Chip for ultrasonic joining, and ultrasonic joining device and ultrasonic joining method using the same

Abstract

To provide a chip for ultrasonic joining which may achieve improvement of the quality of joint between workpieces, and to provide an ultrasonic joining device and an ultrasonic joining method which use the chip.SOLUTION: In a chip for ultrasonic joining, in a direction perpendicular to an axial direction of a rod part 44 having a substantially cylindrical shape, a ratio (D1 / d1) of a length D1 in an axial direction of the rod part 44 to a maximum distance d1 (a radius of a cross section of a substantially cylindrical shape) from a center of a cross section having a maximum cross-sectional area to a peripheral edge part of the cross section is 30 or larger. Meanwhile, in the direction perpendicular to the axial direction of the rod part 44 having the substantially cylindrical shape, the ratio (D1 / d1) of the length D1 in the axial direction of the rod part 44 to the maximum distance d1 from the center of the cross section having the maximum cross-sectional area to the peripheral edge part of the cross section is 120 or smaller.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an ultrasonic bonding tip that is brought into contact with one of workpieces such as metal, semiconductor, and / or plastic workpieces in order to bond the workpieces to each other by ultrasonic vibration, and to an ultrasonic bonding device and an ultrasonic bonding method that use the ultrasonic bonding tip. [Background technology]

[0002] Conventionally, ultrasonic joining has been used to join plastics used in food packs, etc., or metals used in battery parts, etc. A typical ultrasonic joining device ultrasonically vibrates the tip of a joining tip (tool) and joins the objects to be joined (workpieces) by repeatedly applying pressure.

[0003] In ultrasonic bonding, there is an appropriate time for applying ultrasonic vibrations to the workpieces. As described in Non-Patent Document 1 below, if the application time is too long, the bonding strength of the joint will decrease and damage such as cracks may occur in the workpieces.

[0004] Conventionally, a bonding method has been implemented in which bonding is performed according to a predetermined application time of ultrasonic vibration. For example, in the following Patent Document 1, the amplitude of ultrasonic waves is increased at the start of bonding, and then the amplitude of the ultrasonic vibration horn is reduced when a preset attenuation start time is reached. After a certain time has passed, the application of ultrasonic vibration is stopped to complete the bonding process. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Hideo Sakuyama, Takehiko Watanabe, Atsushi Yanagisawa, Shizuyo Konuma, "Ultrasonic Welding of Aluminum Alloy and Steel", "Summary of Lectures at the National Convention of the Japan Welding Society", 2005, Vol. 2005f, 2005 Autumn National Convention, Session ID416, p.167 [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2006-263816 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the above method has the following problems.

[0008] The application time of ultrasonic vibration to one of the workpieces varies depending on the material, shape, how the workpiece is held, and / or the variation in the shape of the workpiece. Therefore, it is difficult to individually or accurately determine the appropriate application time in advance. Also, it may be difficult to stabilize the bonding strength between the workpieces by simply setting the application time in advance in response to the variation in the shape of the workpieces. Furthermore, simply setting the decay time of the tip in advance may result in the application of more ultrasonic waves than necessary, which may reduce the quality of the bonding of the workpieces.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide an ultrasonic bonding tip that can improve the quality of bonding between workpieces, and an ultrasonic bonding device and ultrasonic bonding method using the same. [Means for solving the problem]

[0010] The ultrasonic bonding tip according to the first aspect of the present invention comprises: A rod portion extending axially and continuously from the base portion, The rod portion is formed so that the ratio (D1 / d1) of the axial length D1 of the rod portion to the maximum distance d1 from the center of the cross section having the maximum cross-sectional area to the peripheral edge of the cross section in a direction perpendicular to the axial direction of the rod portion is within the range of 30 to 120.

[0011] According to the ultrasonic bonding tip having this configuration, (D1 / d1) is 30 or more. Therefore, the sensitivity of the ultrasonic bonding tip to changes in amplitude of ultrasonic vibration in response to changes in force acting on the ultrasonic bonding tip from one workpiece before and after completion of ultrasonic bonding of the one workpiece and the other workpiece that the ultrasonic bonding tip is in contact with is improved. Meanwhile, (D1 / d1) is 120 or less. Therefore, the ultrasonic vibration of the ultrasonic bonding tip is efficiently transmitted to the one workpiece, and thus the efficiency of bonding between the one workpiece and the other workpiece is improved.

