Ultrasonic bonding chip and ultrasonic bonding device using the same

Abstract

To provide an ultrasonic bonding chip capable of improving the quality of bonding of workpieces by ultrasonic composite vibration of a new form, and an ultrasonic bonding device using the same.SOLUTION: A rod portion 42 is configured such that there is a relationship represented by 5S1 / 2≤L≤50S1 / 2 between a length L of a second rod portion 422 and a square root S1 / 2 of a cross-sectional area S of the second rod portion 422 at a continuous portion with a first rod portion 421. Therefore, when the ultrasonic composite vibration is applied to workpieces W1 and W2 in a direction (lateral direction) perpendicular to a pressing direction (longitudinal direction) in a state where a distal end portion of a horn chip 40 is pressed against the workpieces W1 and W2, the rod portion 42 of the horn chip 40 can be locally bent in the second rod portion 422.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an ultrasonic bonding tip for bonding multiple workpieces made of various materials such as metals using ultrasonic vibrations, and to an ultrasonic bonding device and ultrasonic bonding method that use the ultrasonic bonding tip. [Background technology]

[0002] The present applicant has proposed a technique for joining workpieces using ultrasonic complex vibration (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7082434 Summary of the Invention [Problem to be solved by the invention]

[0004] Ultrasonic composite vibration is achieved by combining ultrasonic vibrations in two directions perpendicular to the axial direction of the ultrasonic bonding tip, but no consideration is given to ultrasonic vibrations in a direction parallel to the axial direction of the ultrasonic bonding tip.

[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 using a new type of ultrasonic complex vibration, and an ultrasonic bonding device using the same. [Means for solving the problem]

[0006] The ultrasonic bonding tip of the present invention is A rod portion having a first rod portion extending in an axial direction and a second rod portion coaxially continuous with the first rod portion and formed so that the cross-sectional area thereof decreases continuously or intermittently in the axial direction, The length L of the second rod portion and the square root S of the cross-sectional area S at the junction of the second rod portion and the first rod portion 1 / 2 In between, 5S 1 / 2 ≦L≦50S 1 / 2 The rod portion is configured so that the relationship expressed by

[0007] In the ultrasonic bonding tip (hereinafter sometimes simply referred to as "tip") having this configuration, the rod portion has an elongated shape in which the cross-sectional area of ​​the second rod portion gradually decreases toward the tip. Therefore, when the tip of the rod portion of the tip is pressed against a workpiece and ultrasonic complex vibration is applied to the workpiece in a direction (horizontal direction) perpendicular to the pressing direction (vertical direction), the rod portion can bend locally in the second rod portion. This allows the tip of the rod portion or the second rod portion to ultrasonically vibrate not only in the horizontal direction but also in the vertical direction.

[0008] In the early stages of joining multiple workpieces, the pressing force of the tip of the rod portion of the tip against the workpieces is intermittently increased due to the vertical ultrasonic vibrations, suppressing misalignment of the multiple workpieces. In the middle and final stages of joining multiple workpieces, part of the ultrasonic vibration energy applied from the rod portion of the tip to the multiple workpieces can be converted into vertical ultrasonic vibrations of the rod portion, preventing the tip from applying excessive horizontal ultrasonic vibrations to the multiple workpieces. As a result, the quality of the workpieces joined is improved. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating the configuration of an ultrasonic bonding device. [Figure 2] 1 is a diagram illustrating the configuration of an ultrasonic bonding tip according to one embodiment of the present invention; [Figure 3] 3 is a flowchart showing the function of the ultrasonic bonding device. DETAILED DESCRIPTION OF THE INVENTION

[0010] (composition) 1 includes an ultrasonic complex vibration device 10, a horn tip 40 (ultrasonic bonding tip), and an anvil 18. The anvil 18 may be omitted.

[0011] The ultrasonic complex vibration device 10 includes a first ultrasonic vibrator 110 having a substantially cylindrical shape, an intermediate ultrasonic vibrator 100 having a substantially cylindrical, cylindrical, or bottomed cylindrical shape, and a second ultrasonic vibrator 120 having a substantially cylindrical or bottomed cylindrical shape. The first ultrasonic vibrator 110, the intermediate ultrasonic vibrator 100, and the second ultrasonic vibrator 120 constitute "ultrasonic vibrators."

