TWI856332B - Ultrasonic composite vibration device and semiconductor device manufacturing device - Google Patents

Abstract

In an ultrasonic composite vibration device (50), a base end portion (52) having a vibrator (58) for generating longitudinal vibration and torsional vibration, an expansion portion (54) having a larger cross-sectional area than the base end portion (52), and a front end portion (56) having a smaller cross-sectional area than the expansion portion (54) are arranged in a straight line from the base end side toward the front end side, the node of the torsional vibration is located at the expansion portion (54), the antinode of the longitudinal vibration and the antinode of the torsional vibration are located at the base end surface and the front end surface of the ultrasonic composite vibration device (50), and the axial position and axial dimension W of the expansion portion (54) are set to a position and dimension at which the resonance frequency Fa of the longitudinal vibration and the resonance frequency Fb of the torsional vibration are approximately the same.

Description

Ultrasonic composite vibration device and semiconductor device manufacturing device

This specification discloses an ultrasonic composite vibration device used in an ultrasonic processing machine for performing vibration processing (joining, cutting, grinding, etc.) on an object.

For a long time, an ultrasonic composite vibration device that generates longitudinal vibration and torsional vibration has been proposed for vibration processing of an object. However, the resonance frequency of the longitudinal vibration and the resonance frequency of the torsional vibration of most previous ultrasonic composite vibration devices are very different, so that it is impossible to generate two vibrations at one or similar frequencies at the same time.

Therefore, it is proposed to generate longitudinal vibration and torsional vibration at one or close frequencies in a part. For example, Patent Document 1 discloses the following technology: a vibrating body having a step portion and an electrostrictive vibrator is combined with a vibrating body having a step portion and no vibrating element to form an ultrasonic composite device. Patent Document 1 discloses the following content: in each vibrating body, by adjusting the distance from the antinode of the longitudinal vibration to the step portion, the resonant frequency of the longitudinal vibration and the resonant frequency of the torsional vibration are made consistent or close. [Prior art document] [Patent document]

Patent document 1: Japanese Patent Publication No. 2005-288351

[The problem that the invention wants to solve]

In addition, in Patent Document 1, the step portion is adjusted so as to become the antinode of the torsional vibration. However, in general, the vibration attenuation is likely to occur on the step portion, and it is difficult to make the step portion the antinode of the torsional vibration. In addition, in Patent Document 1, two vibrating bodies are combined to form an ultrasonic composite device. Therefore, as a whole, the ultrasonic composite device has two step portions and a joint surface of two vibrating bodies, so its behavior is complicated, and it is difficult to adjust the size or frequency.

Therefore, this specification discloses an ultrasonic composite device that can generate longitudinal vibration and torsional vibration at one or similar frequencies despite having a simpler structure. [Means for solving the problem]

The ultrasonic compound vibration device disclosed in this specification is an ultrasonic compound vibration device, which is characterized in that: it has a base end portion of a vibrator that generates longitudinal vibration and torsional vibration, an expansion portion with a larger cross-sectional area than the base end portion, and a front end portion with a smaller cross-sectional area than the expansion portion, which are arranged in a straight line from the base end side to the front end side, the node of the torsional vibration is located in the expansion portion, the antinode of the longitudinal vibration and the antinode of the torsional vibration are located at the base end surface and the front end surface of the ultrasonic compound vibration device, and the axial position and axial size of the expansion portion are set to a position and size where the resonance frequency of the longitudinal vibration is approximately the same as the resonance frequency of the torsional vibration.

In this case, the axial dimension from the end surface on the front end side of the expansion portion to the end surface on the front end side of the front end portion may be an odd multiple of 1/4 wavelength of the torsional vibration.

Furthermore, an inclined slit that progresses in the axial direction and also in the circumferential direction may be formed at the front end portion.

In addition, the semiconductor device manufacturing device disclosed in this specification includes the ultrasonic composite vibration device described above and a soldering pin installed at the front end and through which the wire is inserted, wherein the vibrator is driven at a driving frequency that is substantially the same as the resonance frequency of the longitudinal vibration and the resonance frequency of the torsional vibration. [Effect of the invention]

According to the technology disclosed in this specification, despite the simple structure, longitudinal vibration and torsional vibration can be generated at one or similar frequencies.

Hereinafter, the structure of the ultrasonic composite vibration device 50 and the semiconductor device manufacturing apparatus 10 equipped with the same will be described with reference to the drawings. FIG1 is a diagram showing the structure of the manufacturing apparatus 10 equipped with the ultrasonic composite vibration device 50.

The manufacturing device 10 is a wire bonding device for manufacturing semiconductor devices by connecting two electrodes provided on an object 30 using a wire 26. The object 30 is, for example, a lead frame on which a semiconductor chip is mounted. Generally, electrodes are provided on the semiconductor chip and the lead frame, respectively, and the electrodes are electrically connected using the wire 26 to manufacture a semiconductor device.

