JP2008212916A - Ultrasonic composite vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily provide a low-frequency to high-frequency ultrasonic composite horizontal vibration device having no vibration component perpendicular to a vibration surface of a two-dimensional vibration locus as a composite vibrator for various kinds of powerful ultrasonic applications. thing.
SOLUTION: A circular vibrating body 2 in which a thickness of a surface perpendicular to a longitudinal vibration direction is obliquely changed between a vibrating rod 1 and 1 'driven by a longitudinal vibration source, or a circle cut obliquely. Insert a pair of discs that combine plates 2 and 7 to excite the bending vibration 6 by creating a phase difference and a vibration velocity difference of the longitudinal vibration wave in the direction of thickness change of the ring of the longitudinal vibration rod by annulus having different sound speeds. Furthermore, the resonance frequencies of the longitudinal vibration 5 and the bending vibration 6 are brought close to each other so that the vibration phase difference is approximately 90 °, and the longitudinal vibration 5 ′ and the bending vibration 6 ′ are combined on the free end face 4 of the vibration rod to thereby form the ellipse. An ultrasonic composite horizontal vibration device having a small vibration component perpendicular to the vibration surface having a circular two-dimensional vibration locus is configured. In addition, an ultrasonic rotating device or the like can be configured by combining a plurality of disk pair converters at different angles.
[Selection] Figure 1

Description

  The present invention relates to an ultrasonic composite vibration device used for an ultrasonic processing machine, a moving device, or the like that vibrates metal (plastics, ceramics, electronic parts, etc.) (bonding, cutting, polishing, plastic processing, etc.). In particular, for flip chip welding of a semiconductor chip having a large number of bumps that require uniform welding over a large area, a composite horizontal vibration device having a small component perpendicular to the vibration surface is desired.

2. Description of the Related Art Conventionally, an ultrasonic composite vibration device described in JP-A-11-87437 is known.
The prior art excites a composite bending vibrator with two orthogonal drive longitudinal vibrators.

    However, in the prior art, the vibration system becomes complicated due to the excitation of the bending vibration bar by two drive longitudinal vibrators, and the combined vibration of the end face of the bending vibration bar is a vertical vibration component around the vibration surface with a large vibration amplitude. Flip chip welding of a large area conductor chip with a large number of bumps cannot be ignored, but the composite vibration requires a smaller vibration amplitude and required static pressure than conventional linear vibration, but a large area uniform welding However, the application range was limited. In addition, it is difficult to process and configure a high-frequency composite vibration system effective for welding.

  For this reason, the vibration component perpendicular to the vibration surface is small for ultrasonic processing such as uniform welding of large area semiconductors, spot bonding of large area metal plates, seam welding, plastic bonding, and metal plastic processing. An ultrasonic composite horizontal vibration device has been desired.

  An object of the present invention is to provide an ultrasonic composite vibration device having an easy structure by simultaneously driving longitudinal vibrations and bending vibrations of a vibration body having a low vibration loss with a vibration transducer using a vibration transducer. It is to provide.

  In order to solve this problem, the present invention provides a thin circular plate or the like (hereinafter referred to as a circular plate) in which the thickness in the plane direction perpendicular to the vertical vibrations having different sound speeds is changed between the circular vibrating bodies driven by the longitudinal vibration source. The longitudinal vibration wave that passes through the disc by inserting and vibrating it is a spatial phase difference / vibration velocity depending on the disc thickness due to the difference in sound velocity between the vibrating body and the obliquely cut disc with different sound velocity. It was made by finding that a bending vibration is excited only in the thickness direction of the disc by making a difference.

  According to the first aspect of the present invention, a circular plate having a thickness in the plane direction perpendicular to a vibrating body and a longitudinal vibration having a different sound velocity is inserted between the vibrating bodies driven by the longitudinal vibration source to cause longitudinal vibration. The longitudinal vibration wave that passes through the plate causes a spatial phase difference / vibration speed difference depending on the disc thickness due to the difference in sound velocity between the vibrating body and the obliquely cut disc with different sound velocity, and vibrates in the thickness direction of the disc. This is an ultrasonic composite vibration device in which a driving force perpendicular to the body is generated and bending vibration is excited only in the thickness changing direction.

  According to a second aspect of the present invention, in the first aspect of the present invention, the two discs having different sound speeds with different thicknesses are combined with the diagonally cut surfaces facing each other, and the end surfaces are parallel to each other or screwed to the center. A short cylinder or short cylinder (hereinafter referred to as an annular pair) with a through hole for use, which is easily inserted between the vibrators and stabilized by joining or integrating them with powder metallurgy. Can be driven.

