Ultrasonic bonding method and ultrasonic bonding structure

Abstract

To provide a joint method etc. which can achieve improvement of sealing strength by a lid member for a through hole of a housing etc.SOLUTION: A first workpiece W1 and a second workpiece W2 are joined so as to close a through hole W20 provided at the second workpiece W2 by a sealing portion included in the first workpiece W1 and formed in a disk-like, columnar, or inverted truncated cone shape. The through hole W20 is formed so that a portion from an opening to an annular step portion W22 in a middle part fits in a shape of the sealing portion of the first workpiece W1. A horn tip 140 (an ultrasonic junction chip) is placed in contact with an upper surface of the first workpiece W1 in a state that the sealing portion is inserted into the through hole W20 of the second workpiece W2. Ultrasonic complex vibrations are caused so that the horn chip 140 has ultrasonic vibration components in two vertical directions on a plane parallel to the upper surface of the first workpiece W1.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an ultrasonic bonding technique for bonding a plurality of workpieces made of various materials such as metals by ultrasonic vibration.

Background Art

[0002] Conventionally, as shown in FIG. 8, a metal lid member 51 has been used to close a through hole 520 (for example, an electrolytic solution injection port) provided in a metal housing 52 (for example, a wall material of a battery housing). The lid member 51 has a substantially cylindrical main body portion 511 and a substantially annular flange portion 512 that projects radially over the entire circumference at the upper part of the main body portion 511. The through hole 520 of the housing 52 has a shape in which three substantially cylindrical spaces with different diameters are coaxially overlapped so that the diameter decreases in two steps from top to bottom. In the housing 52, substantially annular first step portion 522 and second step portion 524 are formed as the two diameter-reducing portions of the through hole 520.

[0003] As shown in FIG. 8, the lid member 51 is inserted into the through hole 520 of the housing 52, the side surface of the flange portion 512 abuts against the inner surface 521 that defines the maximum diameter portion of the through hole 520, and the lower surface of the flange portion 512 abuts against the first step portion 522 of the housing 52. In this state, laser light LB is irradiated along an annular locus along the outer surface of the flange portion 512 of the lid member 51. As a result, the outer surface of the flange portion 512 of the lid member 51 and the inner surface 521 of the maximum diameter portion of the through hole 520 of the housing 52 are welded over the entire circumference, and the through hole 520 of the housing 52 is closed by the lid member 51 (see, for example, Patent Document 1).

[0004] However, residual stress exists between the laser-welded lid member 51 and the housing 52, which may reduce the sealing strength of the lid member 51 over the through-hole 520 of the housing 52, and consequently, the pressure resistance strength of the housing 52. In addition, electrolyte adhering to the liquid injection port is prone to pinhole formation during laser welding, which may reduce the sealing strength of the lid member 51 over the through-hole 520 of the housing 52, and consequently, the pressure resistance strength of the housing 52.

[0005] Therefore, as shown in Figure 9, a technique has been proposed to seal the through-hole 620 of the housing 62 by ultrasonically bonding the lower peripheral edge 612 of a substantially disc-shaped or substantially cylindrical lid member 61 to the tapered side wall 622 of the substantially circular mortar-shaped through-hole 620 provided in the housing 62 over its entire circumference (see Patent Document 2). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2015-219962 [Patent Document 2] Japanese Patent Publication No. 2023-182089 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, because the contact area of ​​the lid member 61 with respect to the housing 62 is small, there is a possibility that the sealing strength of the through hole 620 of the housing 62 by the lid member 61, and consequently the pressure resistance strength of the housing 62, will decrease.

