Ultrasonic welding apparatus and ultrasonic welding method using ultrasonic welding tip

Abstract

To provide: an ultrasonic welding tip capable of improving the quality of welding between workpieces by suppressing the generation of burrs; and an ultrasonic welding apparatus and ultrasonic welding method using the same.SOLUTION: In a state where a plurality of protruding portions 441 and an annular protruding portion 442 surrounding the plurality of protruding portions 441 are pressed against workpieces W1, W2, ultrasonic composite vibration is applied to the workpieces W1, W2 in a direction perpendicular to a direction of the pressing. Therein, although some portions of the workpieces W1 and W2 is moved so as to be pushed away outward by the plurality of protruding portions 441, the movement of the portions of the workpieces W1 and W2 is blocked by the annular protruding portion 442.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an ultrasonic bonding tip for bonding metal workpieces by ultrasonic vibration, and an ultrasonic bonding device and an ultrasonic bonding method that use the ultrasonic bonding tip. [Background technology]

[0002] Currently, ultrasonic joining technology is being adopted in the joining process of metal electrical contacts of batteries and / or electrical components for EVs, and a joining tool called a horn tip is being used. In order to reliably transmit the ultrasonic vibrations of the horn tip (ultrasonic joining tip) to the material to be joined (workpiece), it has been proposed to give the tip of the horn tip an uneven structure (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6861017 Summary of the Invention [Problem to be solved by the invention]

[0004] Metal materials such as aluminum or copper, as well as alloy materials, are used for electrical contact parts. When joining using ultrasonic waves, friction can generate metal burrs, which can cause problems with the electrical connection.

[0005] Therefore, an object of the present invention is to provide an ultrasonic bonding tip that can improve the quality of bonding between workpieces by suppressing the occurrence of burrs, and an ultrasonic bonding device and ultrasonic bonding method using the same. [Means for solving the problem]

[0006] The ultrasonic bonding tip of the present invention is a plurality of protrusions arranged in a specified pattern on the end face and protruding from the end face; The press tool further includes an annular protrusion that surrounds the plurality of protrusions and protrudes from the end face so as to be pressed against the workpiece when the plurality of protrusions are pressed against the workpiece.

[0007] According to the ultrasonic bonding tip having the above configuration, ultrasonic vibration is applied to the workpiece in a direction perpendicular to the pressing direction while the multiple protrusions and the annular protrusion surrounding the multiple protrusions are pressed against the workpiece. At this time, the multiple protrusions move a part of the workpiece (one workpiece, or one workpiece and the other workpiece) outward (outside the area where the multiple protrusions are provided on the end face of the ultrasonic bonding tip), but the movement of the workpiece is stopped by the annular abutment. This prevents the workpiece from moving outward in an unlimited manner, which would cause burrs, and improves the quality of the bonding of the workpieces.

[0008] In the ultrasonic bonding tip having the above configuration, In any cross section of the annular protrusion perpendicular to the extending direction of the end face, the contour of the portion pressed against the workpiece forms a continuous convex curve. It is preferable.

[0009] According to the ultrasonic bonding tip having the above-mentioned configuration, in any cross section of the annular protrusion perpendicular to the extending direction of the end face of the ultrasonic bonding tip, the contour of the portion pressed against the workpiece does not have any corners or discontinuities. Therefore, the corners of the annular protrusion of the ultrasonic bonding tip are prevented from scraping or pushing aside the material of the workpiece, and thus the generation of burrs due to the movement of the material is suppressed, thereby improving the quality of the bonding of the workpiece.

[0010] In the ultrasonic bonding tip having the above configuration, The annular protrusion is formed on the end surface so as to surround all of the plurality of protrusions at intervals. It is preferable.

[0011] According to the ultrasonic bonding tip having this configuration, a relatively large space is secured for the workpiece to move between being pushed outward by the multiple protrusions and being held in place by the annular protrusion. This prevents the workpiece from swelling up when the annular protrusion stops the workpiece from moving, improving the quality of the workpiece bonding. The multiple protrusions push the workpiece outward and hold it in place by the annular protrusion, increasing the pressure acting on the workpiece, and increasing the density of the workpiece, improving the quality of the electrical conductivity. In addition, the increased pressure reduces the energy consumed for bonding.

[0012] In the ultrasonic bonding tip having the above configuration, Any cross section of the annular protrusion perpendicular to the extending direction of the end surface has a shape inclined in a direction away from the plurality of protrusions. It is preferable.

[0013] According to the ultrasonic bonding tip having this configuration, a relatively large space is secured for the workpiece to move between being pushed outward by the multiple protrusions and being held in place by the annular protrusion. This prevents the workpiece from swelling up when the annular protrusion stops the workpiece from moving, improving the quality of the workpiece bonding. The multiple protrusions push the workpiece outward and hold it in place by the annular protrusion, increasing the pressure acting on the workpiece, and increasing the density of the workpiece, improving the quality of the electrical conductivity. In addition, the increased pressure reduces the energy consumed for bonding.