[0012] Therefore, whether or not the joining is completed can be accurately determined according to the change in the value of the designated parameter that changes according to the progress of the joining of the one workpiece and the other workpiece, such as the amplitude of the ultrasonic vibration of the ultrasonic bonding tip. If the determination result indicates that the joining 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 joining of the one workpiece and the other workpiece.

[0013] In the ultrasonic bonding tip having the above configuration, The ratio (S1 / s1) of the maximum cross-sectional area S1 of the base portion in a direction perpendicular to the axial direction to the maximum cross-sectional area s1 of the rod portion in a direction perpendicular to the axial direction is within a range of 6.2 to 52.9. It is preferable.

[0014] According to the ultrasonic bonding tip having this configuration, (S1 / s1) is 6.2 or more. Therefore, the ultrasonic vibration of the ultrasonic bonding tip is efficiently transmitted to one workpiece, and the efficiency of bonding between the one workpiece and the other workpiece is improved. On the other hand, (S1 / s1) is 52.9 or less. Therefore, before and after completion of ultrasonic bonding of the one workpiece and the other workpiece that the ultrasonic bonding tip is in contact with, the sensitivity of the change in the amplitude of the ultrasonic vibration of the ultrasonic bonding tip in response to the change in the force acting from the one workpiece to the ultrasonic bonding tip is improved.

[0015] In the ultrasonic bonding tip having the above configuration, When the ultrasonic bonding tip is not in contact with the one of the workpieces, a ratio f2 / f1 of a resonance frequency f2 of the ultrasonic bonding tip alone to a resonance frequency f1 of an entire vibration system including the ultrasonic bonding tip is set to be within a range of 1.005 to 1.07. It is preferable.

[0016] According to the ultrasonic bonding tip having the above configuration, 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. If 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 workpiece and the other workpiece.

[0017] In the ultrasonic bonding tip having the above configuration, The cross-sectional area of ​​the base portion in a direction perpendicular to the axial direction or the maximum distance to the periphery of the cross section is formed to be smaller toward the rod portion. It is preferable.

[0018] According to the ultrasonic bonding tip having this configuration, the cross-sectional area of ​​the base of the tip in the direction perpendicular to the axial direction decreases toward the rod, so that ultrasonic energy can be transmitted uniformly to one of the workpieces, thereby improving the quality of bonding between the one workpiece and the other workpiece.

[0019] In the ultrasonic bonding tip having the above configuration, The base portion and the rod portion are made of different materials, so that the sound velocity in the rod portion is greater than the sound velocity in the base portion. It is preferable.

[0020] According to the ultrasonic bonding tip having the above-mentioned configuration, the increase rate of the displacement in the direction perpendicular to the axis of the rod portion at the connecting portion with the base portion can be suppressed, which stabilizes the ultrasonic complex vibration in the rod portion and thereby improves the quality of bonding between the one workpiece and the other workpiece.

[0021] The ultrasonic bonding tip according to the second aspect of the present invention is An ultrasonic bonding tip formed to extend in an axial direction, In a cross section perpendicular to an axial direction of the ultrasonic bonding tip, the ultrasonic bonding tip has a single designated portion that is locally narrowed at a middle portion in the axial direction, The ratio (D2 / d2) of the length D2 of the ultrasonic bonding tip in the axial direction to the length d2 of the single specified portion in the axial direction is within a range of 1.5 to 3.5, and The ultrasonic bonding tip is formed so that the ratio (S2 / s2) of the maximum cross-sectional area S2 of the ultrasonic bonding tip to the minimum cross-sectional area s2 of the single specified portion in a cross section perpendicular to the axial direction is within the range of 2-7.

[0022] According to the ultrasonic bonding tip having this configuration, (D2 / d2) is 3.5 or less, and (S2 / s2) is 2 or more. Therefore, the sensitivity of the ultrasonic bonding tip to changes in the amplitude of ultrasonic vibration in response to changes in the force acting on the ultrasonic bonding tip from one workpiece before and after completion of ultrasonic bonding of the one workpiece and the other workpiece that the ultrasonic bonding tip is in contact with is improved. Meanwhile, (D2 / d2) is 1.5 or more, and (S2 / s2) is 7 or less. Therefore, the ultrasonic vibration of the ultrasonic bonding tip is efficiently transmitted to the one workpiece, and thus the efficiency of bonding between the one workpiece and the other workpiece is improved.

