Ultrasonic bonding apparatus, method for bonding metallized resin film and tab lead using the apparatus, and bonded product

Abstract

To satisfactorily bond a metal layer and an electrode material when a metallized resin film obtained by forming the metal layer on a base material made of a resin film is laminated and ultrasonically bonded to the electrode material.SOLUTION: The objects to be bonded W formed by stacking the electrode materials T such as tab leads and a large number of, for example, several tens of, laminated metallized resin films F are sandwiched between the support body 2 and the bonding tool 34 of the horn, the objects to be bonded W are heated to 50 °C or higher and the metallized resin films F are heated to the melting temperature of the resin film for the base material or lower by the heating means 6 to soften the resin film, and in a state where the resin is softened, ultrasonic waves of lateral vibration in a direction parallel to the objects to be bonded W are applied while the objects to be bonded W in a sandwiched state are pressurized. As a result, the resin film of the laminated metallized resin film F is softened to be easily removed, and reliably removed by the application of ultrasonic vibration, so that the metal layer of the metallized resin film F and the electrode material T are solid-phase bonded.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an ultrasonic bonding device that vapor-deposits metal onto a thermoplastic resin film to form a metallized resin film, and bonds multiple laminated metallized resin films to an electrode material using ultrasonic vibrations, as well as a method for bonding a metallized resin film to a tab lead using the device, and a bonded product. [Background technology]

[0002] Conventionally, resistance welding as described in Patent Document 1 and ultrasonic bonding as described in Patent Document 2 have been known as methods for joining a tab to a laminate formed by laminating a current collector having a metal film formed on one or both sides of a resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-000600 [Patent Document 2] International Publication No. 2022 / 208770 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the case of the resistance welding described in Patent Document 1, welding may not be possible depending on the type of metal film. For example, while resistance welding may be possible if the metal film is copper (Cu), welding may not be possible if the metal film is aluminum (Al). In addition, the heat from resistance heating may deform the resin, and the thermal history may have an adverse effect on the resin.

[0005] Furthermore, in the case of the ultrasonic bonding described in Patent Document 2, a convex portion is formed on a horn, and ultrasonic lateral vibrations are applied while the convex portion is pressing, thereby melting the resin in the laminate and forcing the molten resin out of the convex portion, forming a conductive path between the metal layers (conductive layers) of the laminate, thereby bonding. However, if the laminate becomes thick due to an increase in the number of layers in the laminate, ultrasonic vibration alone may not be enough to sufficiently melt and remove the resin, and the resin may remain, which may result in poor electrical connection of the conductive layers and tabs.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to enable good bonding between the metal layer and the electrode material when a metallized resin film having a metal layer formed on a resin film substrate is laminated and ultrasonically bonded to the electrode material. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the ultrasonic bonding device of the present invention forms a metallized resin film by forming a metal layer on a base material made of a resin film, and bonds a plurality of layers of the metallized resin film to an electrode material by ultrasonic vibration, and includes: a support having a mounting surface on which objects to be bonded, each of which is composed of the electrode material and the plurality of layers of the metallized resin film, are placed; a horn that holds the objects to be bonded between the support and the mounting surface; ultrasonic vibration means having a vibrator that ultrasonically vibrates the horn; pressure means that pressurizes the objects to be bonded held between the support and the horn; and heating means that is provided on at least one of the support and the horn and heats the objects to be bonded, and the heating means heats the objects to be bonded held between the support and the horn to a temperature of 50°C or higher and equal to or lower than the resin melting temperature of the base material of the metallized resin film, The ultrasonic vibration means applies ultrasonic vibration to the horn in a direction parallel to the heated objects to be joined.

[0008] Further, the present invention provides a method for joining a metallized resin film and a tab lead of a battery, the method being performed by an ultrasonic joining device including: a support having a mounting surface on which an object to be joined is placed; a horn for clamping the object to be joined between the support and the mounting surface; ultrasonic vibration means having a vibrator for ultrasonically vibrating the horn; pressure means for pressurizing the object to be joined clamped between the support and the horn; and heating means provided on at least one of the support and the horn for heating the object to be joined, the method including: overlapping a plurality of the metallized resin films on the tab lead; a step of placing the objects to be joined on a support surface of a support; a step of clamping the objects to be joined between the support and the horn by the pressure means; a step of heating the objects to be joined held between the support and the horn by the heating means provided on at least one of the support and the horn to a temperature of 50°C or higher but not higher than the melting temperature of the resin constituting the base material of the metallized resin film; and a step of applying ultrasonic vibrations to the horn in a direction parallel to the surface direction of the objects to be joined by the ultrasonic vibration means.

[0009] According to this configuration, the electrode material (tab lead) and the object to be joined, which is made up of multiple overlapping metallized resin films, are clamped between the support and the horn, and the object to be joined is heated by the heating means to a temperature of 50°C or higher but below the melting temperature of the resin film of the metallized resin film to soften the resin film.With the resin film in the softened state, the object to be joined is pressurized by the pressure means, and ultrasonic waves of lateral vibration in a direction parallel to the object to be joined are applied to the horn.Therefore, even if the number of layers is large or the thickness is thick due to the lamination, by heating the object to be joined to a temperature of 50°C or higher but below the melting temperature of the resin film of the metallized resin film, the resin film of the laminated metallized resin film is softened to a state that makes it easy to remove, and by applying ultrasonic vibrations in the softened state, the resin film of the laminated metallized resin film can be reliably removed to join the vapor-deposited metal and the electrode material.