[0014] In the ultrasonic bonding tip having the above configuration, In any cross section perpendicular to the pressing direction of at least the apex of each of the plurality of protrusions against the workpiece, the contour of the portion pressed against the workpiece forms a continuous closed convex curve. It is preferable.

[0015] According to the ultrasonic bonding tip having this configuration, in any cross section perpendicular to the pressing direction of each of the multiple protrusions against the workpiece, there are no corners or discontinuous parts in the outline of the part pressed against the workpiece. This prevents the corners or ridges of the multiple protrusions of the ultrasonic bonding tip from scraping or pushing away the material of the workpiece, and thus suppresses the generation of burrs due to the movement of the material, thereby improving the quality of the joining of the workpiece.

[0016] In the ultrasonic bonding tip having the above configuration, In any cross section of each of the plurality of protrusions parallel to the pressing direction against the workpiece, the contour of the portion pressed against the workpiece forms a continuous curve. It is preferred.

[0017] According to the ultrasonic bonding tip having this configuration, in any cross section parallel to the pressing direction of each of the multiple protrusions against the workpiece, there are no corners or discontinuous parts in the outline of the part pressed against the workpiece. This prevents the corners of the multiple protrusions of the ultrasonic bonding tip from scraping or pushing away the material of the workpiece, and thus suppresses the generation of burrs due to the movement of the material, thereby improving the quality of the joining of the workpiece.

[0018] In the ultrasonic bonding tip having the above configuration, Each of the plurality of protrusions is formed in a shape of a spherical cutout, a spherical frustum, a cone with rounded edges on the upper and lower surfaces, a cone frustum, or a cone frustum and a spherical cutout or a spherical frustum having a common upper and lower surfaces and stacked coaxially. It is preferred.

[0019] According to the ultrasonic bonding tip having the above configuration, in any cross section perpendicular to the pressing direction against the workpiece and any cross section horizontal to the cross section of each of the multiple protrusions, there are no corners or discontinuities in the contour of the portion pressed against the workpiece. This prevents the corners of the multiple protrusions of the ultrasonic bonding tip from scraping or pushing away the material of the workpiece, and thus suppresses the generation of burrs due to the movement of the material, thereby improving the quality of the joining of the workpiece.

[0020] The ultrasonic bonding apparatus of the present invention comprises: A vibration element that induces a composite vibration by combining a longitudinal vibration and a torsional vibration; The ultrasonic bonding tip of the present invention, and a control device for controlling the composite vibration of the vibration element.

[0021] According to the ultrasonic bonding device having the above configuration, the ultrasonic complex vibration is applied to the workpiece in a direction perpendicular to the pressing direction while the multiple protrusions of the ultrasonic bonding tip and the annular protrusion surrounding the multiple protrusions are pressed against the workpiece. At this time, the multiple protrusions move a part of the workpiece (one workpiece, or one workpiece and the other workpiece) outward (outside the area where the multiple protrusions are provided on the end face of the ultrasonic bonding tip), but the movement of the workpiece is stopped by the annular abutment. This prevents the workpiece from moving outward in an unlimited manner, which would cause burrs, and improves the quality of the bonding of the workpiece.

[0022] The ultrasonic bonding method of the present invention comprises the steps of: 1. An ultrasonic bonding method for bonding one workpiece and another workpiece using an ultrasonic bonding device including a vibration element that induces a composite vibration by combining a longitudinal vibration and a torsional vibration, and an ultrasonic bonding tip that is fixed to the vibration element or detachably attached to the vibration element, comprising: a plurality of protrusions arranged in a specified pattern on the end surface and protruding from the end surface; a ring-shaped protrusion surrounding the plurality of protrusions and protruding from the end surface so as to be pressed against the workpiece when the plurality of protrusions are pressed against the workpiece, is used as the ultrasonic bonding tip; a step of determining whether or not the joining of the one workpiece to the other workpiece has been completed based on a signal corresponding to a value of a designated parameter that changes according to a progress state of joining of the one workpiece to the other workpiece while the ultrasonic joining tip is in contact with the one workpiece to be joined; and stopping the composite vibration of the vibration element when it is determined that the joining of the one workpiece and the other workpiece is completed.