[0012] The first ultrasonic vibrator 110 and the intermediate ultrasonic vibrator 100 are coaxially connected by a mechanical connecting mechanism (such as a bolt and / or a clamp mechanism) at the middle or intermediate portion of the ultrasonic complex vibration device 10. The intermediate ultrasonic vibrator 100 and the second ultrasonic vibrator 120 are coaxially connected by a mechanical connecting mechanism at the middle portion of the ultrasonic complex vibration device 10. The first ultrasonic vibrator 110, the intermediate ultrasonic vibrator 100, and the second ultrasonic vibrator 120 may be integrally configured rather than being mechanically connected.

[0013] The intermediate ultrasonic vibrator 100 may be a component of the first ultrasonic vibrator 110. That is, the first ultrasonic vibrator 110 may be composed of two ultrasonic vibrators. In this case, the first ultrasonic vibrator 110 and the intermediate ultrasonic vibrator 100 may be integrally configured rather than being mechanically connected. The intermediate ultrasonic vibrator 100 may be a component of the second ultrasonic vibrator 120. That is, the second ultrasonic vibrator 120 may be composed of two ultrasonic vibrators. In this case, the second ultrasonic vibrator 120 and the intermediate ultrasonic vibrator 100 may be integrally configured rather than being mechanically connected.

[0014] As shown in FIG. 1, the first ultrasonic vibrator 110 is provided with a piezoelectric body 112 whose axial direction (direction parallel to the first axis) is the piezoelectric polarization direction.

[0015] As shown in FIG. 1, the intermediate ultrasonic vibrator 100 has a generally annular plate-shaped intermediate flange 102 formed at a central position in the axial direction, which extends radially over the entire circumference. The intermediate ultrasonic vibrator 100 is configured to be clamped or supported at least at the intermediate flange 102 by a clamping mechanism (not shown) around the entire circumference. If it is ensured that the intermediate ultrasonic vibrator 100 is supported by a mechanical support mechanism, the intermediate flange 102 may be omitted. As shown in FIG. 1, the intermediate ultrasonic vibrator 100 has a generally cylindrical shape with a generally constant outer diameter in the axial direction behind the intermediate flange 102 (leftward in FIG. 1). As shown in FIG. 1, the intermediate ultrasonic vibrator 100 has a generally cylindrical shape (a shape in which a generally truncated conical shape and a generally cylindrical shape are coaxially connected) with a generally constant outer diameter after continuously tapering partway toward the tip portion ahead of the intermediate flange 102 (rightward in FIG. 1).

[0016] 1, the second ultrasonic vibrator 120 is provided with a frequency adjustment element 122 in the shape of a substantially regular octagonal plate with rounded corners, which extends radially around the entire circumference at a midpoint in the axial direction of the second ultrasonic vibrator 120. The frequency adjustment element 122 adjusts the resonance frequencies of the longitudinal vibration component and the torsional vibration component of the ultrasonic vibration. The outer shape of the frequency adjustment element 122 may be a substantially circular, substantially elliptical, or substantially regular n-sided polygonal plate (e.g., n = 4, 6, 8, 12, 16, etc.) plate, columnar, or frustum shape, which shares a common central axis with the second ultrasonic vibrator 120, or any combination thereof.

[0017] 1, the second ultrasonic vibrating body 120 has a plurality of slits 124 formed on its outer surface behind the frequency adjustment element 122. A plurality of slits 124 may be formed on the outer surface of the second ultrasonic vibrating body 120 ahead of the frequency adjustment element 122. The slits 124 extend obliquely in the second ultrasonic vibrating body 120 when viewed from the side, or extend in the axial direction while being displaced in the circumferential direction in phase with each other. 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 ultrasonic vibrating body 120.