[0010] In this case, when the electrode material is a tab lead used in a lithium ion battery, the metal layer of the metallized resin film and the tab lead can be satisfactorily joined by ultrasonic solid-state joining.

[0011] Preferably, the heating means is provided on the support, and a plurality of protrusions are formed on a surface of the support facing the horn, the surface facing the mounting surface.

[0012] According to this configuration, the laminated metallized resin film can be uniformly heated by the heating means provided on the support, so that the resin film of the laminated metallized resin film can be reliably softened and easily removed.

[0013] It is also preferable that the heating means is provided on the support, that a plurality of protrusions are formed facing each other on the mounting surface of the support and on the opposing surface of the horn facing the mounting surface, and that the contact area of ​​the protrusions on the opposing surface of the horn with the object to be joined is smaller than the contact area of ​​the protrusions on the mounting surface with the object to be joined.

[0014] According to this configuration, when the laminated metallized resin film is uniformly heated by the heating means provided on the support, the object to be joined can be uniformly heated through the protrusions on the mounting surface of the support, which have a large contact area with the object to be joined.Therefore, the resin film substrate of the laminated metallized resin film sandwiched between the protrusions on the mounting surface of the opposing support and the protrusions on the opposing surface of the horn is softened to make it easier to remove, and ultrasonic vibrations are applied in the softened state to reliably join the metal layer of the metallized resin film to the electrode material.

[0015] In addition, the heating means may be provided on the horn, and a plurality of protrusions may be formed facing each other on the mounting surface of the support and on the opposing surface of the horn facing the mounting surface, and the contact area of ​​the protrusions on the opposing surface of the horn with the object to be joined may be larger than the contact area of ​​the protrusions on the mounting surface with the object to be joined.

[0016] According to this configuration, when the laminated metallized resin film is uniformly heated by the heating means provided in the horn, the object to be joined can be uniformly heated through the protrusions on the opposing surface of the horn, which have a large contact area with the object to be joined.Therefore, the resin film substrate of the laminated metallized resin film sandwiched between the protrusions on the mounting surface side of the opposing support and the protrusions on the opposing surface side of the horn is softened to make it easier to remove, and by applying ultrasonic vibrations in the softened state, the vapor-deposited metal of the metallized resin film can be reliably joined to the electrode material.

[0017] Furthermore, it is preferable that the shape of the protrusion on the opposing surface of the horn and the shape of the protrusion on the mounting surface are truncated cones or truncated pyramids, and that the protrusions are formed so that the maximum angle formed by the lines extending from the two generatrix of the truncated cone or truncated pyramid is 60° to 120°.

[0018] According to this configuration, by forming the protrusions on the opposing surface of the horn and on the mounting surface of the support, it is possible to concentrate and easily transmit ultrasonic vibration energy.

[0019] The base material of the resin film is preferably a polyester resin, and the polyester resin is preferably polyethylene terephthalate. The metal layer is preferably formed by vacuum deposition. The metal layer is preferably mainly composed of aluminum or copper.

[0020] In this way, when forming a current collector for a battery such as a storage battery or an electrode for a capacitor, a metallized resin film for forming a current collector or an electrode without poor electrical connection can be efficiently produced and provided.

[0021] The electrode material may be a tab lead for a battery or a tab terminal for a capacitor. In this case, a lithium ion battery or a capacitor having a tab lead or tab terminal electrically connected to the laminated metallized resin film can be provided. [Effects of the Invention]

[0022] According to the present invention, when a metallized resin film having a metal layer formed on a resin film substrate is laminated and ultrasonically bonded to an electrode material, the metal layer and the electrode material can be bonded well. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a side view of a first embodiment of the ultrasonic bonding device of the present invention. [Figure 2] FIG. 2 is a front view of FIG. [Figure 3] 2 is an explanatory view of a joining operation in a certain state by the device of FIG. 1. FIG. [Figure 4] FIG. 2 is a cross-sectional view of a metallized resin film to be bonded by the apparatus of FIG. [Figure 5] FIG. 2 is a bottom view of a portion of the pressing surface of the horn of FIG. 1. [Figure 6] 6 is a side view of some of the protrusions formed on the pressing surface of FIG. 5. FIG. [Figure 7] 1 is a diagram showing the results of the bond quality judged based on the resistance values ​​of the bonded portions of Example 1 and Comparative Example 1. FIG. [Figure 8]10 is a diagram showing the results of the bond quality judged based on the resistance values ​​of the bonded portions of Example 2 and Comparative Example 2. FIG. [Figure 9] 10 is a diagram showing the results of the bond quality judged based on the resistance values ​​of the bonded portions of Example 3 and Comparative Example 3. FIG. [Figure 10] 10 is a diagram showing the results of the bond quality judged based on the resistance values ​​of the bonded portions of Example 4 and Comparative Example 4. FIG. [Figure 11] 10A to 10C are explanatory views of the joining operation of the ultrasonic joining device according to the second embodiment of the present invention. [Figure 12] 12 is an explanatory view of a joining operation in a state different from that of FIG. 11 according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] First Embodiment A first embodiment of the ultrasonic bonding device of the present invention will be described with reference to FIGS.

