JP3784391B2 - Ultrasonic processing vibrator and processing apparatus - Google Patents

Description

  The present invention relates to an ultrasonic processing vibrator and a processing apparatus applicable to ultrasonic processing and the like.

  Conventionally, ultrasonic bonding using an ultrasonic transducer has been widely used for wire bonding of integrated circuits because of its high work efficiency and bonding at low temperatures. In addition, ultrasonic processing that performs polishing such as drilling, cutting, and surface finishing of a workpiece using an ultrasonic vibrator is also widely performed.

For example, as shown in FIG. 3, this type of ultrasonic transducer such as ultrasonic bonding has a configuration in which a transducer 12 having an electrostrictive or magnetostrictive shape such as a piezoelectric body is vertically driven by a signal from an ultrasonic oscillator 11. Vibration is generated, and this vibration passes through the horn 13 and is transmitted to the bonding head 14, causing the head 14 to laterally vibrate. The head 14 acts as a point of action, and friction caused by vibration against the workpiece contacting the head 14. Welding by heat or processing by vibration is performed (for example, see Patent Documents 1 to 5).
JP-A-8-198777 CD-ROM of actual application No. 4-81294 (Japanese Utility Model Application No. 6-39392) Microfilm of Japanese Utility Model No. 60-129111 (Japanese Utility Model Application No. 62-39870) Japanese Patent Publication No.54-23349 JP-A-9-122934

  However, in the ultrasonic vibrator as shown in FIG. 3, the horn 13 is for increasing the amplitude of the vibration excited by the vibrator 12, but its shape is intended to increase the vibration magnification. For example, it is necessary to form a substantially conical trapezoidal shape having a complicated curved surface such as an exponential horn, and there is a problem that processing is very difficult.

  Further, since a very complicated calculation is required to obtain the resonance frequency from the shape of the horn, the design of the horn shape has been difficult.

  The present inventor uses a simple rod-like body in place of a conventional horn having a complicated curved surface, and has a vibration projection that resonates with the natural frequency of the longitudinal vibration of the rod-like body to generate a lateral vibration. It has been found that an ultrasonic processing vibrator having a simple shape and a large amplitude can be obtained by forming it at the maximum amplitude part and forming an action point at its tip.

  That is, the ultrasonic processing vibrator according to the present invention has a vibrator attached to a part of a rod-like body, and a vibration base in which longitudinal vibration is urged in the length direction of the rod-like body, and a side surface of the vibration base. The vibration base is formed and resonates with the longitudinal vibration of the vibration base to generate bending vibration resonance, and has a vibration protrusion whose tip serves as an action point.

  Moreover, it is desirable that the rod-shaped bodies have substantially the same cross-sectional shape, and it is desirable that the vibration protrusion is formed at the maximum amplitude portion of the vibration base. It is desirable to have a working head at the tip of the vibration projection. Furthermore, it is desirable that the ultrasonic processing vibrator of the present invention is used for polishing.

  The processing apparatus of the present invention includes the above-described ultrasonic processing vibrator and an oscillator connected to the ultrasonic processing vibrator.

  According to the present invention, it is possible to easily manufacture an ultrasonic processing vibrator having an extremely simple shape and an amplitude amplification performance equivalent to that of a conventional one. In addition, since the ultrasonic processing vibrator of the present invention can be designed relatively easily, it is possible to freely select the frequency of the ultrasonic signal and the resonance frequency at the point of action of the vibrator. is there.

  An example of the ultrasonic processing vibrator of the present invention (hereinafter sometimes referred to as an ultrasonic vibrator) is shown in FIG. FIG. 1 shows a processing apparatus in which an oscillator 6 is connected to an ultrasonic transducer 1. According to FIG. 1, the ultrasonic transducer 1 includes a vibration base 4 including a rod-shaped body 2 and a transducer 3 attached to a part thereof.

  The rod-shaped body 2 is made of metal such as iron, iron-nickel-chromium stainless steel, and nickel-chromium, and the shape thereof is substantially the same in terms of suppression of unnecessary vibration and ease of design. A rod-like body is desirable, and the cross-sectional shape may be circular or polygonal.

