the composite bonding system and composite bonding method of this configuration, and the composite bonded structure W0 manufactured therefrom, reduce the probability of fracture occurring in the laminated metal foil W1 due to this stress.

[0052] (Other Embodiments of the Invention) Figure 8 shows a composite bonded structure as a first embodiment. In fabricating this composite bonded structure, first, a laminated metal foil W1 is ultrasonically bonded in a designated area to form an ultrasonic bonding mark Σ. Subsequently, the laminated metal foil W1 is arranged so as to overlap the metal material W2 in a designated area in the lamination direction (z direction). Then, a laser beam LB is irradiated onto the ultrasonic bonding mark Σ of the laminated metal foil W1, and the metal material W2 is laser-welded at the ultrasonic bonding mark Σ of the laminated metal foil W1. As a result, a composite bonded structure having a laser welding mark Π is fabricated, as shown in Figure 8. This composite bonded structure may constitute, for example, the upper electrode of a battery such as a lithium secondary battery having a substantially rectangular parallelepiped housing.

[0053] Figure 9 shows a composite bonded structure as a second embodiment. In fabricating this composite bonded structure, first, an ultrasonic bonding mark Σ is formed by ultrasonic bonding of the laminated metal foil W1 in a designated area, which is the edge region. Alternatively, the laminated metal foil is processed so that an ultrasonic bonding mark Σ is formed by ultrasonic bonding of the laminated metal foil W1 in a designated area, and the ultrasonic bonding mark Σ becomes the edge. Next, the laminated metal foil W1 is arranged so as to overlap the metal material W2 in a designated area in a direction (y direction) perpendicular to the lamination direction (z direction). Then, a laser beam LB is irradiated onto the metal material W2 from the opposite side of the ultrasonic bonding mark Σ of the laminated metal foil W1, and laser welding is performed to the metal material W2 at the ultrasonic bonding mark Σ of the laminated metal foil W1. As a result, a composite bonded structure having a laser welding mark Π is fabricated, as shown in Figure 9. This composite bonded structure may constitute, for example, a side electrode (current collector plate) of a battery such as a lithium secondary battery having a substantially rectangular parallelepiped housing.

[0054] Figures 10A and 10B show the horn tip 140 in another embodiment. As shown in Figures 10A and 10B, the substantially rectangular plate-shaped tip of the horn tip 140 is provided with a protrusion 142 that extends in the longitudinal direction (x direction) of the rectangle and protrudes from the tip. Fine irregularities, such as a grid-like arrangement or a parallel, wave-like arrangement of irregularities, may be formed on the top surface of the protrusion 142.

[0055] As shown in Figure 11A, when the horn tip 140 is used, the laminated metal foil W1 is ultrasonically bonded in a designated area, forming an ultrasonic bonding mark Σ. Furthermore, as shown in Figures 12A and 12B, the laminated metal foil W1 is positioned so as to overlap the metal material W2 in a part of the designated area and in an adjacent area of ​​the designated area in its lamination direction (y direction). The "adjacent area" means an area that shares at least a part of the boundary of the designated area and at least a part of the boundary, and its shape and area are appropriately defined or designed from the viewpoint of laser spraying efficiency, etc. The laminated metal foil W1 may also be positioned so as to overlap the metal material W2 in the entire designated area and in an adjacent area of ​​the designated area in its lamination direction (y direction). Then, as shown in Figure 12A, at the edge of the laminated metal foil W1, a laser beam LB is irradiated onto the edge of the laminated metal foil W1, a part of the ultrasonic bonding mark Σ, and the metal material W2 from a direction inclined with respect to the lamination direction (y direction) of the laminated metal foil W1. Alternatively, as shown in Figure 12B, laser light LB may be irradiated from a direction parallel to the lamination direction (y-direction) of the laminated metal foil W1 to the edge of the laminated metal foil W1, a portion of the ultrasonic bonding marks Σ, and the metal material W2. As a result, as shown in Figures 11B and 12C, a composite bonded structure is fabricated having laser welding marks Π extending from the ultrasonic bonding marks Σ of the laminated metal foil W1 to the metal material W2. That is, the laminated metal foil W1, the metal material W2, and W1 are welded together in a portion of the designated area where the ultrasonic bonding marks Σ of the laminated metal foil W1 are formed, and in adjacent areas that share a common boundary with that portion of the designated area.

[0056] The second metal material W2 may be used in place of the anvil 118. Subsequently, the laminated metal foil W1 may be laser-welded to the second metal material W2 without being moved (or without changing its orientation). In this case, the translational drive device 122 may be configured such that the convex portion 142 constituting the tip of the horn tip 140 approaches and contacts the laminated metal foil W1 in the y direction shown in Figure 11B, rather than in the z direction shown in Figure 11A.

[0057] Figures 13A and 13B show horn tips 140 in yet another embodiment. As shown in Figures 13A and 13B, the substantially rectangular plate-shaped tip of the horn tip 140 is provided with a pair of protrusions 142 that extend parallel to the longitudinal direction (x direction) of the rectangle and project from the tip. Fine irregularities, such as a grid-like arrangement or a parallel, wave-like arrangement of irregularities, may be formed on the top surface of each protrusion 142.