[0025] (Device configuration) 1 and 2 show an ultrasonic bonding apparatus 1 in which objects to be bonded are sandwiched between a mounting surface 21, which is the upper surface of a support 2, and a horn of a head unit 3 that ultrasonically vibrates in a direction parallel to the mounting surface 21 (the Y-axis direction in FIGS. 1 and 2 ). A control device 4 configured as a microcomputer having a CPU and memory controls a pressure means 5 to apply pressure to the objects to be bonded W shown in FIG. 3 in the vertical direction (the Z-axis direction), while controlling the head unit 3 to apply ultrasonic vibration energy in the form of so-called lateral vibration (vibration in the direction of the double arrow in FIG. 3 ) in the horizontal direction (the Y-axis direction) to the objects to be bonded W, thereby ultrasonically bonding the objects to be bonded W. At this time, the control device 4 controls a heating means 6, such as a sheathed heater built into the support 2, to heat the objects to be bonded W to a predetermined temperature, and then applies ultrasonic vibration energy to the objects to be bonded W while applying pressure to the sandwiched objects to be bonded W, thereby ultrasonically bonding the objects to be bonded W.

[0026] Here, the joining object W will be described. As shown in Fig. 4, a thermoplastic resin film is used as the base material B, and a layer of metal M such as aluminum or copper is formed on the base material B to a thickness of, for example, 1 µm to form a metallized resin film F. As shown in Fig. 3, a large number of metallized resin films F are laminated on an electrode material T to form the joining object W, and ultrasonic vibrations are applied to this to join the electrode material T and the metal M of the metallized resin film F. Note that the metallized resin film F may be formed on both sides of the resin film base material B as shown in Fig. 4, or may be formed on only one side.

[0027] The types of thermoplastic resins that make up the base material B include polyethylene, polypropylene, polystyrene, nylon, polyester resins, etc., and the toughness, adhesion to the metal M, etc. Considering these factors, polyester resins are preferred, and from the viewpoint of film-forming properties, those containing ethylene terephthalate as the main component (polyethylene terephthalate (PET)) are more preferred. Polyester is a general term for polymers in which ester bonds are the main bonding chains in the main chain. Methods for forming the metal M on the substrate B include, for example, vacuum deposition, sputtering, ion plating, and plating. Among these methods, vacuum deposition is preferred because of its excellent productivity.

[0028] The metal constituting the metal M is not particularly limited as long as it is conductive within the scope of the present invention. Examples include aluminum, nickel, gold, silver, copper, iron, and stainless steel. From the viewpoints of high conductivity, ease of film formation, ease of handling, and stability, i.e., the potential difference between the positive and negative electrodes (called the "potential window") to prevent undesirable reactions in the electrode compound, if the storage battery is a lithium-ion battery, it is preferable to use a metal M for the metallized resin film F for the positive electrode that is primarily aluminum, and a metal M for the metallized resin film F for the negative electrode that is primarily copper. If the storage battery is a sodium-ion battery, it is preferable to use a metal M for both the positive and negative electrodes that is primarily aluminum. In the case of a capacitor, since no electrochemical reaction occurs, any of the exemplified metal species may be used, and the same metal species may be used for both electrodes. Here, "major component" means that the corresponding component is contained in 90% by mass or more of the total metal M.

[0029] For example, in the case of lithium-ion batteries (LIBs) installed in electric vehicles and the like, with the recent increase in capacity, it is common to connect several tens (e.g., 20 to 30) of current collector foils to tab leads as battery electrodes. Metal foils currently commonly used in LIB current collector foils can be connected to tab leads using conventional ultrasonic bonding methods, even when more than 30 foils are used. However, when a large number of metallized resin films (e.g., 20 sheets) that have been developed in recent years to improve the safety and energy density of LIBs are laminated and bonded to tab leads, problems such as cracks in the tab leads and peeling of the metallized resin films (F) have occurred. Based on the findings of the present inventors, we have developed a method that enables satisfactory ultrasonic bonding of 20 or more laminated metallized resin films (F) to tab leads (electrode materials (T)).

[0030] 1 and 2, the head unit 3 includes a vibrator 31 that applies ultrasonic vibrations in the Y-axis direction (left-right direction) perpendicular to the Z-axis direction (up-down direction) in the drawing, which is the pressure direction, a horn 32 connected to one end of the vibrator 31, and a support means 33 that supports the vibrator 31 and the horn 32 so that they can move freely in the up-down direction (Z-axis direction) perpendicular to the left-right direction (Y-axis direction), which is the vibration direction, and the vibrator 31 ultrasonically vibrates the horn 32, thereby applying ultrasonic vibrations to the objects to be bonded and bonding the objects. Here, the horn 32 includes a bonding tool 34, and the vibrator 31 and the horn 32 correspond to the "ultrasonic vibration means" in this invention.