  The vibrator 3 can be made of an electrostrictive piezoelectric material such as barium titanate or lead zirconate titanate, or a magnetostrictive magnetic material such as nickel or ferrite, but can be reduced in size and high. A piezoelectric body is most desirable in that the frequency is available.

  In addition, the vibrator 3 is formed on a part of the rod-like body 2 and, specifically, can be attached to the end face of the rod-like body or the side surface of the rod-like body, but the vibrator 3 between the drive surfaces. In order to match the mechanical impedance, the vibrator 3 is attached to the end face of the rod-like body 2, and the vibrator 3 is sandwiched between the rod-like body 2 and the rod-like body 2 'that is the same member as the rod-like body 2. It is desirable to be. Further, in order to obtain a larger displacement, a plurality of vibrators 3 may be formed to overlap each other.

  According to FIG. 1, the vibrator 3 is held by a terminal plate 5, and the terminal plate 5 is connected to an oscillator 6. Then, by applying an ultrasonic signal having a frequency at which the vibrator 3 generates longitudinal vibration to the oscillator 6, the ultrasonic signal is transmitted to the vibrator 3 through the terminal plate 5, and longitudinal vibration occurs in the vibrator 3. The vibration base 4 causes longitudinal vibration.

  According to the present invention, it is important that the vibration protrusion 7 having a specific shape that resonates with the longitudinal vibration of the vibration base 4 is formed on a part of the side surface of the rod-shaped body 2 of the vibration base 4.

The protrusion shape for causing the protrusion provided on the vibration base having the vibrator having the frequency f to resonate is generally a number 1 indicating the relationship between the cantilever rod-like body having substantially the same cross-sectional shape and the frequency f. And can be calculated by Equation 2.

Here, f is the resonance frequency of the vibration protrusion 7, λ is the frequency coefficient (eg, 4.694), z ₄ is the height of the vibration protrusion, E is the Young's modulus of the vibration protrusion, and I is the secondary moment of inertia of the vibration protrusion. , Ρ is the mass density of the vibration protrusion, x ₄ is the length of the vibration protrusion, and y is the width of the vibration protrusion.

According to the present invention, the height z ₄ , the length x ₄ , and the width y of the vibration protrusion 7 are determined so that the resonance frequency of the vibration protrusion 7 expressed by the above formulas 1 and 2 matches the frequency of the vibrator. As a result, the vibration protrusion 7 can resonate with the longitudinal vibration excited by the vibration base 4, and as a result, bending vibration resonance having a large displacement amount can be generated at the tip of the vibration protrusion 7.

  Since the resonance frequency f of the vibration protrusion 7 depends only on the material and shape of the vibration protrusion 7, only the shape of the vibration protrusion 7 satisfies the above conditions in order to obtain the resonance frequency f. Just design.

  Further, by setting the position of the vibration protrusion 7 to a position where the amplitude of the longitudinal vibration in the vibration base 4 is maximized, it is possible to generate a lateral vibration having the largest displacement at the tip of the vibration protrusion 7.

  The vibration protrusion 7 is made of metal such as iron, iron-nickel-chromium stainless steel, nickel-chrome steel, or ceramics such as alumina or zirconia, and it is desirable to use a material having characteristics suitable for the operating frequency and application. The shape of the vibration projection 7 is preferably a rod-like body having substantially the same cross-sectional shape, and the cross-sectional shape is not particularly limited. The shape of the rod-like body may be a cylinder, a polygonal column, or a cylinder. Good.

  Furthermore, in order to increase the symmetry of the vibration mode, the same shape is provided at the position where the vibration protrusion 7 is line-symmetric with respect to the rod-like body 2, that is, the side surface opposite to the side surface where the vibration protrusion 7 of the rod-like body 2 is formed. It is desirable to form the vibration protrusion 7 ′.