[0008] Therefore, the present invention aims to provide a joining method and the like that can further improve the sealing strength of through holes in housings and the like using a cover member. [Means for solving the problem]

[0009] The ultrasonic bonding method of the present invention is The disc shape of the first workpiece or cylinder shapeA method for joining a first workpiece and a second workpiece such that the formed sealing portion closes a through hole provided in the second workpiece so that the portion from the opening to the intermediate annular step portion conforms to the shape of the sealing portion of the first workpiece, The ultrasonic bonding tip is brought into contact with the upper surface of the first workpiece, with the sealing portion inserted into the through hole of the second workpiece. Applying pressure to the first workpiece via the ultrasonic bonding tip The process, The ultrasonic bonding tip is subjected to ultrasonic composite vibration such that it has ultrasonic vibration components in two perpendicular directions on a plane parallel to the upper surface of the first workpiece. As a result, the outer surface of the first workpiece and the inner surface defining the portion of the through-hole of the second workpiece are solid-state bonded around their entire circumference, and additionally or alternatively, the lower peripheral edge of the first workpiece and the stepped portion in the through-hole of the second workpiece are solid-state bonded around their entire circumference. It includes the process. In another embodiment, the ultrasonic bonding method of the present invention is A method for joining a first workpiece and a second workpiece, wherein the sealing portion formed in the shape of an inverted truncated cone of the first workpiece closes a through hole provided in the second workpiece such that the portion from the opening to the intermediate annular step portion conforms to the shape of the sealing portion of the first workpiece, A step of bringing the portion corresponding to the trapezoidal leg of the first workpiece into contact with the opening of the second workpiece, The process involves bringing an ultrasonic bonding tip into contact with the upper surface of the first workpiece, in which the sealing portion is inserted into the through hole of the second workpiece, and applying pressure to the first workpiece via the ultrasonic bonding tip. The process includes: ultrasonically vibrating the ultrasonic bonding tip such that it has ultrasonic vibration components in two perpendicular directions on a plane parallel to the upper surface of the first workpiece, thereby solid-state bonding the outer surface of the first workpiece and the inner surface defining the portion of the through-hole of the second workpiece around its entire circumference; and additionally or alternatively solid-state bonding the lower peripheral edge of the first workpiece and the stepped portion in the through-hole of the second workpiece around its entire circumference.

[0010] The ultrasonic bonding structure of the present invention is The invention comprises a first workpiece having a sealing portion formed in the shape of a disc, cylinder, or inverted truncated cone, and a second workpiece having a through hole provided such that the portion from the opening to the intermediate annular step portion conforms to the shape of the first workpiece. The outer surface of the first workpiece and the inner surface of the second workpiece that defines the portion of the through hole are solid-state bonded around the entire circumference. The lower peripheral edge of the first workpiece and the stepped portion in the through hole of the second workpiece are solid-state bonded together over their entire circumference. [Brief explanation of the drawing]

[0011] [Figure 1] A diagram illustrating the configuration of an ultrasonic bonding apparatus as one embodiment of the present invention. [Figure 2] A flowchart illustrating the procedure for an ultrasonic bonding method as one embodiment of the present invention. [Figure 3] An explanatory diagram showing a method for sealing through-holes in a housing with a lid member. [Figure 4]Configuration explanatory diagram of an ultrasonic bonding structure as an embodiment of the present invention. [Figure 5] Explanatory diagram regarding another sealing method of the through-hole of the housing by the lid member. [Figure 6] Explanatory diagram regarding a sealing method as another embodiment of the through-hole of the housing by the lid member. [Figure 7] Configuration explanatory diagram of an ultrasonic bonding structure as another embodiment of the present invention. [Figure 8] Explanatory diagram regarding a sealing method of the through-hole of the housing by the lid member as Prior Art 1. [Figure 9] Explanatory diagram regarding a sealing method of the through-hole of the housing by the lid member as Prior Art 2.

Mode for Carrying Out the Invention

[0012] (Configuration) The ultrasonic bonding device as an embodiment of the present invention shown in FIG. 1 includes an ultrasonic composite vibration device 10, a horn tip 140 (ultrasonic bonding tip), and an anvil 18. The anvil 18 may be omitted.

[0013] The ultrasonic composite vibration device 10 includes a substantially cylindrical first vibration element 110, a substantially cylindrical, substantially cylindrical or bottomed cylindrical intermediate vibration element 100, and a substantially cylindrical or bottomed cylindrical second vibration element 120. The first vibration element 110, the intermediate vibration element 100, and the second vibration element 120 constitute the "vibration elements".