[0031] Specifically, horn 32 resonates with ultrasonic vibrations generated by transducer 31 controlled by control device 4 and ultrasonically vibrates in the left-right direction (the Y-axis direction in FIGS. 1 and 2 ), which is the direction of its central axis. Horn 32 is formed to a length of one wavelength of the resonant frequency so that its approximate center in the Y-axis direction and its two opposite ends have maximum amplitude points. Furthermore, a joining tool 34 made of the same material as horn 32 is detachably attached to the maximum amplitude point in the center of horn 32. Two positions spaced a quarter wavelength from each maximum amplitude point in the left-right direction (the Y-axis direction) correspond to a first minimum amplitude point and a second minimum amplitude point of horn 32, respectively, and horn 32 is supported by support means 33 at these first and second minimum amplitude points. The horn 32 is formed in the shape of a column whose cross section is, for example, octagonal, and the vibrator 31 is connected to the right end of the horn 32 by a headless screw or the like so that it is coaxial with the central axis of the horn 32.

[0032] Here, horn 32 and welding tool 34 may be formed from various metal materials commonly used to form resonators, such as titanium, titanium alloys, iron, stainless steel, aluminum, and aluminum alloys such as duralumin. Horn 32 is preferably configured so that its resonance frequency is about 15 kHz to about 60 kHz and its vibration amplitude (the amplitude of expansion and contraction in the Y-axis direction in FIGS. 1 and 2) is about 1 μm to about 300 μm.

[0033] Support means 33 includes a base 33a, a vertical support pillar 33b (in the Z-axis direction in FIGS. 1 and 2) whose upper end is connected to base 33a, a support portion 33c connected to the lower end of support pillar 33b, and a pair of clamp portions 33d connected to the lower surface of support portion 33c. Support means 33 supports horn 32 by gripping gripped portions of horn 32 at positions corresponding to the first and second minimum amplitude points with both clamp portions 33d.

[0034] Here, each of the clamping portions 33d is made up of two, upper and lower, separable gripping members 33d1 and 33d2, with the upper gripping member 33d1 fixed to the underside of the support portion 33c, and the upper and lower gripping members 33d1 and 33d2 clamp and grip the gripped portion at positions corresponding to the first and second minimum amplitude points of the horn 32.

[0035] The gripped portion of horn 32 may be supported by support means 33 via an elastic member such as an O-ring or a diaphragm.

[0036] The pressure applying means 5 applies pressure by moving the support means 33 that supports the horn 32 in the vertical direction (Z-axis direction) to move the horn 32 closer to or further away from the support 2. The pressure applying means 5 includes a drive motor 51, a ball screw 52 in the vertical direction (Z-axis direction) that is rotated by the drive motor 51, a base 53 that is U-shaped in side view and that rotatably supports the upper and lower ends of the ball screw 52, ​​and a rectangular parallelepiped movable support 54 that has a base 33a of the support means 33 connected to its front side and has a vertical female screw formed in the center and into which the ball screw 52 is threaded.

[0037] The base 53 includes a flat plate portion 53a that is long in the vertical direction (Z-axis direction), horizontal extension portions 53b that are integral with the upper and lower ends of the flat plate portion 53a and rotatably support the upper and lower ends of the ball screw 52, ​​and a vertical (Z-axis) guide rail 53c that is attached to the front side of the flat plate portion 53a between the upper and lower extension portions 53b and along the flat plate portion 53a. Here, the drive motor 51 is placed on the upper surface of the upper extension portion 53b, and the guide rail 53c is inserted into a vertical (Z-axis) guide groove formed on the rear side of the movable support 54. The drive motor 51 is controlled by the control device 4 to rotate, which rotates the ball screw 52, ​​thereby moving the movable support 54 in the vertical direction (Z-axis direction) along the guide rail 53c.

[0038] At this time, the movable support 54 moves upward or downward depending on the rotation direction of the ball screw 52, ​​causing the base 33a of the support means 33 connected to the movable support 54 to move up and down, and the horn 32 moves closer to the support 2 or away from the support 2. Then, the downward movement of the base 33a caused by the downward movement of the movable support 54 applies pressure to the workpiece W sandwiched between the welding tool 34 of the horn 32 and the support 2.

[0039] Incidentally, a pressure sensor (not shown) constituted by a load cell or the like is provided on the support body 2 or the head unit 3, and the pressure sensor detects the pressure applied by the pressure means 5 to the workpiece W sandwiched between the welding tool 34 and the support body 2. Also, a linear encoder 7 (see FIG. 1) is provided on the movable support body 54, which detects the height of the head unit 3 in the vertical direction (Z-axis direction). Here, the control device 4 controls the drive motor 51 based on the detection signal of the linear encoder 7, thereby adjusting the height of the head unit 3 and thereby adjusting the height of the horn 32 relative to the support body 2.

[0040] One feature of the present invention is that, as shown in FIG. 3 , a workpiece W, which is composed of several tens of sheets of metallized resin film F laminated on electrode material T such as tab leads, is sandwiched between mounting surface 21 of support 2 and the opposing surface of joining tool 34 of horn 32, which is the underside of mounting surface 21. Then, heating means 6 built into support 2 heats workpiece W to a temperature above 50°C but below the melting temperature Tm of the resin film substrate B constituting metallized resin film F. For example, after uniformly heating to 150°C, which is the melting temperature of resin film substrate B of metallized resin film F, ultrasonic vibration energy is applied for a predetermined time while applying a predetermined pressure with pressure means 5. The waiting time between heating and heating is preferably set to 0.2 to 10 seconds. The most preferable temperature conditions are a temperature above 50°C and above the glass transition temperature Tg and / or below the melting temperature Tm of the resin film of metallized resin film F. The melting temperature Tm referred to here is the highest melting peak temperature among the melting peak temperatures determined according to the method described in JIS K-7121 (1987) in a differential scanning calorimetry chart obtained by heating a film sample from room temperature at a heating rate of 20°C / min in accordance with JIS K-7122 (1987). The glass transition temperature Tg referred to here is the highest midpoint glass transition temperature among the midpoint glass transition temperatures determined according to the method described in JIS K-7121 (1987) in a differential scanning calorimetry chart obtained by heating a film sample from room temperature at a heating rate of 20°C / min to a temperature 20°C or more higher than the melting temperature Tm (first run), holding the sample in that state for 5 minutes, then rapidly cooling the sample to 25°C or below, and again heating the sample from 25°C at a heating rate of 20°C / min (second run) in accordance with JIS K-7122 (1987).