[0018] 1, the second ultrasonic vibrating body 12 is provided with a tip portion 126 of a generally regular octagonal shape with rounded corners that protrudes radially around the entire circumference at the tip position in the axial direction. Holes 128 (or through holes) are formed in the tip portion 126 at a plurality of locations spaced apart in the circumferential direction. The M (N=2, 3, ...) holes 128 may be arranged to have M-fold rotational symmetry (e.g., M=4) around the central axis of the second ultrasonic vibrating body 12. A female thread is provided on the inner surface of the hole 128.

[0019] 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 first workpiece W1 and second workpiece W2. A male thread provided at the base end of horn tip 40 is threaded into a female thread provided in hole 128 in tip portion 126 of second ultrasonic vibrator 12, thereby removably fixing horn tip 40 to second ultrasonic vibrator 12. Horn tips 40 of various shapes are available, so that horn tips 40 can be appropriately replaced depending on the type of metal to be joined, etc.

[0020] The balancer for adjusting the phase difference between the longitudinal vibration and the torsional vibration at the tip 126 of the second ultrasonic vibrator 12, and thus at the horn tip 40, may be removably fixed to the tip 126 of the second ultrasonic vibrator 12 by screwing the male thread of the balancer into the female thread of the hole 128.

[0021] The anvil 18 is disposed so as to face the tip of the horn tip 40 in the vertical direction. A first workpiece W1 and a second workpiece W2 as multiple workpieces are placed 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 first workpiece W1 and the second workpiece W2.

[0022] As shown in FIG. 1, the ultrasonic bonding apparatus according to one embodiment of the present invention further includes an operating device 20, a control device 22, a rotational driving device 220, a high-frequency power supply device 221, a translational driving device 222, and a status sensor 224.

[0023] The operation device 20 is configured, for example, by a display, and displays or outputs on the display the displacement amount of the pressure block and / or the time series of the pressure according to the output signal of the status sensor 224. The display may be configured by 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 bonding modes that determine a time series pattern of the target pressure.

[0024] The control device 22 is configured with a microcomputer, an arithmetic processing unit (CPU, microprocessor, processor core, etc.), and a storage device (memory such as ROM and RAM). The control device 22 is configured to control the displacement operation of the pressure block by the translation drive device 222 based on a time series of the displacement amount of the pressure block represented by the output signal of a stroke sensor that constitutes the status sensor 224. The control device 22 is configured to control the power supplied to the piezoelectric body 112 based on the amplitude (corresponding to the specified parameter) of the horn tip 40 represented by the output signal of an amplitude sensor that constitutes the status sensor 224, and thereby to control the ultrasonic vibration power of the ultrasonic vibrators (first ultrasonic vibrator 110, intermediate ultrasonic vibrator 100, and second ultrasonic vibrator 120) and the ultrasonic vibration power of the horn tip 40.

[0025] The high frequency power supply device 221 is configured to excite the first ultrasonic vibrator 110 in the axial direction by applying a high frequency AC voltage to the piezoelectric body 112 of the first ultrasonic vibrator 110 in accordance with power supplied from a commercial power source (not shown).

[0026] The translational drive device 222 is equipped with a pressure block and is configured to apply pressure from the horn tip 40 to the first workpiece W1 and the second workpiece W2 by displacing a support mechanism such as a clamping mechanism that supports the intermediate ultrasonic vibrator 100 using the pressure block.

[0027] The status sensor 224 includes a stroke sensor that outputs a signal corresponding to the displacement of the pressure block that constitutes the translational drive device 222, as well as an amplitude sensor that outputs a signal corresponding to the amplitude (corresponding to a specified 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. As the status sensor 224, a pressure sensor that outputs a signal corresponding to the pressure acting on the intermediate ultrasonic vibrator 100 from the pressure block of the translational drive device 222 (the pressure that the horn tip 40 applies to the first workpiece W1 and the second workpiece W2) may be provided, and the control device 22 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.

[0028] 2, the horn tip 40 includes a connecting member 402, a base 41, and a rod portion 42. The connecting member 402 is formed in a substantially cylindrical shape, and has an outer surface formed with a male thread that screws into a female thread formed in the hole 128 of the tip portion 126 of the second ultrasonic vibrator 120. The base 41 is coaxially continuous with the connecting member 402 and has a substantially columnar or cylindrical first base 411 with a larger diameter than the connecting member 402, and a substantially truncated conical or truncated cylindrical second base 412 with a lower bottom surface having substantially the same diameter as the first base 411.

