JP2002027599A - Method for manufacturing ultrasonic probe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an ultrasonic probe capable of surely grinding a piezoelectric vibrator until the piezoelectric vibrator is allowed to have thickness corresponding to target resonance frequencies even if the frequencies are 50 MHz or more. SOLUTION: In this method for manufacturing an ultrasonic probe in which an electric signal is converted into ultrasonic waves by a piezoelectric vibrator 11, and the ultrasonic waves are converged by an acoustic lens 12, and allowed to outgo toward a sample, and the ultrasonic waves returning from the sample are extracted through the acoustic lens and the piezoelectric vibrator as the electric signal, the metallic bonding of the piezoelectric vibrator having thickness corresponding to resonance frequencies lower than target resonance frequencies to an acoustic lens made of highly rigid materials is carried out, and the piezoelectric vibrator is ground in a state such that the acoustic lens side is supported so that the piezoelectric vibrator can be formed in thickness corresponding to the target resonance frequencies. In this case, it is desired that the target resonance frequencies are 50 MHz or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an ultrasonic probe, and more particularly to a method of manufacturing a piezoelectric vibrator by improving a grinding process so as to obtain a resonance film thickness corresponding to a target high frequency (50 MHz or more). The present invention relates to a method for manufacturing an ultrasonic probe that can be accurately ground.

[0002]

2. Description of the Related Art As a prior art, Japanese Patent Laid-Open No. 5-17639 is known.
No. 6 discloses a method of manufacturing an ultrasonic probe. According to this manufacturing method, for example, in a step of attaching a piezoelectric vibrator made of a lead zirconate titanate-based ceramic material to a damper, a thick piezoelectric vibrator having a resonance frequency lower than a target resonance frequency is bonded to the damper. A method has been proposed in which a piezoelectric vibrator is attached by using an agent, and thereafter, the piezoelectric vibrator is ground to a thickness that exhibits a target resonance frequency, and electrodes are provided on the processed surface.

When a lead zirconate titanate-based ceramic is used for a piezoelectric vibrator, the frequency constant (the product of the resonance frequency and the thickness) is 2000 MHz · μm, so that the resonance film thickness is, for example, 40 μm at 50 MHz. 30 μm at 75 MHz and 20 μm at 100 MHz. When the target resonance frequency is high when a piezoelectric vibrator is made by itself, an extremely thin film thickness piezoelectric vibrator must be made by itself, and the piezoelectric vibrator becomes very brittle. Is difficult to handle when assembling, and the product yield deteriorates. Therefore, as described above,
No. 96, a method of manufacturing an ultrasonic probe is proposed. According to this manufacturing method, an ultrasonic probe including a very thin piezoelectric vibrator corresponding to a high resonance frequency can be manufactured, and a conventional process in which a thin and brittle piezoelectric vibrator must be attached to a damper. Can be eliminated. Note that the above damper is a back plate member for supporting the thin piezoelectric vibrator from the viewpoint of strength, and furthermore, the ultrasonic vibrator transmits ultrasonic waves or receives ultrasonic waves emitted to the back side when receiving echoes thereof. Has the effect of partially absorbing.

[0004]

In the above-described conventional method for manufacturing an ultrasonic probe, a relatively thick piezoelectric vibrator is previously attached to a damper, and the piezoelectric vibrator is directed outward while supporting the damper by a table. The processed surface of the piezoelectric vibrator is ground with a grindstone. That is, the surface of the piezoelectric vibrator fixed on the damper supported by the table is ground. On the other hand, in recent years, the resonance frequency of a piezoelectric vibrator has become higher, and a piezoelectric vibrator having a resonance frequency of 50 MHz or more, for example, 100 MHz or more has been required. The resonance frequency of the piezoelectric vibrator is 50
When the piezoelectric vibrator is ground so as to be higher than MHz, the thickness of the piezoelectric vibrator becomes 40 μm or less as described above. When examining a conventional ultrasonic probe manufacturing method from such a viewpoint, according to the gazette, it is described that it can be ground to a thickness of several tens of μm, but in fact, the damper itself is made of epoxy. Since it is made of resin and metal powder and has elasticity, it is difficult to uniformly grind it to a high-frequency resonance film thickness of 50 MHz or more.

[0005] As for the material of the acoustic lens of the ultrasonic probe, when the resonance frequency is less than 50 MHz, a resin acoustic lens is often used.
When the frequency is 0 MHz or more, quartz glass, sapphire, or the like, which has less attenuation than resin, is exclusively used. In the case of an ultrasonic probe manufactured using an acoustic lens made of a material having high rigidity, it is desirable to assemble the manufacturing process using the characteristics of the acoustic lens.