  As described above, a large amount of lateral vibration is generated at the tip of the vibration protrusion 7 due to the vibration of the vibration base 4 and the vibration protrusion 7, and the working head 8 is formed at the tip of the vibration protrusion 7 using this lateral vibration. To do. The working head 8 generates frictional heat by transverse vibration and is used, for example, as a bonding head in so-called wire bonding for welding a metal such as a gold wire and a semiconductor chip, or in ultrasonic processing for polishing a minute region. It can be used as a polishing head. The working head 8 at the tip of the vibration projection 7 can be processed into a shape that allows easy use of the tip shape according to the application, but a working head 8 made of a different material can be attached to the tip of the vibration projection 7.

  The material of the working head 8 varies depending on the method of use. For example, when the working head 8 is used as the bonding head, the working head 8 is formed of a material having good heat conduction, heat resistance, and no reaction with the substance to be welded. When used as a head, it is desirable to form the head with a material excellent in mechanical properties such as wear resistance and strength.

  Moreover, according to FIG. 1, it is also possible to attach the fixture 9 to the position where the amplitude of the longitudinal vibration of the vibration base 4 becomes zero.

  In FIG. 1, the vibration base 4 and the vibration protrusion 7 are formed as separate bodies, and the ultrasonic vibrator 1 is formed by bonding them together. However, according to the present invention, the invention is limited to this. Instead, the vibration base 4 and the vibration projections 7 may be formed as a single body by grinding or the like.

As shown in FIG. 2, length (x ₁ ) 43 mm × width (y) 3 mm × height (z ₁ ) 3 mm of iron (mass 8 × 10 ⁻¹⁰ kgf · s ² / mm ⁴ , Young's modulus 21000 kgf / mm ² and a terminal plate of a piezoelectric body made of PZT of length (x ₂ ) 2 mm × width (y) 3 mm × height (z ₁ ) 3 mm on _one end face of the rod-like body 2 made of Poisson's ratio 0.29). Further, a rod-shaped body 2 ′ of length (x ₃ ) 5 mm × width (y) 3 mm × height (z ₁ ) 3 mm made of the same material as the rod-shaped body 2 was pasted via a terminal board. . Further, the length (x ₄ ) 2 mm × width (y) 3 mm × height (z ₄ ) 11 mm made of the same material as the rod-like body 2 at a position of 16 mm in the length direction from the piezoelectric body attaching surface of the rod-like body 2. The ultrasonic vibrator of FIG. 3 with the vibration protrusions attached was prepared.

  With respect to the obtained ultrasonic vibrator, an ultrasonic signal of 73 kHz was applied to the piezoelectric body via the terminal plate, and the ultrasonic vibrator generated longitudinal vibration with a maximum amplitude of 10 μm. It was 8.5 times.

It is a perspective view which shows the processing apparatus of this invention. It is a figure for demonstrating the shape of the ultrasonic transducer | vibrator of this invention. It is a side view which shows an example of the conventional ultrasonic transducer | vibrator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic vibrator 2, 2 'Rod-like body 3 Vibrator 4 Vibrating base body 5 Terminal board 6 Oscillator 7, 7' Vibrating protrusion 8 Action head 9 Fixing tool

Claims (6)

A vibrator is attached to a part of the rod-shaped body, and a vibration base that is urged by longitudinal vibration in the length direction of the rod-shaped body is formed on a side surface of the vibration base and resonates with the longitudinal vibration of the vibration base. An ultrasonic processing vibrator having a vibration projection in which bending vibration resonance occurs and a tip thereof serves as an action point. The ultrasonic processing vibrator according to claim 1, wherein the rod-shaped bodies have substantially the same cross-sectional shape. 3. The ultrasonic processing vibrator according to claim 1, wherein the vibration protrusion is formed on a maximum amplitude portion of the vibration base. 4. The ultrasonic processing vibrator according to claim 1, further comprising an action head at a tip of the vibration protrusion. The ultrasonic processing vibrator according to claim 1, wherein the ultrasonic processing vibrator is used for polishing. A processing apparatus comprising: the ultrasonic processing vibrator according to claim 1; and an oscillator connected to the ultrasonic processing vibrator.

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