[0058] By using the horn tip 140, as shown in Figure 14A, the laminated metal foil W1 is ultrasonically bonded in each of a pair of parallel strip-shaped regions designated as areas, thereby forming a pair of ultrasonic bonding marks Σ1 and Σ2. Furthermore, the laminated metal foil W1 is positioned so as to overlap the metal material W2 in the designated area in its lamination direction (y direction). Then, as shown in Figure 14A, in the strip-shaped region sandwiched between the pair of ultrasonic bonding marks Σ1 and Σ2 of the laminated metal foil W1, laser light LB is irradiated onto at least a portion of the laminated metal foil W1 and the metal material W2 from a direction inclined with respect to the lamination direction (y direction) of the laminated metal foil W1 or parallel to it (see Figures 12A and 12B). As a result, as shown in Figure 14B, a composite bonded structure having a laser welding mark Π extending from the laminated metal foil W1 to the metal material W2 is fabricated.

[0059] The second metal material W2 may be used in place of the anvil 118. Subsequently, the laminated metal foil W1 may be laser-welded to the second metal material W2 without being moved (or without changing its orientation). In this case, the translational drive device 122 may be configured such that the convex portion 142 at the tip of the horn tip 140 approaches and contacts the laminated metal foil W1 in the y direction shown in Figure 15B, rather than in the z direction shown in Figure 15A.

[0060] The ultrasonic bonding marks Σ formed by the horn tip 140, which has a fine uneven structure such as a grid-like arrangement or a parallel, wave-like extension on the top surface of each protrusion 142, have a surface shape corresponding to the fine uneven structure. Therefore, it is possible to suppress the reflection of laser light LB by the surface shape of the ultrasonic bonding marks Σ having this uneven structure, and thus it is also possible to suppress laser welding energy loss.

[0061] Furthermore, although the above embodiment uses a composite vibration generated by the second vibration element 112 torsion vibration, the same effect can be obtained in ultrasonic welding using only axial vibration by the first vibration element 111 without torsion vibration. When composite vibration is applied, the bonding load on the laminated metal foil W1 can be reduced, which is advantageous for the shape stability of the laminated metal foil W1.

[0062] 10... Ultrasonic vibration element 102... Intermediate flange 110... Intermediate vibration element 111... First vibration element 1112... Piezoelectric element 112... Second vibration element 1120... Frequency adjustment element 1121... Cylindrical section 1122... Cylindrical section 1124... Slit 1126... Tip 1128... Hole 118... Anvil 120... Control device 121... High-frequency power supply 122... Translational drive device 124... State sensor 126... Interface device 140... Horn tip 20... Laser oscillator 22... Optical cable 24... Output head 220... Optical system control device 222... Camera 240... Relative displacement mechanism LB... Laser light Bd 12 ...bead (laser welding mark) T ij ...recess (ultrasonic bonding mark) W0...composite bonded structure W1...laminated metal foil W2...metal material Σ...ultrasonic bonding mark Π...laser welding mark

Claims

1. A composite bonding system comprising: an ultrasonic bonding device that bonds a laminated metal foil in a designated area by propagating ultrasonic vibrations induced in an ultrasonic vibration element to the designated area of ​​the laminated metal foil via an ultrasonic bonding tip; and a laser welding device that welds the laminated metal foil bonded by the ultrasonic bonding device to a metal material using laser light in at least one of the designated area of ​​the laminated metal foil and an adjacent area of ​​the designated area.

2. A composite joining system according to claim 1, wherein the laser welding apparatus is configured to irradiate the overlapping region of the laminated metal foil, which is arranged to overlap the metal material in at least one of the designated region and the region adjacent to the designated region, with laser light to weld the laminated metal foil and the metal material.

3. A composite joining system according to claim 2, wherein the laser welding apparatus is configured to irradiate the overlapping region of the laminated metal foil and the metal material, which are arranged to overlap in at least a portion of the designated region and the adjacent region, with laser light to weld the laminated metal foil and the metal material in the portion of the designated region and the adjacent region.

4. A composite bonding system according to claim 2, wherein the ultrasonic bonding device is configured to bond the laminated metal foil such that local recesses are formed in the laminated metal foil corresponding to the protrusions by transmitting ultrasonic vibrations induced in the ultrasonic vibration element to the designated region of the laminated metal foil corresponding to the protrusions via the ultrasonic bonding tip having locally protruding protrusions, and the laser welding device is configured to weld the metal material and the laminated metal foil by irradiating laser light onto the recesses formed in the designated region of the laminated metal foil bonded by the ultrasonic bonding device, which is positioned to overlap the metal material.

5. A composite bonding system according to claim 1, wherein the laser welding apparatus is configured to irradiate the overlapping region of the metal material, which is arranged to overlap with at least one of the designated region of the laminated metal foil and an adjacent region of the designated region, with laser light to weld the laminated metal foil and the metal material.

6. A composite bonding method comprising: an ultrasonic bonding step of bonding a laminated metal foil in a designated area by propagating ultrasonic vibrations induced in an ultrasonic vibration element to the designated area of ​​the laminated metal foil via an ultrasonic bonding tip; and a laser welding step of welding the laminated metal foil bonded in the ultrasonic bonding step to a metal material using laser light in at least one of the designated area of ​​the laminated metal foil and an adjacent area of ​​the designated area.

7. A composite bonded structure comprising laminated metal foil and a metal material joined together, wherein a composite ultrasonic welding mark is formed in a designated area of ​​the laminated metal foil, and a laser welding mark is formed in at least one of the designated area and an adjacent area.

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