[0014] The first vibration element 110 and the intermediate vibration element 100 are coaxially connected by a mechanical connection mechanism (such as a bolt and / or clamp mechanism) in the middle part or the intermediate part of the ultrasonic composite vibration device 10. The intermediate vibration element 100 and the second vibration element 120 are coaxially connected by a mechanical connection mechanism in the middle part of the ultrasonic composite vibration device 10. The first vibration element 110, the intermediate vibration element 100, and the second vibration element 120 may be integrally formed instead of being mechanically connected.

[0015] The intermediate vibration element 100 may be a component of the first vibration element 110. That is, the first vibration element 110 may be composed of two vibration elements. In this case, the first vibration element 110 and the intermediate vibration element 100 may be integrally configured rather than being mechanically connected. The intermediate vibration element 100 may be a component of the second vibration element 120. That is, the second vibration element 120 may be composed of two vibration elements. In this case, the second vibration element 120 and the intermediate vibration element 100 may be integrally configured rather than being mechanically connected.

[0016] As shown in Figure 1, the first vibrating element 110 is provided with a piezoelectric body 112 whose axial direction (a direction parallel to the first axis) is the direction of piezoelectric polarization.

[0017] As shown in Figure 1, the intermediate vibration element 100 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 100 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 100 is supported by a mechanical support mechanism. As shown in Figure 1, the intermediate vibration element 100 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 100 is substantially cylindrical (a substantially frustoconical shape and a substantially cylindrical shape coaxially connected) with an outer diameter that is continuously reduced towards the tip partway through.

[0018] As shown in Figure 1, the second vibration element 120 is provided with a frequency adjustment element 122, which is a roughly regular octagonal plate shape with rounded corners, extending radially around its entire circumference at an intermediate position in its axial direction. The frequency adjustment element 122 adjusts the resonant frequencies of the longitudinal and torsional vibration components of the ultrasonic vibration. The external shape of the frequency adjustment element 122 may be a roughly circular, roughly elliptical, or roughly regular n-sided plate shape (e.g., n=4,6,8,12,16...) that shares a central axis with the second vibration element 120, or a columnar or figurines, or any combination thereof.

[0019] As shown in Figure 1, the second vibration element 120 has a plurality of slits 124 formed on its outer surface behind the frequency adjustment element 122. The plurality of slits 124 may also be formed on the outer surface of the second vibration element 120 in front of the frequency adjustment element 122. The slits 124 extend diagonally when viewed from the side of the second vibration element 120, or extend axially while being displaced circumferentially in phase. The N (N=2, 3, ...) slits 124 may be arranged to have N rotational symmetry around the central axis of the second vibration element 120 (for example, N=8, 12, or 16).

[0020] As shown in Figure 1, the second vibrating element 120 is provided with a roughly regular octagonal tip portion 126 with rounded corners that extends radially around its entire circumference at its axial tip position. The tip portion 126 has multiple holes 128 (or through holes) formed at spaced intervals in the circumferential direction. The M (N=2, 3, ...) holes 128 may be arranged to have M rotational symmetry (e.g., M=4) around the central axis of the second vibrating element 120. Internal threads are provided on the inner surfaces of the holes 128.

[0021] The horn tip 140 has a base portion that is roughly frustoconical in shape and a tip portion that contacts the uppermost of the two workpieces W1 and W2. The male thread provided at the base end of the horn tip 140 is screwed into the female thread provided in the hole 128 of the tip portion 126 of the second vibrating element 12, thereby detachably fixing the horn tip 140 to the second vibrating element 120. 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.

[0022] The male thread of the balancer, which adjusts the phase difference between longitudinal and torsional vibrations at the tip 126 of the second vibrating element 120 and, consequently, the horn tip 140, may be screwed into the female thread of the hole 128, thereby allowing the balancer to be detachably fixed to the tip 126 of the second vibrating element 120.

[0023] The anvil 18 is positioned perpendicular to the tip of the horn tip 140. A first workpiece W1 and a second workpiece W2 are placed on the upper surface of the anvil 18. The anvil 18 may be configured to be passively or actively displaced up and down in response to the pressure exerted on the horn tip 140 via the first workpiece W1 and the second workpiece W2.