[0029] The base 41 has a threaded hole 4110 formed therein, extending in the axial direction from the center of the end portion on the first base portion 411 side, and the male thread of the connecting member 402 is screwed into the threaded hole 4110. The thread specifications (reference dimensions of the outer diameter, root diameter, and effective diameter, as well as pitch) of the portion of the male thread of the connecting member 402 that is screwed into the hole 128 (threaded hole) of the second ultrasonic vibrator 120 and the portion that is screwed into the threaded hole 4110 of the base 41 may be the same or different. The rod portion 42 is coaxially continuous with the second base portion 412 of the base 41 and is formed in a generally cylindrical shape with a diameter smaller than the upper bottom surface of the second base portion 412. The base 41 has a fitting hole 4120 that extends in the axial direction from the center of the end portion on the second base 412 side, and the first rod portion 421 of the rod portion 42 is partially fitted into the fitting hole 4120 and then shrink-fitted. In the base 41, the screw hole 4110 and the fitting hole 4120 may or may not be in communication with each other.

[0030] The connecting member 402 may be omitted, and a screw hole may be formed extending axially from the center of the end portion of the base 41 on the side of the first base 411, and the horn tip 40 may be attached to the second ultrasonic vibrator 12 by threading a bolt or male screw threaded or fixed to the tip 126 of the second ultrasonic vibrator 12 into the female thread of the screw hole.

[0031] The base 41 may have a shape other than the combination of the first base 411 having a substantially cylindrical shape and the second base 412 having a substantially truncated cone shape. For example, the base 41 may be substantially cylindrical, substantially prismatic, substantially truncated cone, or substantially truncated pyramid. The cross-sectional shape of the first rod portion 421 and / or the second rod portion 422 of the rod portion 42 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 (e.g., a regular M-gon (e.g., M = 8 to 16), or a substantially star-shaped M-gon (e.g., M = 4 to 16)). The cross-sectional shape of the rod portion 42 in the axial direction may be formed so that it changes in various orders along the axial direction, such as a substantially circular shape, a substantially elliptical shape, a substantially rectangular shape (square shape, parallelogram shape, etc.), or a substantially polygonal shape (e.g., a regular M-gon, a substantially star-shaped M-gon).

[0032] 2, the rod portion 42 in one embodiment of the present invention is composed of a first rod portion 421 and a second rod portion 422 that are continuous in this order from the base end in the axial direction. The first rod portion 421 is formed in a generally cylindrical shape. The second rod portion 422 is formed in a generally truncated cone shape with a lower base surface having generally the same diameter as the first rod portion 421.

[0033] The length L of the second rod portion 422 and the square root S of the cross-sectional area S at the connecting point of the second rod portion 422 with the first rod portion 421 1 / 2 In between, 5S 1 / 2 ≦L≦50S 1 / 2 , 10S 1 / 2 ≦L≦40S 1 / 2 , or 15S 1 / 2 ≦L≦25S 1 / 2 The rod portion 42 is configured so that there is a relationship expressed as follows: The cross-sectional area S of the second rod portion 422 at the continuation point with the first rod portion 421 and the cross-sectional area s of the tip portion of the second rod portion 422 are related by 0.10S≦s≦0.80S, 0.20S≦s≦0.80S, 0.30S≦s≦0.70S, or 0.40S≦s≦0.70S. Because the length L of the second rod portion 422 is not excessively short, the second rod portion 422 or the entire rod portion 422 is likely to bend when subjected to an axial force. Because the length L of the second rod portion 422 is not excessively long, it is possible to avoid a situation in which the second rod portion 422 or the entire rod portion 422 is excessively bent when subjected to an axial force.