[0023] Therefore, whether or not the joining is completed can be accurately determined according to the change in the value of the designated parameter that changes according to the progress of the joining of the workpiece and the other workpiece, such as the amplitude of the ultrasonic vibration of the ultrasonic bonding tip. If the determination result indicates that the joining of the 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 joining of the workpiece and the other workpiece.

[0024] As a first aspect of the present invention, an ultrasonic bonding apparatus includes: A vibration element that induces a composite vibration by combining a longitudinal vibration and a torsional vibration; An ultrasonic bonding tip according to a first aspect of the present invention; A control device for controlling the complex vibration of the vibration element, a designated sensor that outputs a signal corresponding to a value of a designated parameter that changes according to a progress state of joining of one workpiece to the other workpiece while the ultrasonic bonding tip is in contact with the one workpiece, The control device determines whether or not the joining of the one workpiece and the other workpiece has been completed based on the output signal of the designated sensor, and stops the composite vibration of the vibration element when it determines that the joining of the one workpiece and the other workpiece has been completed.

[0025] According to the ultrasonic bonding device having the above configuration, 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 as the first aspect of the present invention. If 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.

[0026] As a second aspect of the present invention, an ultrasonic bonding apparatus includes: A vibration element that induces a composite vibration by combining a longitudinal vibration and a torsional vibration; A tip for ultrasonic bonding according to a second aspect of the present invention, which is fixed or detachably attached to the vibration element; A control device for controlling the complex vibration of the vibration element, a designated sensor that outputs a signal corresponding to a value of a designated parameter that changes according to a progress state of joining of one workpiece to the other workpiece while the ultrasonic bonding tip is in contact with the one workpiece, The control device determines whether or not the joining of the one workpiece and the other workpiece has been completed based on the output signal of the designated sensor, and stops the composite vibration of the vibration element when it determines that the joining of the one workpiece and the other workpiece has been completed.

[0027] According to the ultrasonic bonding device having the above configuration, it is possible to accurately determine whether the bonding is complete 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 as the second aspect of the present invention. If the determination result indicates that the bonding of the one workpiece and the other workpiece is complete, 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]

[0028] [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] 4 is a flow chart of the functioning of the ultrasonic bonding device. [Figure 4] FIG. 1 shows changes in amplitude and power of an ultrasonic bonding tip (conventional). [Diagram 5] FIG. 13 is a configuration explanatory diagram of an ultrasonic bonding tip according to another embodiment of the present invention. [Figure 6] FIG. 13 is an explanatory diagram relating to differences in amplitude change patterns due to differences in the configuration of the ultrasonic bonding tip. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] (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 using 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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).

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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 .

[0042] 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.

[0043] 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.

[0044] The control device 20 is configured with a microcomputer, an arithmetic processing device (CPU, microprocessor, processor core, etc.) and a storage device (memory such as ROM and RAM). 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.

[0045] 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.

[0046] 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.

[0047] The rod portion 44 is formed so that the ratio (D1 / d1) of the axial length D1 of the rod portion 44 to the maximum distance d1 (the radius of the circular cross section) from the center of the approximately circular cross section having the maximum cross-sectional area to the periphery of the approximately circular cross section in a direction perpendicular to the axial direction (or longitudinal direction) of the rod portion 44 is within the range of 40 to 100. For example, when the axial length D1 of the approximately cylindrical rod portion 44 is 60 mm, the radius of the rod portion 44 is designed to be within the range of (60 / 100) to (60 / 40) mm = 0.6 to 1.5 mm.

[0048] The horn tip 40 is formed so that the ratio (S1 / s1) of the maximum cross-sectional area S1 in a direction perpendicular to the axial direction of the base portion 42 to the maximum cross-sectional area s1 in a direction perpendicular to the axial direction of the rod portion 44 is in the range of 6.2 to 52.9. In this embodiment, since the rod portion 44 is substantially cylindrical, the maximum cross-sectional area S1 is calculated by using the radius r of the rod portion 44 as πr 2 Since the base 42 is a combination of a substantially cylindrical first portion and a substantially truncated cone second portion, the maximum cross-sectional area s1 is expressed as πR using the radius R of the first portion. 2 Therefore, the ratio (S1 / s1) = (r 2 / R 2 ) is in the range of 6.2 to 52.9 ((r / R) is in the range of 2.89 to 7.27).