[0024] As shown in Figure 1, an ultrasonic bonding apparatus according to one embodiment of the present invention further comprises an operating device 20, a control device 22, a rotary drive device 220, a high-frequency power supply device 221, a translational drive device 222, and a state sensor 224.

[0025] The operating device 20 is comprised of, for example, a display that displays or outputs the displacement amount and / or pressure of the pressurizing block in response to the output signal of the state sensor 224. The display may be a touch panel display and may be configured to accept setting operations that allow the user to directly or indirectly specify parameters, such as one of several bonding modes that define the time-series pattern of the target pressure.

[0026] The control device 22 is composed of a microcomputer, and by extension, an arithmetic processing unit (CPU, microprocessor, processor core, etc.) and a memory device (ROM, RAM, etc.). The control device 22 is configured to control the displacement operation of the pressure block by the translation drive device 222 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 224. The control device 22 is configured to control the power supplied to the piezoelectric body 112 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 224, and thereby control the ultrasonic vibration power of the vibration elements (first vibration element 110, intermediate vibration element 100, and second vibration element 120) and the ultrasonic vibration power of the horn tip 140.

[0027] The high-frequency power supply unit 221 is configured to excite the first vibrating element 110 in the axial direction by applying a high-frequency AC voltage to the piezoelectric body 112 of the first vibrating element 110 in accordance with the power supplied from the commercial power supply (not shown).

[0028] The translational drive device 222 is equipped with a pressure block and is configured to apply pressure from the horn tip 140 to the first workpiece W1 and the second workpiece W2 by displacing a support mechanism such as a clamp mechanism that supports the intermediate vibration element 100 with the pressure block.

[0029] The state sensor 224 includes a stroke sensor that outputs a signal corresponding to the displacement of the pressure block constituting the translational drive unit 222, 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 consisting of an imaging device and a device that calculates the amplitude by analyzing the image acquired through the imaging device. The state sensor 224 may also include a pressure sensor that outputs a signal corresponding to the pressure acting on the intermediate vibration element 100 from the pressure block of the translational drive unit 222 (~pressure applied by the horn tip 140 to the first workpiece W1 and the second workpiece W2), and the control device 22 may control the time series of the pressure to be constant or controlled in a specified manner based on the output signal of the pressure sensor.

[0030] (Ultrasonic bonding method) The procedure for an ultrasonic bonding method as one embodiment of the present invention using an ultrasonic bonding apparatus 1 will be explained using the flowchart in Figure 2. As shown in Figure 3, the first workpiece W1 is a substantially disc-shaped metal lid member used to seal a through hole W20 provided in the second workpiece W2. The entire first workpiece W1 may constitute the sealing portion, or only a part or the lower part of the first workpiece W1 may constitute the sealing portion. The second workpiece W2 is a metal housing (e.g., a battery housing) or its wall material provided with a through hole W20 (e.g., an electrolyte injection port). The through hole W20 of the second workpiece W2 has a shape in which a substantially cylindrical space of large diameter and a substantially cylindrical space of small diameter are coaxially stacked from top to bottom, such that the diameter narrows midway. The second workpiece W2 has a substantially annular stepped portion W22 formed as the portion of the through hole W20 that narrows in diameter.

[0031] As shown in Figure 3, the first workpiece W1 is inserted into the through hole W20 of the second workpiece W2, the side surface of the first workpiece W1 abuts against the inner surface W21 that defines the large diameter portion of the through hole W20, and the lower surface of the first workpiece W1 abuts against the stepped portion W22 of the second workpiece W2.

[0032] The translational drive unit 222 moves the ultrasonic composite vibrator 10 and the horn tip 140 radially so as to approach the first workpiece W1 and the second workpiece W2 (Figure 2 / STEP 112).

[0033] Furthermore, it is determined whether the pressure P that the horn tip 140 receives from the first workpiece W1 (and the second workpiece W2) is equal to or greater than the first specified pressure P1 (Figure 2 / STEP 114). The pressure P that the horn tip 140 receives from the first workpiece W1 is measured based on the output signal of the pressure sensor that constitutes the state sensor 224. When the tip of the horn tip 140 is separated from the workpiece W1, P=0. When the tip of the horn tip 140 comes into contact with the first workpiece W1, which is inserted into the through hole W20 of the second workpiece W2, for example as shown in Figure 3, it receives a reaction force and P>0.