[0041] By heating in this manner, the resin film of the several dozen stacked metallized resin films F can be softened to a state that makes it easier to remove, and by applying pressure to the softened state while applying ultrasonic vibrations, the resin film of the stacked metallized resin films F can be reliably removed, and the metal M layer of the metallized resin film F can be solid-state joined to the electrode material T such as a tab lead.

[0042] Another feature of the present invention is that a large number of protrusions 341 protruding downward, for example in the shape of a truncated quadrangular pyramid, are formed on the entire lower surface of the joining tool 34 (the surface facing the mounting surface 21), as shown in Fig. 5. In this case, it is preferable that the pitch of the protrusions 341 is 2 mm, the length of one side of the square at the tip plane of the protrusions 341 is 0.4 mm, and the protruding length of the protrusions 341 is 1.5 mm. Note that the pitch of the protrusions 341 may be set appropriately between 0.2 mm and 3 mm depending on the number of layers of metallized resin films F laminated.

[0043] In this way, by forming quadrangular pyramidal protrusions 341 with a pitch of 2 mm, a square with a tip plane side length of 0.4 mm, and a protrusion length of 1.5 mm on the entire underside of the joining tool 34, it becomes possible to transmit ultrasonic vibration energy in a concentrated manner to the joining object W, making it easier to remove the resin film of the metallized resin film F.

[0044] (Example 1 and Comparative Example 1) In Example 1, quadrangular pyramidal protrusions 341 were formed at a pitch of 2 mm on the underside of the joining tool 34 of the horn 32, and the joining object W was heated to 100°C using the heating means 6, with the waiting time for heating set to 0.2 seconds, to soften the resin film substrate B of the metallized resin film F, and ultrasonically join the metal M of the metallized resin film F and a tab lead for a lithium ion battery as the electrode material T. In Comparative Example 1, quadrangular pyramidal protrusions 341 were formed at a pitch of 2 mm on the underside of the joining tool 34 of the horn 32, and the metal M of the metallized resin film F and a tab lead for a lithium ion battery as the electrode material T were ultrasonically joined at room temperature without heating the joining object W with the heating means 6. Here, the metallized resin film F used was a 6 μm-thick polyethylene terephthalate (melting temperature 260° C.) film with aluminum deposited to a thickness of 1 μm on each side by vacuum deposition.The tab lead used was an aluminum one with a thickness of 0.2 mm.

[0045] The results of judging the quality of the bonding based on the resistance values ​​of the bonded portions of the metallized resin films F in Example 1 and Comparative Example 1 are shown in FIG. 7. In both Example 1 and Comparative Example 1, when the number of layers of the metallized resin films F was 10, the resistance of all of the metallized resin films F was low (for example, 65 mΩ or less), and the bonding was good (indicated by the circle in FIG. 7). When the number of layers was 20, Example 1 showed good bonding (indicated by the circle in FIG. 7), whereas Comparative Example 1 showed mechanical bonding, but the resistance of the metallized resin films F was generally higher than 65 mΩ, as indicated by the triangle in FIG. 7. Furthermore, when the number of layers was 30, Example 1 showed good bonding (indicated by the circle in FIG. 7), whereas Comparative Example 1 showed mechanical bonding, but the resistance of the metallized resin films F, particularly those other than the few layers on the tab lead side, was high at around 120 mΩ, as indicated by the triangle in FIG. 7.

[0046] (Example 2 and Comparative Example 2) In Example 2, quadrangular pyramidal protrusions 341 were formed on the underside of the joining tool 34 of the horn 32 at a pitch of 1 mm, which was smaller than that of Example 1, and the object to be joined W was heated to 100°C using the heating means 6, with the waiting time for heating set to 0.2 seconds, to soften the resin of the metallized resin film F and ultrasonically join the metal M of the metallized resin film F and a tab lead for a lithium ion battery as the electrode material T. In Comparative Example 2, quadrangular pyramidal protrusions 341 were formed on the underside of the joining tool 34 of the horn 32 at a pitch of 1 mm, which was even smaller than in Comparative Example 1, and the metal M of the metallized resin film F and a tab lead for a lithium ion battery as electrode material T were ultrasonically joined at room temperature without heating the joining object W with the heating means 6. The metallized resin film F and tab lead used were the same as those used in Example 1 and Comparative Example 1.