[0049] 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.

[0050] The horn tip 40 may be formed so that the ratio (f2 / f1) of the resonance frequency f2 of the horn tip 40 alone to the resonance frequency f1 of the entire vibration system including the horn tip 40 when the horn tip 40 is resonating at the resonance frequency in a state where the horn tip 40 is not in contact with the workpiece W1 is within the range of 1.005 to 1.07. With this configuration, it is possible to accurately determine whether or not the joining is completed according to the change in the value of a designated parameter that changes according to the progress of the joining of the one workpiece W1 and the other workpiece W2, such as the amplitude of the ultrasonic vibration of the horn tip 40. Then, when the determination result indicates that the joining of the one workpiece W1 and the other workpiece W2 is completed, the ultrasonic vibration of the horn tip 40 is stopped, and as a result, the period during which the horn tip 40 is ultrasonically vibrated can be appropriately controlled from the viewpoint of improving the quality of the joining of the workpiece W1 and the other workpiece W2.

[0051] When the horn tip 40 is not in contact with the workpiece W1, the free end of the rod portion 44 becomes an antinode of the standing wave of the ultrasonic complex vibration. Therefore, the phase difference between the free end of the rod portion 44 and the node position of the standing wave closest to the free end is (π / 2). In FIG. 2, the standing wave (amplitude represents the amplitude in the direction perpendicular to the axial direction or the displacement amount of the horn tip 40) of the ultrasonic complex vibration when resonating at the resonance frequency in the state where the horn tip 40 is in contact with the workpiece W1 is shown by a solid line. In FIG. 2, the change in the bending angle of the horn tip 40 is shown by a broken line. The contact state (contact pressure, etc.) of the horn tip 40 and the workpiece W1 may be adjusted so that the phase difference of the standing wave between the base end of the rod portion 44 and the node position closest to the free end of the standing wave is within the range of 0.10π to 0.21π.

[0052] A reference amplitude A0 is set (FIG. 3 / 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 a user.

[0053] 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. 3 / 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. 3 / 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.

[0054] It is determined whether the pressure P received by the horn tip 40 is equal to or greater than the designated pressure P0 (FIG. 3 / STEP 06). If the determination result is negative (FIG. 3 / 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. 3 / 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).

[0055] If the determination result is positive (FIG. 3 / STEP 06...YES), ultrasonic vibration is generated in the vibration element (FIG. 3 / 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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. 3 / 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. 3 / 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 started to decrease as a reference value.

[0060] If the result of the determination is negative (FIG. 3 / STEP 12...NO), ultrasonic vibrations are continuously generated in the vibration element (FIG. 3 / STEP 08). On the other hand, if the result of the determination is positive (FIG. 3 / STEP 12...YES), the generation of ultrasonic vibrations in the vibration element is stopped (FIG. 3 / 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.

[0061] (effect) According to the ultrasonic complex vibration device 1 having the above configuration, the ratio (D1 / d1) of the axial length D1 of the rod portion 44 to the maximum distance d1 (the radius of the substantially circular cross-section) from the center of the cross-section having the maximum cross-section area to the periphery of the cross-section in the direction perpendicular to the axial direction of the substantially cylindrical rod portion 44 is 40 or more. The ratio (S1 / s1) of the maximum cross-sectional area S1 in the direction perpendicular to the axial direction of the base portion 42 to the maximum cross-sectional area s1 in the direction perpendicular to the axial direction of the rod portion 44 is 52.9 or less. Therefore, before and after the completion of ultrasonic bonding of the workpieces W1 and W2 to which the horn tip 40 is in contact, the sensitivity of the amplitude A of the ultrasonic vibration of the horn tip 40 to the change in the force acting on the horn tip 40 from the workpiece W1 is improved.

[0062] On the other hand, in a direction perpendicular to the axial direction of the substantially cylindrical rod portion 44, the ratio (D1 / d1) of the length D1 in the axial direction of the rod portion 44 to the maximum distance d1 from the center of the cross section having the maximum cross section area to the peripheral edge of the cross section is 100 or less. Also, the ratio (S1 / s1) of the maximum cross section area S1 in the direction perpendicular to the axial direction of the base portion 42 to the maximum cross section area s1 in the direction perpendicular to the axial direction of the rod portion 44 is 6.2 or more. Therefore, the ultrasonic vibration of the horn tip 40 is efficiently transmitted to one workpiece W1 and the other workpiece W2, thereby improving the joining efficiency of the one workpiece W1 and the other workpiece W2.