SUMMARY OF THE INVENTION In view of the above problems and demands, an object of the present invention is to provide an ultrasonic wave grinding apparatus capable of accurately grinding a piezoelectric vibrator up to a thickness corresponding to the target resonance frequency even if the target resonance frequency is 50 MHz or higher. An object of the present invention is to provide a method for manufacturing a probe.

[0007]

A method for manufacturing an ultrasonic probe according to the present invention has the following configuration to achieve the above object.

A method for manufacturing an ultrasonic probe according to the present invention (corresponding to claim 1): In this manufacturing method, an electric signal is converted into an ultrasonic wave by a piezoelectric vibrator, and the ultrasonic wave is converged by an acoustic lens. This is a method for manufacturing an ultrasonic probe that emits toward a sample and takes out the ultrasonic wave returned from the sample as an electric signal via an acoustic lens and a piezoelectric vibrator. The characteristic configuration is
Joining a piezoelectric vibrator having a thickness having a resonance frequency lower than the target resonance frequency to an acoustic lens made of a highly rigid material, and holding the piezoelectric vibrator while supporting the acoustic lens side Grinding and forming the piezoelectric vibrator to have a thickness corresponding to a target resonance frequency. Here, the target resonance frequency is preferably 50 MHz or more, and more preferably 100 MHz or more. Further, when grinding the piezoelectric vibrator with a grindstone or the like, the acoustic lens needs to have sufficient rigidity so that deformation is not caused by the pressing pressure or grinding pressure of the grindstone. After that, at least
Steps such as providing electrodes on the grinding surface of the piezoelectric vibrator are provided.

In the method of manufacturing an ultrasonic probe including the characteristic steps described above, a thick piezoelectric vibrator is bonded to a rigid acoustic lens in advance, and is fixed on the acoustic lens while supporting the acoustic lens. Since the piezoelectric vibrator is ground, even a very thin piezoelectric vibrator having a characteristic of a high resonance frequency of 100 MHz or more can be manufactured with high precision by grinding.

In the above method for manufacturing an ultrasonic probe,
Preferably, the material of the acoustic lens is quartz glass or sapphire (corresponding to claim 2).

In the above method for manufacturing an ultrasonic probe,
More preferably, the acoustic lens is provided with an electrode, coated with a film-like metal such as an electrode, and then the piezoelectric vibrator is bonded to the acoustic lens via the metal film provided on the piezoelectric vibrator. (Corresponding to claim 3).

[0012]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

A typical embodiment of a method for manufacturing an ultrasonic probe according to the present invention will be described with reference to FIGS. Figure 1
Is a longitudinal sectional view showing the structure of an ultrasonic probe manufactured by the manufacturing method according to the present invention, FIG. 2 is a process diagram of the manufacturing method of the ultrasonic probe according to the present invention, and FIG. FIG. 4 is a side view showing a grinding step, and FIG. 4 is a plan view of the grinding step shown in FIG.

Referring to FIG. 1, the structure of an ultrasonic probe according to the present invention will be described. 11 is a piezoelectric vibrator, 12 is an acoustic lens, 13 is a damper, and 14 is a case. Piezoelectric vibrator 1
1 is made of, for example, a lead zirconate titanate-based ceramic, has a thin plate shape, and has a function of performing mutual conversion between electric signals and ultrasonic waves. That is, the piezoelectric vibrator 11
When an electric signal is input, the signal is converted into an ultrasonic wave and output. When the ultrasonic wave is input, the signal is converted into an electric signal and output. The acoustic lens 12 is coupled to the piezoelectric vibrator 11 by metal bonding,
For example, it has an action of causing the ultrasonic wave output from the piezoelectric vibrator 11 to propagate while converging. In this embodiment,
The acoustic lens 12 is made of a highly rigid material such as quartz glass or sapphire. On the lower surface of the acoustic lens 12, an ultrasonic radiation / incident surface 12a is formed. The damper 13 is provided at a position on the piezoelectric vibrator 11 opposite to the side where the acoustic lens 12 is provided. The damper 13 is made of a resin 13a and a metal powder 13b, and is provided inside a cylindrical pipe 15, for example. The pipe 15 is provided upright at a position above the piezoelectric vibrator 11. The case 14 is a container having a cylindrical shape, the ceiling is closed, and the lower part is the acoustic lens 12.
It is closed by providing. Inside the case 14, the above-described piezoelectric vibrator 11, acoustic lens 12, damper 1
3, a pipe 15 and the like are accommodated.