[0023] According to the ultrasonic bonding method of the present invention, it is possible to accurately determine whether the bonding is completed or not according to the change in the value of a designated parameter that changes according to the progress of the bonding of the one workpiece and the other workpiece, such as the amplitude of the ultrasonic vibration of the ultrasonic bonding tip of the present invention.When the determination result indicates that the bonding of the one workpiece and the other workpiece is completed, the ultrasonic vibration of the ultrasonic bonding tip is stopped, and as a result, the period during which the ultrasonic bonding tip is ultrasonically vibrated can be appropriately controlled from the viewpoint of improving the quality of the bonding of the one workpiece and the other workpiece. [Brief description of the drawings]

[0024] [Figure 1] FIG. 2 is a diagram illustrating the configuration of an ultrasonic bonding device. [Diagram 2] FIG. 1 is a diagram illustrating the configuration of an ultrasonic bonding tip according to one embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram illustrating the configuration of an end portion of an ultrasonic bonding tip according to one embodiment of the present invention. [Figure 4] 3A and 3B are diagrams illustrating the configuration of an end portion of the ultrasonic bonding tip of the present invention. [Diagram 5] FIG. 13 is a configuration explanatory diagram of an ultrasonic bonding tip according to another embodiment of the present invention. [Figure 6] 4 is a flow chart of the functioning of the ultrasonic bonding device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] (composition) 1 is a component of an ultrasonic bonding apparatus that bonds workpieces W1 and W2, which are objects to be bonded such as metal plates, by utilizing ultrasonic complex vibration, which will be described later. The ultrasonic bonding apparatus is used, for example, for bonding electrodes of lithium ion batteries and / or semiconductor elements, and bonding of the same or different metals.

[0026] 1, the ultrasonic complex vibration device 1 includes a first vibration element 11 having a substantially cylindrical shape, an intermediate vibration element 10 having a substantially cylindrical, cylindrical or bottomed cylindrical shape, and a second vibration element 12 having a substantially cylindrical or bottomed cylindrical shape. The first vibration element 11, the intermediate vibration element 10, and the second vibration element 12 constitute "vibration elements." The ultrasonic bonding device includes the ultrasonic complex vibration device 1, a horn tip 40 (ultrasonic bonding tip), and an anvil 18.

[0027] The first vibration element 11 and the intermediate vibration element 10 are coaxially connected by a mechanical connection mechanism (such as a bolt and / or a clamp mechanism) at the middle or intermediate portion of the ultrasonic complex vibration device 1. The intermediate vibration element 10 and the second vibration element 12 are coaxially connected by a mechanical connection mechanism at the middle portion of the ultrasonic complex vibration device 1. The first vibration element 11, the intermediate vibration element 10 and the second vibration element 12 may be integrally configured instead of being mechanically connected.

[0028] The intermediate vibration element 10 may be a component of the first vibration element 11. That is, the first vibration element 11 may be composed of two vibration elements. In this case, the first vibration element 11 and the intermediate vibration element 10 may be integrally configured, rather than being mechanically connected. The intermediate vibration element 10 may be a component of the second vibration element 12. That is, the second vibration element 12 may be composed of two vibration elements. In this case, the second vibration element 12 and the intermediate vibration element 10 may be integrally configured, rather than being mechanically connected.

[0029] As shown in FIG. 1, the first vibration element 11 is provided with a piezoelectric body 112 whose axial direction is the piezoelectric polarization direction.

[0030] As shown in FIG. 1, the intermediate vibration element 10 is formed with an intermediate flange 100 in the shape of a substantially annular plate, which protrudes radially over the entire circumference at the middle position in the axial direction. The intermediate vibration element 10 is configured to be clamped or supported at least at the intermediate flange 100 by a clamping mechanism (not shown) over the entire circumference. If it is ensured that the intermediate vibration element 10 is supported by a mechanical support mechanism, the intermediate flange 100 may be omitted. As shown in FIG. 1, the intermediate vibration element 10 is substantially cylindrical with an outer diameter that is substantially constant in the axial direction behind the intermediate flange 100 (leftward in FIG. 1). As shown in FIG. 1, the intermediate vibration element 10 is substantially cylindrical (a shape in which a substantially truncated cone shape and a substantially cylindrical shape are coaxially connected) with an outer diameter that is substantially constant after continuously reducing in diameter halfway toward the tip portion ahead of the intermediate flange 100 (rightward in FIG. 1).

[0031] 1, the second vibration element 12 is provided with a frequency adjustment element 120 having a generally regular octagonal shape with rounded corners, which protrudes radially around the entire circumference at a midpoint in the axial direction. The frequency adjustment element 120 adjusts the resonance frequencies of the longitudinal vibration component and the torsional vibration component of the ultrasonic vibration.