[0063] Therefore, whether or not the joining is completed can be accurately determined according to the manner in which the value of a designated parameter, such as the amplitude A of the ultrasonic vibration of the horn tip 40, changes depending on the progress of the joining of the one workpiece W1 and the other workpiece W2 (see FIG. 3 / STEP 12 and the amplitude of the horn tip in FIG. 4). Then, when the determination result indicates that the joining of the one workpiece W1 and the other workpiece W2 is completed, the ultrasonic vibration of the horn tip 40 can be stopped (see FIG. 3 / STEP 12 . . . YES → STEP 14 and the ultrasonic vibration power after time t = t2 in FIG. 4). As a result, the period during which the horn tip 40 is ultrasonically vibrated can be appropriately controlled from the viewpoint of improving the quality of the joining of the one workpiece W1 and the other workpiece 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.

[0065] As shown in FIG. 5, in the horn tip 40 according to another embodiment of the present invention, a single designated portion 440 in the middle portion along the axial direction is locally reduced in diameter compared to the base end portion 441 and the tip portion 442. The base end portion 441 is formed in a substantially cylindrical shape. The tip portion 442 is formed in a shape in which a first portion, which is substantially cylindrical and has a smaller diameter than the base end portion 441, and a second portion, which is substantially truncated cone-shaped and has a lower bottom surface of substantially the same diameter as the first portion, are combined so as to be coaxially continuous. The designated portion 440 is formed in a substantially cylindrical shape with a smaller diameter than the first portion of the tip portion 442. The attachment portion 41 may be provided on the base end side of the base end portion 441 as in the above embodiment.

[0066] Designated portion 440 may be formed in a generally corrugated shape that gradually reduces in diameter from one end on the base end 441 side to the other end on the tip end 442 side (in the axial or longitudinal direction of horn tip 40) to a minimum diameter in an intermediate region and then gradually expands in diameter, so that the generally corrugated shape has a minimum diameter of horn tip 40 at least in the intermediate region. In this case, designated portion 440 may have approximately the same diameter as or a smaller diameter than base end 441 at one end, and may have approximately the same diameter as or a smaller diameter than a first portion of tip end 442 at the other end. In addition, the second derivative (=2(d 2 r / dx 2 The designated portion 440 may be defined as the portion from where the positive voltage changes from negative to where the positive voltage changes from positive to negative.

[0067] The shapes of the base end 441, the designated portion 440, and the tip portion 442 may be changed in various ways. For example, each of the base end 441, the designated portion 440, and the tip portion 442 may be substantially cylindrical, substantially prismatic, substantially truncated conical, or substantially truncated pyramidal, or a combination thereof. Each of the base end 441, the designated portion 440, and the tip portion 442 may be formed so that the cross-sectional shape in the axial direction changes in various orders to various shapes, such as substantially circular, substantially elliptical, substantially rectangular (square, parallelogram, etc.), substantially polygonal (for example, regular M-gon (for example, M=8 to 16), substantially star-shaped M-gon (for example, M=4 to 16)), etc. along the axial direction.

[0068] The ratio (D2 / d2) of the axial length D2 of the horn tip 40 to the axial length d2 of a single designated portion 440 is within the range of 1.5 to 3.5 (preferably, 1.8 to 3.0, 2.0 to 3.0, or 2.2 to 2.8). In a cross section perpendicular to the axial direction, the ratio (S2 / s2) of the maximum cross-sectional area S2 of the horn tip 40 to the minimum cross-sectional area s2 of the designated portion 440 is within the range of 2 to 7 (preferably, 2.5 to 6.2, 3.2 to 5.5, or 3.8 to 4.6). In this embodiment, since the designated portion 440 is approximately cylindrical, the minimum cross-sectional area s2 is calculated using its radius q as πq 2In this embodiment, the cross-sectional area of ​​horn tip 40 is maximum at the cross section of the substantially cylindrical base end 441, so the maximum cross-sectional area S2 of horn tip 40 is expressed as πQ 2 Therefore, the ratio of the maximum cross-sectional area S2 of the horn tip 40 to the minimum cross-sectional area s2 of the designated portion 440 (S2 / s2)=(Q 2 / q 2 ) is in the range of 2 to 7 ((Q / q) is in the range of 1.14 to 2.65).