  According to a third aspect of the present invention, in the first aspect of the invention, the bending of the resonant frequency excited at the end face of the vibrating body is close to the longitudinal vibration by using an annular pair whose end faces having different sound speeds having different thicknesses are parallel. By combining the vibrations, an elliptical to circular vibration locus is generated on the side surface of the vibration body tip, and an ultrasonic composite horizontal vibration having no vibration component perpendicular to the vibration surface is generated in a plane parallel to the bending vibration direction.

  According to a fourth aspect of the present invention, in addition to the first aspect of the present invention, two or a plurality of pairs of circular rings in which the end surfaces with different sound speeds with different thicknesses are parallel are installed with the bending excitation direction changed. The bending vibration excited by the resonance frequency close to the longitudinal vibration on the vibration body end face is combined to generate a circular vibration locus from the ellipse to the side surface of the vibration body. And an ultrasonic rotating device or the like.

  One or two discs with different sound speeds that are obliquely cut in the plane direction perpendicular to the vertical vibrations with different vibration speeds between the vibrators and driven by a longitudinal vibration source using piezoelectric ceramics, etc. The longitudinal vibration wave that passes through the disk part by inserting and moving the disk causes a spatial phase difference / vibration speed difference due to the difference in sound speed between the vibrating body and the obliquely cut disk with different sound speeds. A driving force perpendicular to the vibrating body is generated in the thickness direction, bending vibration is excited only in the thickness changing direction, and the resonance frequency of the bending vibration is brought close to the longitudinal vibration frequency driven by changing the vibrating body thickness, A vibration locus close to a circle can be obtained by setting both frequency differences so that the phase difference is approximately 90 ° and combining longitudinal vibration and bending vibration. Since bending vibration is not driven in the direction perpendicular to the thickness change direction of the disk, vibration perpendicular to the composite vibration surface is not excited.

  Two pairs of circular rings with parallel end faces with different sound velocities are installed by screw fastening, etc., with the direction of exciting the bending vibration being 90 °, and the bending vibration excited at the resonance frequency close to the longitudinal vibration is coupled on the vibration body end face. A circular vibration locus from an ellipse is generated on the side surface of the front end of the vibrating body, and a plurality of bending vibrations having frequencies close to each other are excited in the peripheral direction of the vibrating body to excite ultrasonic rotational vibration.

  Therefore, by installing a tool / slider etc. for ultrasonic composite horizontal vibration processing or rotational vibration processing according to the purpose at the tip of this vibration round bar, or by installing a tool etc. directly through a transducer, It is possible to provide an ultrasonic composite vibration processing machine / moving device.

  1 is a conceptual diagram showing the principle of an ultrasonic composite vibration device of the present invention, a cross section of a vibration bar, a longitudinal-bending vibration conversion ring pair, FIG. 2 is an external view showing an example of the configuration of a vibration system, and FIG. FIG. 6 is an actual measurement diagram showing a bending vibration excitation direction along and a bending vibration distribution in an orthogonal direction. FIG. 4 shows an ultrasonic rotating device using two pairs of longitudinal-bending vibration conversion ring pairs. FIG. 5 shows an example of a vibration locus in which longitudinal vibration and bending vibration are combined, and an example of a vibration locus in which orthogonal bending vibrations are combined. FIG. 6 shows an electrical terminal of the entire ultrasonic rotating apparatus in which longitudinal vibration and two bending vibrations are combined. An example of vibration characteristics and free admittance loop measured from the side is shown.

The longitudinal vibration velocity u _z of the incident wave and the reflected wave of the longitudinal wave in the z-axis direction in the uniform medium vibrating rod is obtained from the general solution of the wave equation: u _z = kA cos (ωt−kz) + kA cos (ωt + kz) k = c / ω
= (D / ω) [A cos (ωt− (c / ω) z) + A cos (ωt + kz)]
ω = 2πf angular frequency f frequency t time k = c / ω wavelength constant c sound speed z position where kz is a spatial phase.

In FIG. 1, the longitudinal vibration wave in the vibration rod driven by the longitudinal vibration source is incident on the obliquely cut portion (2) having a different sound velocity, and the phase difference of the longitudinal vibration wave propagating through the distance ΔL is k. The phase change of the longitudinal vibration propagating through the distance ΔL through the transducer cut at an angle of ₁ × ΔL, which is inserted at the lower part of the vibrating rod and is obliquely different, is k ₂ × ΔL. The maximum phase difference of the longitudinal vibration wave propagating through the upper and lower parts of the vibrating bar is obtained from the above equation: Δθ = (k ₁ −k ₂ ) × ΔL = (c ₁ −c ₂ ) ΔL / ω = Δc × ΔL / ω (c ₁ −c ₂ ) = ± Δc
Thus, ± Δc × ΔL / 2ω is obtained in the vertical direction from the center of the vibrating rod.
Since the phase difference of the vibration displacement amplitude is also the same, similarly, the displacement changes ± Δξ ₁ up and down from the center of the vibration bar due to the phase difference.