[0032] As shown in FIG. 1, the second vibration element 12 has a plurality of slits 124 formed on its outer surface behind the frequency adjustment element 120. A plurality of slits 124 may be formed on the outer surface of the second vibration element 12 ahead of the frequency adjustment element 120. The slits 124 extend obliquely in the second vibration element 12 when viewed from the side, or extend in the axial direction while being displaced in the circumferential direction in the same phase. The N (N=2, 3, . . . ) slits 124 may be arranged to have N-fold rotational symmetry (e.g., N=8, 12, or 16) around the central axis of the second vibration element 12.

[0033] 1, the second vibration element 12 is provided with a tip portion 126 of a generally regular octagonal shape with rounded corners that protrudes radially over the entire circumference at the tip position in the axial direction. The tip portion 126 is provided with holes 128 (or through holes) at a plurality of locations spaced apart in the circumferential direction. The N (N=2, 3, . . . ) holes 128 may be arranged to have N-fold rotational symmetry (e.g., N=4) around the central axis of the second vibration element 12. The hole 128 is provided with a female thread on the inner surface.

[0034] Horn tip 40 has a substantially truncated cone-shaped base portion and a tip portion that abuts against workpiece W1, which is the uppermost of workpieces W1 and W2. A male screw provided at the base end of horn tip 40 is screwed into a female screw provided in hole 128 of tip portion 126 of second vibration element 12, thereby removably fixing horn tip 40 to second vibration element 12. Horn tips 40 of various shapes are prepared, so that horn tips 40 can be appropriately replaced depending on the type of metal to be joined, etc.

[0035] The balancer for adjusting the phase difference between the longitudinal vibration and the torsional vibration at the tip 126 of the second vibration element 12, and therefore at the horn tip 40, may be removably fixed to the tip 126 of the second vibration element 12 by screwing the male thread of the balancer into the female thread of the hole 128.

[0036] The anvil 18 is disposed so as to face the tip of the horn tip 40 in the vertical direction. For example, substantially flat workpieces W1 and W2 are placed one on top of the other on the upper surface of the anvil 18. The anvil 18 may be configured to passively or actively displace up and down in response to the pressure of the horn tip 40 received through the workpieces W1 and W2.

[0037] As shown in FIG. 1, the ultrasonic bonding apparatus further includes a control device 20, a high-frequency power supply device 21, a pressure device 22, a status sensor 24, and an interface device .

[0038] The high-frequency power supply device 21 is configured to apply a high-frequency AC voltage to the piezoelectric body 112 of the first vibration element 11 in response to power supplied from a commercial power source (not shown), thereby exciting the first vibration element 11 in the axial direction. The pressure device 22 is configured to apply pressure to the workpieces W1 and W2 from the horn tip 40 by displacing a support mechanism such as a clamp mechanism that supports the intermediate vibration element 10 with the pressure block. The state sensor 24 includes a stroke sensor that outputs a signal corresponding to the displacement amount of the pressure block that constitutes the pressure device 22, as well as an amplitude sensor that outputs a signal corresponding to the amplitude (corresponding to the designated parameter) of the horn tip 40. The amplitude sensor may be a sensor module composed of an imaging device and a device that calculates the amplitude by analyzing an image acquired through the imaging device.

[0039] The interface device 26 is, for example, configured with a display, and displays or outputs on the display the amount of displacement of the pressurizing block and / or the time series of pressure according to the output signal of the state sensor 24. The display may be configured with a touch panel display, and may be configured to accept a setting operation for allowing the user to directly or indirectly specify parameters, such as one of a plurality of joining modes that defines a time series pattern of the target pressure.

[0040] The control device 20 is configured with a microcomputer, an arithmetic processing device (S2PU, microprocessor, processor core, etc.) and a storage device (memory such as ROM and RS1M). The control device 20 is configured to control the displacement operation of the pressure block by the pressure device 22 based on the time series of the displacement amount of the pressure block represented by the output signal of the stroke sensor constituting the state sensor 24, for example. The control device 20 is configured to control the power supplied to the piezoelectric body 112 based on the amplitude (corresponding to the designated parameter) of the horn tip 40 represented by the output signal of the amplitude sensor constituting the state sensor 24, and thus to control the ultrasonic vibration power of the vibration elements (first vibration element 11, intermediate vibration element 10, and second vibration element 12) and the ultrasonic vibration power of the horn tip 40. As the status sensor 24, a pressure sensor is provided that outputs a signal corresponding to the pressure acting on the intermediate vibration element 10 from the pressure block of the pressure device 22 (~ the pressure that the horn tip 40 applies to the workpieces W1 and W2), and the control device 20 may control the time series of the pressure to be constant or in a specified manner based on the output signal of the pressure sensor.