[0034] The first rod portion 421 may be formed into various cylindrical shapes, such as a circular cylinder, an elliptical cylinder, an n-sided prism (n=3, 4, 5, ...) (e.g., an isosceles triangular prism, a trapezoidal prism, or a parallelogram prism), a regular n-sided prism, or a combination thereof (multiple different prisms connected coaxially). The second rod portion 422 may be formed to taper in various shapes, such as a circular truncated cone, an elliptical truncated cone, an n-sided prism (n=3, 4, 5, ...) (e.g., an isosceles triangular prism, a trapezoidal prism, or a parallelogram prism), a regular n-sided prism, or multiple different prisms and / or frustums connected coaxially. The outer circumferential surfaces of the first rod portion 421 and the second rod portion 422 may be G0 continuous, G1 continuous, or G2 continuous. The outer circumferential surfaces of the multiple prisms constituting the first rod portion 421 may be G0 continuous, G1 continuous, or G2 continuous. The outer circumferential surfaces of the plurality of frustums and / or pillars constituting the second rod portion 422 may be G0 continuous, G1 continuous, or G2 continuous.

[0035] The tip of the rod portion 42 (or the second rod portion 422) that is pressed against the workpiece W1 may be provided with a plurality of protrusions.

[0036] In the second rod portion 422, the rod portion 42 may have a spiral notch formed therein, or may have a plurality of annular notches spaced apart in the axial direction, or may have a plurality of annular notches spaced apart in the axial and / or circumferential direction.

[0037] The base 41 and the rod 42 are formed of the same or different types of cemented carbide alloys. Examples of cemented carbide alloys that can be used include WC-Co alloys, WC-TiC-Co alloys, WC-TaC-Co alloys, WC-TiC-TaC-Co alloys, WC-Ni alloys, and WC-Ni-Cr alloys. The connecting member 402 is made of stainless steel. Examples of stainless steel that can be used include martensitic stainless steel, ferritic stainless steel, austenitic stainless steel, and precipitation-hardened stainless steel.

[0038] The Young's modulus E of the cemented carbide constituting base 41 and rod portion 42 of horn tip 40 is, for example, within the range of 450 to 650 GPa. The Young's modulus E0 of the stainless steel constituting connecting member 402 is, for example, within the range of 180 to 220 GPa. The ratio (E0 / E) of the Young's modulus E of the cemented carbide constituting base 41 and rod portion 42 of horn tip 40 to the Young's modulus E0 of the stainless steel constituting connecting member 402 is, for example, within the range of 0.28 to 0.49.

[0039] (Ultrasonic bonding method) The procedure of an ultrasonic bonding method according to one embodiment of the present invention using an ultrasonic bonding device will be described with reference to the flowchart in Fig. 2. As shown in Fig. 1, a first workpiece W1 and a second workpiece W2 are placed on an anvil 18 in a stacked state from top to bottom.

[0040] The ultrasonic complex vibration device 10 and the horn tip 40 are moved in the radial direction by the translational drive device 222 so as to approach the first workpiece W1 and the second workpiece W2 (FIG. 3 / STEP 112).

[0041] Furthermore, it is determined whether the pressure P that horn tip 40 receives from first workpiece W1 (and second workpiece W2) is equal to or greater than first specified pressure P1 (FIG. 3 / STEP 114). The pressure P that horn tip 40 receives from first workpiece W1 is measured based on the output signal of a pressure sensor that constitutes state sensor 224. When the tip of horn tip 40 is separated from workpiece W1, P=0. For example, as shown in FIG. 3, when the tip of horn tip 40 comes into contact with first workpiece W1 that is inserted into through-hole W20 of second workpiece W2, a reaction force is received, so that P>0.

[0042] If the determination result is negative (FIG. 3 / STEP 114...NO), the translational drive device 222 moves the ultrasonic complex vibration device 10 and the horn tip 40 in the radial direction so as to approach the first workpiece W1 inserted into the through-hole W20 of the second workpiece W2 (FIG. 2 / connector X1 →STEP 112). As a result, the position of the horn tip 40, and therefore the static pressure applied from the horn tip 40 to the first workpiece W1 and the second workpiece W2, is adjusted to be within a specified static pressure range (e.g., 200 N to 800 N).

