JP2005288351A - Ultrasonic compound vibrator and forming method of ultrasonic compound vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic compound vibrator for an ultrasonic processing machine which is rich in rigidity of a vibrator, has high positioning accuracy of a top end and has low loss. <P>SOLUTION: The ultrasonic compound vibrator in which phase difference between a longitudinal wave and a twisting wave at a driving frequency of a vibrator in close proximity of a longitudinal wave resonance frequency is not zero but is near π/2 and further which is formed so that one end face is a node face of vibration and another end face is an antinode face of vibration, is designed and its optimal structure is determined by simulation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultrasonic composite vibrator used in an ultrasonic processing machine for vibration processing (bonding, cutting, polishing, etc.) of semiconductor integrated circuits, metals, plastics, ceramics, and the like.

Conventionally, Patent Document 1 is known as an ultrasonic composite vibrator.
In the above prior art, as illustrated in FIG. 7, longitudinal and torsional vibrations are realized by making the vibration system have a horn structure (hereinafter referred to as a screw vibration horn) that synthesizes longitudinal vibrations and torsional vibrations.

  However, the screw vibration horn 1 has one wavelength resonance due to longitudinal vibration and 1.5 wavelength resonance due to torsion vibration, and there is no vibration node common to both vibration modes. Accordingly, when the screw vibration horn 1 is supported by the holding body, there is a problem that vibration loss increases when the screw vibration horn 1 is firmly fixed and rigidity is lacking when the screw vibration horn 1 is supported so as to have a low loss.

Further, the screw vibration horn 1 is provided with a horn 2 for applying longitudinal vibration and a horn 3 for applying torsional vibration on the base end side thereof, so that the distal end of the horn 2 is torsionally vibrated. The tip of the horn 3 is driven by bending vibration due to longitudinal vibration. Each of the horn 2 and the horn 3 has a nodal surface for longitudinal vibration, but the nodal surface does not coincide with a nodal surface for torsional vibration or bending vibration.
Therefore, when the horn 2 and the horn 3 are supported, the vibration loss increases when the horn 2 and the horn 3 are firmly fixed.

For this reason, when supporting the composite vibration body constituting the ultrasonic processing machine, a composite vibration body having a small vibration loss at the support portion while being highly rigid support is desired.
JP-A-6-29357

  In forming an ultrasonic composite vibration body that can meet the above requirements, the present invention provides a condition having a common nodal surface and abdominal surface at resonance frequencies close to each other in the longitudinal wave and torsion wave vibration modes constituting the composite vibration. Is obtained in advance, and the composite vibration body is supported on the node surface, so that the composite vibration body for an ultrasonic processing machine has high rigidity but has little vibration loss on the support surface and high tip positioning accuracy. The issue is to provide

  The configuration of the composite vibrator of the present invention made for the purpose of solving the above-described problems is that when installing the frequency adjustment element in the composite vibrator, the longitudinal wave and the frequency wave are adjusted by adjusting the installation position of the frequency adjustment element. In the torsional wave vibration mode, the main feature is that one end face of the composite vibrator is formed as a vibration nodal face and the other end face is a vibration antinode.

  According to the present invention, in the above-described configuration, the frequency adjusting element to be installed in the composite vibrator is formed by a stepped portion that is installed under a constant condition between a quarter wavelength from the abdominal surface to the node surface of the longitudinal wave vibration of the vibrator. Thus, the vibration mode of the longitudinal vibration and torsional vibration of the composite vibrator is completed based on the acoustic transmission line theory in which one end face of the vibrator is a nodal face and the other end face is a ventral face. Is.

  That is, according to the first aspect of the present invention, the phase adjustment between the longitudinal wave and the torsional wave is not zero but π / 2 at the driving frequency of the vibrating body close to the longitudinal wave resonance frequency by installing the frequency adjusting unit in the composite vibrating body. Thus, an ultrasonic composite vibration body in which one end face is a nodal surface and the other end face is an abdominal face at the resonance frequencies of both the longitudinal and torsional vibration modes of the composite vibration body is formed. The invention of claim 2 is a configuration in which an electrostrictive element or a slit for longitudinal / torsional conversion is installed at a middle node of the longitudinal wave vibration of the ultrasonic composite vibrator of claim 1, According to the invention, an ultrasonic composite vibrator in which the electrostrictive element of claim 2 is installed and an ultrasonic composite vibrator in which a slit for longitudinal / torsion conversion is installed in consideration of transmission characteristics are coupled at a common node surface. According to a fourth aspect of the present invention, when the frequency adjusting element is installed in the ultrasonic composite vibrator while adjusting the position thereof, one end face of the composite vibrator becomes a vibration nodal surface. The frequency adjustment element is provided by adjusting so that the other end surface becomes the antinode of vibration.