More specifically, between the piezoelectric vibrator 11 and the acoustic lens 12, an electrode 21, a metal film 22, and an electrode 2 are provided.
3 are provided in a stacked state. The electrode 21 is attached to the entire lower surface of the piezoelectric vibrator 11, and the electrode 23 is attached to the entire upper surface of the acoustic lens 12. The electrode is made of Cr / Au, for example. The thickness of the electrode or metal film portion is preferably set to 5 μm or less. The pipe 15 includes an electrode 23 provided on the upper surface of the acoustic lens 12.
Standing on top of Also, the piezoelectric vibrator 11 and the damper 1
Electrodes 24 are provided between the three. In the above structure, the signal line (cable) 25 is drawn from the upper electrode 24 of the piezoelectric vibrator 11, and the electrode 23 of the acoustic lens 12 is
A signal line (cable) 26 is drawn out from the terminal. Signal line 2
Reference numerals 5 and 26 denote connectors 2 provided outside the case 14.
7 are connected to the internal terminals 27a and 27b, respectively. With this wiring structure, a necessary electric signal is given to the piezoelectric vibrator 11, and an electric signal corresponding to a reflection echo obtained by the acoustic lens 12 and the piezoelectric vibrator 11 with respect to the ultrasonic wave returned from the sample is externally transmitted. To be taken out.

According to the structure of the ultrasonic probe described above, the piezoelectric vibrator 11 is formed to have an extremely thin film thickness so as to have an extremely high resonance frequency of, for example, 100 MHz or more. In addition, no special adhesive is used in principle when assembling the piezoelectric vibrator 11, the acoustic lens 12, and the damper 13. Therefore, an ultrasonic probe using a high resonance frequency of 50 MHz or more, preferably 100 MHz or more has been realized.

Next, a method of manufacturing the ultrasonic probe having the above structure will be described with reference to FIGS. FIG. 2 shows six states A to F, and steps A to O that change from one state to another. State A is a state in which the piezoelectric vibrator 11 and the acoustic lens 1
2 shows a state before joining. The piezoelectric vibrator 11 has, for example, a disk shape, and has a thickness corresponding to a resonance frequency lower than a target resonance frequency. An electrode 21 is attached to the lower surface of the piezoelectric vibrator 11. Further, a metal film 22 is coated on the lower surface of the electrode 21 on the lower surface side of the piezoelectric vibrator 11 by, for example, sputtering. An electrode 23 is attached to the upper surface of the substantially cylindrical acoustic lens 12 so as to cover the entire surface. In the step (a), the piezoelectric vibrator 11 and the acoustic lens 12 having the above structure are brought into contact with each other by bringing the metal film 22 and the electrode 23 into contact with each other and joining them by metal bonding. In this metal bonding, the piezoelectric vibrator 11 and the acoustic lens 12 are placed in a vacuum chamber and heated to perform bonding. The resulting state is shown in FIG. In state B, the acoustic lens 12 and the piezoelectric vibrator 11
Are integrated. Further, in the state B, the acoustic lens 1
In a state where the piezoelectric vibrator 11 is joined to the piezoelectric vibrator 11,
Of the piezoelectric vibrator 11 is ground (film thickness).
Is processed to have an extremely small thickness corresponding to a target (frequency to be used) resonance frequency. In the state B, the broken line 31 is a line representing the final ground surface that is the target of the grinding process in the piezoelectric vibrator 11. Piezoelectric vibrator 1
In the grinding of No. 1, a grinding wheel (not shown in FIG. 2) is provided on the upper surface of the piezoelectric vibrator 11 while the acoustic lens 12 is supported.
(Step a). The result is shown in state C of FIG.

Here, the contents of the step A of the grinding operation from the state B to the state C in FIG. 2 will be described with reference to FIG. 3 and FIG.
In FIGS. 3 and 4, the acoustic lens 12 and the piezoelectric vibrator 11 shown in the state B of FIG. 2 are integrated (a lens unit) in a state where the acoustic lens 12 is held by a jig 32. In addition, the piezoelectric vibrator 11 is attached to the jig 32 in a downward facing posture. The jig 32 has a belt 35 stretched between a pulley 34 attached to a rotating shaft 33 a of a motor 33, and a rotating force of the motor 33 causes a rotating force to be transmitted by the pulley 34 and the belt 35 to rotate the jig 32. Is done. With the rotation of the jig 32, the acoustic lens 1
2 and the piezoelectric vibrator 11 also rotate. On the other hand, a disc-shaped grindstone plate 37 rotated by a motor 36 is disposed below the piezoelectric vibrator 11. The grindstone plate 37 is
6 is fixed to a high-strength support plate 38 fixed to the rotating shaft 36a. The upper surface (the lower surface in FIG. 3) of the piezoelectric vibrator 11 is pressed against the surface of the grindstone plate 37. Based on this configuration, the piezoelectric vibrator 12 and the grindstone plate 3
7 are rotated in predetermined directions, and the upper surface of the piezoelectric vibrator 11 is ground until the grinding surface indicated by the broken line 31 is reached. In this grinding step, the piezoelectric vibrator 11 is supported while supporting the acoustic lens 12 having high rigidity such as quartz glass.
Is pressed against the grindstone plate 37 to grind the piezoelectric vibrator 11, so that unlike the conventional configuration supported by the resin damper, the thickness of the piezoelectric vibrator 11 is reduced to the target resonance frequency (100 MHz or more). ) Can be accurately ground to a thickness corresponding to (1). Although FIGS. 3 and 4 conceptually show the structure of a device capable of performing a grinding operation, illustration of a support structure and the like as a specific device is omitted.