[0034] If the determination result is negative (Figure 2 / STEP114...NO), the translational drive device 222 moves the ultrasonic composite vibrator 10 and the horn tip 140 radially so that they approach the first workpiece W1 which is inserted into the through hole W20 of the second workpiece W2 (Figure 2 / connector X1 → STEP112). This adjusts the position of the horn tip 140, and consequently the static pressure applied from the horn tip 140 to the first workpiece W1 and the second workpiece W2, so that it falls within the specified static pressure range (for example, 200N to 800N).

[0035] If the judgment result is positive (Figure 2 / STEP114...YES), ultrasonic vibration is generated in the vibrating element (Figure 2 / STEP116). Specifically, in response to power being supplied to the high-frequency power supply 221 from a commercial power source (not shown) via a slip ring or the like, the high-frequency power supply 221 applies a high-frequency AC voltage to the piezoelectric body 112 of the first vibrating element 110. As a result, the first vibrating element 110 vibrates in its axial direction at, for example, about 20 kHz, generating ultrasonic vibration. The ultrasonic vibration is transmitted from the first vibrating element 110 to the intermediate vibrating element 100 in its axial direction, and the amplitude of the ultrasonic vibration is amplified. Furthermore, the amplified ultrasonic vibration is transmitted from the intermediate vibrating element 100 to the second vibrating element 120 in its axial direction.

[0036] In this way, a portion of the longitudinal vibration component (the axial component of the second vibration element 120) of the ultrasonic vibration transmitted to the second vibration element 120 is converted into a torsional vibration component by the multiple slits 124 formed on the outer surface of the second vibration element 120. The combined vibration resulting from the combination of the longitudinal and torsional vibration components is then transmitted to the horn tip 140 fixed to the tip of the second vibration element 120.

[0037] In response, the horn tip 140 is displaced or vibrates in a circular or elliptical orbit in a plane perpendicular to the contact direction of the first workpiece W1. As a result, the amplitude and ultrasonic vibration power of the horn tip 140 gradually increase from the vibration start time t=t0. During this time, impurities on the contact surfaces of the first workpiece W1 and the second workpiece W2 are removed, and plastic deformation of the contact surfaces of the first workpiece W1 and the second workpiece W2 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 again. This is because oxide films and the like of the metal constituting the respective joining surfaces of the first workpiece W1 and the second workpiece W2 are removed, clean and activated metal atoms appear on the joining surfaces, and the motion of the atoms becomes more active due to the temperature rise caused by frictional heat, resulting in mutual attraction between atoms.

[0038] In this process, the amount of indentation of the first workpiece W1 and the second workpiece W2 by the horn tip 140 and / or the static pressure applied to the first workpiece W1 and the second workpiece W2 are adjusted while a compound vibration is applied to the first workpiece W1 and the second workpiece W2. As a result, as shown in Figure 4, the outer surface and lower peripheral edge of the first workpiece W1 can be solid-state bonded to the stepped portion W22 of the second workpiece W2 over its entire circumference.

[0039] It is determined whether the time derivative δA (= current amplitude A(k) - previous amplitude A(k-1)) of the amplitude A of the horn tip 140 is negative, and whether the amplitude A is less than or equal to the reference amplitude A0 (Figure 2 / STEP 118). The amplitude sensor constituting the state sensor 224 optically measures the amplitude A at a specified location on the horn tip 140 (for example, a location with a relatively large amplitude). Alternatively, 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 operating device 20, such as one of several junction modes that define the reference amplitude A0.

[0040] If the determination result is negative (Figure 2 / STEP118...NO), ultrasonic vibration is continuously generated in the vibration element (Figure 2 / Coupler X2 →STEP116). On the other hand, if the determination result is positive (Figure 2 / STEP118...YES), the translational drive device 222 moves the ultrasonic composite vibrator 10 and the horn tip 140 so as to move away from the first workpiece W1 and the second workpiece W2 (Figure 2 / STEP122).