[0041] As shown in FIG. 2, the horn tip 40 includes a mounting portion 41, a base portion 42, and a rod portion 44. The mounting portion 41 is formed in a substantially cylindrical shape, and a male thread is formed on its outer surface to be screwed into a female thread formed in a hole 128 of the tip portion 126 of the second vibration element 12. The base portion 42 has a substantially cylindrical first portion that is coaxially connected to the mounting portion 41 and has a larger diameter than the mounting portion 41, and a substantially truncated cone-shaped second portion that has a lower bottom surface with a diameter substantially the same as that of the first portion. The rod portion 44 is formed in a substantially cylindrical shape that is coaxially connected to the second portion of the base portion 42 and has a smaller diameter than the upper bottom surface of the second portion.

[0042] The mounting portion 41 may be omitted, and a screw hole may be formed extending axially from the end face of the first part of the base 42, and the horn tip 40 may be attached to the second vibration element 12 by screwing a bolt or male screw screwed or fixed to the tip portion 126 of the second vibration element 12 into the female thread of the screw hole.

[0043] The base 42 may have a shape different from the combination of the first part having a substantially cylindrical shape and the second part having a substantially truncated cone shape. For example, the base 42 may be substantially cylindrical, substantially prismatic, substantially truncated cone, or substantially truncated pyramid. The cross-sectional shape of the rod portion 44 may be various shapes such as a substantially circular shape, a substantially elliptical shape, a substantially rectangular shape (square shape, parallelogram shape, etc.), a substantially polygonal shape (for example, a regular M-gon (for example, M=8 to 16), a substantially star-shaped M-gon (for example, M=4 to 16)), etc. The cross-sectional shape of the rod portion 44 in the axial direction may be formed so that it changes in various orders along the axial direction into various shapes such as a substantially circular shape, a substantially elliptical shape, a substantially rectangular shape (square shape, parallelogram shape, etc.), a substantially polygonal shape (for example, a regular M-gon, a substantially star-shaped M-gon), etc.

[0044] As shown in FIG. 3, the horn tip 40 has a plurality of approximately quadrangular pyramid-shaped protrusions 441 arranged in a square lattice pattern (specified pattern) on a substantially circular end face 440 (tip surface) of its rod portion 44, and protruding from the end face 440, and an annular protrusion 442 extending in a substantially annular shape along the periphery of the end face 440 so as to surround the plurality of protrusions 441 and protruding from the end face 440 so as to be pressed against the workpieces W1, W2 when the plurality of protrusions 441 are pressed against the workpieces W1, W2.

[0045] The shape of the end face 440 may be various shapes such as a substantially circular shape, a substantially oval shape, a substantially elliptical shape, a substantially rectangular shape, a substantially trapezoid shape, a substantially parallelogram shape, etc. The annular protrusion 442 may extend along the periphery of the end face 440 of the rod portion 44 (or regardless of the shape of the periphery) in various shapes such as a substantially circular shape, a substantially oval shape, a substantially elliptical shape, a substantially rectangular shape, a substantially trapezoid shape, a substantially parallelogram shape, etc. The end face 440 may be flat, or may be curved and raised in a substantially spherical crown shape or a substantially spherical truncated shape.

[0046] The multiple protrusions 441 may be arranged according to various specified patterns on the end surface 440 of the horn tip 40, such as a square lattice pattern, a rectangular lattice pattern, a diagonal lattice (rhombic lattice, central rectangular lattice, isosceles triangular lattice) pattern, a hexagonal lattice (regular triangular lattice) pattern, or a parallelepiped lattice (distorted diagonal lattice) pattern.

[0047] The plurality of protruding portions 441 may all have the same shape, or some of the protruding portions 441 may have different shapes from the other protruding portions 441. Each of the plurality of protruding portions 441 may be formed in various shapes, such as a substantially quadrangular pyramid shape, or a substantially rectangular column shape.

[0048] It is preferable that the outline of the portion of each of the multiple protrusions 441 pressed against the workpieces W1 and W2 forms a continuous convex closed curve in any cross section (cross section parallel to end face 440 of horn tip 40) perpendicular to the axial direction of horn tip 40 (the pressing direction against workpieces W1 and W2). For example, each of the multiple protrusions 441 may be formed entirely or at least at the tip into a shape such as a substantially cylindrical shape, a substantially elliptical cylindrical shape, a substantially conical shape, a substantially truncated cone shape, a substantially truncated elliptical cone shape, a substantially indented elliptical sphere shape, a substantially indented elliptical sphere shape, a substantially indented elliptical crown shape, a substantially indented elliptical sphere crown shape, a shape in which a truncated cone and a indented sphere or a spherical crown (the upper and lower surfaces of the truncated cone are common) are stacked coaxially, or the like.