  When an electric signal is applied to the ultrasonic composite vibrator of the present invention in which an electrostrictive vibrator for longitudinal vibration is installed, the ultrasonic composite vibrator is excited in the longitudinal vibration mode. When this ultrasonic composite vibrator is coupled with an ultrasonic composite vibrator having a longitudinal / torsion conversion slit at a common node, the longitudinal vibration becomes a longitudinal / torsion composite vibration to excite both ultrasonic composite vibrators. .

  Since the combined ultrasonic composite vibrator has a common nodal surface and both ends vibrate as vibration surfaces, the ultrasonic composite having a conversion slit installed by supporting the common nodal surface. Ultrasonic machining can be realized by the combined vibration of the tip of the vibrating body.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory diagram showing the motional admittance in the vicinity of the resonance frequency in the vibration mode of longitudinal vibration and torsional vibration, and the phase characteristics thereof, and FIG. 2 is equipped with a frequency adjusting element according to the present invention, and an electrostrictive vibrator is installed. An example of the ultrasonic composite vibrator of the present invention, and a schematic diagram of the composite vibration mode, FIG. 3 is an ultrasonic composite of the present invention provided with a frequency adjusting element according to the present invention and provided with a slit portion for longitudinal / torsional vibration conversion. FIG. 4 is a schematic diagram of an example of a vibrating body and a composite vibration mode thereof. FIG. 4 is an installation position of the frequency adjusting element (x) using the diameter ratio (M) of the vibrating body and the frequency adjusting element in the composite vibrating body of FIG. FIG. 5 is a frequency characteristic diagram of the frequency adjustment element of FIG. 3 using the diameter ratio (M) of the vibration body and the frequency adjustment element as a parameter, and FIG. Is the ultrasonic composite of FIG. 2 and FIG. Body is a schematic view of another example and its complex vibration modes of the present invention the ultrasonic complex vibration member for an ultrasonic processing machine coupled at a common node plane.

In Figure 1, 11, 12 and 13, 14, motional at the resonance frequency f _l and f _t of both vibration modes, respectively longitudinal vibration and torsional vibration admittance | Ymo | if equal motional admittance | Ym | and phase It is a frequency characteristic of Φ.
Reference numeral 15 denotes a phase difference between the two vibration modes, which is represented by a difference between the phase of the longitudinal vibration mode and the phase of the torsional vibration mode. This phase difference 15 is π / 2 at the drive frequencies f _d1 and f _d2 .
Here, if both resonance frequencies are equal (f ₁ = f _t ), the phase characteristics 13 and 14 of both vibration modes are substantially the same curve, so the phase difference 15 becomes zero and π / 2 Don't be.
The condition for the phase difference 15 to be π / 2 is when both the resonance frequency differences are _{expressed by the} following [Equation 1] with the mechanical sharpness at the time of resonance in both vibration modes as Q _l and Q _t .

In FIG. 1, when the composite vibrator is excited at the drive frequency f _d1 (or f _d2 ), the motional admittance and the phase angle indicating the operating points of the longitudinal and torsional vibration modes are indicated by reference numerals 16, 17 and 18, respectively, in FIG. In the longitudinal vibration and torsional vibration modes, the vibration phase difference is π / 2, and the vibration at the peripheral edge of the vibrating body induces circular vibration. Further, when the vibration phase difference approaches π / 2, the vibration is changed from elliptical vibration to circular vibration.

  In FIG. 2, 2 is an ultrasonic composite vibrator of the present invention schematically shown, and 21, 22, 23, 24, and 25 are components of the ultrasonic composite vibrator 2. Each of the components 21 to 25 is a columnar integrated structure having a common axis, or a combined structure in which a plurality of columnar bodies are fastened by a center bolt (not shown), but the center bolt is ignored in the following description. To do.

The condition that one end (left side in the figure) of the ultrasonic composite vibrator 2 in FIG. 2 is a vibration nodal surface and the other end is a vibration antinode is that the length of the component i is l _i , and the cross-sectional area is S _i , longitudinal wave acoustic impedance is Z _li , torsional wave acoustic impedance is Z _ti , longitudinal wave wavelength constant is β _i , torsion wave wavelength constant is α _i , and polar moment of inertia is I _i. When cos β _i ≠ 0 and cos α _i ≠ 0 with respect to the longitudinal wave and torsion wave vibration modes, they are expressed by the following [Equation 2] and [Equation 3], respectively.