[0041] Furthermore, it is determined whether the pressure P that the horn tip 140 receives from the first workpiece W1 (and the second workpiece W2) has become less than or equal to the second specified pressure P2 (Figure 2 / 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.

[0042] If the determination result is negative (Figure 2 / STEP124...NO), the translational drive device 222 moves the ultrasonic composite vibrator 10 and the horn tip 140 so that they are separated from the first workpiece W1 and the second workpiece W2 (Figure 2 / coupler X4 →STEP122). This adjusts the radial position of the horn tip 140, and consequently the static pressure applied from the horn tip 140 to the first workpiece W1 and the second workpiece W2, to decrease.

[0043] If the judgment result is positive (Figure 2 / STEP124...YES), the generation of ultrasonic vibration in the vibration element is stopped (Figure 2 / STEP126). 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. This stops the series of processes.

[0044] (effect) According to the ultrasonic bonding apparatus with the above configuration, the outer surface and lower peripheral edge of the first workpiece W1 are ultrasonically bonded or solid-state bonded around the entire circumference to the inner surface and stepped portion W22 of the large-diameter portion of the through-hole W20 of the second workpiece W2. This reduces residual stress between the first workpiece W1 and the second workpiece W2, thereby improving the sealing strength of the through-hole W20 of the second workpiece W2 by the lid member, which is the first workpiece W1, and consequently, the pressure resistance strength of the housing, which is the second workpiece W2. Furthermore, since the first workpiece W1 only needs to be formed in a substantially disc shape or a substantially cylindrical shape, manufacturing costs can be reduced compared to the lid member 51 in the conventional technology (see Figure 5). Furthermore, even if foreign matter such as electrolyte is present on the side surface of the through-hole W20, the horn tip 140 applies ultrasonic composite vibration, circular vibration, or elliptical vibration to the first workpiece W1, thereby removing the foreign matter from the joining surface of the first workpiece W1 and the second workpiece W2, thus preventing a decrease in joining strength caused by the foreign matter.

[0045] (Other embodiments of the present invention) In the above embodiment, both the first workpiece W1 (or the sealing portion of the first workpiece W1) and the large-diameter space of the through-hole W20 in the second workpiece W2 into which the first workpiece W1 is inserted were substantially disc-shaped or substantially cylindrical. In contrast, in other embodiments, the first workpiece W1 (or the sealing portion of the first workpiece W1) and / or the large-diameter space of the through-hole W20 in the second workpiece W2 into which the first workpiece W1 is inserted may be substantially frustoconical in shape (inverted) with the lower side being the upper base.

[0046] For example, as shown in Figure 5, the first workpiece W1 may have a first sealing portion that is roughly in the shape of an inverted frustocone, and a second sealing portion that is connected to the upper end of the first sealing portion and is roughly cylindrical or disc-shaped with roughly the same diameter as the upper end of the first sealing portion. For example, as shown in Figure 5, the large-diameter portion of the roughly two-stage cylindrical through hole W20 provided in the second workpiece W2 is larger in diameter than the lower end of the first sealing portion, while being formed as a roughly cylindrical shape with a smaller diameter than the upper end of the first sealing portion (and consequently the second sealing portion). With the first sealing portion of the first workpiece W1 inserted into the large-diameter portion of the through hole W0, the first workpiece W1 is pushed downward by the horn tip 140, and ultrasonic composite vibration is applied to the first workpiece W1 from the horn tip 140.

[0047] As a result, as shown in Figure 6, the first workpiece W1 is gradually inserted into the second workpiece W2 so that it conforms to the shape of the through hole W20, with the first sealing portion of the first workpiece W1 being roughly frustoconical in shape, and a portion of the second sealing portion deforming into a roughly cylindrical shape to conform to the shape of the large diameter portion of the through hole W20 of the second workpiece W2.

[0048] As shown in Figure 7, the first workpiece W1, which has been deformed into a roughly two-stage cylindrical shape, is solid-state bonded at the side surface of the small-diameter cylindrical portion to the inner surface W21 that defines the large-diameter portion of the through-hole W20, solid-state bonded at the peripheral edge of the lower end surface to the roughly annular stepped portion W22 which is the reduced-diameter portion of the through-hole W20, and bonded at the lower end surface of the large-diameter portion (flange portion) to the peripheral edge of the through-hole W20 of the second workpiece W2. As a result, the bonding area between the first workpiece W1 and the second workpiece W2 is further increased. In other words, the sealing strength of the through-hole W20 of the second workpiece W2 by the first workpiece W1 (or the sealing portion derived from its first and second sealing portions) is improved.