[0069] According to the horn tip 40 having this configuration, (D2 / d2) is 3.5 or less, and (S2 / s2) is 2 or more. Therefore, before and after completion of ultrasonic bonding of one workpiece W1 and the other workpiece W2 to which the horn tip 40 is in contact, the sensitivity of the horn tip 40 to the change in the amplitude of ultrasonic vibration in response to the change in the force acting on the horn tip 40 from the one workpiece W1 is improved. On the other hand, (D2 / d2) is 1.5 or more, and (S2 / s2) is 7 or less. Therefore, the ultrasonic vibration of the horn tip 40 is efficiently transmitted to the one workpiece W1, and thus the bonding efficiency between the one workpiece W1 and the other workpiece W2 is improved.

[0070] Therefore, whether or not the joining is completed can be accurately determined according to the manner in which the value of a designated parameter, such as the amplitude A of the ultrasonic vibration of the horn tip 40, changes depending on the progress of the joining of the one workpiece W1 and the other workpiece W2 (see FIG. 3 / STEP 12 and the amplitude of the horn tip in FIG. 4). Then, when the determination result indicates that the joining of the one workpiece W1 and the other workpiece W2 is completed, the ultrasonic vibration of the horn tip 40 can be stopped (see FIG. 3 / STEP 12 . . . YES → STEP 14 and the ultrasonic vibration power after time t = t2 in FIG. 4). As a result, the period during which the horn tip 40 is ultrasonically vibrated can be appropriately controlled from the viewpoint of improving the quality of the joining of the one workpiece W1 and the other workpiece W2.

[0071] As shown in FIG. 2, the outer shape of the horn tip 40 has a step at the connecting portion between the base portion 42 and the rod portion 44 due to the difference in diameter or cross-sectional area. If the step, and therefore the change in the cross-sectional area of ​​the horn tip 40, is excessively large, the amplitude (amount of displacement in a direction perpendicular to the axial direction) at the connecting portion between the rod portion 44 and the base portion 42 may become excessively large. This not only increases the possibility of breakage at the connecting portion of the horn tip 40, but also may cause the vibration state to become unstable. For this reason, it is preferable that the horn tip 40 is integrally formed and the outer shape is designed so that the change in the cross-sectional area at the connecting portion between the base portion 42 and the rod portion 44 is reduced, but this leads to an increase in the manufacturing cost of the horn tip.

[0072] In order to reduce manufacturing costs, the horn tip 40 is composed of a separately formed base portion 42 and rod portion 44. The rear end portion of the rod portion 44 is press-fitted into a hole formed in the tip portion of the rod portion 42, or the male thread formed in the rear end portion of the rod portion 44 is screwed into the female thread formed in the hole in the tip portion of the rod portion 42.

[0073] In order to solve the above problem, the sound velocity c in the base 42 is reduced by using different materials for constructing the base 42 and the rod portion 44. s42 The sound velocity c in the rod portion 44 is s44 It is preferable that the speed of sound c is large. s (The speed of vertical vibration of the rod-shaped member) is (E / ρ) 1 / 2 (E: Young's modulus, ρ: specific gravity), so the Young's modulus E of the material constituting the base 42 is 42 and specific gravity ρ 42 and the Young's modulus E of the material constituting the rod portion 44. 44 and specific gravity ρ 44 And, (E 42 / ρ 42 ) 1 / 2 <(E 44 / ρ 44 ) 1 / 2It is preferable that the material (e.g., a metal material such as stainless steel) is selected so as to satisfy the magnitude relationship. For example, it is preferable that stainless steel is used as the material constituting the base portion 42, and an alloy such as a tungsten alloy is used as the material constituting the rod portion 44.