The manufacturing apparatus 10 has a bonding head 12 that can be moved in the horizontal direction by an XY stage 20. An ultrasonic welding head 16 and a camera 22 are mounted on the bonding head 12 so as to be movable in the vertical direction. The ultrasonic welding head 16 is mounted on the bonding head 12 via a welding head bracket 14. The ultrasonic welding head 16 is an ultrasonic composite vibration device 50 that generates longitudinal vibration and torsional vibration and transmits them to a welding needle. The welding needle 18 is a cylindrical member mounted at the end of the ultrasonic welding head 16 and through which a wire 26 is inserted. The longitudinal vibration and torsional vibration are transmitted to the wire 26 via the welding needle 18. Furthermore, a clamp 19 that moves together with the welding needle 18 and clamps the wire 26 is provided above the welding needle 18.

The camera 22 takes a picture of the object 30 as required. The controller 32 determines the position of the welding needle 18 relative to the object 30 based on the image taken by the camera 22, and positions the welding needle 18. A reel 24 around which a wire 26 is wound is further provided in the bonding head 12, and the wire 26 is successively unwound from the reel 24 as required. The controller 32 controls the driving of each part constituting the manufacturing device 10. For example, the controller 32 applies an alternating voltage of a specified frequency to the vibrator 58 provided in the ultrasonic welding head 16 (i.e., the ultrasonic composite vibration device 50), thereby generating vibration of the specified frequency. Furthermore, the structure of the manufacturing device 10 is an example, and the ultrasonic composite vibration device 50 described in detail later can also be assembled in a vibration processing machine with other structures.

Next, the structure of the ultrasonic compound vibration device 50 mounted on the manufacturing device 10 is described. FIG. 2 is a three-dimensional view of the ultrasonic compound vibration device 50. In addition, FIG. 3 is a schematic side view of the ultrasonic compound vibration device 50. Furthermore, in the upper section of FIG. 3 , the solid line WVa represents the waveform of the longitudinal vibration, and the one-point chain line WVb represents the waveform of the torsional vibration. In addition, in order to simplify the description, the ultrasonic compound vibration device 50 is simplified in FIG. 3 . Therefore, the illustration of the mounting portion of the welding needle 18 and the flange 51 is omitted in FIG. 3 .

As described above, the ultrasonic composite vibration device 50 functions as an ultrasonic welding head 16, and a welding needle 18 is installed at its end. The ultrasonic composite vibration device 50 has a base end 52, an expansion part 54, and a front end 56 arranged in a straight line from the base end side to the front end side. The base end 52 and the front end 56 are round rods of approximately the same diameter. The base end 52 is further roughly divided into a vibrator 58 and a relay part 60 between the vibrator 58 and the expansion part 54. The vibrator 58 is a vibration generating source that generates longitudinal vibration and torsional vibration by receiving a voltage signal. The vibrator 58 is, for example, a bolt-fixed Langevin type vibrator (commonly known as a BLT (Bolt clamped Langevintype Transducer) or a BL (Bolt clamped Langevintype) vibrator) that has lead zirconate titanate (commonly known as PZT (Pb-based Lanthanumdoped Zirconate Titanates)) that vibrates when receiving an alternating voltage, and a pressure is applied to the PZT by clamping it with a metal block and tightening it with a bolt. The vibrator 58 of this example has not only a PZT element that generates longitudinal vibration, but also a PZT element that generates torsional vibration by changing the polarization direction. Therefore, the vibrator 58 can generate both longitudinal vibration and torsional vibration.

The expansion portion 54 is a portion having a larger diameter than the base portion 52 and the front portion 56. The diameter D2 of the expansion portion 54 is not particularly limited as long as it is larger than the diameter D1 of the front portion 56. However, the larger the diameter D2 of the expansion portion 54, the higher the attenuation effect of the torsional vibration, and the easier it is for the expansion portion 54 to become a node of the torsional vibration. Therefore, the diameter D2 of the expansion portion 54 can be set to, for example, 1.5 times or more of the diameter D1 of the front portion 56. In addition, the axial dimension W of the expansion portion 54 is set to make the resonance frequency Fa of the longitudinal vibration and the resonance frequency Fb of the torsional vibration consistent or close, which will be described later. A flange 51 is provided between the expansion portion 54 and the intermediate portion 60. The flange 51 is used when the ultrasonic composite vibration device 50 is mounted on the welding head bracket 14 .