[0043] If the determination result is affirmative (FIG. 3 / STEP 114...YES), ultrasonic vibrations are generated in the ultrasonic vibrator (FIG. 3 / STEP 116). Specifically, in response to power being supplied to the high-frequency power supply device 221 from a commercial power source (not shown) via a slip ring or the like, the high-frequency power supply device 221 applies a high-frequency AC voltage to the piezoelectric body 112 of the first ultrasonic vibrator 110. This causes the first ultrasonic vibrator 110 to vibrate in its axial direction at, for example, approximately 20 KHz, generating ultrasonic vibrations. The ultrasonic vibrations are transmitted from the first ultrasonic vibrator 110 to the intermediate ultrasonic vibrator 100 in its axial direction, and the amplitude of the ultrasonic vibrations is amplified. Furthermore, the ultrasonic vibrations with amplified amplitude are transmitted from the intermediate ultrasonic vibrator 100 to the second ultrasonic vibrator 120 in its axial direction.

[0044] In this way, a portion of the longitudinal vibration component (axial component of the second ultrasonic vibrator 120) of the ultrasonic vibration transmitted to the second ultrasonic vibrator 120 is converted into a torsional vibration component by the plurality of slits 124 formed on the outer surface of the second ultrasonic vibrator 120. 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 of the second ultrasonic vibrator 120.

[0045] In response, the horn tip 40 displaces or vibrates in a circular or elliptical orbit in a plane (xy plane) perpendicular to the contact direction (z direction) of the first workpiece W1. As a result, the amplitude and ultrasonic vibration power of the horn tip 40 gradually increase from the vibration start time t=t0. During this process, impurities on the contact surface between the first workpiece W1 and the second workpiece W2 are removed, further promoting plastic deformation of the contact surface between the first workpiece W1 and the second workpiece W2. After the rate of increase in the amplitude and ultrasonic vibration power of the horn tip 40 significantly decreases at time t=t1, the amplitude and ultrasonic vibration power of the horn tip 40 gradually increase. This is because the oxide coatings and other metals constituting the joining surfaces of the first workpiece W1 and the second workpiece W2 are removed, revealing clean, activated metal atoms on the joining surfaces. The temperature rise due to frictional heat activates the atomic movement, generating mutual attraction between the atoms.

[0046] At this time, the composite vibration is applied to the first workpiece W1 and the second workpiece W2 while adjusting the amount of pressing of the first workpiece W1 and the second workpiece W2 by the horn tip 40 and / or the static pressure applied to the first workpiece W1 and the second workpiece W2. As a result, as shown in Fig. 3, the outer surface and the peripheral edge of the lower surface of the first workpiece W1 can be solid-state welded to the stepped portion W22 of the second workpiece W2 over the entire circumference.

[0047] 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 less than the reference amplitude A0 (FIG. 3 / STEP 118). An amplitude sensor constituting the state sensor 224 optically measures the amplitude A at a specified location (e.g., a location where the amplitude is relatively large) of the horn tip 40. Instead of this determination process, it may be determined whether the amplitude A has decreased by the reference amplitude A0 (or a reference ratio based on the maximum value) using the maximum value at the time when the amplitude A started to decrease as a reference. For example, the reference amplitude A0, such as one of multiple joining modes for which the reference amplitude A0 is determined, may be directly or indirectly specified via a touch panel display constituting the operation device 20.

[0048] If the determination result is negative (FIG. 3 / STEP 118...NO), ultrasonic vibrations are continuously generated in the ultrasonic vibrator (FIG. 3 / connector X2 →STEP 116). On the other hand, if the determination result is positive (FIG. 3 / STEP 118...YES), the translational drive device 222 moves the ultrasonic complex vibration device 10 and the horn tip 40 away from the first workpiece W1 and the second workpiece W2 (FIG. 3 / STEP 122).

[0049] Furthermore, it is determined whether the pressure P that the horn tip 40 receives from the first workpiece W1 (and the second workpiece W2) has become equal to or less than a second designated pressure P2 (FIG. 3 / STEP 124). The second designated pressure P2 is set to a value smaller than the first designated pressure P1, for example, 0 or a very small value.