[0074] In Figure 6, s42 The sound velocity c in the rod portion 44 is s44 The amplitude (amount of displacement in a direction perpendicular to the axial direction) of the rod portion 44 when the materials constituting the base portion 42 and the rod portion 44 are differentiated so that the amplitude (amount of displacement in a direction perpendicular to the axial direction) of the rod portion 44 is shown by a solid line. s42 =c s44 The amplitude of the rod portion 44 in the case of (a) is shown by a dashed line. It can be seen that the rate of increase in the axial direction of the displacement at the rear end of the rod portion 44 is smaller in the former case than in the latter case, and thus the possibility of damage to the horn tip 40 is reduced. Since a material with a high sound velocity usually also has a high Young's modulus E, the amplitude of the rod portion 44 is also reduced, making it possible to maintain a stable vibration state without the vibration deviating from the central axis. [Explanation of symbols]

[0075] 1. Ultrasonic complex vibration device 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. Stroke sensor 26. Interface device. 40. Horn tip (Ultrasonic bonding tip) 41. Mounting part 42‥Base 44. Rod section 440‥Specified part 441‥Proximal end 442‥Tip W1: One work W2: The other work.

Claims

1. a base portion and a rod portion extending axially and continuously from the base portion; The rod portion is formed so that the ratio (D1 / d1) of the length D1 in the axial direction of the rod portion to the maximum distance d1 from the center of a cross section having the largest cross-sectional area to the periphery of the cross section is within a range of 30 to 120, and The ultrasonic bonding tip is formed so that when the ultrasonic bonding tip is not in contact with one of the workpieces, the ratio f2 / f1 of the resonant frequency f2 of the ultrasonic bonding tip alone to the resonant frequency f1 of the entire vibration system including the ultrasonic bonding tip is within the range of 1.005 to 1.

07.

2. 2. The ultrasonic bonding tip according to claim 1, The ratio (S1 / s1) of the maximum cross-sectional area S1 of the base portion in a direction perpendicular to the axial direction to the maximum cross-sectional area s1 of the rod portion in a direction perpendicular to the axial direction is set to be within a range of 6.2 to 52.

9. Ultrasonic bonding tip.

3. 3. The ultrasonic bonding tip according to claim 1, The cross-sectional area of ​​the base in a direction perpendicular to the axial direction or the maximum distance to the periphery of the cross section is formed to become smaller as it approaches the rod portion. Ultrasonic bonding tip.

4. 3. The ultrasonic bonding tip according to claim 1, The base portion and the rod portion are made of different materials, so that the sound velocity in the rod portion is greater than the sound velocity in the base portion. Ultrasonic bonding tip.

5. An ultrasonic bonding tip formed to extend in an axial direction, In a cross section perpendicular to an axial direction of the ultrasonic bonding tip, the ultrasonic bonding tip has a single designated portion that is locally narrowed at a middle portion in the axial direction, The ratio (D2 / d2) of the length D2 of the ultrasonic bonding tip in the axial direction to the length d2 of the single specified portion in the axial direction is within a range of 1.5 to 3.5, and The ultrasonic bonding tip is formed so that the ratio (S2 / s2) of the maximum cross-sectional area S2 of the ultrasonic bonding tip to the minimum cross-sectional area s2 of the single specified portion in a cross section perpendicular to the axial direction is within a range of 2 to 7, and When the ultrasonic bonding tip is not in contact with the one of the workpieces, the ratio f2 / f1 of the resonance frequency f2 of the ultrasonic bonding tip alone to the resonance frequency f1 of the entire vibration system including the ultrasonic bonding tip is set to be within the range of 1.005 to 1.

07. Ultrasonic bonding tip.

6. a vibration element that induces a composite vibration by combining longitudinal vibration and torsional vibration; an ultrasonic bonding tip; a control device that controls the complex vibration of the vibration element, a designated sensor that outputs a signal corresponding to a value of a designated parameter that changes according to a progress state of joining of one workpiece to the other workpiece while the ultrasonic welding tip is in contact with the one workpiece, The ultrasonic bonding tip comprises: a base portion fixed to or detachably attached to the vibration element, and a rod portion extending continuously in an axial direction relative to the base portion, The rod portion is formed so that the ratio (D1 / d1) of the length D1 in the axial direction of the rod portion to the maximum distance d1 from the center of a cross section having the largest cross-sectional area to the periphery of the cross section is within a range of 30 to 120, and When the ultrasonic bonding tip is not in contact with the one of the workpieces, a ratio f2 / f1 of a resonance frequency f2 of the ultrasonic bonding tip alone to a resonance frequency f1 of an entire vibration system including the ultrasonic bonding tip is set to be within a range of 1.005 to 1.07, The control device determines whether or not joining of the one workpiece and the other workpiece is completed based on the output signal of the designated sensor, and stops the composite vibration of the vibration element when it determines that joining of the one workpiece and the other workpiece is completed. Ultrasonic bonding equipment.

