JPH0478471A - Ultrasonic oscillator and production thereof - Google Patents

Abstract

PURPOSE:To exhibit the performance equal to the performance of a radiation plate made of a metal even if a nonconductive material, such as quartz, is used as a radiation plate by adhering a piezoelectric oscillator via a conductive metallic film on the rear surface of the radiation plate made of the nonconductor and mounting a cathode to the desired point of the conductive metallic film. CONSTITUTION:The surface of the radiation plate 1 to be formed with this conductive metallic film 8 is subjected to surface roughening equiv. to #600 in order to improve the strength of adhesion of the conductive metallic film 8. The conductive metallic film 8 is formed by depositing nichrome as a substrate by evaporation at about 500Angstrom , then applying gold plating thereon and growing this gold plating layer to about 1mum thickness. The conductive metallic film has the sufficient adhesive strength by the roughening of the surface of the radiation plate 1 and the adequate washing treatment before vapor deposition. The piezoelectric oscillator 3 is adhered by an epoxy adhesive onto this conductive metallic film 8. An epoxy adhesive is used as the adhesive 4 and is cured under heating by applying 1kg load to the piezoelectric oscillator 3 in order to assure an electrical conductivity. Further, a cathode 5 is formed onto the conductive metallic film 8 near the piezoelectric oscillator 3 and an anode 6 on the piezoelectric oscillator 3 by soldering or a conductive adhesive. The resonance frequency over the entire part of the oscillation system is approximated to the resonance frequency of the piezoelectric oscillator 3 in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of M Tojo) The present invention relates to an ultrasonic vibrator used in an ultrasonic cleaning device, etc., and a method for manufacturing the same.

(Prior art) Ultrasonic vibrators used in ultrasonic cleaning equipment, etc. require a radiation plate that radiates ultrasonic vibrations into the air or into liquid, and the method of attaching the piezoelectric vibrator to the radiation plate is by bolts. There are fixed types and adhesive types.

Figure 1 shows an example of a bolt-fastened type ultrasonic vibrator. In the figure, 1 is a radiating plate, 2 is a bolt installed in this radiating plate 1, and 3 is fixed to a radiating plate I by this bolt 2. It is a piezoelectric vibrator.

In addition, Figure 1g2 is an example of an adhesive type ultrasonic vibrator, in which a piezoelectric vibrator 3 is bonded to a conductive radiation plate l via an adhesive 4, and a cathode 5 is attached to the radiation plate 1. ,
Each piezoelectric vibrator 3 is provided with an anode 6.

Note that this adhesive type is the mainstream for vibrators with a natural frequency of 100 KHz or more.

-Metal materials such as stainless steel have traditionally been widely used as materials for power and radiation plates, but in recent years, in addition to metal materials, PV
C (vinyl chloride), quartz, etc. are used depending on the type of liquid used for cleaning, and quartz is often used as a radiation plate used in semiconductor manufacturing from the standpoint of dustproofness and corrosion resistance.

However, when this quartz is used as a radiation plate, the electrodes of the piezoelectric vibrator cannot be removed from the radiation plate because quartz has no conductivity, and as shown in Figure 3, the piezoelectric vibrator is connected to the radiation plate. Insert gold ribbon 7 in between.

This gold ribbon 7 was used as an electrode (cathode), or a piezoelectric vibrator having a wrap-around electrode structure was used as shown in FIG.

(Problems to be solved) However, the vibrators used in recent years have become increasingly high-frequency, and at 6.8 MHz, the plate thickness is 200 m.
Since the thickness of the gold ribbon 7 used is about 20 gm,
When a radiant plate is made using these materials, the thickness of the bonded area acts as a load, which inevitably leads to a decrease in the performance of the radiant plate.

In addition, since no adhesive is present at the joint between the gold ribbon 7 and the vibrator 3, the adhesive force is weak and there is a drawback that peeling may occur during long-term operation. On the other hand, in the case of the piezoelectric vibrator 3 with the wrap-around electrode structure shown in FIG. 4, a part of the cathode 5 exists on the same surface as the anode 6, so the area of the anode 6 cannot be secured sufficiently, resulting in a decrease in efficiency. There were some drawbacks that led to this. The purpose of this invention is to solve the above-mentioned conventional problems regarding non-conductive ultrasonic vibrators such as quartz having a radiating plate. It is an object of the present invention to provide an ultrasonic vibrating body that can exhibit performance equivalent to that of a metal radiation plate, has sufficient strength, and has excellent durability, and a method for manufacturing the same.

(Means for Solving the Problems) This invention forms a conductive metal film on the back surface of a radiation plate made of a nonconductor, adheres a piezoelectric vibrator to the conductive metal film, and adheres a piezoelectric vibrator to the conductive metal film. The above problem is attempted to be solved by configuring an ultrasonic vibrator by providing a cathode.