Now, the density of each component 21 to 25 of the composite vibrating body 2 in FIG. 2 is ρ _i , the longitudinal sound velocity is C _li , the torsion wave sound velocity is C _ti , the radius is r _i, and the resonance frequency of the longitudinal and torsion waves. If f ₁ and f _t , each parameter is given by the following equation [Equation 4].

  Table 1 shows necessary data when the components 21 to 25 of the ultrasonic composite vibrator 2 are aluminum alloys and electrostrictive elements (zircon lead titanate (PZT)).

In the ultrasonic composite vibrator 2 of FIG. 2, the component 24 is a longitudinal wave electrostrictive element (PZT), and the component 24 is sandwiched by the component 25 on both sides, and is a bolted Langevin type vibrator with half wavelength resonance. Then, the resonance condition is expressed by the following equation [Formula 5] when cosβ _i l _i ≠ 0 .

When f = 40 (kHz), S ₄ = S ₅ , and l ₄ = 10 (mm) in the above equation [Formula 5], l ₅ = 24.82 (mm) is obtained.

2, the components 21 to 23 and 25 other than the electrostrictive element 24 are made of an aluminum alloy of the same material, the thickness of the frequency adjusting column 22 is 8 (mm), and the abdomen in the longitudinal vibration mode. When the distance from is set to x and the condition of the following equation [Equation 6] and the data of Table 1 are substituted into the above equation [Equation 2] to obtain the distance from the vibration node surface to the abdominal surface, the distance Is 40.27 (mm), so l ₁ = 40.27 + x.

When the cross-sectional area of the frequency adjusting element 22 is M ² S (M is a diameter ratio) and M is a parameter, the correlation between x and f is expressed by the above l ₁ and the equations [Equation 2], [Equation 3] and When obtained from [Equation 6], the frequency characteristic of FIG. 4 is obtained.

In FIG. 4, 41, 42, and 43 are longitudinal vibration characteristics when the aforementioned diameter ratio M is M = 1.1, 1.2, and 1.3, and 44, 45, and 46 are the diameter ratio M is M = Torsional vibration characteristics when 1.1, 1.2, and 1.3.
From the characteristics shown in FIG. 4, when x is lengthened, the resonance frequency of longitudinal vibration increases, and after the resonance frequency of torsional vibration decreases, it increases gently.

  Both vibration characteristic curves are shown in FIG. 4 at point 47 (x = 4.8) when the diameter ratio M = 1.1, at point 48 (x = 3.2) in FIG. 4 when M = 1.2, and when M = 1.3. They intersect at point 49 (x = 2.8) in FIG. Therefore, when the frequency adjusting element 22 shown in FIGS. 2 and 3 is installed at any one of the above-mentioned intersections 47, 48, and 49 corresponding to the diameter ratio M, both vibration modes have the same frequency and one end. Is the nodal surface and the other end is the abdominal surface.

Since the longitudinal vibration mode and the torsional vibration mode in this case are the same resonance frequency, if the drive frequency is set to both resonance frequencies (f _d = f _l = _ft ), the peripheral edge of the tip of the composite vibrator 2 is linear vibration. Become.

  The resonance frequencies of the longitudinal vibration mode and the torsional vibration mode are set in the vicinity of the same resonance frequency in FIG. 4 (points 47, 48, and 49 in FIG. 4), and the difference between both resonance frequencies is made equal to ΔF in the above-described equation [Equation 1]. The vibration modes of the longitudinal vibration and the torsional vibration when selected in FIG. In FIG. 2, N represents a vibration node and L represents a vibration abdominal surface.

In FIG. 3, 3 is an example of the ultrasonic composite vibrator of the present invention provided with slits for longitudinal / torsional vibration conversion, and 31, 32, 33, 34 and 35 are constituent elements of the ultrasonic composite vibrator 3. is there.
In FIG. 3, each of the components 31 to 35 has a columnar integrated structure having a common axis. If the component 34 is a slit for vibration conversion, and the component 34 is a half-wave resonance aluminum alloy horn having both sides sandwiched between the components 33 and 35, the above-described equation [Equation 5], From Table 1, f = 40 kHz, S ₄ = n ² S ₅ (n ² is an equivalent cross-sectional area ratio by slit, and n ² = (r ₄ −t) ² / r ₅ ² in the case of a slit of depth t. And l ₄ = 7 (mm), l ₅ = 25.16 (mm) is obtained.