The front end portion 56 is a round rod having substantially the same diameter as the base end portion 52, and the welding needle 18 is mounted at the end of the front end portion 56. The axial dimension L3 of the front end portion 56 is not particularly limited, and is generally substantially the same as an odd multiple of 1/4 wavelength of torsional vibration. The reason for this is that the wavelength λb and phase of the torsional vibration generated at the front end portion 56 are automatically adjusted so that the expansion portion 54 becomes a node of the torsional vibration and the end of the front end portion 56 becomes an antinode of the torsional vibration. Therefore, when the wavelength of the torsional vibration is set to λb, L3≒λb/4×(2n+1). Furthermore, as shown in the upper part of FIG. 3 , in this example, the respective wavelengths λa and λb are set so that the antinodes of the longitudinal vibration and the torsional vibration are located at the base end surface 50a and the front end surface 50b of the ultrasonic composite vibration device 50.

Next, the setting of the axial dimension W of the expansion part 54 and the driving frequency F1 of the vibrator 58 is described. When the axial dimension L1 of the vibrator 58, the axial dimension L2 of the intermediate part 60, and the axial dimension Lall of the ultrasonic composite vibration device 50 are set to be constant, by changing the axial dimension W of the expansion part 54, the natural vibration frequency of the ultrasonic composite vibration device 50 changes, and the resonance frequency Fa of the longitudinal vibration and the resonance frequency Fb of the torsional vibration change. FIG4 is a graph showing the correlation between the axial dimension W of the expansion part 54 and the resonance frequency Fa and the resonance frequency Fb. In Fig. 4 , the horizontal axis represents the axial dimension W of the expansion portion 54, and the vertical axis represents the resonance frequency. In Fig. 4 , the solid line represents the resonance frequency Fa of the longitudinal vibration, and the one-dot link represents the resonance frequency Fb of the torsional vibration.

In the example of FIG4 , the resonance frequency Fa of the longitudinal vibration decreases in proportion to the increase in the axial dimension W. On the other hand, the resonance frequency Fb of the torsional vibration increases in proportion to the increase in the axial dimension W. Furthermore, when the axial dimension W is a predetermined value W1, the resonance frequency Fa of the longitudinal vibration and the resonance frequency Fb of the torsional vibration are consistent, that is, Fa=Fb=F1.

In this example, the axial dimension W of the expansion portion 54 is set to the axial dimension W1 when Fa=Fb=F1. That is, W=W1. In addition, the frequency of the AC voltage applied to the vibrator 58 when driving the ultrasonic composite vibration device 50, that is, the driving frequency, is set to F1. Thereby, the resonance of the longitudinal vibration and the torsional vibration can be generated at a single frequency F1, and the driving control of the ultrasonic composite vibration device 50 can be simplified.

4 shows an example in which the resonance frequency Fa and the resonance frequency Fb are proportional to the axial dimension W, but the correlation between the resonance frequency Fa and the resonance frequency Fb and the axial dimension W is appropriately different depending on the shape or material of the ultrasonic composite vibration device 50, the characteristics of the vibrator 58, etc. Therefore, the axial dimension W and the driving frequency F1 are determined by experiments or simulations at the design stage of the ultrasonic composite vibration device 50.

In addition, in this example, the front end of the ultrasonic composite vibration device 50 is used as the antinode of the longitudinal vibration and the torsional vibration, so that large longitudinal vibration and torsional vibration can be obtained at the front end of the ultrasonic composite vibration device 50, that is, the mounting portion of the welding needle 18. As a result, the welding needle 18 can be ultrasonically vibrated in a planar manner, and the processing efficiency of wire bonding can be improved.

Furthermore, in the description so far, the driving frequency F1 is determined to be Fa=Fb=F1 by changing the values of W and L3=Wall-L1-L2-W. However, the resonance frequency Fa and the resonance frequency Fb change not only according to the axial size W of the expansion portion 54, but also according to the axial position of the expansion portion 54. Therefore, in order to determine the driving frequency F1, the axial position of the expansion portion 54 may be changed.

For example, consider the following case: let the distance from the base end surface 50a of the ultrasonic composite vibration device 50 to the front end side surface of the expansion portion 54 be Py, and keep the axial dimension L1 of the vibrator 58, the axial dimension Lall of the ultrasonic composite vibration device 50, and the axial dimension W of the expansion portion 54 constant. In this case, the axial dimension L2 of the intermediate portion 60 is L2=Py-W-L1, and the axial dimension L3 of the front end portion 56 is L3=Lall-Py. That is, the axial dimensions L2 and L3 of the intermediate portion 60 and the front end portion 56 change according to the axial position Py of the expansion portion 54. Furthermore, by changing these dimensions L2 and L3, the natural vibration frequency of the ultrasonic composite vibration device 50 changes, and the resonance frequency Fa and the resonance frequency Fb change. Therefore, when designing the ultrasonic composite vibration device 50, the axial position Py of the expansion portion 54 can be changed instead of the axial dimension W of the expansion portion 54 to determine the appropriate position of the expansion portion 54 and the driving frequency F1. Furthermore, in this case, the value of the axial dimension W of the expansion portion 54 is not particularly limited, and for example, it can also be set to about 1/4 times the wavelength λb of the torsional vibration. That is, it can also be set to W≒λb/4.