(Function) When a voltage with the same frequency as the resonant frequency of the piezoelectric vibrator 3 is applied from the cathode on the conductive metal film and the anode on the piezoelectric vibrator 3, the piezoelectric vibrator starts to vibrate, and the vibration is caused by the conductivity. The waves are transmitted to a radiation plate via a metal film, and are emitted from the radiation plate as ultrasonic waves into the air or into a liquid, and are used for purposes such as ultrasonic cleaning.

At this time, since the conductive metal film is significantly thinner than the conventional gold ribbon, there is no deterioration in the performance of the radiation plate, and ultrasonic waves can be radiated with high efficiency.

In addition, there is no risk of peeling of the piezoelectric vibrator due to long-term operation, and it has excellent durability and sensitivity.

(Embodiment) FIG. 5 is a sectional view of an embodiment of an ultrasonic vibrator according to the present invention.

In the figure, reference numeral 1 denotes a non-conductive radiation plate made of quartz or the like, and a conductive metal film 8 is formed on the surface of this radiation plate l.

The surface of the radiation plate 1 on which this conductive metal film 8 is formed is made of #600 to improve the adhesive strength of this conductive metal film 8.
The surface has been subjected to considerable roughening, and its thickness T is determined from the resonance frequency F of the piezoelectric vibrator 3 to be bonded and the sound velocity C of the radiant plate 1 according to the following formula.

T=N−C/2·F (N is an integer) By the way, when a PZT piezoelectric vibrator with a resonant frequency of 850 KHz is used, the thickness of the radiant plate 1 is about 3.5 mm or an integer multiple thereof.

The conductive metal Wi8 is made by depositing about 500 nichrome as a base, then applying gold plating on top of it, and growing the gold plating layer to a thickness of about lpm. Sufficient adhesion strength is maintained through surface roughening and appropriate cleaning treatment before vapor deposition.

The most effective cleaning method is a combination of ultrasonic cleaning and plasma dry cleaning.

The piezoelectric vibrator 3 is bonded onto the conductive metal film 8 using an adhesive 4.

In this embodiment, an epoxy adhesive is used as the adhesive 4, and in order to ensure conductivity, a load of I kg is applied to the piezoelectric vibrator 3 and the adhesive is heated and cured. Further, a cathode 5 is formed on the conductive gold 1uiB near the piezoelectric vibrator 3, and an anode 6 is formed on the piezoelectric vibrator 3 by soldering or conductive adhesive. Note that in normal cases, a plurality of piezoelectric vibrators 3 may be attached to one radiation plate 1, or the cathode 5 may be provided at only one location if the current value is within the allowable value.

and cathode 5. When a voltage with the same frequency as the resonant frequency of the piezoelectric vibrator 3 is applied between the anodes 6, the piezoelectric vibrator 3 starts to vibrate, and the vibration is transmitted to the radiation plate 1 through the conductive metal film 8.
and is emitted from the radiation plate 1 into the air or liquid as an ultrasonic wave.

(Effects of the Invention) The ultrasonic vibrating body according to the present invention has the above-mentioned configuration, and the total thickness of the conductive metal film 8 and adhesive 4 is about 1/20th that of the conventional one. Since the resonant frequency of the entire vibration system can be brought close to the resonant frequency of the piezoelectric vibrator 3, efficient ultrasonic radiation can be achieved.

In addition, the area of the cathode 5 can be increased, thereby improving the electrical characteristics, and the conductive metal film 8 can be used to cool the heat generated from the piezoelectric vibrator 3. Because it only needs to be provided at one location, the wiring can be simplified and this has an extremely excellent practical effect.

[Brief explanation of the drawing]

1. Radiant plate 2. Bolt 3, piezoelectric vibrator 4. Adhesive 5, #pole 6. Anode patent applicant Shimada Rika Kogyo Co., Ltd. Agent Shigebe Tsugamura and 1 other person Figure 1 Figure 3 Figure 5

Claims (4)

[Claims] (1) A piezoelectric vibrator is bonded to the back surface of a nonconductive radiation plate via a conductive metal film, and a cathode is attached to a desired location on the conductive metal film. Ultrasonic vibrator. (2) The ultrasonic vibrator according to claim 1, wherein the conductive metal film is made of gold. (3) Claim 1 characterized in that the radiation plate is made of quartz.
Ultrasonic vibrator described. (4) After forming a conductive metal film on the back surface of a non-conductive radiation plate, a piezoelectric vibrator is adhered to this conductive metal film, and a cathode is attached to the conductive metal film. A method for manufacturing an ultrasonic vibrator.