[0049] In the above embodiment, the amplitude A of the horn tip 140 was measured as a specified parameter that changes according to the progress of joining the first workpiece W1 and the second workpiece W2. In other embodiments, the axial displacement, displacement velocity, and / or displacement acceleration of a vibrating element (e.g., the second vibrating element 120) may be measured as specified parameters. [Explanation of Symbols]

[0050] 10. Ultrasonic combined vibration device 100...Intermediate vibration element 102...Intermediate flange 110...First vibration element 112. Piezoelectric material 120...Second vibration element 122...Frequency adjustment element 124... Slit 140... Horn tip (tip for ultrasonic bonding) 18... Anvil 20‥Operation device 22. Control device 220... Rotary drive device 221‥High frequency power supply equipment 222... Translational drive device 224... State sensor W1...First workpiece (lid component) W2...Second work (enclosure) W20...Through hole W22‥ Segment difference portion.

Claims

1. A method for joining a first workpiece and a second workpiece, wherein the disc-shaped or cylindrical sealing portion of the first workpiece seals a through hole provided in the second workpiece such that the portion from the opening to the intermediate annular step portion conforms to the shape of the sealing portion of the first workpiece, The process involves bringing an ultrasonic bonding tip into contact with the upper surface of the first workpiece, in which the sealing portion is inserted into the through hole of the second workpiece, and applying pressure to the first workpiece via the ultrasonic bonding tip. An ultrasonic bonding method comprising the steps of: ultrasonically vibrating the ultrasonic bonding tip such that it has ultrasonic vibration components in two perpendicular directions on a plane parallel to the upper surface of the first workpiece, thereby solid-state bonding the outer surface of the first workpiece and the inner surface defining the portion of the through hole of the second workpiece over its entire circumference; and additionally or alternatively solid-state bonding the lower peripheral edge of the first workpiece and the stepped portion in the through hole of the second workpiece over its entire circumference.

2. A method for joining a first workpiece and a second workpiece such that the sealing portion formed in the shape of an inverted truncated cone of the first workpiece seals a through hole provided in the second workpiece such that the portion from the opening to the intermediate annular stepped portion conforms to the shape of the sealing portion of the first workpiece, A step of bringing the portion corresponding to the trapezoidal leg of the first workpiece into contact with the opening of the second workpiece, The process involves bringing an ultrasonic bonding tip into contact with the upper surface of the first workpiece, in which the sealing portion is inserted into the through hole of the second workpiece, and applying pressure to the first workpiece via the ultrasonic bonding tip. An ultrasonic bonding method comprising the steps of: ultrasonically vibrating the ultrasonic bonding tip such that it has ultrasonic vibration components in two perpendicular directions on a plane parallel to the upper surface of the first workpiece, thereby solid-state bonding the outer surface of the first workpiece and the inner surface defining the portion of the through hole of the second workpiece over its entire circumference; and additionally or alternatively solid-state bonding the lower peripheral edge of the first workpiece and the stepped portion in the through hole of the second workpiece over its entire circumference.

3. The invention comprises a first workpiece having a sealing portion formed in the shape of a disc, cylinder, or inverted truncated cone, and a second workpiece having a through hole provided such that the portion from the opening to the intermediate annular step portion conforms to the shape of the first workpiece. The outer surface of the first workpiece and the inner surface of the second workpiece that defines the portion of the through hole are solid-state bonded around the entire circumference. The lower peripheral edge of the first workpiece and the stepped portion in the through hole of the second workpiece are solid-state bonded together over their entire circumference. Ultrasonic bonded structure.

4. In the ultrasonic bonding structure according to claim 3, A battery comprising a lid member of the first workpiece and a housing as the second workpiece having an electrolyte injection port as a through hole, Ultrasonic bonded structure.

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