[0049] In any longitudinal section (a section perpendicular to the end face 440 of the horn tip 40) parallel to the axial direction of the horn tip 40 (the direction of pressing against the workpieces W1 and W2) of each of the multiple protrusions 441, it is preferable that the contour of the portion pressed against the workpieces W1 and W2 forms a continuous convex curve. For example, each of the multiple protrusions 441 may be formed in a shape such as a substantially cylindrical shape, a substantially elliptical cylindrical shape, a substantially truncated cone shape, a substantially truncated elliptical cone shape, a substantially indented elliptical indented elliptical cone shape, a substantially ... cone truncated cone and a cone truncated elliptical cone or a cone (the upper and lower surfaces of the cone truncated cone are common) stacked coaxially, or the like. As shown in FIG. 4, when the upper end surface of each of the multiple protrusions 441 is a plane shape substantially parallel (or inclined) to the end face 440 of the horn tip 40, the peripheral portion of the upper end surface may be formed to be rounded.

[0050] As shown in FIG. 4, in any vertical cross section of the horn tip 40 (any cross section perpendicular to the extending direction of the end surface 440 of the horn tip 40), it is preferable that the contour of the portion (tip) of the annular protrusion 442 pressed against the workpieces W1 and W2 forms a continuous convex curve. For example, the vertical cross section of the annular protrusion 442 may be a substantially trapezoidal shape with both corners on the upper base side rounded, a substantially rectangular shape with both corners on the upper side rounded, a substantially arched shape (substantially semicircular shape), a substantially elliptical arched shape (substantially semi-elliptical sphere shape), a shape that combines a trapezoid and an arched shape (the upper base and lower sides of the trapezoid are common). As shown in FIG. 4, the cross section of the annular protrusion 442 may be inclined in a direction away from the multiple protrusions 441 (leftward in FIG. 4).

[0051] As shown in FIG. 3, an annular protrusion 442 is formed on end face 440 of horn tip 40 so as to be continuous with some of the multiple protrusions 441. Alternatively, as shown in FIG. 5, an annular protrusion 442 may be formed on end face 440 of horn tip 40 so as to surround all of the multiple protrusions 441 at intervals.

[0052] In any longitudinal section of the horn tip 40, the height H2 (amount of protrusion) of the annular protrusion 442 based on the end face 440 may be the same as the height H1 (amount of protrusion) of at least some of the multiple protrusions 441, or may be lower (for example, H2 = 0.90H1 to 0.99H1), or may be higher (for example, H2 = 1.01H1 to 1.10H1). The heights H1 of all of the multiple protrusions 441 based on the end face 440 of the horn tip 40 may be the same, or the heights H1 of some of the protrusions 441 may differ from the heights H1 of the other protrusions 441. The height H2 of the annular protrusion 442 based on the end face 440 of the horn tip 40 may be the same overall, or may be partially different (higher / lower than the height H1 of the protrusion 441). The annular protrusion 442 may be formed such that at least a portion of the annular protrusion 442 extends inwardly beyond the periphery of the end surface 440 of the horn tip 40 .

[0053] As shown in Fig. 5, the upper part of the annular protrusion 442 may be locally cut in a substantially semicircular shape in the extension direction to form a notch 4420 such that the height H2 of the annular protrusion 442 is locally lowered at one or more points in the extension direction. In Fig. 5, a total of eight notches 4420 are formed in the annular protrusion 442 at positions of 2:45 and 3:15, 5:45 and 6:15, 8:45 and 9:15, and 11:45 and 12:15 (0:15) based on the center of the substantially annular annular protrusion 442. The number of notches 4420 in the annular protrusion 442 may be less than eight or more than eight. The arrangement pattern may be changed in various ways, such as a case where the plurality of notches 442 are arranged in a form that does not have rotational symmetry based on the center of the annular protrusion 4420. The shape of the cutout 4420 may be various shapes such as a substantially semicircular shape, a substantially rectangular shape, a substantially triangular shape, a substantially trapezoidal shape, etc. The height H2 of the annular protrusion 442 in the cutout 4420 may be higher than, the same as, or lower than the height H1 of at least a part of the protrusion 441.

[0054] (action) The procedure of the ultrasonic bonding method for the workpieces W1 and W2 using the ultrasonic bonding device 1 will be described. A reference amplitude A0 is set (FIG. 6 / STEP 01). For example, the reference amplitude A0 may be directly or indirectly designated, such as one of a plurality of bonding modes for which the reference amplitude A0 is determined, via a touch panel display constituting the interface device 26 by the user.

[0055] The first vibration element 11, the intermediate vibration element 10, the second vibration element 12, and the horn tip 40 are moved downward by the pressure device 22 (FIG. 6 / STEP 02). The pressure P that the tip of the horn tip 40 (the free end of the rod portion 44) receives from the workpieces W1 and W2 is measured based on the output signal of the pressure sensor that constitutes the state sensor 24 (FIG. 6 / STEP 04). When the tip of the horn tip 40 is separated from the workpiece W1, P=0, and when it comes into contact with the workpiece W1, P>0.