[0047] The results of judging the quality of the bond based on the resistance value of the bonded portion of the metallized resin film F in Example 2 and Comparative Example 2 are shown in Figure 8. In Example 2, when the number of layers of the metallized resin film F was 10 or 20, the resistance of the metallized resin film F was low (65 mΩ or less), and good bonding was achieved (indicated by a circle in Figure 8), but when the number of layers was 30, poor bonding occurred, as indicated by an x ​​in Figure 8. In contrast, in Comparative Example 2, when the number of layers of the metallized resin film F was 10, good bonding was achieved (indicated by a circle in Figure 8), but when the number of layers was 20 or 30, poor bonding occurred in both cases, as indicated by an x ​​in Figure 8.

[0048] (Example 3 and Comparative Example 3) In Example 3, quadrangular pyramidal protrusions 341 were formed at a pitch of 2 mm on the underside of the joining tool 34 of the horn 32, and the joining object W was heated to 100°C using the heating means 6, with the waiting time for heating set to 0.2 seconds, to soften the resin film substrate B of the metallized resin film F, and ultrasonically join the metal M of the metallized resin film F and a tab lead for a lithium ion battery as the electrode material T. In Comparative Example 3, quadrangular pyramidal protrusions 341 were formed at a pitch of 2 mm on the underside of the joining tool 34 of the horn 32, and the metal M of the metallized resin film F and a tab lead for a lithium ion battery as the electrode material T were ultrasonically joined at room temperature without heating the joining object W with the heating means 6. Here, the metallized resin film F used was a 6 μm-thick polyethylene terephthalate (melting temperature 260°C) film with 1 μm-thick copper formed on each side by vacuum deposition.The tab lead used was a 0.2 mm-thick copper plated with 100 nm-thick nickel.

[0049] The results of judging the quality of the bonding based on the resistance values ​​of the bonded portions of the metallized resin films F in Example 3 and Comparative Example 3 are shown in FIG. 9. In both Example 3 and Comparative Example 3, when the number of layers of the metallized resin films F was 10, the resistance of all of the metallized resin films F was low (for example, 35 mΩ or less), and the bonding was good (indicated by circles in FIG. 9). When the number of layers was 20, Example 3 showed good bonding (indicated by circles in FIG. 9), whereas Comparative Example 3 showed mechanical bonding, but the resistance of the metallized resin films F was generally higher than 35 mΩ, as indicated by triangles in FIG. 9. Furthermore, when the number of layers was 30, Example 3 showed good bonding (indicated by circles in FIG. 9), whereas Comparative Example 3 showed mechanical bonding, but the resistance of the metallized resin films F, particularly those other than the few layers on the tab lead side, was higher than 35 mΩ, as indicated by triangles in FIG. 9.

[0050] (Example 4 and Comparative Example 4) In Example 4, quadrangular pyramidal protrusions 341 were formed on the underside of the joining tool 34 of the horn 32 at a pitch of 1 mm, which was smaller than that of Example 3, and the object to be joined W was heated to 100°C using the heating means 6, with the waiting time for heating set to 0.2 seconds, to soften the resin of the metallized resin film F and ultrasonically join the metal M of the metallized resin film F and a tab lead for a lithium ion battery as the electrode material T. In Comparative Example 4, quadrangular pyramidal protrusions 341 were formed on the underside of the joining tool 34 of the horn 32 at a pitch of 1 mm, which was smaller than that of Comparative Example 3, and the metal M of the metallized resin film F and a tab lead for a lithium ion battery as the electrode material T were ultrasonically joined at room temperature without heating the joining object W with the heating means 6. The metallized resin film F and tab lead used were the same as those used in Example 3 and Comparative Example 3.

[0051] The results of judging the quality of the bonding based on the resistance value of the bonded portion of the metallized resin film F in Example 4 and Comparative Example 4 are shown in Figure 10. In Example 4, when the number of layers of the metallized resin film F was 10 or 20, the resistance of the metallized resin film F was low (35 mΩ or less), and good bonding was achieved (indicated by the circle in Figure 8), but when the number of layers was 30, poor bonding occurred, as indicated by the cross in Figure 10. In contrast, in Comparative Example 4, when the number of layers of the metallized resin film F was 10, good bonding was achieved (indicated by the circle in Figure 10), but when the number of layers was 20 or 30, poor bonding occurred in both cases, as indicated by the cross in Figure 10.

[0052] From the above results, it was found that good joining results, as in Example 1, could be obtained by heating the objects to be joined W to 100°C, which is below the melting temperature of the resin for the base material B of the metallized resin film F (for example, below 150°C), and by setting the pitch of the protrusions 341 formed on the joining tool 34 of the horn 32 to 2 mm so that 30 sheets of the metallized resin film F could be stacked and joined. In this case, the support 2, the tab lead which is the electrode material T, the stacked metallized resin film F, and the horn 32 were arranged in this order, and heated by the heating means 6 built into the support 2 having the flat mounting surface 21, which allowed the resin of the metallized resin film F to be uniformly softened and good joining to be achieved.

[0053] (Effects of the embodiment) According to the first embodiment, an object to be joined W, which is composed of an electrode material T such as a tab lead for a lithium ion battery and a large number of laminated metallized resin films F, such as several tens of sheets, is clamped between the support 2 and the joining tool 34 of the horn 32, and the object to be joined W is heated by the heating means 6 to 50°C or higher and the metallized resin film F to a temperature below the melting temperature of the resin film for the substrate B to soften the resin film.In the softened resin state, the clamped object to be joined W is pressurized by the pressure means 5 while applying ultrasonic waves with lateral vibrations in a direction parallel to the object to be joined W, thereby softening the resin film (substrate B) of the laminated metallized resin film F and making it easier to remove.The resin of the laminated metallized resin film is reliably removed by applying ultrasonic vibrations, and the metal M layer of the metallized resin film F and the electrode material T are solid-state joined to electrically connect them.