[0050] If the determination result is negative (FIG. 3 / STEP 124...NO), the translational drive device 222 moves the ultrasonic complex vibration device 10 and the horn tip 40 away from the first workpiece W1 and the second workpiece W2 (FIG. 3 / connector X4 →STEP 122). This adjusts the radial position of the horn tip 40, and therefore the static pressure applied by the horn tip 40 to the first workpiece W1 and the second workpiece W2, so as to decrease.

[0051] If the determination result is affirmative (FIG. 3 / STEP 124...YES), the generation of ultrasonic vibrations in the ultrasonic vibrator is stopped (FIG. 3 / STEP 126). For example, after the time t=t2 when the amplitude of the horn tip 40 changes from increasing to decreasing and becomes equal to or less than the reference amplitude A0, the ultrasonic power of the horn tip 40 is controlled to become 0 with a slight response delay. This stops the series of processes.

[0052] (effect) The horn tip 40 having the above-described configuration has an elongated shape in which the cross-sectional area of ​​the rod portion 42 gradually decreases toward the tip end of the second rod portion 422. The square root S of the cross-sectional area S at the junction of the second rod portion 422 and the first rod portion 421 is 1 / 2 In between, 5S 1 / 2 ≦L≦50S 1 / 2 , 10S 1 / 2 ≦L≦40S 1 / 2 , or 15S 1 / 2 ≦L≦25S 1 / 2 The rod portion 42 is configured to satisfy the relationship expressed by the following equation. Therefore, when the tip of the rod portion 42 is pressed against the workpiece W1 and ultrasonic complex vibration is applied to the workpiece W1 in a direction (horizontal direction) perpendicular to the pressing direction (vertical direction), the rod portion 42 can bend locally in the second rod portion 422. This allows the tip of the rod portion 42 to ultrasonically vibrate not only in the horizontal direction but also in the vertical direction (three-dimensionally).

[0053] In the early stages of joining the multiple workpieces W1 and W2, the pressing force of the tip of the rod portion 42 against the workpieces W1 and W2 is intermittently increased due to the vertical ultrasonic vibrations, thereby suppressing misalignment of the multiple workpieces W1 and W2. In the middle and final stages of joining the multiple workpieces W1 and W2, part of the ultrasonic vibration energy applied to the multiple workpieces W1 and W2 can be converted into vertical ultrasonic vibrations of the rod portion 42, thereby preventing excessive horizontal ultrasonic vibrations from being applied to the multiple workpieces W1 and W2. As a result, the quality of joining the workpieces W1 and W2 is improved.

[0054] (Example) An ultrasonic bonding apparatus of Example 1 was constructed according to one embodiment of the present invention shown in Figure 2. The ultrasonic vibrator or second ultrasonic vibrator 12 or its tip 126 was made of stainless steel CR20 (Young's modulus 200 GPa). The connecting member 402 constituting the horn tip 40 was made of chromium-molybdenum steel SCM435 (Young's modulus 214 GPa), the base 41 was made of stainless steel SUS304 (Young's modulus 193 GPa), and the rod portion 42 was made of cemented carbide MC20 (Young's modulus 620 GPa) (see Figure 2). The connecting member 402 was formed in a roughly cylindrical shape with a diameter of 9 mm and a length of 23 mm. Base 41 is formed in a shape in which a substantially cylindrical first base portion 411 having an inner diameter of 7.25 mm, an outer diameter of 15 mm, and a length of 36.2 mm is coaxially connected to a substantially truncated conical second base portion 412 having an inner diameter of 7 mm, a lower bottom outer diameter of 8.2 mm, an upper bottom outer diameter of 15 mm, and a length of 21 mm. Rod portion 42 is formed in a shape in which a substantially cylindrical first rod portion 421 having a diameter of 3.5 mm and a length of 20.5 mm is connected to a substantially truncated conical second rod portion 422 having a lower bottom diameter of 1.5 mm, an upper bottom diameter of 3.0 mm, and a height (length) of 87.75 mm, with their central axes aligned.