7. a vibration element that induces a composite vibration by combining longitudinal vibration and torsional vibration; an ultrasonic bonding tip that is fixed or detachably attached to the vibration element; a control device that controls the complex vibration of the vibration element, a designated sensor that outputs a signal corresponding to a value of a designated parameter that changes according to a progress state of joining of one workpiece to the other workpiece while the ultrasonic welding tip is in contact with the one workpiece, The ultrasonic bonding tip comprises: In a cross section perpendicular to an axial direction of the ultrasonic bonding tip, the ultrasonic bonding tip has a single designated portion that is locally narrowed at a middle portion in the axial direction, a ratio (D2 / d2) of the length D2 of the ultrasonic bonding tip in the axial direction to the length d2 of the single designated portion in the axial direction is within a range of 1.5 to 3.5; In a cross section perpendicular to the axial direction, the ratio (S2 / s2) of the maximum cross-sectional area S2 of the ultrasonic bonding tip to the minimum cross-sectional area s2 of the single specified portion is within a range of 2 to 7, and When the ultrasonic bonding tip is not in contact with the one of the workpieces, a ratio f2 / f1 of a resonance frequency f2 of the ultrasonic bonding tip alone to a resonance frequency f1 of an entire vibration system including the ultrasonic bonding tip is set to be within a range of 1.005 to 1.07, The control device determines whether or not joining of the one workpiece and the other workpiece is completed based on the output signal of the designated sensor, and stops the composite vibration of the vibration element when it determines that joining of the one workpiece and the other workpiece is completed. Ultrasonic bonding equipment.

8. An ultrasonic bonding method for bonding a workpiece and another workpiece using an ultrasonic bonding device including a vibration element that induces a composite vibration by combining longitudinal vibration and torsional vibration, and an ultrasonic bonding tip that is fixed to or detachably attached to the vibration element, a designated sensor that outputs a signal corresponding to a value of a designated parameter that changes depending on the progress of joining of one workpiece to the other workpiece while the ultrasonic welding tip is in contact with the workpieces to be joined, a base portion fixed to or detachably attached to the vibration element, and a rod portion extending continuously in an axial direction relative to the base portion, The ultrasonic bonding tip is formed so that the ratio (D1 / d1) of the length D1 of the rod portion in the axial direction to the maximum distance d1 from the center of a cross section having the largest cross-sectional area to the periphery of the cross section satisfies 40≦(D1 / d1)≦100, and the ratio f2 / f1 of the resonance frequency f2 of the ultrasonic bonding tip alone to the resonance frequency f1 of the entire vibration system including the ultrasonic bonding tip is within the range of 1.005 to 1.07 when the ultrasonic bonding tip is not in contact with the one workpiece. a step of determining whether or not the joining of the one workpiece and the other workpiece has been completed based on a signal corresponding to a value of a designated parameter that changes depending on the progress 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 has been completed. Ultrasonic bonding method.

9. An ultrasonic bonding method for bonding a workpiece and another workpiece using an ultrasonic bonding device including a vibration element that induces a composite vibration by combining longitudinal vibration and torsional vibration, and an ultrasonic bonding tip that is fixed to or detachably attached to the vibration element, In a cross section perpendicular to the axial direction, the ultrasonic bonding tip has a single designated portion that is locally narrowed at a middle portion in the axial direction, a ratio (D2 / d2) of the length D2 of the ultrasonic bonding tip in the axial direction to the length d2 of the single designated portion in the axial direction is within a range of 1.5 to 3.5; In a cross section perpendicular to the axial direction, the ratio (S2 / s2) of the maximum cross-sectional area S2 of the ultrasonic bonding tip to the minimum cross-sectional area s2 of the single specified portion is within a range of 2 to 7, and a tip formed so that when the ultrasonic bonding tip is not in contact with the one workpiece, a ratio f2 / f1 of a resonance frequency f2 of the ultrasonic bonding tip alone to a resonance frequency f1 of an entire vibration system including the ultrasonic bonding tip is within a range of 1.005 to 1.07 is used as the ultrasonic bonding tip; a step of determining whether or not the joining of the one workpiece and the other workpiece has been completed based on a signal corresponding to a value of a designated parameter that changes depending on the progress 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 has been completed. Ultrasonic bonding method.

Images