[0054] Furthermore, by forming the quadrangular pyramidal protrusions 341 at a pitch of 2 mm on the joining tool 34 of the horn 32, the ultrasonic vibration energy can be concentrated on the joining object W more effectively than when the protrusions are formed at a pitch smaller than 2 mm.

[0055] Furthermore, since the support body 2, which can come into contact with the object to be joined W over a large contact area, is equipped with a heating means 6 to heat the object to be joined W, the laminated metallized resin film F can be efficiently heated to uniformly soften the resin film for the substrate B, and when ultrasonic vibration energy is applied, the resin film can be almost completely removed and joined.

[0056] Second Embodiment A second embodiment of the ultrasonic bonding device of the present invention will be described with reference to Fig. 11. Note that the overall configuration of the ultrasonic bonding device of the second embodiment is the same as that of the first embodiment described above, and therefore the following mainly describes the differences from the first embodiment. Note that the following description will also refer to Figs. 1 to 6.

[0057] 11, a plurality of protrusions 211 similar to the protrusions 341 of the welding tool 34 are formed on the entire surface of the mounting surface 21 of the support body 2, and the protrusions 211 are formed so that the flat surface of the tip of each protrusion 341 of the welding tool 34 faces the flat surface of the tip of each protrusion 211 of the support body 2, and the protrusions 341, 211 are formed so that the area of ​​the flat surface of the tip of the protrusion 211 is larger than the flat surface of the tip of the protrusion 341 of the welding tool 34. Here, similar to the first embodiment, the support body 2 has a built-in heating means 6.

[0058] Then, as shown in Figure 8, two metallized resin films Fa, each having metal Ma vapor-deposited on one side of a resin film substrate Ba, are stacked together so that the metal Ma overlaps each other, and the metallized resin films Fa are heated to 50°C or higher by heating means 6 to a temperature lower than the melting temperature of the resin film for the substrate Ba to soften the resin film, and the two metallized resin films Fa in their softened state are pressurized by pressure means 5 while applying ultrasonic vibrations.

[0059] As a result, as shown in Figure 12, the protrusions 211 of the support body 2 come into contact with the metallized resin film Fa over a larger contact area than the protrusions 341 of the joining tool 34, so that the heat from the heating means 6 built into the support body 2 can be efficiently transferred to the metallized resin film Fa, and the portion of the resin film (substrate Ba) of the two metallized resin films Fa that is sandwiched between the protrusions 211 of the support body 2 and the protrusions 341 of the joining tool 34 softens and is removed by ultrasonic vibration, exposing the metals Ma and enabling solid-state joining.

[0060] Therefore, even when joining a large number of metallized resin films F (see Figure 4) having metal M vapor-deposited on both sides or metallized resin films Fa as shown in Figure 11 having metal Ma layers formed only on both sides by a vacuum deposition method or the like to an electrode material T such as a tab lead, the portions of the base materials B and Ba of the metallized resin films F and Fa that are sandwiched between the protrusions 211 of the support body 2 and the protrusions 341 of the joining tool 34 can be softened and reliably removed by applying ultrasonic vibration energy, exposing the metal M and Ma layers and allowing solid-state joining to the electrode material T.

[0061] Therefore, according to the second embodiment, it is possible to achieve the same effects as the first embodiment described above.

[0062] The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, a heating means may be built into the horn 32 as well as the support 2.

[0063] Furthermore, contrary to the second embodiment described above, the area of ​​the planar surface of the tip of the protrusion 211 of the support body 2 may be made smaller than that of the protrusion 341 of the joining tool 34 on the horn 32 side, and a heating means may be built only in the horn 32 to heat the objects to be joined.

[0064] Furthermore, the shape of the protrusion 341 of the welding tool 34 in the first and second embodiments described above is preferably formed so that the maximum angle formed by lines extending from the two generatrix of the quadrangular pyramid is 60° to 120°. Furthermore, the protrusion 341 may be formed in a truncated cone shape or other truncated pyramid shape. Note that, when a protrusion 211 is also formed on the support body 2 side as in the second embodiment, the shape of the protrusion may be a truncated cone shape, a truncated cone shape, or other truncated pyramid shape in which the maximum angle formed by lines extending from the two generatrix is ​​60° to 120°.

[0065] Furthermore, the heating means 6 is not limited to the sheathed heater described above, but may be any means capable of heating up to the melting temperature of the material of the resin film substrates B, Ba that constitute the metallized resin films F, Fa.

[0066] Furthermore, in the above-described embodiment, the electrode material T is described as a tab lead of a LIB, but the electrode material T is not limited to a tab lead of a LIB, and may be a conductive plate-shaped material such as a tab terminal of a capacitor, or other material used as an electrode.