In any case, in this example, only one expansion part 54 is provided in the ultrasonic composite vibration device 50. Therefore, in order to determine the driving frequency F1=Fa=Fb, the number of parameters that change in strain can be suppressed. As a result, the optimal size and driving frequency of the ultrasonic composite vibration device 50 can be easily determined.

In the description so far, the longitudinal vibration generated by the vibrator 58 is directly transmitted to the front end as the longitudinal vibration. However, a vibration conversion portion that converts a part of the longitudinal vibration into a torsional vibration may be provided at the front end portion 56. For example, as shown in FIG5 , an inclined slit 64 that moves in the circumferential direction as well as in the axial direction may be provided on the circumferential surface of the front end portion 56, thereby converting a part of the longitudinal vibration into a torsional vibration. By adopting the above structure, the torsional vibration can be more reliably applied to the end of the front end portion 56, and further applied to the welding needle 18. In addition, the cross-sectional shape of the ultrasonic composite vibration device 50 is not limited to a circle, and may be other shapes, such as a rectangle.

In addition, in the description so far, the ultrasonic composite vibration device 50 is assembled in a wire bonding device, but the ultrasonic composite vibration device 50 disclosed in this specification is not limited to being assembled in a wire bonding device, and can also be assembled in other ultrasonic processing machines, such as ultrasonic welding devices.

10: Manufacturing device 12: Joining head 14: Welding head holder 16: Ultrasonic welding head 18: Welding needle 19: Clamp 20: XY stage 22: Camera 24: Reel 26: Wire 30: Object 32: Controller 50: Ultrasonic composite vibration device 50a: Base end surface of ultrasonic composite vibration device 50 50b: Front end surface of ultrasonic composite vibration device 50 51: Flange 52: Base end portion 54: Enlarged portion 56: Front end portion 58: Vibrator 60: Intermediate portion 64: Slit D1, D2: Diameter F1: Driving frequency (frequency) Fa: Resonance frequency of longitudinal vibration (resonance frequency) Fb: Resonance frequency of torsional vibration (resonance frequency) L1: Axial dimension of vibrator 58 L2: Axial dimension of intermediate section 60 (dimension) L3: Axial dimension of front end section 56 (axial dimension/dimension) Lall: Axial dimension of ultrasonic composite vibration device 50 Py: Axial position of expansion section 54 W: Axial dimension of expansion section 54 (axial dimension) W1: Axial dimension WVa: Solid line WVb: One-point link

FIG1 is a diagram showing the structure of a semiconductor device manufacturing apparatus. FIG2 is a perspective view of an ultrasonic composite vibration device functioning as an ultrasonic welding head. FIG3 is a diagram showing a side view of the ultrasonic composite vibration device and a waveform of vibration. FIG4 is a graph showing the correlation between the axial dimension of the expansion portion and the resonance frequency. FIG5 is a perspective view of another ultrasonic composite vibration device.

10: Manufacturing equipment

12:Joint head

14: Welding head bracket

16: Ultrasonic welding head

18: Soldering needle

19: Clamp

20: XY stage

22: Camera

24: Reel

26: Conductor wire

30: Object

32: Controller

50: Ultrasonic composite vibration device

Claims (4)

An ultrasonic composite vibration device is characterized in that it has a base end portion of a vibrator that generates longitudinal vibration and torsional vibration, an expansion portion having a larger cross-sectional area than the base end portion, and a front end portion having a smaller cross-sectional area than the expansion portion are arranged in a straight line from the base end side to the front end side, the node of the torsional vibration is located in the expansion portion, the antinode of the longitudinal vibration and the antinode of the torsional vibration are located at the base end surface and the front end surface of the ultrasonic composite vibration device, the axial position and axial size of the expansion portion are set to a position and size where the resonance frequency of the longitudinal vibration is approximately the same as the resonance frequency of the torsional vibration. The ultrasonic composite vibration device as described in claim 1, wherein the axial dimension from the end surface of the front end side of the expansion portion to the end surface of the front end side of the front end portion is an odd multiple of 1/4 wavelength of the torsional vibration. An ultrasonic composite vibration device as described in claim 1 or claim 2, wherein a slit is formed at the front end portion that is inclined and moves in the circumferential direction as it moves in the axial direction. A semiconductor device manufacturing device, characterized by comprising: an ultrasonic composite vibration device as described in any one of claim 1 to claim 3, and a soldering needle mounted on the front end for inserting a wire, wherein the vibrator is driven at a driving frequency substantially the same as the resonance frequency of the longitudinal vibration and the resonance frequency of the torsional vibration.