[0056] It is determined whether the pressure P received by the horn tip 40 is equal to or greater than the designated pressure P0 (FIG. 6 / STEP 06). If the determination result is negative (FIG. 6 / STEP 06...NO), the first vibration element 11, the intermediate vibration element 10, the second vibration element 12, and the horn tip 40 are moved downward by the pressurizing device 22 (FIG. 6 / STEP 02). This adjusts the vertical position of the horn tip 40, and therefore the static pressure applied from the tip of the horn tip 40 to the workpieces W1 and W2, to be within the designated static pressure range (e.g., 200N to 800N).

[0057] If the determination result is positive (FIG. 6 / STEP 06...YES), ultrasonic vibration is generated in the vibration element (FIG. 6 / STEP 08). Specifically, in response to power being supplied to the high-frequency power supply device 21 from a commercial power source (not shown), a high-frequency AC voltage is applied to the piezoelectric body 112 of the first vibration element 11 by the high-frequency power supply device 21. This causes the first vibration element 11 to vibrate in its axial direction at, for example, about 20 KHz, generating ultrasonic vibration. The ultrasonic vibration is transmitted from the first vibration element 11 to the intermediate vibration element 10 in its axial direction, and the amplitude of the ultrasonic vibration is amplified. Furthermore, the ultrasonic vibration with the amplified amplitude is transmitted from the intermediate vibration element 10 to the second vibration element 12 in its axial direction.

[0058] In this way, a part of the longitudinal vibration component (axial component of the second vibration element 12) of the ultrasonic vibration transmitted to the second vibration element 12 is converted into a torsional vibration component by the multiple slits 124 formed on the outer surface of the second vibration element 12. Then, a composite vibration generated by combining the longitudinal vibration component and the torsional vibration component is transmitted to the horn tip 40 fixed to the tip portion 126 of the second vibration element 12.

[0059] In response to this, the tip of the horn tip 40 is displaced or vibrated in the horizontal direction so as to draw a circular or elliptical orbit. As a result, as shown in FIG. 4, the amplitude and ultrasonic vibration power of the horn tip 40 gradually increase from the vibration start time t=t0. At this time, impurities on the contact surface of the workpieces W1 and W2 are removed, and plastic deformation of the contact surface of the workpieces W1 and W2 can be promoted. Then, as shown in FIG. 4, the increase rate of the amplitude and ultrasonic vibration power of the horn tip 40 is greatly reduced at time t=t1, and then the amplitude and ultrasonic vibration power of the horn tip 40 gradually increase. This is because the oxide film of the metal constituting the respective joint surfaces of the workpieces W1 and W2 on one side are removed, and clean and activated metal atoms appear on the joint surface, and the temperature rise due to frictional heat activates the movement of the atoms, resulting in the generation of mutual attraction between the atoms.

[0060] At this time, the amount of pressing of the workpieces W1 and W2 by the horn tip 40 and / or the static pressure applied to the workpieces W1 and W2 are adjusted, and a composite vibration is applied to one of the workpieces W1 and W2, thereby allowing the workpieces W1 and W2 to be solid-state joined.

[0061] The amplitude A at a specified location (e.g., a location where the amplitude is relatively large) of the horn tip 40 is optically measured by an amplitude sensor constituting the state sensor 24 (FIG. 6 / STEP 10). 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 40 is negative and whether the amplitude A is equal to or smaller than a reference amplitude A0 (FIG. 6 / STEP 12). Instead of this determination process, it may be determined whether the amplitude A has decreased by a reference amplitude A0 (or a reference ratio based on the maximum value) using the maximum value at the time when the amplitude A starts to decrease as a reference value.

[0062] If the result of the determination is negative (FIG. 6 / STEP 12...NO), ultrasonic vibrations are continuously generated in the vibration element (FIG. 6 / STEP 08). On the other hand, if the result of the determination is positive (FIG. 6 / STEP 12...YES), the generation of ultrasonic vibrations in the vibration element is stopped (FIG. 6 / STEP 14). For example, as shown in FIG. 4, after time t=t2 when the amplitude of horn tip 40 changes from increasing to decreasing and becomes equal to or less than reference amplitude A0, the ultrasonic power of horn tip 40 is controlled to become 0 with a slight response delay.

[0063] (effect) According to the ultrasonic complex vibration device 1 equipped with the ultrasonic bonding tip 40 having the above-mentioned configuration, the ultrasonic complex vibration is applied to the workpieces W1 and W2 in a direction perpendicular to the pressing direction while the multiple protrusions 441 and the annular protrusion 442 surrounding the multiple protrusions 441 are pressed against the workpieces W1 and W2. At this time, although some of the material of the workpieces W1 and W2 is pushed outward by the multiple protrusions 441, the movement of the material of the workpieces W1 and W2 is stopped by the annular protrusion 442. This prevents the material of the workpieces W1 and W2 from moving outward in an unlimited manner, which would cause burrs, and improves the quality of the bonding of the workpieces W1 and W2.