Next, in the state C in which the grinding step A is completed, the electrode 24 is mounted on the upper surface of the piezoelectric vibrator 11, and signal lines 25 and 26 for extracting signals are connected to the electrode 23 and the electrode 24. (Step c), whereby the structure in the state D is formed. In the next step d, the damper 13
Is provided above the electrode 23 and above the piezoelectric vibrator 11 using, for example, a cylindrical pipe 15. Damper 1
3 is provided directly on the electrode 23 of the acoustic lens 12, and no adhesive layer is formed. Therefore, there is no variation in the performance due to the variation in the thickness of the adhesive layer. In step d, specifically, the damper fixes the pipe 15 on the electrode 23 on the upper surface of the acoustic lens 12, and injects the epoxy resin 13a and the metal powder 13b into the pipe 15,
Thereafter, the metal powder is densely formed on the side of the piezoelectric vibrator 11 and solidified by a separating action using a centrifuge to form the metal powder. The damper 13 is formed in close contact with the upper electrode 24 of the piezoelectric vibrator 11. Since the damper 13 uses an epoxy-based resin 13a, this substantially acts as an adhesive. As a result, the unit shown in the state E is formed.

In the last step (e), the unit including the acoustic lens 12, the piezoelectric vibrator 11, and the damper 13 is housed in the case 14 having the connector 27, and the lead wires 25, 26 are connected to the connector 27. You. The finally completed ultrasonic probe is shown in a state F.

[0021]

As is apparent from the above description, according to the present invention, a piezoelectric vibrator is mounted on an acoustic lens having high rigidity such as quartz glass, and the surface of the piezoelectric vibrator is ground while supporting the acoustic lens. Therefore, an extremely thin piezoelectric vibrator corresponding to a target high resonance frequency (50 MHz or more, preferably 100 MHz or more) can be manufactured with high accuracy. According to this manufacturing method, a high-quality ultrasonic probe corresponding to a high resonance frequency can be manufactured with high yield. Furthermore, since a configuration that does not use an adhesive is employed, it is possible to easily cope with a higher resonance frequency.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a structure of an ultrasonic probe manufactured by a method of manufacturing an ultrasonic probe according to the present invention.

FIG. 2 is a process chart of a method for manufacturing an ultrasonic probe according to the present invention.

FIG. 3 is a side view showing an apparatus configuration in a step of grinding a piezoelectric vibrator in the manufacturing method according to the present invention.

FIG. 4 is a plan view of an apparatus configuration in a grinding process shown in FIG. 3;

[Explanation of symbols]

 Reference Signs List 11 piezoelectric vibrator 12 acoustic lens 13 damper 14 case 15 pipe 21, 23, 24 electrode 22 metal film 25, 26 signal line 27 connector 32 jig 33, 36 motor 37 grinding wheel plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G047 CA01 GB11 GB25 GB32 GB35 GB37 GB38 5D019 AA08 AA26 AA27 BB02 BB25 GG03 GG09 HH01 HH03

Claims (3)

[Claims] 1. A piezoelectric vibrator converts an electric signal into ultrasonic waves, converges the ultrasonic waves with an acoustic lens, emits the ultrasonic waves toward a sample, and transmits the ultrasonic waves returned from the sample to the acoustic lens and the piezoelectric lens. A method for manufacturing an ultrasonic probe that extracts an electric signal through a vibrator, wherein the piezoelectric lens having a resonance frequency lower than a target resonance frequency is made of a rigid material. Grinding the piezoelectric vibrator while supporting the acoustic lens side, forming the piezoelectric vibrator to have a thickness corresponding to the target resonance frequency, and grinding the piezoelectric vibrator. A method for manufacturing an ultrasonic probe, comprising: providing an electrode on a surface. 2. The method according to claim 1, wherein the material of the acoustic lens is quartz glass or sapphire. 3. The manufacturing of the ultrasonic probe according to claim 1, wherein an electrode is provided on the acoustic lens, and then the piezoelectric vibrator is joined to the acoustic lens via a metal film. Method.