[0067] The present invention can be applied to an ultrasonic bonding device that vapor-deposits metal onto a resin film substrate to form a metallized resin film, and bonds multiple stacked metallized resin films to an electrode material using ultrasonic vibrations, as well as a method of bonding a metallized resin film to a tab lead using the device. [Explanation of symbols]

[0068] 1...Ultrasonic bonding equipment 2...Support 5...Pressure means 6...Heating means 21...Placement surface 31...Vibrator (ultrasonic vibration means) 32...Horn (ultrasonic vibration means) 211,341…protrusion W: Object to be joined F, Fa...metallized resin film B, Ba: Base material (resin film) M,Ma …metal T... Electrode material (tab lead)

Claims

1. 1. An ultrasonic bonding apparatus for forming a metallized resin film by forming a metal layer on a substrate made of a resin film, and bonding a plurality of the laminated metallized resin films to an electrode material by ultrasonic vibration, a support having a mounting surface on which the electrode material and the object to be joined, which is made up of the plurality of laminated metallized resin films, are placed; an ultrasonic vibration means having a horn that holds the object to be joined between the support and the mounting surface of the support, and a vibrator that ultrasonically vibrates the horn; a pressure applying means for applying pressure to the object to be joined that is sandwiched between the support body and the horn; a heating means provided on at least one of the support body and the horn for heating the objects to be joined; Equipped with the heating means heats the object to be joined, which is sandwiched between the support and the horn, to a temperature of 50°C or higher and equal to or lower than the resin melting temperature of the base material of the metallized resin film, The ultrasonic vibration means applies ultrasonic vibration to the horn in a direction parallel to the heated objects to be joined.

1. An ultrasonic bonding device comprising:

2. the heating means is provided on the support; 2. The ultrasonic bonding device according to claim 1, wherein a plurality of protrusions are formed on a surface of the support member facing the mounting surface of the horn.

3. the heating means is provided on the support; a plurality of protrusions are formed on the mounting surface of the support and on an opposing surface of the horn that faces the mounting surface, 2. The ultrasonic bonding device according to claim 1, wherein a contact area between the protrusions on the opposing surface of the horn and the workpiece is smaller than a contact area between the protrusions on the placement surface and the workpiece.

4. the heating means is provided on the horn; a plurality of protrusions are formed on the mounting surface of the support and on an opposing surface of the horn that faces the mounting surface, 2. The ultrasonic bonding device according to claim 1, wherein a contact area between the protrusions on the opposing surface of the horn and the workpiece is larger than a contact area between the protrusions on the placement surface and the workpiece.

5. the protrusion on the opposing surface of the horn and the protrusion on the mounting surface are shaped like a truncated cone or a truncated pyramid, 5. The ultrasonic bonding device according to claim 2, wherein the protrusions are formed so that the maximum angle formed by the lines extending from the two generatrices of the truncated cone or truncated pyramid is 60° to 120°.

6. 2. The ultrasonic bonding device according to claim 1, wherein the base material of the resin film is made of a polyester resin.

7. 7. The ultrasonic bonding device according to claim 6, wherein the polyester resin is polyethylene terephthalate.

8. 2. The ultrasonic bonding apparatus according to claim 1, wherein the metal layer is formed by vacuum deposition.

9. 2. The ultrasonic bonding device according to claim 1, wherein the metal layer is mainly made of aluminum or copper.

10. 2. The ultrasonic bonding device according to claim 1, wherein the electrode material is a tab lead of a battery or a tab terminal of a capacitor.

11. A method for joining a metallized resin film, which has a metal layer laminated on at least one surface of a base material made of a resin film, to a tab lead of a battery, using an ultrasonic joining device comprising: a support having a mounting surface on which an object to be joined is placed; a horn that holds the object to be joined between the support and the mounting surface; ultrasonic vibration means having a vibrator that ultrasonically vibrates the horn; pressure means that pressurizes the object to be joined held between the support and the horn; and heating means that is provided on at least one of the support and the horn and heats the object to be joined, a step of placing the joining object, which is formed by overlapping a plurality of the metallized resin films on the tab lead, on a mounting surface of a support; a step of holding the object to be joined between the horn of the ultrasonic vibration means and the mounting surface of the support; a step of applying pressure to the object to be joined that is sandwiched between the support body and the horn by the pressure applying means; a step of heating the object to be joined, which is sandwiched between the support and the horn, to a temperature of 50°C or higher and lower than a melting temperature of a resin constituting the base material of the metallized resin film by the heating means provided on at least one of the support and the horn; and applying ultrasonic vibration to the horn in a direction parallel to a surface direction of the objects to be joined by the ultrasonic vibration means to join the objects to be joined.

1. A method for joining a metallized resin film and a tab lead, comprising:

12. 12. The method for joining a metallized resin film and a tab lead according to claim 11, wherein a base material of the metallized resin film is made of a polyester-based resin.

13. 13. The method for joining a metallized resin film and a tab lead according to claim 12, wherein the polyester resin is polyethylene terephthalate.

14. 12. The method for joining a metallized resin film and a tab lead according to claim 11, wherein a main component of the metal layer is aluminum or copper.

15. 12. The method for joining a metallized resin film and a tab lead according to claim 11, wherein the metal layer of the metallized resin film is formed by vacuum deposition.

16. 16. The method for joining a metallized resin film and a tab lead according to claim 11, wherein the tab lead is used in a lithium ion battery.

17. A bonded product of the metallized resin film and the tab lead produced by the method according to claim 11.

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