In FIG. 3, the components 31 to 35 are all made of an aluminum alloy of the same material, the thickness of the frequency adjusting column 32 is 7 (mm), the distance from the abdomen in the longitudinal vibration mode is x, and the above equation [several 7] and the data in Table 1 are substituted into the previous equation [Equation 2], and the distance from the vibration node surface to the abdominal surface is 31.25 (mm), and l ₁ = 31.25 + x Is obtained.

The cross-sectional area of the frequency adjusting element 32 is M ² S (M is a diameter ratio), and the correlation between x and f when M is a parameter is the above-mentioned l ₁ , and the equations [Equation 2], [Equation 3] and [Equation 3] From the equation (7), the frequency characteristic of FIG. 5 is obtained.

In FIG. 5, 51, 52, and 53 are longitudinal vibration characteristics when the diameter ratio M = 1.1, 1.2, and 1.3, and 54, 55, and 56 are those when the diameter ratio M = 1.1, 1.2, and 1.3. Each torsional vibration characteristic.
From the characteristics shown in FIG. 5, when x is lengthened, the resonance frequency of longitudinal vibration increases and the resonance frequency of torsional vibration decreases rapidly.

Both vibration characteristic curves have no intersection when M = 1.1, intersect at point 57 (x = 13.2) when M = 1.2, and at point 58 (x = 11.4) when M = 1.3. When the frequency adjustment element 32 is installed at the position of the above-mentioned intersection corresponding to M, both vibration modes have the same resonance frequency. Therefore, when the drive frequency is both resonance frequencies (f _d = f ₁ = _ft ), the composite vibration body The peripheral edge of the tip 3 is linearly oscillated.

When the resonance frequency of the vibration mode of longitudinal vibration and torsional vibration is selected so that the difference between both resonance frequencies in the vicinity of the same resonance frequency (57, 58) in FIG. The vibration modes of vibration and torsional vibration are shown as waveforms 36 and 37 in FIG. 3, respectively. In FIG. 3, N represents a vibration nodal surface and L represents a vibration abdominal surface.
2 and 3, the electrostrictive element 24 and the longitudinal / torsional conversion unit 34 are installed at the vibration node and have the maximum distortion force, so that the vibration efficiency of the electrostrictive element is maximized. In addition, the vertical / torsion conversion efficiency of the vertical / torsion conversion unit is maximized.

As another example of the ultrasonic composite vibrator of the present invention, FIG. 6 shows an ultrasonic composite vibration for an ultrasonic machine having a structure in which the joints N of the vibrators 2 and 3 of FIGS. Shows the body and its vibration modes.
In FIG. 6, from the frequency characteristics of FIGS. 4 and 5, assuming that M = 1.2, when the resonance frequency difference is selected to be equal to ΔF in the vicinity of the intersection 48 in FIG. 4 and the intersection 57 in FIG. The average resonance frequency of both vibration modes is about 39.9 kHz. In this case, the driving frequency f _d of the composite vibration body is expressed by [Equation 8] from FIG. 1 and Equation [Equation 1].

From the formula [Equation 8], when the mechanical sharpness Q _l and Q _t at the time of resonance in the longitudinal and torsional vibration modes are almost equal, if the drive frequency is selected to be the average resonance frequency of 39.9 KHz, both vibration modes The phase difference is π / 2, and the peripheral edge of the tip of the composite vibrator is elliptically oscillated.

Note that there is an effect of expanding (reducing) the amplitude at the common nodal plane N, and in the longitudinal vibration mode corresponding to the diameter ratio r (r = r ₂₁ / r ₃₁ ) of the components 21 and 31 of the ultrasonic composite vibrator. The amplitude of the tip is proportional to the square of r, and the amplitude of the outer periphery of the tip in the torsional vibration mode is proportional to the cube of r.

  Moreover, in the said Example, although the frequency adjustment element 22 or 32 was made into the convex (M> 1) step, the same effect can be anticipated even if it is a concave (M <1) step.

  Furthermore, in the above-described embodiment, the component of the composite vibrating body 3 has a structure with a diametrically oscillating disk, so that the disk is excited by a combined vibration of longitudinal and radial vibrations and torsional vibrations. An elliptical vibration mode can be induced on the outer periphery of the disc.