[0064] (Another embodiment of the present invention) In the above embodiment, the amplitude A of the horn tip 40 was measured as a specified parameter that changes depending on the progress of joining one workpiece W1 and the other workpiece W2, but in other embodiments, the axial displacement amount, displacement velocity and / or displacement acceleration of the vibration element (e.g., the second vibration element 12) may be measured as a specified parameter. [Explanation of symbols]

[0065] 1‥Ultrasonic bonding equipment 10. Intermediate vibration element 100...Intermediate flange 11. First vibration element 112 Piezoelectric material 12. Second vibration element 120 Frequency adjustment element 121. Cylindrical part 122 Cylindrical part 124. Slit 126‥Tip 128 holes 18. Anvil 20. Control device 21‥High frequency power supply equipment 22. Pressurizing device 24. Status sensor 26. Interface device 40. Horn tip 41. Mounting part 42‥Base 44. Rod section 440‥End face 441...Multiple protrusions 442 Annular protrusion W1: One work W2: The other work.

Claims

1. a plurality of protrusions arranged in a specified pattern on the end surface and protruding from the end surface; and an annular protruding portion that surrounds the plurality of protruding portions and protrudes from the end surface so as to be pressed against the workpiece when the plurality of protruding portions are pressed against the workpiece. Tip for ultrasonic bonding.

2. 2. The ultrasonic bonding tip according to claim 1, In any cross section of the annular protrusion perpendicular to the extending direction of the end face, the contour of the portion pressed against the workpiece forms a continuous convex curve. Tip for ultrasonic bonding.

3. 2. The ultrasonic bonding tip according to claim 1, The annular protrusion is formed on the end surface so as to surround all of the plurality of protrusions at intervals. Tip for ultrasonic bonding.

4. 2. The ultrasonic bonding tip according to claim 1, Any cross section of the annular protrusion perpendicular to the extending direction of the end surface has a shape inclined in a direction away from the plurality of protrusions. Tip for ultrasonic bonding.

5. 2. The ultrasonic bonding tip according to claim 1, In any cross section perpendicular to the pressing direction of each of the plurality of protrusions against the workpiece, the contour of the portion pressed against the workpiece forms a continuous convex closed curve. Tip for ultrasonic bonding.

6. 6. The ultrasonic bonding tip according to claim 5, In any cross section of each of the plurality of protrusions parallel to the pressing direction against the workpiece, the contour of the portion pressed against the workpiece forms a continuous convex curve. Tip for ultrasonic bonding.

7. 7. The ultrasonic bonding tip according to claim 6, Each of the plurality of protrusions is formed in a shape of a spherical cutout, a spherical frustum, a cone with rounded edges on the upper and lower surfaces, a cone frustum, or a cone frustum and a spherical cutout or a spherical frustum having a common upper and lower surfaces and stacked coaxially. Tip for ultrasonic bonding.

8. A vibration element that induces a composite vibration by combining a longitudinal vibration and a torsional vibration; An ultrasonic bonding tip; A control device for controlling the complex vibration of the vibration element, The ultrasonic bonding tip comprises: a plurality of protrusions arranged in a specified pattern on the end surface and protruding from the end surface; and an annular protruding portion that surrounds the plurality of protruding portions and protrudes from the end surface so as to be pressed against the workpiece when the plurality of protruding portions are pressed against the workpiece. Ultrasonic bonding equipment.

9. 1. An ultrasonic bonding method for bonding one workpiece and another workpiece using an ultrasonic bonding device including a vibration element that induces a composite vibration by combining a longitudinal vibration and a torsional vibration, and an ultrasonic bonding tip that is fixed to the vibration element or detachably attached to the vibration element, comprising: a plurality of protrusions arranged in a specified pattern on the end surface and protruding from the end surface; a ring-shaped protrusion surrounding the plurality of protrusions and protruding from the end surface so as to be pressed against the workpiece when the plurality of protrusions are pressed against the workpiece, is used as the ultrasonic bonding tip; a step of determining whether or not the joining of the one workpiece to the other workpiece has been completed based on a signal corresponding to a value of a designated parameter that changes according to a progress state of joining of the one workpiece to the other workpiece while the ultrasonic joining tip is in contact with the one workpiece to be joined; and stopping the composite vibration of the vibration element when it is determined that the joining of the one workpiece and the other workpiece is completed. Ultrasonic bonding method.

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