A value F = ηEΔξ _l obtained by multiplying the displacement by the Young's modulus E of the material and the distance from the center and integrated over the entire cross-sectional area is an alternating driving force of bending vibration. η varies depending on the cross-sectional shape.
If it is considered that the Young's modulus E is large and there is no change in the bending vibration direction, the surface displacement of the node portion of the bending vibration is considered to be approximately ± Δξ _t, and the bending vibration of the displacement corresponding to this is excited.

Since the longitudinal vibration resonance frequency f ₀ of the entire vibrating rod is considered to be the resonance frequency of the center portion, the round-trip propagation time t _{c in} the z direction of the center portion is the portion other than the diagonally cut transducer, the distance L−ΔL / 2 section. Since it is the sum of the average sound velocity C ₁ and the sound velocity c ₂ = c ₁ ± Δc of the converter partial distance ΔL / 2, it is assumed that the longitudinal vibration is resonated by one wavelength, and f ₀ = 1 / t _c = 1 / [2 (L−ΔL / 2) / c ₁ + (2 × ΔL / 2) / c ₂ ]
= C ₁ / [2L + (c ₁ / c ₂ −1) ΔL]
Thus, longitudinal vibration and bending vibration are driven in the vicinity of this frequency.

If the vibration phase difference is 90 ° in order to obtain a circular vibration locus from an ellipse at the end of the vibration bar, the resonance sharpness of the longitudinal vibration f ₁ and the bending vibration f ₁ Quality factorQ = f ₀ / (f _{1 to} f _t ) = If f ₀ / Δf is substantially equal, the frequency difference may be adjusted to about Δf = f ₀ / Q. Usually, the value of Q is very large from 500 to 2000 or more.

  The longitudinal vibration resonance frequency is substantially constant depending on the length of the vibration bar, and the bending vibration resonance frequency changes according to the vibration bar cross-sectional shape 4 in FIG. 1 (2). Adjustable by changing the radius R of a part or the whole, changing the thickness as a rectangle, or making the whole or a part of the vibration rod cylindrical (processing a hole with an appropriate depth at the center of the end). is there.

  Fig. 1 (3) shows that the transducer part can be easily installed in the vibration system, so that two circular rings 2 and 7 with different acoustic velocities are combined with their diagonally cut surfaces facing each other, and fixed with a through screw at the center. An annular pair for longitudinal vibration-bending vibration conversion that is easy to install between short cylindrical vibrating bodies with paralleled both end faces joined to a vibration system provided with a hole for use.

  Fig. 2 shows a toroidal transducer with a thickness of 6.0 mm (material: brass and iron, sound speed of 3480 m / s) by a longitudinal vibration drive source using a prototype piezoelectric ceramic (PZT) and a stepped horn (speed transformation ratio 4). And 5120 m / s) is a configuration diagram of a 150 kHz composite vibration device that drives a stainless steel round bar.

  FIG. 3 shows the y-direction and x-direction vibration distributions measured with a laser Doppler vibrometer along the length of the composite vibration bar of the prototype 150 kHz composite vibration device. It can be seen that the ring-pair transducer causes bending vibration in the y direction and no bending vibration in the x direction.

  Fig. 4 shows a stainless steel round bar with a longitudinal vibration drive source using a 15 mm diameter piezoelectric ceramic (PZT) and two pairs of annular transducers (thickness: 14.8 mm, material: brass and iron). It is a block diagram of the ultrasonic rotating apparatus of about 70 kHz to drive.

  FIG. 5 (1) is an actual measurement diagram using two laser Doppler vibrometers of an elliptical vibration locus parallel to the z-axis and perpendicular to the free end face of the vibration rod end face combined with longitudinal vibration and bending vibration of close frequencies. It is.

  FIG. 5 (2) is an actual measurement diagram using two laser Doppler vibrometers of an elliptical vibration locus around the z-axis at the free end where two adjacent bending vibrations of two frequencies are combined.

  FIG. 6 is a measurement result of a free admittance loop in which the vibration characteristics of the entire ultrasonic rotating apparatus in which the longitudinal vibration and the two bending vibrations having sufficiently close resonance frequencies are excited and coupled are measured by changing the driving frequency from the electric terminal side. Thus, since the frequencies are close to each other, it is shown that the single loop operates well regardless of the presence or absence of the rotor.