[0055] (Reference example 1) An ultrasonic bonding device of Reference Example 1 was constructed having the same configuration as that of the Example, except that the rod portion 42 constituting the horn tip 40 was formed in a substantially cylindrical shape with a diameter of 2.0 mm and a length of 87.75 mm.

[0056] (Reference example 2) An ultrasonic bonding device of Reference Example 1 was constructed having the same configuration as that of the Example, except that the rod portion 42 constituting the horn tip 40 was formed in a substantially cylindrical shape with a diameter of 3.0 mm and a length of 87.75 mm.

[0057] (evaluation) Then, the amplitudes in the x- and y-directions (two directions perpendicular to the horizontal direction) and z-direction (vertical direction) were evaluated by simulation for (1) the unloaded state and (2) the loaded state. In (1) the unloaded state, the ultrasonic complex vibration device 10 was driven at 10% of its maximum driving power (which varies depending on the specifications of the ultrasonic complex vibration device 10), and the horn tip 40 was in an unloaded state (not in contact with the workpiece). In (2) the unloaded state, the ultrasonic complex vibration device 10 was driven at 20% of its maximum driving power, and a load of 150 N was applied to the horn tip 40 in the axial direction. Table 1 summarizes the evaluation results.

[0058] [Table 1]

[0059] As is clear from Table 1, it was confirmed that in the horn tip 40 of the example according to one embodiment of the present invention, an amplitude in the z direction was generated in both the unloaded state and the loaded state.

[0060] (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 ultrasonic vibrator (e.g., the second ultrasonic vibrator 12) may be measured as a specified parameter. [Explanation of symbols]

[0061] 1‥Ultrasonic bonding equipment 100...Intermediate ultrasonic vibrator 102...Intermediate flange 110...First ultrasonic vibrator 112. Piezoelectric material 120...Second ultrasonic vibrator 122...Frequency adjustment element 124. Slit 126‥Tip 128 holes 18. Anvil 20‥Operation device 22. Control device 221‥High frequency power supply equipment 222...Translation drive device 224...Status sensor 40. Horn tip 402...Connecting member 41‥Base 42...Rod section 441...First rod part 442...Second rod part W1: One of the workpieces W2: The other work.

Claims

1. A rod portion having a first rod portion extending in an axial direction and a second rod portion coaxially continuous with the first rod portion and formed so that the cross-sectional area thereof decreases continuously or intermittently in the axial direction, The length L of the second rod portion and the square root S of the cross-sectional area S at the junction of the second rod portion and the first rod portion 1 / 2 In between, 5S 1 / 2 ≦L≦50S 1 / 2 The rod portion is configured so that there is a relationship expressed as follows: Ultrasonic bonding tip.

2. 2. The ultrasonic bonding tip according to claim 1, The rod portion is configured such that a cross-sectional area S at a portion where the second rod portion is continuous with the first rod portion and a cross-sectional area s at a tip end of the second rod portion satisfy the relationship expressed as 0.10S≦s≦0.80S. Ultrasonic bonding tip.

3. 2. The ultrasonic bonding tip according to claim 1, The rod portion has a shape that has rotational symmetry around the central axis. Ultrasonic bonding tip.

4. 2. The ultrasonic bonding tip according to claim 1, The first rod portion is configured as a column having rotational symmetry about a central axis, and the second rod portion is configured as a frustum having rotational symmetry about a central axis. Ultrasonic bonding tip.

5. an ultrasonic vibrator that induces a composite vibration by combining longitudinal vibration and torsional vibration; an ultrasonic bonding tip; a control device for controlling the complex vibration of the ultrasonic vibrator, The ultrasonic bonding tip comprises: A rod portion having a first rod portion extending in an axial direction and a second rod portion coaxially continuous with the first rod portion and formed so that the cross-sectional area thereof decreases continuously or intermittently in the axial direction, The length L of the second rod portion and the square root S of the cross-sectional area S at the junction of the second rod portion and the first rod portion 1 / 2 In between, 5S 1 / 2 ≦L≦50S 1 / 2 The rod portion is configured so that there is a relationship expressed as follows: Ultrasonic bonding equipment.

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