  On the other hand, in the said Example, although each component 21, 22, 23, 24, 25 of the composite vibrating bodies 2 and 3 and the component 31, 32, 33, 34, 35 similarly made a column shape, it demonstrated. Each component does not necessarily have a cylindrical shape. For example, an exponential type in which a change in the cross-sectional area in the length direction including its axis is represented by an exponential function, or a conical type by a cone function. By applying the design formulas corresponding to the above cross-sectional area changes to the catenoidal type represented by the hyperbola, the Fourier type represented by the Fourier series, etc., the same applies. The effect can be expected.

  Further, in the above-described embodiment, the component of the composite vibrating body 3 has a structure with a bending vibration rod, so that the vibration rod is excited by a combined vibration of longitudinal and bending direction vibrations and torsional vibrations. An elliptical vibration mode can be induced at the tip.

  Further, in the above-described embodiment, the component of the composite vibrating body 3 has a structure with a bending vibration disk so that the disk is excited by a combined vibration of longitudinal / bending vibration and torsional vibration. An elliptical vibration mode can be induced on the outer periphery.

    The present invention is as described above, and by forming an ultrasonic composite vibration body having a frequency adjusting element according to the present invention, it is possible to simulate both longitudinal and torsional vibration modes. A composite vibrator can be realized.

  Further, in the composite vibrator of the present invention in which a plurality of vibrators are coupled, by supporting the common nodal surface, it is possible to realize a support with rich rigidity of the vibrator, a high tip positioning system, and highly efficient ultrasonic machining. The composite vibrator for use can be obtained.

Explanatory drawing of this invention which shows the motional admittance and phase characteristic of an ultrasonic composite vibrator The schematic diagram of the ultrasonic composite vibrator which applied the present invention and installed the electrostrictive vibrator, and its vibration mode. The schematic diagram of the ultrasonic compound vibrator which applied the present invention and installed the slit for length and torsion conversion, and its vibration mode. The frequency characteristic figure of the setting position of the frequency adjustment element in the case of FIG. The frequency characteristic figure of the setting position of the frequency adjustment element in the case of FIG. FIG. 4 is a schematic diagram of an ultrasonic composite vibrator for an ultrasonic processing machine having the vibrator shown in FIGS. 2 and 3 as a common node and its vibration mode. Explanatory drawing of the example of the conventional composite vibrating body.

Explanation of symbols

11, 12 Motional admittance characteristics of longitudinal / torsional vibration modes 13, 14 Phase characteristics of longitudinal / torsional vibration modes 15 Phase differences of longitudinal / torsional vibration modes 2, 3 Ultrasonic composite vibrators 22, 32 Frequency adjustment element 24 Electrostriction Vibration element 34 Longitudinal / torsional conversion slit 26, 36 Longitudinal vibration mode 27, 37 Torsional vibration mode 41-43 Frequency characteristic of longitudinal vibration mode 16 44-46 Frequency characteristic of torsional vibration mode 17 47-49 Longitudinal / torsional vibration mode Frequency matching points 51 to 53 Frequency characteristics of longitudinal vibration mode 26 54 to 56 Frequency characteristics of torsional vibration mode 27 57, 58 Frequency matching points of longitudinal and torsional vibration modes

Claims (4)

  In the ultrasonic composite vibrator that vibrates in the longitudinal wave and torsion wave modes, a stepped portion is installed as a frequency adjusting element in the section from the abdominal surface 1/4 wavelength to the nodal surface 1/2 wavelength of the longitudinal vibration of the vibrator. Sometimes, by adjusting the installation position of the stepped portion, the phase difference between the longitudinal wave and the torsional wave at the driving frequency of the vibrator close to the longitudinal wave resonance frequency is not zero but close to π / 2, and the longitudinal wave and An ultrasonic composite vibrator characterized in that one end face of each torsion wave at a resonance frequency is a vibration nodal face and the other end face is a vibration antinode.   The ultrasonic composite vibrator according to claim 1, wherein a longitudinal wave electroacoustic transducer or a longitudinal / torsional conversion slit is provided at a longitudinal wave mode node of the ultrasonic composite vibrator.   Whether the ultrasonic composite vibrator having the electroacoustic transducer for longitudinal waves and the ultrasonic composite vibrator having slits for converting longitudinal / torsional vibrations are coupled to each other with the same axis. 3. The ultrasonic composite vibrator according to claim 1 or 2, wherein both composite vibrators are integrally formed to form a longitudinal mode mode joint face in common. When installing a frequency adjustment element on an ultrasonic composite vibrator, make sure that one end face of this composite vibrator becomes a vibration node and the other end face becomes a vibration antinode in both longitudinal and torsional vibration modes. And adjusting the installation position of the frequency adjusting element.

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