  The ring pair for vibration conversion may be installed in any part of the longitudinal vibration system, but if it is installed in the vicinity of the position of the vibration loop, the vibration stress becomes small and the vibration pair is installed more stably.

  The sound velocity of the ring pair may be larger or smaller than that of the vibrating body, but a combined vibration transducer with high strength can be obtained by combining it with steel, stainless steel, etc. that can be joined to high-strength, high-strength cemented carbide. It is done.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and there are design changes within a scope not departing from the gist of the present invention. Are also included in the present invention. For example, it is possible to obtain a larger vibration amplitude by changing the cross-sectional shape of the vibrating body to increase the vibration speed (stepped vibrating body, catenoidal horn, etc.).

  If a metal ring or a pair of metal rings that are cut obliquely at different sound speeds is installed at a plurality of positions, the conversion effect can be enhanced.

  When two sets of metal ring pairs are installed and used at different angles, a common material can be placed adjacent to each other and integrally processed at an arbitrary angle to reduce the joint surface. Of course, it is also possible to install an integrally processed ring directly on the vibrating body.

  A similar effect can be obtained by obliquely cutting a piezoelectric ceramic that converts an electrical signal into mechanical vibration and changing the vibration phase difference and the driving force. Of course, the same effect can be obtained even if the piezoelectric ceramic is subjected to gradient polarization in the diameter direction.

  As described above, according to the present invention, it is possible to obtain an ultrasonic composite horizontal vibration device and a rotary vibration device in which the configuration of the vibrating body rich in rigidity is easy.

  FIG. 1 is a conceptual diagram showing the principle of a composite vibration system using thin plates with different sound speeds cut obliquely in the thickness direction of the present invention, and a composite that performs longitudinal-bending vibration conversion by superposing two metal rings with different sound speeds. It is a figure of a vibration converter (metal ring pair).   FIG. 2 is an external view of a prototype of an apparatus for driving the composite vibration transducer of the present invention in a longitudinal vibration system to obtain composite horizontal vibration at the tip of the composite vibration rod.   FIG. 3 is an example of an actual measurement diagram of the bending vibration distribution in the y-axis direction and the vibration distribution in the x-axis direction along the composite vibration bar of the ultrasonic composite vibration device of the present invention.   The block diagram which prototyped the ultrasonic rotating apparatus which installed 2 sets of ring pairs from which the speed of sound of this invention differs by changing a 90 degree angle.   (1) Elliptical vibration trajectory when combining longitudinal vibration and bending vibration at the tip of the composite vibration bar, (2) Example of substantially circular vibration trajectory when combining bending vibration in the x-axis direction and y-axis direction.   Example of actual measurement of vibration characteristics (free admittance loop) of an ultrasonic rotating device that uses two pairs of rings to combine longitudinal vibration, bending vibration and bending vibration in the x and y directions

Explanation of symbols

1, 1 ', 7 Vibrating body 2 Vibrating body 3, 3' Vibration phase difference, vibration displacement distribution 4 Vibration body cross-sectional shape 5, 6 Longitudinal and bending vibration distributions 5 ', 6' Longitudinal vibration of the end face of the vibrating body, Bending vibration 8 Center through-holes 9 and 9 ′ for screw fastening Parallel plane Δc of a short cylindrical transducer combined with an obliquely cut ring A sound velocity difference Δξ _{l A} longitudinal vibration vibration displacement difference Δξ _{t A} bending vibration node Surface vibration displacement

Claims (4)

  The phase difference of the longitudinal vibration wave is perpendicular to the axis of the longitudinal vibration system by using a ring or the like made of a metal material with different sound speeds that is inserted in the middle of the longitudinal vibration system and whose thickness in the vertical direction is obliquely cut. An ultrasonic composite vibration device driven by a longitudinal vibration system using a longitudinal-bending vibration transducer that generates bending vibrations in a direction.   An ultrasonic composite vibration transducer comprising a pair of rings formed by combining two kinds of rings made of materials having different sound speeds, wherein the longitudinal vibration and the thickness in the vertical direction are obliquely cut.   An ultrasonic composite horizontal vibration device having a vibration component perpendicular to an ellipse-to-circular vibration surface in which a composite vibration converter composed of a pair of rings is inserted and longitudinal vibration and bending vibration frequencies are brought close to each other.   Inserting and fixing multiple sets of composite vibration transducers with slightly different cutting angles consisting of the above-mentioned ring pairs and close bending vibration resonance frequencies to the vertical vibration system by changing the installation angle, it is almost uniform around the longitudinal vibration axis. An ultrasonic compound rotary vibration device that excites bending vibrations and generates a circular vibration locus from an ellipse in a plane parallel to the axial direction in combination with longitudinal vibrations having a frequency close to those bending vibrations.

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